Electrode Potentials of l-Tryptophan, l-Tyrosine, 3-Nitro-l-tyrosine, 2,3-Difluoro-l-tyrosine, and 2,3,5-Trifluoro-l-tyrosine.

PubMed

Mahmoudi, Leila; Kissner, Reinhard; Nauser, Thomas; Koppenol, Willem H

2016-05-24

Electrode potentials for aromatic amino acid radical/amino acid couples were deduced from cyclic voltammograms and pulse radiolysis experiments. The amino acids investigated were l-tryptophan, l-tyrosine, N-acetyl-l-tyrosine methyl ester, N-acetyl-3-nitro-l-tyrosine ethyl ester, N-acetyl-2,3-difluoro-l-tyrosine methyl ester, and N-acetyl-2,3,5-trifluoro-l-tyrosine methyl ester. Conditional potentials were determined at pH 7.4 for all compounds listed; furthermore, Pourbaix diagrams for l-tryptophan, l-tyrosine, and N-acetyl-3-nitro-l-tyrosine ethyl ester were obtained. Electron transfer accompanied by proton transfer is reversible, as confirmed by detailed analysis of the current waves, and because the slopes of the Pourbaix diagrams obey Nernst's law. E°'(Trp(•),H(+)/TrpH) and E°'(TyrO(•),H(+)/TyrOH) at pH 7 are 0.99 ± 0.01 and 0.97 ± 0.01 V, respectively. Pulse radiolysis studies of two dipeptides that contain both amino acids indicate a difference in E°' of approximately 0.06 V. Thus, in small peptides, we recommend values of 1.00 and 0.96 V for E°'(Trp(•),H(+)/TrpH) and E°'(TyrO(•),H(+)/TyrOH), respectively. The electrode potential of N-acetyl-3-nitro-l-tyrosine ethyl ester is higher, while because of mesomeric stabilization of the radical, those of N-acetyl-2,3-difluoro-l-tyrosine methyl ester and N-acetyl-2,3,5-trifluoro-l-tyrosine methyl ester are lower than that of tyrosine. Given that the electrode potentials at pH 7 of E°'(Trp(•),H(+)/TrpH) and E°'(TyrO(•),H(+)/TyrOH) are nearly equal, they would be, in principle, interchangeable. Proton-coupled electron transfer pathways in proteins that use TrpH and TyrOH are thus nearly thermoneutral.

Chronic N(G)-nitro-L-arginine methyl ester-induced hypertension : novel molecular adaptation to systolic load in absence of hypertrophy

NASA Technical Reports Server (NTRS)

Bartunek, J.; Weinberg, E. O.; Tajima, M.; Rohrbach, S.; Katz, S. E.; Douglas, P. S.; Lorell, B. H.; Schneider, M. (Principal Investigator)

2000-01-01

BACKGROUND: Chronic N(G)-nitro-L-arginine methyl ester (L-NAME), which inhibits nitric oxide synthesis, causes hypertension and would therefore be expected to induce robust cardiac hypertrophy. However, L-NAME has negative metabolic effects on protein synthesis that suppress the increase in left ventricular (LV) mass in response to sustained pressure overload. In the present study, we used L-NAME-induced hypertension to test the hypothesis that adaptation to pressure overload occurs even when hypertrophy is suppressed. METHODS AND RESULTS: Male rats received L-NAME (50 mg. kg(-1). d(-1)) or no drug for 6 weeks. Rats with L-NAME-induced hypertension had levels of systolic wall stress similar to those of rats with aortic stenosis (85+/-19 versus 92+/-16 kdyne/cm). Rats with aortic stenosis developed a nearly 2-fold increase in LV mass compared with controls. In contrast, in the L-NAME rats, no increase in LV mass (1. 00+/-0.03 versus 1.04+/-0.04 g) or hypertrophy of isolated myocytes occurred (3586+/-129 versus 3756+/-135 microm(2)) compared with controls. Nevertheless, chronic pressure overload was not accompanied by the development of heart failure. LV systolic performance was maintained by mechanisms of concentric remodeling (decrease of in vivo LV chamber dimension relative to wall thickness) and augmented myocardial calcium-dependent contractile reserve associated with preserved expression of alpha- and beta-myosin heavy chain isoforms and sarcoplasmic reticulum Ca(2+) ATPase (SERCA-2). CONCLUSIONS: When the expected compensatory hypertrophic response is suppressed during L-NAME-induced hypertension, severe chronic pressure overload is associated with a successful adaptation to maintain systolic performance; this adaptation depends on both LV remodeling and enhanced contractility in response to calcium.

Gallic acid attenuates hypertension, cardiac remodeling, and fibrosis in mice with NG-nitro-L-arginine methyl ester-induced hypertension via regulation of histone deacetylase 1 or histone deacetylase 2.

PubMed

Jin, Li; Lin, Ming Quan; Piao, Zhe Hao; Cho, Jae Yeong; Kim, Gwi Ran; Choi, Sin Young; Ryu, Yuhee; Sun, Simei; Kee, Hae Jin; Jeong, Myung Ho

2017-07-01

Gallic acid, a natural chemical found in plants, has been reported to show antioxidant, anticancer, and anti-inflammatory effects. We investigated the efficacy of a short-term or long-term treatment with gallic acid in N-nitro-L-arginine methyl ester (L-NAME)-induced hypertensive mice and the underlying regulatory mechanism. Hypertension was sufficiently induced after 2 weeks of L-NAME administration. Cardiac remodeling was assessed by echocardiography. Hypertrophic markers, transcription factors, and fibrosis-related gene expression were evaluated by quantitative real-time polymerase chain reaction and western blotting. Gallic acid effectively lowered SBP, regardless of the administration route (intraperitoneal or oral). L-NAME increased the left ventricular (LV) thickness without an increase in the total heart weight. Weekly echocardiography demonstrated that gallic acid significantly reduced LV posterior wall and septum thickness in chronic L-NAME mice from 3 to 7 weeks. The administration of gallic acid to mice showed a dual preventive and therapeutic effect on the L-NAME-induced LV remodeling. The effect was associated with the suppression of the gene expression of hypertrophy markers and the GATA-binding factor 6 (GATA6) transcription factor. Short-term or long-term treatment with gallic acid attenuated cardiac fibrosis and reduced the expression of histone deacetylase 1 and 2 in H9c2 cells and in rat primary cardiac fibroblasts, as well as in vivo. Small interfering RNA knockdown confirmed the association of these enzymes with L-NAME-induced cardiac remodeling and fibrosis. These results suggested that gallic acid may be a potential therapeutic agent for the treatment of cardiovascular diseases with hypertension and cardiac fibrosis.

Melatonin prevents fibrosis but not hypertrophy development in the left ventricle of NG-nitro-L-arginine-methyl ester hypertensive rats.

PubMed

Paulis, Ludovit; Pechanova, Olga; Zicha, Josef; Krajcirovicova, Kristina; Barta, Andrej; Pelouch, Vaclav; Adamcova, Michaela; Simko, Fedor

2009-08-01

Melatonin was shown to reduce blood pressure, enhance nitric oxide availability and scavenge free radicals. There is, however, a shortage of data with respect to the effect of melatonin on pathological left ventricular remodelling associated with haemodynamic overload. We investigated whether melatonin was able to prevent left ventricular hypertrophy (LVH) and fibrosis associated with N(G)-nitro-L-arginine-methyl ester (L-NAME)-induced hypertension. Four groups of male Wistar rats were investigated: control, L-NAME (50 mg/kg per day), melatonin (10 mg/kg per day) and L-NAME plus melatonin. Blood pressure was measured non-invasively each week. After 5 weeks of treatment the animals were killed and nitric oxide synthase (NOS) activity, endothelial and inducible NOS expression, the level of collagenous proteins, hydroxyproline and conjugated dienes in the left ventricle were determined. The administration of L-NAME inhibited NOS activity, increased conjugated dienes concentration, elevated blood pressure and induced LVH and fibrosis (indicated by increased collagenous proteins and hydroxyproline levels). The addition of melatonin to L-NAME treatment failed to prevent the attenuation of NOS activity and the development of LVH and prevented hypertension only partly. The administration of melatonin, however, completely prevented the increase in conjugated dienes concentration and the development of left ventricular fibrosis. NOS expression was not different among experimental groups. Melatonin prevented the development of left ventricular fibrosis and the increase in oxidative load in rats with L-NAME-induced hypertension. The antifibrotic effect of melatonin seems to be independent of its effects on NOS activity and might be linked to its antioxidant properties.

Effect of N(G)-nitro-L-arginine methyl ester on intestinal permeability following intestinal ischemia-reperfusion injury in a rat model.

PubMed

Luo, C C; Chen, H M; Chiu, C H; Lin, J N; Chen, J C

2001-07-01

Subclinical intestinal ischemia-reperfusion injury (IRI) causes an increase in mucosal permeability and may represent an early event in the pathogenesis of necrotizing enterocolitis in premature infants. Previous studies suggested that continuous, endogenous formation of nitric oxide (NO) maintains the mucosal integrity of the intestine, thus protecting the gut from injuries from blood-borne toxins and tissue-destructive mediators. This study was undertaken to assess whether the inhibition of NO production causes an increase in intestinal permeability in rats following IRI. Sprague-Dawley rats weighing 200-300 g were divided into 4 groups: (1) untreated group (normal control); (2) ischemia-reperfusion group; (3) early N(G)-nitro-L-arginine methyl ester (L-NAME), a specific inhibitor of NO production, treatment group, and (4) late L-NAME treatment group. Transient IRI was induced by 30-min occlusion, followed by reperfusion of the isolated ileal loop. The L-NAME was administered 15 min before and after mesenteric ischemia as a 25-mg/kg bolus. Fluorescein isothiocyanate-dextran (FITC-D) was used to quantitatively assess the alteration in mucosal permeability of the intestine. There was no significant increase in the portal vein FITC-D level among normal controls, ischemia-reperfusion group and late L-NAME-treated group, but there was an approximately 6-fold increase in the early L-NAME treatment group. The pathological features of the intestine following IRI include denudation of the villus epithelium and reduction of villus height, associated with marked inflammatory cell infiltration over the lamina propria. These results suggest that endogenous NO may play a role in the protecting intestinal integrity after IRI. Copyright 2001 S. Karger AG, Basel

Photodynamic therapy-induced nitric oxide production in neuronal and glial cells

NASA Astrophysics Data System (ADS)

Kovaleva, Vera D.; Uzdensky, Anatoly B.

2016-10-01

Nitric oxide (NO) has been recently demonstrated to enhance apoptosis of glial cells induced by photodynamic therapy (PDT), but to protect glial cells from PDT-induced necrosis in the crayfish stretch receptor, a simple neuroglial preparation that consists of a single mechanosensory neuron enveloped by satellite glial cells. We used the NO-sensitive fluorescent probe 4,5-diaminofluorescein diacetate to study the distribution and dynamics of PDT-induced NO production in the mechanosensory neuron and surrounding glial cells. The NO production in the glial envelope was higher than in the neuronal soma axon and dendrites both in control and in experimental conditions. In dark NO generator, DEA NONOate or NO synthase substrate L-arginine hydrochloride significantly increased the NO level in glial cells, whereas NO scavenger 2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO) or inhibitors of NO synthase L-NG-nitro arginine methyl ester and Nω-nitro-L-arginine decreased it. PDT induced the transient increase in NO production with a maximum at 4 to 7 min after the irradiation start followed by its inhibition at 10 to 40 min. We suggested that PDT stimulated neuronal rather than inducible NO synthase isoform in glial cells, and the produced NO could mediate PDT-induced apoptosis.

Effects of supplemental L-arginine on the intestinal adaptive response after massive small-bowel resection in rats.

PubMed

Oztürk, Hayrettin; Dokucu, Ali Ihsan; Yağmur, Yusuf; Sari, Ibrahim

2002-09-01

To evaluate whether L-arginine methyl ester (L-Arg) can improve the structure of the small intestine and enhance adaptation in an experimental model of short-bowel syndrome (SBS), 40 Sprague-Dawley rats were divided randomly into four groups of 10 each. In one group only a laparotomy was performed (G1). The remaining 30 rats underwent 90% small-bowel resection (SBR) and formed the three experimental groups: the SBR/untreated group (G2), the SBR/L-NAME-treated group (G3), and the SBR/ L-Arg-treated group (G4). Rats in G2 received no therapeutic treatment. Rats in the SBR/L-NAME and SBR/L-Arg treated groups received N-G-nitro-L-arginine-methyl ester (L-NAME) and L-Arg intraperitoneally for 3 weeks, respectively. The animals were weighed daily. All rats underwent a relaparotomy on day 21 of the experiment. Remnant small bowel was excised and evaluated for villus height and crypt cell mitoses. After the 90% SBR, all animals had from diarrhea and weight loss between the 1st and 6th postoperative days (POD). The body weight of the SBR/L-Arg group showed significant increases at POD 10 and 21 in comparison to the SBR/untreated and SBR/L-NAME groups (P < 0.001). The rats treated with L-Arg had significantly greater villus height and crypt-cell mitoses compared to the other groups (P < 0.0001, P < 0.001). These observations suggest that L-Arg treatment increases villus height and crypt-cell mitoses after massive SBR and may play a considerable role in the mucosal adaptive response in SBS in rats.

Arginine affects appetite via nitric oxide in ducks.

PubMed

Wang, C; Hou, S S; Huang, W; Xu, T S; Rong, G H; Xie, M

2014-08-01

The objective of the study was to investigate the mechanism by which arginine regulates feed intake in Pekin ducks. In experiment 1, one hundred forty-four 1-d-old male Pekin ducks were randomly allotted to 3 dietary treatments with 6 replicate pens of 8 birds per pen. Birds in each group were fed a corn-corn gluten meal diet containing 0.65, 0.95, and 1.45% arginine. Ducks fed the diet containing 0.65% arginine had lower feed intake and plasma nitric oxide level (P < 0.05) than the other 2 groups. In experiment 2, twenty 11-d-old ducks were allotted to 1 of 2 treatments. After 2 h fasting, birds in the 2 groups were intraperitoneally administrated saline and l-NG-nitro-arginine methyl ester HCl (L-NAME) for 3 d, respectively. Feed intake (P < 0.07) and plasma nitric oxide concentration (P < 0.05) 2 h postinjection in the L-NAME administered group were lower than those of the control group. In conclusion, the study implied that arginine modifies feeding behavior possibly through controlling endogenous synthesis of nitric oxide in Pekin ducks. © Poultry Science Association Inc.

Coronary responses to endothelin-1 and acetylcholine during partial coronary ischaemia and reperfusion in anaesthetized goats.

PubMed

Martínez, Maria Angeles; Fernández, Nuria; Monge, Luis; García-Villalón, Angel Luis; Sanz, Elena; Diéguez, Godofredo

2002-08-01

To examine coronary reactivity to acetylcholine and endothelin-1 (ET-1) during partial ischaemia and reperfusion, flow in the left circumflex coronary artery was measured electromagnetically, and coronary partial ischaemia was induced by stenosis of this artery in anaesthetized goats. In eight animals not treated with N(G)-nitro-l-arginine methyl ester (l-NAME), coronary stenosis reduced coronary flow by 45%, mean arterial pressure by 16% and coronary vascular conductance by 34%. During this ischaemia, coronary vasodilatation to acetylcholine (0.003-0.1 microg) and sodium nitroprusside (SNP; 1-10 microg) was markedly reduced, and coronary vasoconstriction to ET-1 (0.01-0.3 nmol) was attenuated. After 30 min of reperfusion, coronary flow, mean arterial pressure and coronary vascular conductance remained decreased, and the effects of acetylcholine, SNP and ET-1 were as in control animals. In six goats treated with N(G)-nitro-l-arginine methyl ester, coronary stenosis reduced coronary flow by 26% and coronary vascular conductance by 24%, but did not affect mean arterial pressure. During this ischaemia, coronary vasodilatation to acetylcholine and SNP was also markedly reduced, but vasoconstriction to ET-1 was unaffected. After 30 min of reperfusion, coronary flow and coronary vascular conductance remained decreased and mean arterial pressure was normal; in addition, the effects of acetylcholine were lower, those of SNP were similar and those of ET-1 were higher than in control animals. Therefore partial ischaemia reduces the coronary vasodilator reserve and blunts coronary vasoconstriction to ET-1, and reperfusion does not alter the endothelium-dependent and -independent coronary vasodilatation or vasoconstriction to ET-1.

Effects of short term and long term Extremely Low Frequency Magnetic Field on depressive disorder in mice: Involvement of nitric oxide pathway.

PubMed

Madjid Ansari, Alireza; Farzampour, Shahrokh; Sadr, Ali; Shekarchi, Babak; Majidzadeh-A, Keivan

2016-02-01

Previous reports on the possible effects of Extremely Low Frequency Magnetic Fields (ELF MF) on mood have been paradoxical in different settings while no study has yet been conducted on animal behavior. In addition, it was shown that ELF MF exposure makes an increase in brain nitric oxide level. Therefore, in the current study, we aimed to assess the possible effect(s) of ELF MF exposure on mice Forced Swimming Test (FST) and evaluate the probable role of the increased level of nitric oxide in the observed behavior. Male adult mice NMRI were recruited to investigate the short term and long term ELF MF exposure (0.5 mT and 50 Hz, single 2h and 2 weeks 2h a day). Locomotor behavior was assessed by using open-field test (OFT) followed by FST to evaluate the immobility time. Accordingly, NΩ-nitro-l-arginine methyl ester 30 mg/kg was used to exert anti-depressant like effect. According to the results, short term exposure did not alter the immobility time, whereas long term exposure significantly reduces immobility time (p<0.01). However, it was revealed that the locomotion did not differ among all experimental groups. Short term exposure reversed the anti-depressant like effect resulting from 30 mg/kg of NΩ-nitro-l-arginine methyl ester (p<0.01). It has been concluded that long term exposure could alter the depressive disorder in mice, whereas short term exposure has no significant effect. Also, reversing the anti-depressant activity of L-NAME indicates a probable increase in the brain nitric oxide. Copyright © 2016 Elsevier Inc. All rights reserved.

Possible involvement of nitric oxide in pilocarpine induced seminal emission in rats.

PubMed

Tomé, A R; da Silva, J C; Souza, A A; Mattos, J P; Vale, M R; Rao, V S

1999-12-01

Intraperitoneal injection of pilocarpine (0.75-3.0 mg/kg) caused a dose-related seminal emission in adult male rats. The seminal emission response to 3 mg/kg of pilocarpine was greatly reduced in atropinized (5 and 10 mg/kg, SC) animals, suggesting a cholinomimetic effect. Nw-nitro-L-arginine methyl ester (5, 10, and 20 mg/kg, SC), a nitric oxide synthesis inhibitor, also inhibited the pilocarpine-induced seminal emission, which was reversed by L-arginine (600 mg/kg, SC) or by coinjection of sodium nitroprusside (0.5 mg/kg, SC). Urine analysis for levels of nitric oxide metabolites, nitrate/nitrite (NO3-/NO2-), showed marked alterations in accordance with the drug treatments. The results suggest that nitric oxide mediates the inhibitory neurotransmission responsible for seminal emission in pilocarpine stimulated rats.

Cellular transport of l-arginine determines renal medullary blood flow in control rats, but not in diabetic rats despite enhanced cellular uptake capacity.

PubMed

Persson, Patrik; Fasching, Angelica; Teerlink, Tom; Hansell, Peter; Palm, Fredrik

2017-02-01

Diabetes mellitus is associated with decreased nitric oxide bioavailability thereby affecting renal blood flow regulation. Previous reports have demonstrated that cellular uptake of l-arginine is rate limiting for nitric oxide production and that plasma l-arginine concentration is decreased in diabetes. We therefore investigated whether regional renal blood flow regulation is affected by cellular l-arginine uptake in streptozotocin-induced diabetic rats. Rats were anesthetized with thiobutabarbital, and the left kidney was exposed. Total, cortical, and medullary renal blood flow was investigated before and after renal artery infusion of increasing doses of either l-homoarginine to inhibit cellular uptake of l-arginine or N ω -nitro- l-arginine methyl ester (l-NAME) to inhibit nitric oxide synthase. l-Homoarginine infusion did not affect total or cortical blood flow in any of the groups, but caused a dose-dependent reduction in medullary blood flow. l-NAME decreased total, cortical and medullary blood flow in both groups. However, the reductions in medullary blood flow in response to both l-homoarginine and l-NAME were more pronounced in the control groups compared with the diabetic groups. Isolated cortical tubular cells displayed similar l-arginine uptake capacity whereas medullary tubular cells isolated from diabetic rats had increased l-arginine uptake capacity. Diabetics had reduced l-arginine concentrations in plasma and medullary tissue but increased l-arginine concentration in cortical tissue. In conclusion, the reduced l-arginine availability in plasma and medullary tissue in diabetes results in reduced nitric oxide-mediated regulation of renal medullary hemodynamics. Cortical blood flow regulation displays less dependency on extracellular l-arginine and the upregulated cortical tissue l-arginine may protect cortical hemodynamics in diabetes. Copyright © 2017 the American Physiological Society.

Pulmonary Hypertension in Lambs Transfused with Stored Blood is Prevented by Breathing Nitric Oxide

PubMed Central

Baron, David M.; Yu, Binglan; Lei, Chong; Bagchi, Aranya; Beloiartsev, Arkadi; Stowell, Christopher P.; Steinbicker, Andrea U.; Malhotra, Rajeev; Bloch, Kenneth D.; Zapol, Warren M.

2012-01-01

Background During extended storage, erythrocytes undergo functional changes. These changes reduce the viability of erythrocytes leading to release of oxyhemoglobin, a potent scavenger of nitric oxide. We hypothesized that transfusion of ovine packed erythrocytes (PRBC) stored for prolonged periods would induce pulmonary vasoconstriction in lambs, and that reduced vascular nitric oxide concentrations would increase this vasoconstrictor effect. Methods We developed a model of autologous stored blood transfusion in lambs (n=36). Leukoreduced blood was stored for either 2 days (fresh PRBC) or 40 days (stored PRBC). Fresh or stored PRBC were transfused into donors instrumented for awake hemodynamic measurements. Hemodynamic effects of PRBC transfusion were also studied after infusion of NG-nitro-L-arginine methyl-ester (25 mg/kg) or during inhalation of nitric oxide (80 ppm). Results Cell-free hemoglobin levels were higher in the supernatant of stored PRBC than in supernatant of fresh PRBC (Mean±SD, 148±20 versus 41±13 mg/dl, respectively, P<0.001). Pulmonary artery pressure during transfusion of stored PRBC transiently increased from 13±1 to 18±1 mmHg (P<0.001) and was associated with increased plasma hemoglobin concentrations. NG-nitro-L-arginine methyl-ester potentiated the increase in pulmonary arterial pressure induced by transfusing stored PRBC, whereas inhalation of nitric oxide prevented the vasoconstrictor response. Conclusions Our results suggest that patients with reduced vascular nitric oxide levels due to endothelial dysfunction may be more susceptible to adverse effects of transfusing blood stored for prolonged periods. These patients might benefit from transfusion of fresh PRBC, when available, or inhaled nitric oxide supplementation to prevent the pulmonary hypertension associated with transfusion of stored PRBC. PMID:22293717

Structural alterations in rat myocardium induced by chronic l-arginine and l-NAME supplementation.

PubMed

Hmaid, Amal Abdussalam Ali A; Markelic, Milica; Otasevic, Vesna; Masovic, Sava; Jankovic, Aleksandra; Korac, Bato; Korac, Aleksandra

2018-03-01

Structural changes affecting cardiomyocyte function may contribute to the pathophysiological remodeling underlying cardiac function impairment. Recent reports have shown that endogenous nitric oxide (NO) plays an important role in this process. In order to examine the role of NO in cardiomyocyte remodeling, male rats were acclimated to room temperature (22 ± 1 °C) or cold (4 ± 1 °C) and treated with 2.25% l-arginine·HCl or 0.01% l-NAME (N ω -nitro-l-arginine methyl ester)·HCl for 45 days. Untreated groups served as controls. Right heart ventricles were routinely prepared for light microscopic examination. Stereological estimations of volume densities of cardiomyocytes, surrounding blood vessels and connective tissue, as well as the morphometric measurements of cardiomyocyte diameters were performed. Tissue sections were also analyzed for structural alterations. We observed that both l-arginine and l-NAME supplementation induced cardiomyocyte hypertrophy, regardless of ambient temperature. However, cardiomyocyte hypertrophy was associated with fibrosis and extra collagen deposition only in the l-NAME treated group. Taken together, our results suggest that NO has a modulatory role in right heart ventricle remodeling by coordinating hypertrophy of cardiomyocytes and fibrous tissue preventing cardiac fibrosis.

Spontaneous, L-arginine-induced and spironolactone-induced regression of protein remodeling of the left ventricle in L-NAME-induced hypertension.

PubMed

Simko, F; Potácová, A; Pelouch, V; Paulis, L; Matúsková, J; Krajcírovicová, K; Pechánová, O; Adamcová, M

2007-01-01

N(G)-nitro-L-arginine-methyl ester (L-NAME)-induced hypertension is associated with protein remodeling of the left ventricle. The aim of the study was to show, whether aldosterone receptor blocker spironolactone and precursor of NO-production L-arginine were able to reverse the protein rebuilding of the left ventricle. Six groups of male Wistar rats were investigated: control 4 (4 weeks placebo), L-NAME (4 weeks L-NAME), spontaneous-regression (4 weeks L-NAME + 3 weeks placebo), spironolactone-regression (4 weeks L-NAME + 3 weeks spironolactone), L-arginine-regression (4 weeks L-NAME + 3 weeks arginine), control 7 (7 weeks placebo). L-NAME administration induced hypertension, hypertrophy of the left ventricle (LV), and the increase of metabolic and contractile as well as soluble and insoluble collagenous protein concentration. The systolic blood pressure and relative weight of the LV decreased in all three groups with regression, while the most prominent attenuation of the LVH was observed after spironolactone treatment. In the spontaneous-regression and L-arginine-regression groups the concentrations of individual proteins were not significantly different from the control value. However, in the spironolactone-regression group the concentration of metabolic, contractile and insoluble collagenous proteins remained significantly increased in comparison with the control group. The persistence of the increased protein concentration in the spironolactone group may be related to the more prominent reduction of myocardial water content by spironolactone.

Evidence against nitrergic neuromodulation in the rat vas deferens.

PubMed

Ventura, S; Burnstock, G

1997-09-03

Electrical field stimulation (60 V, 1 ms, single pulses or 20 s trains of 1-10 Hz) of the nerve terminals within the rat vas deferens produced biphasic contractions in preparations oriented to measure either longitudinal or circular muscle contractions. In confirmation of earlier reports, these contractions were blocked by tetrodotoxin (1 microM). The initial fast purinergic contraction was dominant in prostatic halves of the vas deferens while the second slower noradrenergic contraction was greater in epididymal halves. Although previous studies have shown nitric oxide synthase immuno-positive nerves in the vas deferens, electrical field stimulation-induced contractions were unaffected by L-arginine, sodium nitroprusside, N-nitro-L-arginine methyl ester (L-NAME) or superoxide dismutase in concentrations up to I mM. In concentrations above 1 mM, L-NAME reduced the size of the field stimulation-induced contractions but this effect could not be reversed by either L-arginine or sodium nitroprusside. Furthermore, L-arginine, sodium nitroprusside and L-NAME did not affect the contractions induced by exogenous application of noradrenaline (10 microM), ATP (1 mM) or BaCl2 (1-10 mM). We conclude that nitric oxide does not act as a neuromodulator in isolated preparations of rat vas deferens.

Effect of selective inhibition of renal inducible nitric oxide synthase on renal blood flow and function in experimental hyperdynamic sepsis.

PubMed

Ishikawa, Ken; Calzavacca, Paolo; Bellomo, Rinaldo; Bailey, Michael; May, Clive N

2012-08-01

Nitric oxide plays an important role in the control of renal blood flow and renal function. In sepsis, increased levels of inducible nitric oxide synthase produce excessive nitric oxide, which may contribute to the development of acute kidney injury. We, therefore, examined the effects of intrarenal infusion of selective inducible nitric oxide synthase inhibitors in a large animal model of hyperdynamic sepsis in which acute kidney injury occurs in the presence of increased renal blood flow. Prospective crossover randomized controlled interventional studies. University-affiliated research institute. Twelve unilaterally nephrectomized Merino ewes. Infusion of a selective (1400W) and a partially selective inducible nitric oxide synthase inhibitor (aminoguanidine) into the renal artery for 2 hrs after the induction of sepsis, and comparison with a nonselective inhibitor (Nω-nitro-L-arginine methyl ester). In sheep with nonhypotensive hyperdynamic sepsis, creatinine clearance halved (32 to 16 mL/min, ratio [95% confidence interval] 0.51 [0.28-0.92]) despite increased renal blood flow (241 to 343 mL/min, difference [95% confidence interval] 102 [78-126]). Infusion of 1400W did not change renal blood flow, urine output, or creatinine clearance, whereas infusion of Nω-nitro-L-arginine methyl ester and a high dose of aminoguanidine normalized renal blood flow, but did not alter creatinine clearance. In hyperdynamic sepsis, intrarenal infusion of a highly selective inducible nitric oxide synthase inhibitor did not reduce the elevated renal blood flow or improve renal function. In contrast, renal blood flow was reduced by infusion of a nonselective NOS inhibitor or a high dose of a partially selective inducible nitric oxide synthase inhibitor. The renal vasodilatation in septic acute kidney injury may be due to nitric oxide derived from the endothelial and neural isoforms of nitric oxide synthase, but their blockade did not restore renal function.

Effects of aqueous leaf extract of Tridax procumbens on contractile activity of corpus cavernosum in N-nitro-l-arginine methyl ester-induced hypertensive male rats.

PubMed

Salami, Shakiru Ademola; Salahdeen, Hussein Mofomosara; Ugbebor, Evangelshane Chukwudubem; Murtala, Babatunde Adekunle; Raji, Yinusa

2018-01-01

This study investigated the effects of aqueous leaf extract of Tridax procumbens (ALETP) on contractile activity of corpus cavernosum in N-nitro-l-arginine methyl ester (l-NAME)-induced hypertensive male rats. Twenty normal, adult male rats (130-150 g) were divided into four groups of five rats each. Group I (control) was given normal saline (0.6 mL/kg) and group II was given l-NAME (40 mg/kg) for 6 weeks. Groups III and IV also received l-NAME (40 mg/kg) for 6 weeks but were further co-treated with 100 and 200 mg/kg of ALETP, respectively, from week 4 to week 6. All treatments were given orally. Strips of corpus cavernosum from each of the four groups were exposed to increasing concentrations of acetylcholine (ACh) and sodium nitroprusside (SNP) (10 -9 -10 -5 mol/L) after contraction with phenylephrine (10 -7  mol/L) to test for a dose-response effect. Response to potassium and calcium was also measured after cumulatively adding potassium and calcium (10-50 mmol/L) to potassium- and calcium-free organ chamber. Isometric contractions were recorded through an Ugo Basile data capsule acquisition system. Mean arterial blood pressure was significantly reduced in the ALETP co-treated group compared to the control and l-NAME-only groups (P < 0.05). Cavernosa strips from ALETP co-treated rats exhibited significant inhibition of contraction in response to phenylephrine, potassium chloride, and calcium chloride (P < 0.05). Relaxation in response to Ach and SNP was also significantly impaired in cavernosa strips from the l-NAME-only treated group (P < 0.05), while ALETP co-treated groups showed enhanced percentage relaxation. ALETP treatment of l-NAME-induced hypertensive rats promotes a relaxant effect on isolated cavernosa strips. ALETP shows potential in correcting erectile dysfunction in hypertension. Copyright © 2017 Shanghai Changhai Hospital. Published by Elsevier B.V. All rights reserved.

The effects of nitric oxide synthase inhibitors on the sedative effect of clonidine.

PubMed

Soares de Moura, R; Rios, A A; de Oliveira, L F; Resende, A C; de Lemos Neto, M; Santos, E J; Correia, M L; Tano, T

2001-11-01

The mechanism underlying the Niteroi, Rio de Janeiro sedative effect of clonidine, an alpha2-adrenoceptor agonist, remains uncertain. Because activation of alpha2-adrenoceptors induces release of nitric oxide (NO), we tested the hypothesis that the sedative effect of clonidine depends on NO-related mechanisms. The effect of 7-nitro indazole on the sleeping time induced by clonidine was studied in Wistar rats. In addition, we examined the effect of clonidine, alpha-methyldopa, and midazolam on the thiopental-induced sleeping time in rats pretreated with N(G)-nitro-L-arginine-methyl-ester (L-NAME). The sleeping time induced by clonidine was significantly decreased by 7-nitro indazole. Thiopental sleeping time was increased by clonidine, alpha-methyldopa, and midazolam. L-NAME reduced the prolongation effect of clonidine and alpha-methyldopa, but did not alter the effect of midazolam on the thiopental-induced sleeping time. The inhibitory effect of L-NAME on clonidine-dependent prolongation of thiopental-induced sleeping time was reversed by L-arginine. These results suggest that NO-dependent mechanisms are involved in the sedative effect of clonidine. In addition, this effect seems to be specific for the sedative action of alpha2-adrenoceptors agonists. Clonidine, an antihypertensive drug, is also a sedative. This sedative effect, although an adverse event in the treatment of hypertensive patients, can be helpful for sedation of surgical patients. The mechanism of this effect, however, is unknown. In this study, we show that the sedative effect of clonidine is mediated by nitric oxide, because it could be prevented by pretreatment with nitric oxide synthase inhibitors.

Pentadecapeptide BPC 157, in clinical trials as a therapy for inflammatory bowel disease (PL14736), is effective in the healing of colocutaneous fistulas in rats: role of the nitric oxide-system.

PubMed

Klicek, Robert; Sever, Marko; Radic, Bozo; Drmic, Domagoj; Kocman, Ivan; Zoricic, Ivan; Vuksic, Tihomir; Ivica, Mihovil; Barisic, Ivan; Ilic, Spomenko; Berkopic, Lidija; Vrcic, Hrvoje; Brcic, Luka; Blagaic, Alenka Boban; Coric, Marijana; Brcic, Iva; Rokotov, Dinko Stancic; Anic, Tomislav; Seiwerth, Sven; Sikiric, Predrag

2008-09-01

We focused on the therapeutic effect of the stable gastric pentadecapeptide BPC 157 and how its action is related to nitric oxide (NO) in persistent colocutaneous fistula in rats (at 5 cm from anus, colon defect of 5 mm, skin defect of 5 mm); this peptide has been shown to be safe in clinical trials for inflammatory bowel disease (PL14736) and safe for intestinal anstomosis therapy. BPC 157 (10 microg/kg, 10 ng/kg) was applied i) in drinking water until the animals were sacrificed at post-operative day 1, 3, 5, 7, 14, 21, and 28; or ii) once daily intraperitoneally (first application 30 min following surgery, last 24 h before sacrifice) alone or with N(G)-nitro-L-arginine methyl ester (L-NAME) (5 mg/kg), L-arginine (200 mg/kg), and their combinations. Sulphasalazine (50 mg/kg) and 6-alpha-methylprednisolone (1 mg/kg) were given once daily intraperitoneally. BPC 157 accelerated parenterally or perorally the healing of colonic and skin defect, leading to the suitable closure of the fistula, macro/microscopically, biomechanically, and functionally (larger water volume sustained without fistula leaking). L-NAME aggravated the healing failure of colocutaneous fistulas, skin, and colon wounds (L-NAME groups). L-Arginine was effective only with blunted NO generation (L-NAME + L-arginine groups) but not without (L-arginine groups). All of the BPC 157 beneficial effects remained unchanged with blunted NO-generation (L-NAME + BPC 157 groups) and with NO substrate (L-arginine + BPC 157 groups) as well as L-NAME and L-arginine co-administration (L-NAME + L-arginine + BPC 157 groups). Sulphasalazine was only moderately effective, and corticosteroid even had an aggravating effect.

Inhibition of the gap junctional component of endothelium-dependent relaxations in rabbit iliac artery by 18-α glycyrrhetinic acid

PubMed Central

Taylor, Hannah J; Chaytor, Andrew T; Evans, W Howard; Griffith, Tudor M

1998-01-01

The gap junction inhibitor 18-α-glycyrrhetinic acid (α-GA, 100 μM) attenuated endothelium-dependent relaxations to acetylcholine and cyclopiazonic acid by ∼20% in rings of pre-constricted rabbit iliac artery. The nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 300 μM) inhibited relaxations to both agents by ∼65% and these were further attenuated by α-GA to <10% of control. In endothelium-denuded preparations, relaxations to sodium nitroprusside were not affected by α-GA. Heterocellular gap junctional communication may therefore account for nitric oxide-independent relaxations evoked both by receptor-dependent and -independent mechanisms in rabbit iliac artery. PMID:9776336

Effects of nitric oxide on red blood cell deformability.

PubMed

Bor-Kucukatay, Melek; Wenby, Rosalinda B; Meiselman, Herbert J; Baskurt, Oguz K

2003-05-01

In addition to its known action on vascular smooth muscle, nitric oxide (NO) has been suggested to have cardiovascular effects via regulation of red blood cell (RBC) deformability. The present study was designed to further explore this possibility. Human RBCs in autologous plasma were incubated for 1 h with NO synthase (NOS) inhibitors [N(omega)-nitro-l-arginine methyl ester (l-NAME) and S-methylisothiourea], NO donors [sodium nitroprusside (SNP) and diethylenetriamine (DETA)-NONOate], an NO precursor (l-arginine), soluble guanylate cyclase inhibitors (1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one and methylene blue), and a potassium channel blocker [triethylammonium (TEA)]. After incubation, RBC deformability at various shear stresses was determined by ektacytometry. Both NOS inhibitors significantly reduced RBC deformability above a threshold concentration, whereas the NO donors increased deformability at optimal concentrations. NO donors, as well as the NO precursor l-arginine and the potassium blocker TEA, were able to reverse the effects of NOS inhibitors. Guanylate cyclase inhibition reduced RBC deformation, with both SNP and DETA-NONOate able to reverse this effect. These results thus indicate the importance of NO as a determinant of RBC mechanical behavior and suggest its regulatory role for normal RBC deformability.

NO involvement in the inhibition of ghrelin on voltage-dependent potassium currents in rat hippocampal cells.

PubMed

Lu, Yong; Dang, Shaokang; Wang, Xu; Zhang, Junli; Zhang, Lin; Su, Qian; Zhang, Huiping; Lin, Tianwei; Zhang, Xiaoxiao; Zhang, Yurong; Sun, Hongli; Zhu, Zhongliang; Li, Hui

2018-01-01

Ghrelin is a peptide hormone that plays an important role in promoting appetite, regulating distribution and rate of use of energy, cognition, and mood disorders, but the relevant neural mechanisms of these function are still not clear. In this study, we examined the effect of ghrelin on voltage-dependent potassium (K + ) currents in hippocampal cells of 1-3 days SD rats by whole-cell patch-clamp technique, and discussed whether NO was involved in this process. The results showed that ghrelin significantly inhibited the voltage-dependent K + currents in hippocampal cells, and the inhibitory effect was more significant when l-arginine was co-administered. In contrast, N-nitro- l-arginine methyl ester increased the ghrelin inhibited K + currents and attenuated the inhibitory effect of ghrelin. While d-arginine (D-AA) showed no significant impact on the ghrelin-induced decrease in K + current. These results show that ghrelin may play a physiological role by inhibiting hippocampal voltage dependent K + currents, and the NO pathway may be involved in this process. Copyright © 2017 Elsevier B.V. All rights reserved.

L-arginine and Arginase Products Potentiate Dexmedetomidine-induced Contractions in the Rat Aorta.

PubMed

Wong, Emily S W; Man, Ricky Y K; Ng, Kwok F J; Leung, Susan W S; Vanhoutte, Paul M

2018-03-01

The α2-adrenergic sedative/anesthetic agent dexmedetomidine exerts biphasic effects on isolated arteries, causing endothelium-dependent relaxations at concentrations at or below 30 nM, followed by contractions at higher concentrations. L-arginine is a common substrate of endothelial nitric oxide synthase and arginases. This study was designed to investigate the role of L-arginine in modulating the overall vascular response to dexmedetomidine. Isometric tension was measured in isolated aortic rings of Sprague Dawley rats. Cumulative concentrations of dexmedetomidine (10 nM to 10 μM) were added to quiescent rings (with and without endothelium) after previous incubation with vehicle, N-nitro-L-arginine methyl ester hydrochloride (L-NAME; nitric oxide synthase inhibitor), prazosin (α1-adrenergic antagonist), rauwolscine (α2-adrenergic antagonist), L-arginine, (S)-(2-boronethyl)-L-cysteine hydrochloride (arginase inhibitor), N-hydroxy-L-arginine (arginase inhibitor), urea and/or ornithine. In some preparations, immunofluorescent staining, immunoblotting, or measurement of urea content were performed. Dexmedetomidine did not contract control rings with endothelium but evoked concentration-dependent increases in tension in such rings treated with L-NAME (Emax 50 ± 4%) or after endothelium-removal (Emax 74 ± 5%; N = 7 to 12). Exogenous L-arginine augmented the dexmedetomidine-induced contractions in the presence of L-NAME (Emax 75 ± 3%). This potentiation was abolished by (S)-(2-boronethyl)-L-cysteine hydrochloride (Emax 16 ± 4%) and N-hydroxy-L-arginine (Emax 18 ± 4%). Either urea or ornithine, the downstream arginase products, had a similar potentiating effect as L-arginine. Immunoassay measurements demonstrated an upregulation of arginase I by L-arginine treatment in the presence of L-NAME (N = 4). These results suggest that when vascular nitric oxide homeostasis is impaired, the potentiation of the vasoconstrictor effect of dexmedetomidine by L-arginine depends on arginase activity and the production of urea and ornithine.

Inducible nitric oxide synthase evoked nitric oxide counteracts capsaicin-induced airway smooth muscle contraction, but exacerbates plasma extravasation.

PubMed

Li, Ping-Chia; Shaw, Chen-Fu; Kuo, Tin-Fan; Chien, Chiang-Ting

2005-04-18

The contribution of nitric oxide (NO) to capsaicin-evoked airway responses was investigated in rats. The measurement of plasma NO level, airway dynamics, airway smooth muscle electromyogram, and plasma extravasation by India ink and Evans blue leakage technique was adapted. Capsaicin-evoked hypotension, bronchoconstriction, trachea plasma extravasation as well as increases in plasma NO level in a dose-dependent manner. L-732138 (NK1 receptor antagonist) or SR-48968 (NK2 receptor antagonist) pretreatment reduced capsaicin-enhanced hypotension, bronchoconstriction, plasma extravasation, and plasma NO level. N(G)-nitro-L-Arginine methyl ester (L-NAME, 10 mg/kg, i.v.), a non-selective NO synthase (NOS) inhibitor, or aminoguanidine (10 mg/kg, i.v.), a selective inducible NOS (iNOS) inhibitor, reduced capsaicin-induced increases in plasma NO level and protected against capsaicin-induced plasma extravasation, whereas L-arginine (150 mg/kg, i.v.), a NO precursor, enhanced capsaicin-evoked plasma NO level and plasma extravasation. L-Arginine pretreatment ameliorated capsaicin-induced bronchoconstriction, whereas L-NAME and aminoguanidine exaggerated capsaicin-induced bronchoconstriction. In summary, NK1 and NK2 receptors and iNOS play a role in NO formation and on capsaicin-induced bronchoconstriction and plasma extravasation. NO generated by iNOS counteracts tachykinin-mediated bronchoconstriction, but exacerbates tachykinin-mediated plasma extravasation.

Arginine supplementation induces myoblast fusion via augmentation of nitric oxide production.

PubMed

Long, Jodi H D; Lira, Vitor A; Soltow, Quinlyn A; Betters, Jenna L; Sellman, Jeff E; Criswell, David S

2006-01-01

The semi-essential amino acid, L-arginine (L-Arg), is the substrate for endogenous synthesis of nitric oxide, a molecule that is involved in myoblast proliferation and fusion. Since L-Arg supply may limit nitric oxide synthase (NOS) activity in endothelial cells, we examined L-Arg supplementation in differentiating mouse myoblasts and tested the hypothesis that L-Arg exerts direct effects on myoblast fusion via augmentation of endogenous nitric oxide production. C(2)C(12) myoblasts in differentiation media received one of the following treatments for 120 h: 1 mM L-Arg, 0.1 mM N-nitro-L-arginine methyl ester (L-NAME), L-Arg + L-NAME, 10 mM L-Lysine, or no supplement (Control). Cultures were fixed and stained with hematoxylin and eosin for microphotometric image analysis of myotube density, nuclear density, and fusion index (% of total nuclei in myotubes). Endogenous production of nitric oxide during the treatment period peaked between 24 and 48 h. L-Arg amplified nitric oxide production between 0 and 24 h and increased myotube density, total nuclei number, and nuclear fusion index. These L-Arg effects were prevented by the NOS inhibitor, L-NAME. Further, L-Lysine, a competitive inhibitor of L-Arg uptake, repressed nitric oxide production and reduced myotube density and fusion index. In summary, L-Arg augments myotube formation and increases nitric oxide production in a process limited by cellular L-Arg uptake.

The sex differences in nature of vascular endothelial stress: nitrergic mechanisms

NASA Astrophysics Data System (ADS)

Sindeev, Sergey; Gekaluyk, Artem; Ulanova, Maria; Agranovich, Ilana; Sharref, Ali Esmat; Semyachkina-Glushkovskaya, Oxana

2016-04-01

Here we studied the role of nitric oxide in cardiovascular regulation in male and female hypertensive rats under normal and stress conditions. We found that the severity of hypertension in females was lower than in males. Hypertensive females demonstrated more favorable pattern of cardiovascular responses to stress. Nitric oxide blockade by NG-nitro-L-arginine methyl ester (L-NAME) increased the mean arterial pressure and decreased the heart rate more effectively in females than in males. During stress, L-NAME modified the stress-induced cardiovascular responses more significantly in female compared with male groups. Our data show that hypertensive females demonstrated the more effective nitric oxide control of cardiovascular activity under normal and especially stress conditions than male groups. This sex differences may be important mechanism underlying greater in females vs. males stress-resistance of cardiovascular system and hypertension formation.

5-HT2A receptors control body temperature in mice during LPS-induced inflammation via regulation of NO production.

PubMed

Voronova, Irina P; Khramova, Galina M; Kulikova, Elizabeth A; Petrovskii, Dmitrii V; Bazovkina, Daria V; Kulikov, Alexander V

2016-01-01

G protein-coupled 5-HT2A receptors are involved in the regulation of numerous normal and pathological physiological functions. At the same time, its involvement in the regulation of body temperature (Tb) in normal conditions is obscure. Here we study the effect of the 5-HT2A receptor activation or blockade on Tb in sick animals. The experiments were carried out on adult C57BL/6 mouse males. Systemic inflammation and sickness were produced by lipopolysaccharide (LPS, 0.1mg/kg, ip), while the 5-HT2A receptor was stimulated or blocked through the administration of the receptor agonist DOI or antagonist ketanserin (1mg/kg), respectively. LPS, DOI or ketanserin alone produced no effect on Tb. However, administration of LPS together with a peripheral or central ketanserin injection reduced Tb (32.2°C). Ketanserin reversed the LPS-induced expression of inducible NO synthase in the brain. Consequently, an involvement of NO in the mechanism of the hypothermic effect of ketanserin in sick mice was hypothesized. Administration of LPS together with NO synthase inhibitor, l-nitro-arginine methyl ester (60mg/kg, ip) resulted in deep (28.5°C) and prolonged (8h) hypothermia, while administration of l-nitro-arginine methyl ester alone produced no effect on Tb. Thus, 5-HT2A receptors play a key role in Tb control in sick mice. Blockade of this GPCR produces hypothermia in mice with systemic inflammation via attenuation of LPS-induced NO production. These results indicate an unexpected role of 5-HT2A receptors in inflammation and NO production and have a considerable biological impact on understanding the mechanism of animal adaptation to pathogens and parasites. Moreover, adverse side effects of 5-HT2A receptor antagonists in patients with inflammation may be expected. Copyright © 2015 Elsevier Ltd. All rights reserved.

Pretreatment with the nitric oxide donor SNAP or nerve transection blocks humoral preconditioning by remote limb ischemia or intra-arterial adenosine.

PubMed

Steensrud, Tor; Li, Jing; Dai, Xiaojing; Manlhiot, Cedric; Kharbanda, Rajesh K; Tropak, Michael; Redington, Andrew

2010-11-01

We have previously shown that remote ischemic preconditioning (rIPC) by transient limb ischemia leads to the release of a circulating factor(s) that induces potent myocardial protection. Intra-arterial injection of adenosine into a limb also leads to cardioprotection, but the mechanism of its signal transduction is poorly understood. Eleven groups of rabbits received saline control or rIPC or adenosine administration with additional pretreatment with the nitric oxide (NO) synthase blocker N(G)-nitro-l-arginine methyl ester, the NO donor S-nitroso-N-acetylpenicillamine, its non-NO-donating derivative N-acetylpenicillamine, or femoral nerve section. Blood was then drawn from each animal, and the dialysate of the plasma was used to perfuse a naïve heart from an untreated donor. Infarct size was measured after 30 min of global ischemia and 120 min reperfusion. When compared with that of the control, mean infarct size was significantly smaller in groups treated with rIPC alone (P < 0.01) and intra-arterial adenosine (P < 0.01). Pretreatment with N(G)-nitro-l-arginine methyl ester or N-acetylpenicillamine did not affect the level of protection induced by rIPC (P = not significant, compared with rIPC alone) or intra-arterial adenosine (P = not significant, compared with intra-arterial adenosine alone), but prior femoral nerve transection or pretreatment with S-nitroso-N-acetylpenicillamine abolished the cardioprotective effect of intra-arterial adenosine and rIPC. Intra-arterial adenosine, like rIPC, releases a blood-borne cardioprotective factor(s) that is dependent on an intact femoral nerve and is inhibited by pretreatment with a NO donor. These results may be important when designing or assessing the results of clinical trials of adenosine or rIPC cardioprotection, where NO donors are used as part of therapy.

Neuroprotective Efficacy of Mitochondrial Antioxidant MitoQ in Suppressing Peroxynitrite-Mediated Mitochondrial Dysfunction Inflicted by Lead Toxicity in the Rat Brain.

PubMed

Maiti, Arpan Kumar; Saha, Nimai Chandra; More, Sunil S; Panigrahi, Ashish Kumar; Paul, Goutam

2017-04-01

Lead (Pb) is one of the most pollutant metals that accumulate in the brain mitochondria disrupting mitochondrial structure and function. Though oxidative stress mediated by reactive oxygen species remains the most accepted mechanism of Pb neurotoxicity, some reports suggest the involvement of nitric oxide ( • NO) and reactive nitrogen species in Pb-induced neurotoxicity. But the impact of Pb neurotoxicity on mitochondrial respiratory enzyme complexes remains unknown with no relevant report highlighting the involvement of peroxynitrite (ONOO - ) in it. Herein, we investigated these effects in in vivo rat model by oral application of MitoQ, a known mitochondria-specific antioxidant with ONOO - scavenging activity. Interestingly, MitoQ efficiently alleviated ONOO - -mediated mitochondrial complexes II, III and IV inhibition, increased mitochondrial ATP production and restored mitochondrial membrane potential. MitoQ lowered enhanced caspases 3 and 9 activities upon Pb exposure and also suppressed synaptosomal lipid peroxidation and protein oxidation accompanied by diminution of nitrite production and protein-bound 3-nitrotyrosine. To ascertain our in vivo findings on mitochondrial dysfunction, we carried out similar experiments in the presence of different antioxidants and free radical scavengers in the in vitro SHSY5Y cell line model. MitoQ provided better protection compared to mercaptoethylguanidine, N-nitro-L-arginine methyl ester and superoxide dismutase suggesting the predominant involvement of ONOO - compared to • NO and O 2 •- . However, dimethylsulphoxide and catalase failed to provide protection signifying the noninvolvement of • OH and H 2 O 2 in the process. The better protection provided by MitoQ in SHSY5Y cells can be attributed to the fact that MitoQ targets mitochondria whereas mercaptoethylguanidine, N-nitro-L-arginine methyl ester and superoxide dismutase are known to target mainly cytoplasm and not mitochondria. Taken together the results from the present study clearly brings out the potential of MitoQ against ONOO - -induced toxicity upon Pb exposure indicating its therapeutic potential in metal toxicity.

6-Gingerol alleviates exaggerated vasoconstriction in diabetic rat aorta through direct vasodilation and nitric oxide generation.

PubMed

Ghareib, Salah A; El-Bassossy, Hany M; Elberry, Ahmed A; Azhar, Ahmad; Watson, Malcolm L; Banjar, Zainy Mohammed

2015-01-01

The aim of the present study is to investigate the effect and potential mechanism of action of 6-gingerol on alterations of vascular reactivity in the isolated aorta from diabetic rats. Male Wistar rats were divided into two experimental groups, control and diabetics. Diabetes was induced by a single intraperitoneal injection of streptozotocin (50 mg kg(-1)), and the rats were left for 10 weeks to develop vascular complications. The effect of in vitro incubation with 6-gingerol (0.3-3 μM) on the vasoconstrictor response of the isolated diabetic aortae to phenylephrine and the vasodilator response to acetylcholine was examined. Effect of 6-gingerol was also examined on aortae incubated with methylglyoxal as an advanced glycation end product (AGE). To investigate the mechanism of action of 6-gingerol, the nitric oxide synthase inhibitor Nω-nitro-l-arginine methyl ester hydrochloride (100 μM), guanylate cyclase inhibitor methylene blue (5 μM), calcium-activated potassium channel blocker tetraethylammonium chloride (10 mM), and cyclooxygenase inhibitor indomethacin (5 μM) were added 30 minutes before assessing the direct vasorelaxant effect of 6-gingerol. Moreover, in vitro effects of 6-gingerol on NO release and the effect of 6-gingerol on AGE production were examined. Results showed that incubation of aortae with 6-gingerol (0.3-10 μM) alleviated the exaggerated vasoconstriction of diabetic aortae to phenylephrine in a concentration-dependent manner with no significant effect on the impaired relaxatory response to acetylcholine. Similar results were seen in the aortae exposed to methylglyoxal. In addition, 6-gingerol induced a direct vasodilation effect that was significantly inhibited by Nω-nitro-l-arginine methyl ester hydrochloride and methylene blue. Furthermore, 6-gingerol stimulated aortic NO generation but had no effect on AGE formation. In conclusion, 6-gingerol ameliorates enhanced vascular contraction in diabetic aortae, which may be partially attributed to its ability to increase the production of NO and stimulation of cyclic guanosine monophosphate.

6-Gingerol alleviates exaggerated vasoconstriction in diabetic rat aorta through direct vasodilation and nitric oxide generation

PubMed Central

Ghareib, Salah A; El-Bassossy, Hany M; Elberry, Ahmed A; Azhar, Ahmad; Watson, Malcolm L; Banjar, Zainy Mohammed

2015-01-01

The aim of the present study is to investigate the effect and potential mechanism of action of 6-gingerol on alterations of vascular reactivity in the isolated aorta from diabetic rats. Male Wistar rats were divided into two experimental groups, control and diabetics. Diabetes was induced by a single intraperitoneal injection of streptozotocin (50 mg kg−1), and the rats were left for 10 weeks to develop vascular complications. The effect of in vitro incubation with 6-gingerol (0.3–3 μM) on the vasoconstrictor response of the isolated diabetic aortae to phenylephrine and the vasodilator response to acetylcholine was examined. Effect of 6-gingerol was also examined on aortae incubated with methylglyoxal as an advanced glycation end product (AGE). To investigate the mechanism of action of 6-gingerol, the nitric oxide synthase inhibitor Nω-nitro-l-arginine methyl ester hydrochloride (100 μM), guanylate cyclase inhibitor methylene blue (5 μM), calcium-activated potassium channel blocker tetraethylammonium chloride (10 mM), and cyclooxygenase inhibitor indomethacin (5 μM) were added 30 minutes before assessing the direct vasorelaxant effect of 6-gingerol. Moreover, in vitro effects of 6-gingerol on NO release and the effect of 6-gingerol on AGE production were examined. Results showed that incubation of aortae with 6-gingerol (0.3–10 μM) alleviated the exaggerated vasoconstriction of diabetic aortae to phenylephrine in a concentration-dependent manner with no significant effect on the impaired relaxatory response to acetylcholine. Similar results were seen in the aortae exposed to methylglyoxal. In addition, 6-gingerol induced a direct vasodilation effect that was significantly inhibited by Nω-nitro-l-arginine methyl ester hydrochloride and methylene blue. Furthermore, 6-gingerol stimulated aortic NO generation but had no effect on AGE formation. In conclusion, 6-gingerol ameliorates enhanced vascular contraction in diabetic aortae, which may be partially attributed to its ability to increase the production of NO and stimulation of cyclic guanosine monophosphate. PMID:26609223

Celecoxib-induced gastrointestinal, liver and brain lesions in rats, counteraction by BPC 157 or L-arginine, aggravation by L-NAME

PubMed Central

Drmic, Domagoj; Kolenc, Danijela; Ilic, Spomenko; Bauk, Lara; Sever, Marko; Zenko Sever, Anita; Luetic, Kresimir; Suran, Jelena; Seiwerth, Sven; Sikiric, Predrag

2017-01-01

AIM To counteract/reveal celecoxib-induced toxicity and NO system involvement. METHODS Celecoxib (1 g/kg b.w. ip) was combined with therapy with stable gastric pentadecapeptide BPC 157 (known to inhibit these lesions, 10 μg/kg, 10 ng/kg, or 1 ng/kg ip) and L-arginine (100 mg/kg ip), as well as NOS blockade [N(G)-nitro-L-arginine methyl ester (L-NAME)] (5 mg/kg ip) given alone and/or combined immediately after celecoxib. Gastrointestinal, liver, and brain lesions and liver enzyme serum values in rats were assessed at 24 h and 48 h thereafter. RESULTS This high-dose celecoxib administration, as a result of NO system dysfunction, led to gastric, liver, and brain lesions and increased liver enzyme serum values. The L-NAME-induced aggravation of the lesions was notable for gastric lesions, while in liver and brain lesions the beneficial effect of L-arginine was blunted. L-arginine counteracted gastric, liver and brain lesions. These findings support the NO system mechanism(s), both NO system agonization (L-arginine) and NO system antagonization (L-NAME), that on the whole are behind all of these COX phenomena. An even more complete antagonization was identified with BPC 157 (at both 24 h and 48 h). A beneficial effect was evident on all the increasingly negative effects of celecoxib and L-NAME application and in all the BPC 157 groups (L-arginine + BPC 157; L-NAME + BPC 157; L-NAME + L-arginine + BPC 157). Thus, these findings demonstrated that BPC 157 may equally counteract both COX-2 inhibition (counteracting the noxious effects of celecoxib on all lesions) and additional NOS blockade (equally counteracting the noxious effects of celecoxib + L-NAME). CONCLUSION BPC 157 and L-arginine alleviate gastrointestinal, liver and brain lesions, redressing NSAIDs’ post-surgery application and NO system involvement. PMID:28839430

Celecoxib-induced gastrointestinal, liver and brain lesions in rats, counteraction by BPC 157 or L-arginine, aggravation by L-NAME.

PubMed

Drmic, Domagoj; Kolenc, Danijela; Ilic, Spomenko; Bauk, Lara; Sever, Marko; Zenko Sever, Anita; Luetic, Kresimir; Suran, Jelena; Seiwerth, Sven; Sikiric, Predrag

2017-08-07

To counteract/reveal celecoxib-induced toxicity and NO system involvement. Celecoxib (1 g/kg b.w. ip) was combined with therapy with stable gastric pentadecapeptide BPC 157 (known to inhibit these lesions, 10 μg/kg, 10 ng/kg, or 1 ng/kg ip) and L-arginine (100 mg/kg ip), as well as NOS blockade [N(G)-nitro-L-arginine methyl ester (L-NAME)] (5 mg/kg ip) given alone and/or combined immediately after celecoxib. Gastrointestinal, liver, and brain lesions and liver enzyme serum values in rats were assessed at 24 h and 48 h thereafter. This high-dose celecoxib administration, as a result of NO system dysfunction, led to gastric, liver, and brain lesions and increased liver enzyme serum values. The L-NAME-induced aggravation of the lesions was notable for gastric lesions, while in liver and brain lesions the beneficial effect of L-arginine was blunted. L-arginine counteracted gastric, liver and brain lesions. These findings support the NO system mechanism(s), both NO system agonization (L-arginine) and NO system antagonization (L-NAME), that on the whole are behind all of these COX phenomena. An even more complete antagonization was identified with BPC 157 (at both 24 h and 48 h). A beneficial effect was evident on all the increasingly negative effects of celecoxib and L-NAME application and in all the BPC 157 groups (L-arginine + BPC 157; L-NAME + BPC 157; L-NAME + L-arginine + BPC 157). Thus, these findings demonstrated that BPC 157 may equally counteract both COX-2 inhibition (counteracting the noxious effects of celecoxib on all lesions) and additional NOS blockade (equally counteracting the noxious effects of celecoxib + L-NAME). BPC 157 and L-arginine alleviate gastrointestinal, liver and brain lesions, redressing NSAIDs' post-surgery application and NO system involvement.

Effects of exercise and L-arginine on ventricular remodeling and oxidative stress.

PubMed

Xu, Xiaohua; Zhao, Weiyan; Lao, Shunhua; Wilson, Bryan S; Erikson, John M; Zhang, John Q

2010-02-01

Our aim was to characterize the changes in messenger RNA (mRNA) abundance, protein, and activity levels of the enzymatic antioxidants, superoxide dismutase (SOD), glutathione peroxidase, and catalase by exercise training combined with L-arginine after myocardial infarction (MI). L-Arginine (1 g x kg(-1) x d(-1)) and N(G)-nitro-L-arginine methyl ester (L-NAME; 10 mg x kg(-1) x d(-1)) were administered in drinking water for 8 wk. Sprague-Dawley rats were randomized to the following groups: sham-operated control (Sham); MI sedentary (Sed); MI exercise (Ex); MI sedentary + L-arginine (Sed + LA); MI exercise + L-arginine (Ex + LA); MI sedentary + L-NAME (Sed + L-NAME); and MI exercise + L-NAME (Ex + L-NAME). The glutathione peroxidase, catalase, and gp91(phox) mRNA levels were comparable among all the groups. The SOD mRNA level was significantly increased in the Ex group (5.43 +/- 0.87) compared with the Sed group (1.74 +/- 0.29), whereas this effect was pronouncedly down-regulated by the L-NAME intervention (2.51 +/- 1.17, P < 0.05). The protein levels of SOD in the Sed and Ex groups were both significantly decreased with the administration of L-NAME. The protein levels of catalase were significantly higher in the Ex and Ex + LA groups than that in the Sed, Sed + LA, and L-NAME-treated groups. The collagen volume fraction was significantly lowered by the exercise and/or L-arginine treatment when compared with the Sed group. Fractional shortening was significantly preserved in the trained groups compared with their corresponding sedentary groups with or without drug treatments. However, the beneficial effect was not further improved by L-arginine treatment. Our results suggest that exercise training exerts antioxidative effects and attenuates myocardial fibrosis in the MI rats. These improvements, in turn, alleviate cardiac stiffness and preserve post-MI cardiac function. In addition, L-arginine appears to have no additive effect on cardiac function or expression of enzymatic antioxidants.

Regression of left ventricular hypertrophy and aortic remodelling in NO-deficient hypertensive rats: effect of L-arginine and spironolactone.

PubMed

Paulis, L; Matuskova, J; Adamcova, M; Pelouch, V; Simko, J; Krajcirovicova, K; Potacova, A; Hulin, I; Janega, P; Pechanova, O; Simko, F

2008-09-01

We investigated, whether the substrate for nitric oxide (NO) formation -L-arginine - and the aldosterone receptor antagonist - spironolactone - are able to reverse alterations of the left ventricle (LV) and aorta in N(omega)-nitro-L-arginine methyl ester (L-NAME)-induced hypertension. Six groups of male adult Wistar rats were investigated: controls after 4 and 7 weeks of experiment, rats treated with L-NAME for 4 weeks and three recovery groups: spontaneous-reversion (4 weeks L-NAME + 3 weeks placebo), spironolactone-induced reversion (4 weeks L-NAME + 3 weeks spironolactone) and L-arginine-induced reversion (4 weeks L-NAME+ 3 weeks L-arginine). Blood pressure was measured by tail-cuff plethysmography. Relative weight of the LV, myocardial fibrosis (based upon histomorphometry and hydroxyproline determination) and conjugated dienes in the LV and aortic cross-sectional area, inner diameter and wall thickness were determined. NO-synthase activity was investigated in the LV and aorta. L-NAME administration induced hypertension, left ventricular hypertrophy (LVH), LV fibrosis, aortic thickening and diminution of NO-synthase activity in the LV and aorta. Reduction in blood pressure and regression of LVH were observed in all recovery groups, yet reduction in LV fibrosis and aortic thickening were not. NO-synthase activity was restored only in the L-arginine and spironolactone group. In our study, the reversion of hypertension and LVH was not dependent on the restoration of NO-synthase activity. Moreover, LV fibrosis and aortic remodelling seem to be more resistant to conditions resulting in regression of LVH. Preserved level of fibrosis in the initial period of LVH regression might result in loss of structural homogeneity and possible functional alterations of the LV.

Evidence that spinal segmental nitric oxide mediates tachyphylaxis to peripheral local anesthetic nerve block.

PubMed

Wang, C; Sholas, M G; Berde, C B; DiCanzio, J; Zurakowski, D; Wilder, R T

2001-09-01

Tachyphylaxis to sciatic nerve blockade in rats correlates with hyperalgesia. Spinal inhibition of nitric oxide synthase with N(G)nitro-L-arginine methyl ester (L-NAME) has been shown to prevent hyperalgesia. Given systemically, L-NAME also prevents tachyphylaxis. The action of L-NAME in preventing tachyphylaxis therefore may be mediated at spinal sites. We compared systemic versus intrathecal potency of L-NAME in modulating tachyphylaxis to sciatic nerve block. Rats were prepared with intrathecal catheters. Three sequential sciatic nerve blocks were placed. Duration of block of thermal nocifensive, proprioceptive and motor responses was recorded. We compared spinal versus systemic dose-response to L-NAME, and examined effects of intrathecal arginine on tachyphylaxis. An additional group of rats underwent testing after T10 spinal cord transection. In these rats duration of sciatic nerve block was assessed by determining the heat-induced flexion withdrawal reflex. L-NAME was 25-fold more potent in preventing tachyphylaxis given intrathecally than intraperitoneally. Intrathecal arginine augmented tachyphylaxis. Spinalized rats exhibited tachyphylaxis to sciatic block. The increased potency of intrathecal versus systemic L-NAME suggests a spinal site of action in inhibiting tachyphylaxis. Descending pathways are not necessary for the development of tachyphylaxis since it occurs even after T10 spinal cord transection. Thus tachyphylaxis, like hyperalgesia, is mediated at least in part by a spinal site of action.

The role of inducible nitric oxide synthase in vascular hyporeactivity of endotoxin-treated and portal hypertensive rats.

PubMed

Heinemann, A; Stauber, R E

1995-05-04

The involvement of the inducible nitric oxide (NO) synthase in the vascular hyporeactivity in portal vein-ligated rats was assessed in isolated perfused mesenteric arterial beds. Aminoguanidine, a selective inhibitor of the inducible NO synthase, restored the pressor responses to methoxamine in arteries of endotoxin-treated rats, but was ineffective in hyporeactive portal vein-ligated vessels. NG-Nitro-L-arginine methyl ester enhanced the responsiveness both in portal vein-ligated and sham-operated rats, without changing the difference between the two groups. These results not only indicate that the inducible NO synthase is not involved in the hyporeactivity to methoxamine in mesenteric arteries of portal hypertensive rats, but also suggest a role for factors other than NO.

Arginase Inhibition Restores Peroxynitrite-Induced Endothelial Dysfunction via L-Arginine-Dependent Endothelial Nitric Oxide Synthase Phosphorylation

PubMed Central

Nguyen, Minh Cong; Park, Jong Taek; Jeon, Yeong Gwan; Jeon, Byeong Hwa; Hoe, Kwang Lae; Kim, Young Myeong

2016-01-01

Purpose Peroxynitrite plays a critical role in vascular pathophysiology by increasing arginase activity and decreasing endothelial nitric oxide synthase (eNOS) activity. Therefore, the aims of this study were to investigate whether arginase inhibition and L-arginine supplement could restore peroxynitrite-induced endothelial dysfunction and determine the involved mechanism. Materials and Methods Human umbilical vein endothelial cells (HUVECs) were treated with SIN-1, a peroxynitrite generator, and arginase activity, nitrite/nitrate production, and expression levels of proteins were measured. eNOS activation was evaluated via Western blot and dimer blot analysis. We also tested nitric oxide (NO) and reactive oxygen species (ROS) production and performed a vascular tension assay. Results SIN-1 treatment increased arginase activity in a time- and dose-dependent manner and reciprocally decreased nitrite/nitrate production that was prevented by peroxynitrite scavenger in HUVECs. Furthermore, SIN-1 induced an increase in the expression level of arginase I and II, though not in eNOS protein. The decreased eNOS phosphorylation at Ser1177 and the increased at Thr495 by SIN-1 were restored with arginase inhibitor and L-arginine. The changed eNOS phosphorylation was consistent in the stability of eNOS dimers. SIN-1 decreased NO production and increased ROS generation in the aortic endothelium, all of which was reversed by arginase inhibitor or L-arginine. NG-Nitro-L-arginine methyl ester (L-NAME) prevented SIN-1-induced ROS generation. In the vascular tension assay, SIN-1 enhanced vasoconstrictor responses to U46619 and attenuated vasorelaxant responses to acetylcholine that were reversed by arginase inhibition. Conclusion These findings may explain the beneficial effect of arginase inhibition and L-arginine supplement on endothelial dysfunction under redox imbalance-dependent pathophysiological conditions. PMID:27593859

Arginase Inhibition Restores Peroxynitrite-Induced Endothelial Dysfunction via L-Arginine-Dependent Endothelial Nitric Oxide Synthase Phosphorylation.

PubMed

Nguyen, Minh Cong; Park, Jong Taek; Jeon, Yeong Gwan; Jeon, Byeong Hwa; Hoe, Kwang Lae; Kim, Young Myeong; Lim, Hyun Kyo; Ryoo, Sungwoo

2016-11-01

Peroxynitrite plays a critical role in vascular pathophysiology by increasing arginase activity and decreasing endothelial nitric oxide synthase (eNOS) activity. Therefore, the aims of this study were to investigate whether arginase inhibition and L-arginine supplement could restore peroxynitrite-induced endothelial dysfunction and determine the involved mechanism. Human umbilical vein endothelial cells (HUVECs) were treated with SIN-1, a peroxynitrite generator, and arginase activity, nitrite/nitrate production, and expression levels of proteins were measured. eNOS activation was evaluated via Western blot and dimer blot analysis. We also tested nitric oxide (NO) and reactive oxygen species (ROS) production and performed a vascular tension assay. SIN-1 treatment increased arginase activity in a time- and dose-dependent manner and reciprocally decreased nitrite/nitrate production that was prevented by peroxynitrite scavenger in HUVECs. Furthermore, SIN-1 induced an increase in the expression level of arginase I and II, though not in eNOS protein. The decreased eNOS phosphorylation at Ser1177 and the increased at Thr495 by SIN-1 were restored with arginase inhibitor and L-arginine. The changed eNOS phosphorylation was consistent in the stability of eNOS dimers. SIN-1 decreased NO production and increased ROS generation in the aortic endothelium, all of which was reversed by arginase inhibitor or L-arginine. N(G)-Nitro-L-arginine methyl ester (L-NAME) prevented SIN-1-induced ROS generation. In the vascular tension assay, SIN-1 enhanced vasoconstrictor responses to U46619 and attenuated vasorelaxant responses to acetylcholine that were reversed by arginase inhibition. These findings may explain the beneficial effect of arginase inhibition and L-arginine supplement on endothelial dysfunction under redox imbalance-dependent pathophysiological conditions.

Peripheral NMDA Receptor/NO System Blockage Inhibits Itch Responses Induced by Chloroquine in Mice

PubMed Central

Haddadi, Nazgol-Sadat; Foroutan, Arash; Ostadhadi, Sattar; Azimi, Ehsan; Rahimi, Nastaran; Nateghpour, Mehdi; Lerner, Ethan A.; Dehpour, Ahmad Reza

2017-01-01

Intradermal administration of chloroquine (CQ) provokes scratching behavior in mice. Chloroquine-induced itch is histamine-independent and we have reported that the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway is involved in CQ-induced scratching behavior in mice. Previous studies have demonstrated that activation of N-methyl-d-aspartate receptors (NMDARs) induces NO production. Here we show that NMDAR antagonists significantly decrease CQ-induced scratching in mice while a non-effective dose of an NMDAR agonist potentiates the scratching behavior provoked by sub-effective doses of CQ. In contrast, combined pre-treatment with sub-effective doses of an NMDAR antagonist, MK-801, and the NO synthase inhibitor, L-N-nitro arginine methyl ester (L-NAME), decreases CQ-induced scratching behavior. While intradermal administration of CQ significantly increases the concentration of intradermal nitrite, the end product of NO metabolism, effective doses of intraperitoneal and intradermal MK-801 significantly decrease intradermal nitrite levels. Likewise, administration of an effective dose of L-NAME significantly decreases CQ-induced nitrite production. We conclude that the NMDA/NO pathway in the skin modulates CQ-induced scratching behavior. PMID:28119997

Role of the anterior region of the third ventricle in the cardiovascular responses produced by systemic injection of a nitric oxide synthase inhibitor

NASA Technical Reports Server (NTRS)

Lewis, S. J.; Whalen, E. J.; Beltz, T. G.; Johnson, A. K.

1999-01-01

This study examined whether a prior electrolytic lesion of the tissue surrounding the anteroventral third ventricle (AV3V) would affect the increase in mean arterial blood pressure (MAP) and the fall in heart rate (HR) produced by systemic injection of the nitric oxide synthesis (NOS) inhibitor, NG-nitro-L-arginine methyl ester (L-NAME; 25 micromol/kg, i.v.) in conscious rats. L-NAME produced a smaller increase in MAP in AV3V-lesion than in sham-lesion rats (+19+/-3 vs. +40+/-3 mmHg, respectively; P<0.05). In contrast, L-NAME produced similar falls in HR in the AV3V-lesion and sham-lesion rats (-103+/-15 vs. -97+/-8 bpm, respectively; P<0.05). These findings demonstrate that the L-NAME-induced pressor response is dependent upon the integrity of the AV3V region, whereas the L-NAME-induced bradycardia is not. Copyright 1999 Elsevier Science B. V.

Enteral Arginine Does Not Increase Superior Mesenteric Arterial Blood Flow but Induces Mucosal Growth in Neonatal Pigs123

PubMed Central

Puiman, Patrycja J.; Stoll, Barbara; van Goudoever, Johannes B.; Burrin, Douglas G.

2011-01-01

Arginine is an essential amino acid in neonates synthesized by gut epithelial cells and a precursor for NO that regulates vasodilatation and blood flow. Arginine supplementation has been shown to improve intestinal integrity in ischemia-reperfusion models and low plasma levels are associated with necrotizing enterocolitis. We hypothesized that enteral arginine is a specific stimulus for neonatal intestinal blood flow and mucosal growth under conditions of total parenteral nutrition (TPN) or partial enteral nutrition (PEN). We first tested the dose dependence and specificity of acute (3 h) enteral arginine infusion on superior mesenteric artery (SMA) blood flow in pigs fed TPN or PEN. We then determined whether chronic (4 d) arginine supplementation of PEN increases mucosal growth and if this was affected by treatment with the NO synthase inhibitor, NG-nitro-l-arginine methyl ester (L-NAME). Acute enteral arginine infusion increased plasma arginine dose dependently in both TPN and PEN groups, but the plasma response was markedly higher (100–250%) in the PEN group than in the TPN group at the 2 highest arginine doses. Baseline SMA blood flow was 90% higher in the PEN (2.37 ± 0.32 L⋅kg−1⋅h−1) pigs than in the TPN pigs (1.23 ± 0.17 L⋅kg−1⋅h−1), but was not affected by acute infusion individually of arginine, citrulline, or other major gut fuels. Chronic dietary arginine supplementation in PEN pigs induced mucosal growth in the intestine, but this effect was not prevented by treatment with L-NAME. Intestinal crypt cell proliferation, protein synthesis, and phosphorylation of mammalian target of rapamycin and p70S6 kinase were not affected by dietary arginine. We conclude that partial enteral feeding, but not acute enteral arginine, increases SMA blood flow in the neonatal pig. Furthermore, supplementing arginine in partial enteral feeding modestly increases intestinal mucosal growth and was NO independent. PMID:21106927

Nitric oxide mediates lung injury induced by ischemia-reperfusion in rats.

PubMed

Kao, Shang Jyh; Peng, Tai-Chu; Lee, Ru Ping; Hsu, Kang; Chen, Chao-Fuh; Hung, Yu-Kuen; Wang, David; Chen, Hsing I

2003-01-01

Nitric oxide (NO) has been reported to play a role in lung injury (LI) induced by ischemia-reperfusion (I/R). However, controversy exists as to the potential beneficial or detrimental effect of NO. In the present study, an in situ, perfused rat lung model was used to study the possible role of NO in the LI induced by I/R. The filtration coefficient (Kfc), lung weight gain (LWG), protein concentration in the bronchoalveolar lavage (PCBAL), and pulmonary arterial pressure (PAP) were measured to evaluate the degree of pulmonary hypertension and LI. I/R resulted in increased Kfc, LWG, and PCBAL. These changes were exacerbated by inhalation of NO (20-30 ppm) or 4 mM L-arginine, an NO precursor. The permeability increase and LI caused by I/R could be blocked by exposure to 5 mM N omega-nitro-L-arginine methyl ester (L-NAME; a nonspecific NO synthase inhibitor), and this protective effect of L-NAME was reversed with NO inhalation. Inhaled NO prevented the increase in PAP caused by I/R, while L-arginine had no such effect. L-NAME tended to diminish the I/R-induced elevation in PAP, but the suppression was not statistically significant when compared to the values in the I/R group. These results indicate that I/R increases Kfc and promotes alveolar edema by stimulating endogenous NO synthesis. Exogenous NO, either generated from L-arginine or delivered into the airway, is apparently also injurious to the lung following I/R. Copyright 2003 National Science Council, ROC and S. Karger AG, Basel

L-arginine and arginine analogues: effects on isolated blood vessels and cultured endothelial cells.

PubMed Central

Schmidt, H. H.; Baeblich, S. E.; Zernikow, B. C.; Klein, M. M.; Böhme, E.

1990-01-01

1. The present study examined effects of arginine (Arg) and various Arg analogues on the vascular tone of rabbit and rat aortic rings, the release of nitrite from cultured bovine aortic endothelial cells and the metabolism of L-Arg in bovine and porcine endothelial cell homogenates. The respective D-enantiomers or N-alpha-benzoyl-L-arginine ethyl ester did not substitute for L-Arg. 2. In bovine aortic endothelial cells, the release of nitrite was only observed in the presence of L-Arg or L-Arg methyl ester in the cell culture medium. 3. In dialyzed homogenates of porcine and bovine aortic endothelial cells, L-Arg was metabolized independently of NADPH and Ca2+ to yield L-ornithine (L-Orn) and L-citrulline (L-Cit). No concomitant nitrite formation was detected. 4. Pretreatment of rabbit and rat aortic rings with L-canavanine (L-Can) or NG-monomethyl-L-Arg (L-NMMA) inhibited ATP- and acetylcholine-induced relaxations (endothelium-dependent) but not glyceryltrinitrate-induced relaxations (endothelium-independent). 5. In rabbit aortic rings, Arg and monomeric Arg analogues induced endothelium-independent relaxations. L-Arg methyl ester induced an endothelium-independent contraction, and L-NMMA induced a relaxation in the absence of endothelium and a contraction in the presence of endothelium. Polymeric basic amino acids such as poly L-Arg induced endothelium-dependent relaxations (inhibited by L-Can), a subsequent refractoriness to endothelium-dependent vasodilators (not prevented by L-Can) and endothelial cell death.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2282457

Dependence of endotoxin-induced vascular hyporeactivity on extracellular L-arginine.

PubMed

Schott, C A; Gray, G A; Stoclet, J C

1993-01-01

1. The dependence on extracellular L-arginine of vascular hyporeactivity induced by bacterial lipopolysaccharide (LPS) was studied in vivo in rats infused with LPS and in vitro in endothelium-denuded rat thoracic aortic rings exposed to LPS. 2. Infusion of LPS during 50 min at a dose of 10 mg kg-1 h-1 produced a significant impairment of the pressor effect of noradrenaline, while in tissues collected 60 min after the start of LPS infusion, no significant alteration in either plasma arginine concentration or aortic arginine content was found compared to saline-infused controls (where plasma arginine was 78.5 +/- 7 microM and aortic arginine 394 +/- 124 nmol g-1 tissue). 3. Incubation of isolated, endothelium-denuded aortic rings with LPS (10 micrograms ml-1) in the absence of L-arginine for 4 h at 37 degrees C produced a 6 fold (P < 0.01) rightward shift in the noradrenaline concentration-effect curve compared to polymyxin B (1 micrograms ml-1, a LPS neutralizing agent) and reduced by 15% the maximum observed tension. 4. The presence of L-arginine (100 microM) during the incubation with LPS and throughout the following contraction experiments caused a 15 fold (P < 0.01) increase in the EC50 of noradrenaline and greater depression (45%) of the maximum observed tension compared to polymyxin B-treated controls. Responses in control, non LPS-treated rings were unaffected by the presence of L-arginine. 5. The addition of L-arginine to rings incubated with LPS in the absence of L-arginine and maximally precontracted with noradrenaline (10 microM) induced a dose-dependent relaxation. The EC50 of L-arginine was 8.0+/-0.3mu.6. The reactivity of LPS-treated rings to noradrenaline both in the absence and presence of L-arginine was restored to control levels by N0-nitro-L-arginine methyl ester (L-NAME, 300 mu), an inhibitor of NO production and by methylene blue (3 JAM), an inhibitor of guanylate cyclase.7. Incubation of isolated aortae in the absence of L-arginine did not significantly decrease the tissue arginine content, whether LPS (10 fg ml-') was present or not. Similarly, the presence of L-arginine(100 mu) in the incubation medium did not modify the tissue arginine content.8. These results show that the LPS-induced impairment of vasoconstriction elicited by noradrenaline is dependent on extracellular L-arginine, although the tissue arginine content is not depleted after LPS pretreatment, and that circulating L-arginine is sufficient to activate maximally the vascular L-arginine/NO pathway in endotoxaemic rats.

Endothelial cellular senescence is inhibited by nitric oxide: Implications in atherosclerosis associated with menopause and diabetes

PubMed Central

Hayashi, Toshio; Matsui-Hirai, Hisako; Miyazaki-Akita, Asaka; Fukatsu, Akiko; Funami, Jun; Ding, Qun-Fang; Kamalanathan, Sumitra; Hattori, Yuichi; Ignarro, Louis J.; Iguchi, Akihisa

2006-01-01

Senescence may contribute to the pathogenesis of atherosclerosis. Although the bioavailability of nitric oxide (NO) is limited in senescence, the effect of NO on senescence and its relationship to cardiovascular risk factors have not been investigated fully. We studied these factors by investigating senescence-associated β-galactosidase (SA-β-gal) and human telomerase activity in human umbilical venous endothelial cells (HUVECs). Treatment with NO donor (Z)-1-[2-(2-aminoethyl)-N-(2-aminoethyl)amino]diazen-1-ium-1,2-diolate (DETA-NO) and transfection with endothelial NO synthase (eNOS) into HUVECs each decreased the number of SA-β-gal positive cells and increased telomerase activity. The NOS inhibitor NG-nitro-l-arginine methyl ester (l-NAME) abolished the effect of eNOS transfection. The physiological concentration of 17β-estradiol activated hTERT, decreased SA-β-gal-positive cells, and caused cell proliferation. However, ICI 182780, an estrogen receptor-specific antagonist, and l-NAME each inhibited these effects. Finally, we investigated the effect of NO bioavailability on high glucose-promoted cellular senescence of HUVECs. Inhibition by eNOS transfection of this cellular senescence under high glucose conditions was less pronounced. Treatment with l-arginine or l-citrulline of eNOS-transfected cells partially inhibited, and combination of l-arginine and l-citrulline with antioxidants strongly prevented, high glucose-induced cellular senescence. These data demonstrate that NO can prevent endothelial senescence, thereby contributing to the anti-senile action of estrogen. The ingestion of NO-boosting substances, including l-arginine, l-citrulline, and antioxidants, can delay endothelial senescence under high glucose. We suggest that the delay in endothelial senescence through NO and/or eNOS activation may have clinical utility in the treatment of atherosclerosis in the elderly. PMID:17075048

The interaction of central nitrergic and GABAergic systems on food intake in neonatal layer-type chicks.

PubMed

Mokhtarpouriani, Kasra; Zendehdel, Morteza; Jonaidi, Hossein; Babapour, Vahab; Shayan, Parviz

2016-05-01

Most physiological behaviors such as food intake are controlled by the hypothalamus and its nuclei. It has been demonstrated that injection of the paraventricular nucleus of the hypothalamus with nitric oxide (NO) donors elicited changes in the concentration of some amino acids, including GABA. Also, central nitrergic and GABAergic systems are known to provide inputs to the paraventricular nucleus and are involved in food intake control. Therefore, the present study examines the probable interaction of central nitrergic and GABAergic systems on food intake in neonatal layer-type chicks. The results of this study showed that intracerebroventricular (ICV) injection of L-arginine (400 and 800 nmol), as a NO donor, significantly decreased food intake (P < 0.001), but ICV injection of Nω-Nitro-L-arginine methyl ester (L-NAME) (200 and 400 nmol), a NO synthesis inhibitor, increased food intake (P < 0.001). In addition, the orexigenic effect of gaboxadol (0.2 µg), a GABAA agonist, was significantly attenuated in ICV co-injection of L-arginine (200 nmol) and gaboxadol (0.2 µg) (P < 0.001), but it was significantly amplified in ICV co-injection of L-NAME (100 nmol) and gaboxadol (0.2 µg) (P < 0.001). On the other hand, the orexigenic effect of baclofen (0.2 µg), a GABAB agonist, did not change in ICV co-injection of L-arginine (200 nmol) or L-NAME (100 nmol) with baclofen (0.2 µg) (P > 0.05). Also, the hypophagic effect of L-arginine (800 nmol) was significantly amplified in ICV co-injection of picrotoxin (0.5 µg), a GABAA antagonist, or CGP54626 (21 ng), a GABAB antagonist, with L-arginine (800 nmol) (P < 0.001). These results probably suggest an interaction of central nitrergic and GABAergic systems on food intake in neonatal layer-type chicks and GABAA receptors play a major role in this interaction.

Effects of propolis, caffeic acid phenethyl ester, and pollen on renal injury in hypertensive rat: An experimental and theoretical approach.

PubMed

Salmas, Ramin Ekhteiari; Gulhan, Mehmet Fuat; Durdagi, Serdar; Sahna, Engin; Abdullah, Huda I; Selamoglu, Zeliha

2017-08-01

The objective of this study was to evaluate the antioxidant effects of propolis, caffeic acid phenethyl ester (CAPE; active compound in propolis), and pollen on biochemical oxidative stress biomarkers in rat kidney tissue inhibited by N ω -nitro-L-arginine methyl ester (L-NAME). The biomarkers evaluated were paraoxonase (PON1), oxidative stress index (OSI), total antioxidant status (TAS), total oxidant status (TOS), asymmetric dimethylarginine (ADMA), and nuclear factor kappa B (NF-κB). TAS levels and PON1 activity were significantly decreased in kidney tissue samples in the L-NAME-treated group (P < 0.05). The levels of TAS and PONI were higher in the L-NAME plus propolis, CAPE, and pollen groups compared with the L-NAME-treated group. TOS, ADMA, and NF-κB levels were significantly increased in the kidney tissue samples of the L-NAME-treated group (P < 0.05). However, these parameters were significantly lower in the L-NAME plus propolis, CAPE, and pollen groups (P < 0.05) compared with rats administered L-NAME alone (P < 0.05). Furthermore, the binding energy of CAPE within catalytic domain of glutathione reductase (GR) enzyme as well as its inhibitory mechanism was determined using molecular modeling approaches. In conclusion, experimental and theoretical data suggested that oxidative alterations occurring in the kidney tissue of chronic hypertensive rats may be prevented via active compound of propolis, CAPE administration. Copyright © 2017 John Wiley & Sons, Ltd.

Role of intrinsic nitrergic neurones on vagally mediated striated muscle contractions in the hamster oesophagus

PubMed Central

Izumi, Noriaki; Matsuyama, Hayato; Ko, Mifa; Shimizu, Yasutake; Takewaki, Tadashi

2003-01-01

Oesophageal peristalsis is controlled by vagal motor neurones, and intrinsic neurones have been identified in the striated muscle oesophagus. However, the effect(s) of intrinsic neurones on vagally mediated contractions of oesophageal striated muscles has not been defined. The present study was designed to investigate the role of intrinsic neurones on vagally evoked contractions of oesophageal striated muscles, using hamster oesophageal strips maintained in an organ bath. Stimulation (30 μs, 20 V) of the vagus nerve trunk produced twitch contractions. Piperine inhibited vagally evoked contractions, while capsaicin and NG-nitro-L-arginine methyl ester (L-NAME) abolished the inhibitory effect of piperine. The effect of L-NAME was reversed by subsequent addition of L-arginine, but not by D-arginine. L-NAME did not have any effect on the vagally mediated contractions and presumed 3H-ACh release. NONOate, a nitric oxide donor, and dibutyryl cyclic GMP inhibited twitch contractions. Inhibition of vagally evoked contractions by piperine and NONOate was fully reversed by ODQ, an inhibitor of guanylate cyclase. Immunohistochemical staining showed immunoreactivity for nitric oxide synthase (NOS) in nerve cell bodies and fibres in the myenteric plexus and the presence of choline acetyltransferase and NOS in the motor endplates. Only a few NOS-immunoreactive portions in the myenteric plexus showed vanilloid receptor 1 (VR1) immunoreactivity. Our results suggest that there is a local neural reflex that involves capsaicin-sensitive neurones, nitrergic myenteric neurones and vagal motor neurones. PMID:12813149

Involvement of NO/cGMP pathway in the antidepressant-like effect of gabapentin in mouse forced swimming test.

PubMed

Ostadhadi, Sattar; Kordjazy, Nastaran; Haj-Mirzaian, Arya; Ameli, Sanaz; Akhlaghipour, Golnoosh; Dehpour, AhmadReza

2016-04-01

Based on clinical studies regarding the beneficial effect of gabapentin in depression, we aimed to evaluate the antidepressant-like properties of gabapentin in mice and also the participation of nitric oxide (NO)/cyclic guanosine monophosphate pathway in this effect. The following drugs were used in this study: gabapentin; N(G)-nitro-L-arginine methyl ester (L-NAME), a non-specific NO synthase (NOS) inhibitor; 7-nitroindazole, a specific neuronal NOS inhibitor; aminoguanidine, a specific inducible NOS inhibitor; L-arginine, a NO precursor; and sildenafil, a phosphodiestrase inhibitor. Finally, we studied the behavioral effects through the forced swimming test (FST) and the changes of the hippocampus NO level through nitrite assay. The immobility time was significantly reduced after gabapentin administration. Co-administration of non-effective doses of gabapentin and L-NAME or 7-nitroindazole (7-NI) resulted in antidepressant-like effect in FST, while aminoguanidine did not affect the immobility time of gabapentin-treated mice. Furthermore, the antidepressant-like property of gabapentin was prevented by L-arginine or sildenafil. Also, the hippocampal nitrite level was significantly lower in gabapentin-treated mice relative to saline-injected mice, and co-administration of 7-NI with sub-effective gabapentin caused a significant decrease in hippocampal nitrite levels. Our results indicate that the antidepressant-like effect of gabapentin in the mice FST model is mediated at least in part through nitric oxide/cyclic guanosine monophosphate (cGMP) pathway.

Nitric oxide synthase and soluble guanylate cyclase are involved in spinal cord wind-up activity of monoarthritic, but not of normal rats.

PubMed

Laurido, Claudio; Hernández, Alejandro; Constandil, Luis; Pelissier, Teresa

2003-11-27

While increasing evidence points to a role for the nitric oxide (NO)/cyclic guanosine 3,5-monophosphate (GMPc) cascade in hyperalgesia and allodynia, participation of the NO/GMPc pathway in synaptic processing in the spinal cord, i.e. wind-up activity, is less clear. We studied the effects of intrathecal administration of Nomega-nitro-L-arginine methyl ester (L-NAME) and methylene blue, inhibitors of NO synthase and guanylate cyclase respectively, on wind-up activity developed in a C-fiber reflex response paradigm. 5, 10 and 20 microg i.t. of L-NAME or methylene blue did not modify spinal wind-up in normal rats, while a dose-dependent inhibition of wind-up was observed in monoarthritic rats. Results suggest that the NO/GMPc pathway plays a non-significant role in wind-up activity evoked in normal animals, while it may be essential in chronic pain processing.

Effects of quercetin on heart nitric oxide metabolism in l-NAME treated rats.

PubMed

Calabró, Valeria; Litterio, María C; Fraga, Cesar G; Galleano, Monica; Piotrkowski, Barbara

2018-06-01

This study investigated the effects of a quercetin-supplemented diet on the biochemical changes installed in the heart of NO-deficient rats in terms of oxidants production and NO bioavailability determinants. Sprague-Dawley rats were subjected to N ω -nitro-l-arginine methyl ester (l-NAME) treatment (360 mg/L l-NAME in the drinking water, 4 d) with or without supplementation with quercetin (4 g/kg diet). l-NAME administration led to increased blood pressure (BP) (30%), decreased nitric oxide synthase (NOS) activity (50%), and increases in NADPH oxidase (NOX)-dependent superoxide anion production (60%) and p47 phox protein level (65%). The co-administration of quercetin prevented the increase in BP and the activation of NOX but did not modify the decrease in NOS activity caused by l-NAME. In addition, quercetin affected oxidative stress parameters as glutathione oxidation, and the activities of oxidant detoxifying enzymes superoxide dismutase, glutathione peroxidase, and catalase. Thus, quercetin administration counteracts l-NAME effects on NO bioavailability determinants in vivo, essentially through controlling NOX-mediated superoxide anion production. Copyright © 2018. Published by Elsevier Inc.

Decreased Arteriolar Tetrahydrobiopterin is Linked to Superoxide Generation from Nitric Oxide Synthase in Mice Fed High Salt

PubMed Central

Nurkiewicz, Timothy R.; Wu, Guoyao; Li, Peng; Boegehold, Matthew A.

2012-01-01

Objective Impaired endothelium-dependent arteriolar dilation in mice fed high salt is due to local oxidation of nitric oxide (NO) by superoxide anion (O2-). We explored the possibility that “uncoupled” endothelial nitric oxide synthase (eNOS) is the source of this O2-. Methods Levels of L-arginine (L-Arg), tetrahydrobiopterin (BH4) and O2- (hydroethidine oxidation) were measured in spinotrapezius muscle arterioles of mice fed normal salt (0.45%, NS) or high salt (4%, HS) diets for 4 weeks, with or without dietary L-Arg supplementation. The contribution of NO to endothelium-dependent dilation was determined from the effect of Nω-nitro-L-arginine methyl ester (L-NAME) on responses to acetylcholine (ACh). Results Arterioles in HS mice had lower [BH4] and higher O2- levels than those in NS mice. ACh further increased arteriolar O2- in HS mice only. L-Arg supplementation prevented the reduction in [BH4] in arterioles of HS mice, and O2- was not elevated in these vessels. Compared to NS mice, arteriolar ACh responses were diminished and insensitive to L-NAME in HS mice, but not in HS mice supplemented with L-Arg. Conclusions These findings suggest that eNOS uncoupling due to low [BH4] is responsible for O2- generation and reduced NO-dependent dilation in arterioles of mice fed a high salt diet. PMID:20163541

Kinetics of the hydrolysis of N-benzoyl-l-serine methyl ester catalysed by bromelain and by papain. Analysis of modifier mechanisms by lattice nomography, computational methods of parameter evaluation for substrate-activated catalyses and consequences of postulated non-productive binding in bromelain- and papain-catalysed hydrolyses

PubMed Central

Wharton, Christopher W.; Cornish-Bowden, Athel; Brocklehurst, Keith; Crook, Eric M.

1974-01-01

1. N-Benzoyl-l-serine methyl ester was synthesized and evaluated as a substrate for bromelain (EC 3.4.22.4) and for papain (EC 3.4.22.2). 2. For the bromelain-catalysed hydrolysis at pH7.0, plots of [S0]/vi (initial substrate concn./initial velocity) versus [S0] are markedly curved, concave downwards. 3. Analysis by lattice nomography of a modifier kinetic mechanism in which the modifier is substrate reveals that concave-down [S0]/vi versus [S0] plots can arise when the ratio of the rate constants that characterize the breakdown of the binary (ES) and ternary (SES) complexes is either less than or greater than 1. In the latter case, there are severe restrictions on the values that may be taken by the ratio of the dissociation constants of the productive and non-productive binary complexes. 4. Concave-down [S0]/vi versus [S0] plots cannot arise from compulsory substrate activation. 5. Computational methods, based on function minimization, for determination of the apparent parameters that characterize a non-compulsory substrate-activated catalysis are described. 6. In an attempt to interpret the catalysis by bromelain of the hydrolysis of N-benzoyl-l-serine methyl ester in terms of substrate activation, the general substrate-activation model was simplified to one in which only one binary ES complex (that which gives rise directly to products) can form. 7. In terms of this model, the bromelain-catalysed hydrolysis of N-benzoyl-l-serine methyl ester at pH7.0, I=0.1 and 25°C is characterized by Km1 (the dissociation constant of ES)=1.22±0.73mm, k (the rate constant for the breakdown of ES to E+products, P)=1.57×10−2±0.32×10−2s−1, Ka2 (the dissociation constant that characterizes the breakdown of SES to ES and S)=0.38±0.06m, and k′ (the rate constant for the breakdown of SES to E+P+S)=0.45±0.04s−1. 8. These parameters are compared with those in the literature that characterize the bromelain-catalysed hydrolysis of α-N-benzoyl-l-arginine ethyl ester and of α-N-benzoyl-l-arginine amide; Km1 and k for the serine ester hydrolysis are somewhat similar to Km and kcat. for the arginine amide hydrolysis and Kas and k′ for the serine ester hydrolysis are somewhat similar to Km and kcat. for the arginine ester hydrolysis. 9. A previous interpretation of the inter-relationships of the values of kcat. and Km for the bromelain-catalysed hydrolysis of the arginine ester and amide substrates is discussed critically and an alternative interpretation involving substantial non-productive binding of the arginine amide substrate to bromelain is suggested. 10. The parameters for the bromelain-catalysed hydrolysis of the serine ester substrate are tentatively interpreted in terms of non-productive binding in the binary complex and a decrease of this type of binding by ternary complex-formation. 11. The Michaelis parameters for the papain-catalysed hydrolysis of the serine ester substrate (Km=52±4mm, kcat.=2.80±0.1s−1 at pH7.0, I=0.1, 25.0°C) are similar to those for the papain-catalysed hydrolysis of methyl hippurate. 12. Urea and guanidine hydrochloride at concentrations of 1m have only small effects on the kinetic parameters for the hydrolysis of the serine ester substrate catalysed by bromelain and by papain. PMID:4455211

Evidence that tachykinins relax the guinea-pig trachea via nitric oxide release and by stimulation of a septide-insensitive NK1 receptor.

PubMed Central

Figini, M.; Emanueli, C.; Bertrand, C.; Javdan, P.; Geppetti, P.

1996-01-01

1. This study investigated the possibility that tachykinins relax the guinea-pig isolated trachea by releasing nitric oxide (NO) from the epithelium. The types of tachykinin receptor mediating both relaxation and contraction of the trachea were also studied. Isometric tension was recorded in isolated tracheal tube preparations precontracted with acetylcholine (10 microM) in which compounds were administered intraluminally in the presence of phosphoramidon and indomethacin (both 1 microM) and the tachykinin NK2 receptor antagonist, SR 48,968 ((S)-N-methyl-N[4-(4-acetyl amino-4-phenylpiperidino)-2-(3,4-dichlorophenyl)butyl]benzamide), 0.1 microM). 2. In the presence of the inactive enantiomer of an NO-synthase inhibitor, NG-monomethyl-D-arginine (D-NMMA, 100 microM), substance P (SP), neurokinin A (NKA), neurokinin B (NKB) and the selective NK1 receptor agonist, [Sar9, Met(O2)11]-SP, (0.1-10 nM) relaxed tracheal tube preparations. This relaxation was changed into a contraction by pretreatment with the NO-synthase inhibitor, NG-monomethyl-L-arginine (L-NMMA, 100 microM). The effect of L-NMMA on SP- and [Sar9, Met(O2)11]-SP-induced responses was reversed by L-arginine (L-Arg, 1 mM), but not by D-Arg (1 mM). After removal of the epithelium SP, NKA and NKB and [Sar9, Met(O2)11]-SP (0.1-10 nM) evoked contractile responses in the presence of either L-NMMA (100 microM) or D-NMMA (100 microM). The effects of SP and [Sar9, Met(O2)11]-SP obtained in the presence of another NO-synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME, 100 microM) or its inactive enantiomer, NG-nitro-D-arginine methyl ester (D-NAME, 100 microM) were similar to those observed with L-NMMA or D-NMMA, respectively. 3. The selective NK1 receptor agonist, [pGlu6, Pro9]-SP(6-11) (septide, 0.1-10 nM) evoked contractile responses of tracheal tube preparations in the presence of either D-NMMA (100 microM) or L-NMMA (100 microM). The log concentration-response curve to septide obtained in the presence of L-NMMA was similar to that obtained in the presence of D-NMMA. [Sar9, Met(O2)11]-SP (0.1-10 nM) relaxed tracheal tube preparations precontracted with septide (1 microM), whereas septide (0.1 nM-1 microM) further contracted tracheal tube preparations precontracted with [Sar9, Met(O2)11]-SP (1 microM). 4. Relaxant and contractile responses evoked by SP, NKA, NKB and by [Sar9, Met(O2)11]-SP (0.1-10 nM) were not affected by a combination of the histamine H1 (pyrilamine, 1 microM) and H2 (cimetidine, 1 microM) receptor antagonists, but were abolished by the tachykinin NK1 receptor antagonist, CP-99,994 ((2S,3S)-3-(2-methoxybenzylamino)-2-phenylpiperidine, 1 microM), though not by its inactive enantiomer CP-100,263 (1 microM). Contractile responses evoked by septide (10 nM and 1 microM) were also abolished by CP-99,994 (1 microM) but not by CP-100,263 (1 microM). 5. These results demonstrate that tachykinins relax guinea-pig tracheal tube preparations by releasing NO via the stimulation of epithelial NK1 receptors by a mechanism independent of histamine release. The NK1 receptor type involved is sensitive to SP, NKA, NKB and [Sar9, Met(O2)11]-SP but not to septide, and is pharmacologically distinct from the NK1 receptor that mediates contraction, which is stimulated by all the agonists, including septide. PMID:8882625

Magnolol inhibits colonic motility through down-regulation of voltage-sensitive L-type Ca2+ channels of colonic smooth muscle cells in rats.

PubMed

Zhang, Man; Zang, Kai-Hong; Luo, Jia-Lie; Leung, Fung-Ping; Huang, Yu; Lin, Cheng-Yuan; Yang, Zhi-Jun; Lu, Ai-Ping; Tang, Xu-Dong; Xu, Hong-Xi; Sung, Joseph Jao-yiu; Bian, Zhao-Xiang

2013-11-15

This study aimed to investigate the effect of magnolol (5,5'-diallyl-2,2'-biphenyldiol) on contraction in distal colonic segments of rats and the underlying mechanisms. Colonic segments were mounted in organ baths for isometric force measurement. Whole-cell voltage-sensitive L-type Ca(2+) currents were recorded on isolated single colonic smooth muscle cells using patch-clamp technique. The spontaneous contractions and acetylcholine (ACh)- and Bay K 8644-induced contractions were inhibited by magnolol (3-100 μM). In the presence of Bay K8644 (100 nM), magnolol (10-100 μM) inhibited the contraction induced by 10 μM ACh. By contrast, tetrodotoxin (100 nM) and Nώ-nitro-L-arginine methyl ester (L-NAME 100 μM) did not change the inhibitory effect of magnolol (10 μM). In addition, magnolol (3-100 μM) inhibited the L-type Ca(2+) currents. The present results suggest that magnolol inhibits colonic smooth muscle contraction through downregulating L-type Ca(2+) channel activity. Copyright © 2013 Elsevier GmbH. All rights reserved.

Vascular smooth muscle cell polyploidy and cardiomyocyte hypertrophy due to chronic NOS inhibition in vivo.

PubMed

Devlin, A M; Brosnan, M J; Graham, D; Morton, J J; McPhaden, A R; McIntyre, M; Hamilton, C A; Reid, J L; Dominiczak, A F

1998-01-01

To assess the vascular and cardiac response to NO (nitric oxide) synthase (NOS) blockade in vivo, Wistar-Kyoto rats (WKY) were treated for 3 wk with NG-nitro-L-arginine methyl ester (L-NAME; 10 mg.kg-1.day-1). L-NAME treatment induced hypertension that was associated with increased plasma renin activity. Flow cytometry cell cycle DNA analysis showed that aortic vascular smooth muscle cells (VSMC) from L-NAME-treated WKY had a significantly higher polyploid population compared with WKY controls. Using organ bath experiments, we have shown that aortic rings from L-NAME-treated WKY have an increased contractile response to phenylephrine and impaired relaxation to carbachol compared with control rings. NOS blockade in vivo caused a significant increase in cardiac and left ventricular hypertrophy. Northern mRNA analysis of the myocardium showed that L-NAME treatment caused reexpression of the fetal skeletal alpha-actin isoform without alterations in collagen type I expression, a pattern indicating true hypertrophy of the cardiomyocytes. These studies provide further insight to confirm that NO deficiency in vivo results in the development of vascular and cardiac hypertrophy.

Preinduction of heat shock protein 70 protects mice against post-infection irritable bowel syndrome via NF-κB and NOS/NO signaling pathways.

PubMed

Zhou, Xuchun; Dong, Liwei; Yang, Bo; He, Zhoutao; Chen, Yiyao; Deng, Taozhi; Huang, Baili; Lan, Cheng

2015-12-01

This study aimed to investigate the protective effects of preinduction of heat shock protein 70 (HSP70) on Trichinella spiralis infection-induced post-infectious irritable bowel syndrome (PI-IBS) in mice. Trichinella spiralis infection significantly reduced HSP70 abundance, ileal villus height and crypt depth, expression of tight junctions, serum lysine and arginine concentrations, and ileal SCL7A6 and SCL7A7 mRNA levels, induced inflammatory response, and activated NF-κB signaling pathway. Meanwhile, the heat treatment upregulated HSP70 expression, and then reversed intestinal dysfunction and inflammatory response. Preinduction of HSP70 enhanced serum arginine and intestinal SCL7A7 expression and inhibited NF-κB activation compared with PI-IBS model. Treatment with pyrrolidine dithiocarbamate (PDTC, an NF-κB inhibitor) and N-nitro-L-arginine methyl ester hydrochloride (L-NAME, a nitric oxide synthase inhibitor, NOS) further demonstrated that preinduction of HSP70 might inhibit NF-κB and activated NOS/nitric oxide (NO) signaling pathways. In conclusion, preinduction of HSP70 by heat treatment may confer beneficial effects on Trichinella spiralis infection-induced PI-IBS in mice, and the protective effect of HSP70 may be associated with inhibition of NF-κB and stimulation of NOS/NO signaling pathways.

Effects of penicillin on procaine-elicited bursts of potential in central neuron of snail, Achatina fulica.

PubMed

Chen, Yi-Hung; Lu, Kuan-Ling; Hsiao, Ru-Wan; Lee, Ya-Ling; Tsai, Hong-Chieh; Lin, Chia Hsien; Tsai, Ming-Cheng

2008-08-01

Effects of penicillin on changes in procaine-elicited bursts of potential (BoP) were studied in a central neuron (RP4) of snail, Achatina fulica Ferussac. Procaine elicited BoP in the RP4 neuron while penicillin elicited depolarization of the neuron. Penicillin decreased the BoP elicited by procaine in a concentration-dependent manner. The effect of penicillin on the procaine-elicited BoP was not altered in the preparations treated with ascorbate or L-NAME (N-nitro-L-arginine methyl ester). However, the inhibitory effect of penicillin on the procaine-elicited BoP was enhanced with a decrease in extracellular sodium ion. Sodium ion was one of the important ions contributing to the action potential of the neuron. Two-electrode voltage-clamp studies revealed that penicillin decreased the fast sodium inward current of the neuron. It is concluded that penicillin inhibited the BoP elicited by procaine and sodium ion altered the effect of penicillin on procaine-elicited BoP.

Contrasting effects of exercise and NOS inhibition on tissue-specific fatty acid and glucose uptake in mice.

PubMed

Rottman, Jeffrey N; Bracy, Deanna; Malabanan, Carlo; Yue, Zou; Clanton, Jeff; Wasserman, David H

2002-07-01

Isotopic techniques were used to test the hypothesis that exercise and nitric oxide synthase (NOS) inhibition have distinct effects on tissue-specific fatty acid and glucose uptakes in a conscious, chronically catheterized mouse model. Uptakes were measured using the radioactive tracers (125)I-labeled beta-methyl-p-iodophenylpentadecanoic acid (BMIPP) and deoxy-[2-(3)H]glucose (DG) during treadmill exercise with and without inhibition of NOS. [(125)I]BMIPP uptake at rest differed substantially among tissues with the highest levels in heart. With exercise, [(125)I]BMIPP uptake increased in both heart and skeletal muscles. In sedentary mice, NOS inhibition induced by nitro-L-arginine methyl ester (L-NAME) feeding increased heart and soleus [(125)I]BMIPP uptake. In contrast, exercise, but not L-NAME feeding, resulted in increased heart and skeletal muscle [2-(3)H]DG uptake. Significant interactions were not observed in the effects of combined exercise and L-NAME feeding on [(125)I]BMIPP and [2-(3)H]DG uptakes. In the conscious mouse, exercise and NOS inhibition produce distinct patterns of tissue-specific fatty acid and glucose uptake; NOS is not required for important components of exercise-associated metabolic signaling, or other mechanisms compensate for the absence of this regulatory mechanism.

Effect of systemic nitric oxide synthase inhibition on optic disc oxygen partial pressure in normoxia and in hypercapnia.

PubMed

Petropoulos, Ioannis K; Pournaras, Jean-Antoine C; Stangos, Alexandros N; Pournaras, Constantin J

2009-01-01

To investigate the effect of systemic nitric oxide synthase (NOS) inhibition on optic disc oxygen partial pressure (PO(2)) in normoxia and hypercapnia. Intervascular optic disc PO(2) was measured in 12 anesthetized minipigs by using oxygen-sensitive microelectrodes placed <50 microm from the optic disc. PO(2) was measured continuously during 10 minutes under normoxia, hyperoxia (100% O(2)), carbogen breathing (95% O(2), 5% CO(2)), and hypercapnia (increased inhaled CO(2)). Measurements were repeated after intravenous injection of N(omega)-nitro-L-arginine methyl ester (L-NAME) 100 mg/kg. Intravenous L-arginine 100 mg/kg was subsequently given to three animals. Before L-NAME injection, an increase was observed in optic disc PO(2) during hypercapnia (DeltaPO(2) = 3.2 +/- 1.7 mm Hg; 18%; P = 0.001) and carbogen breathing (DeltaPO(2) = 12.8 +/- 5.1 mm Hg; 69%; P < 0.001). Optic disc PO(2) in normoxia remained stable for 30 minutes after L-NAME injection (4% decrease from baseline; P > 0.1), despite a 21% increase of mean arterial pressure. Optic disc PO(2) increase under hypercapnia was blunted after L-NAME injection (DeltaPO(2) = 0.6 +/- 1.1 mm Hg; 3%; P > 0.1), and this effect was reversible by L-arginine. Moreover, L-NAME reduced the response to carbogen by 29% (DeltaPO(2) = 9.1 +/- 4.4 mm Hg; 49%; P = 0.01 versus before L-NAME). The response to hyperoxia was not affected. Whereas systemic NOS inhibition did not affect optic disc PO(2) in normoxia, a blunting effect was noted on the CO(2)-induced optic disc PO(2) increase. Nitric oxide appears to mediate the hypercapnic optic disc PO(2) increase.

Involvement of l-arginine-nitric oxide pathway in anxiolytic-like effects of zinc chloride in rats.

PubMed

Navabi, Seyedeh Parisa; Eshagh Harooni, Hooman; Moazedi, Ahmad Ali; Khajepour, Lotfolah; Fathinia, Kosar

2016-10-01

Zinc is crucial for normal development of the brain, and Zinc deficiency has been shown to associate with neurological disorders (e.g. anxiety) through interactions with several neurotransmitter systems such as nitric oxide (NO). In this regard, our study aimed to evaluate the possible involvement of l-arginine NO pathway on anxiolytic effects of zinc in adult male rats. Zinc chloride at doses of 2.5 and 10mg/kg (intraperitoneal or ip) or saline (1ml/kg, ip) were injected 30min before the anxiety test. Zinc administrated rats (10mg/kg) were pre-treated with intra-CA1 microinjection of l-arginine in sub-effective dose of 1μg/rat (dorsal hippocampus, vehicle: saline1μl/rat). In addition, zinc chloride and NG-nitro-l-arginine methyl ester (l-NAME) were intraperitoneally co-administrated in sub-effective doses of 2.5mg/kg and 80mg/kg, respectively. The percentage of open arm time (OAT%), percentage of open arm entry (OAE%), as measures of anxiety, and total number of arm entries, as measures of locomotor activity, were recorded. Treatment with zinc (10mg/kg) markedly produced an increase in OAT% and OAE% in the Elevated plus maze test (EPM). A decrease of OAT% and OAE% was shown in groups which received zinc (10mg/kg) and l-arginine (1μg/rat) concomitantly as compared to the control group. Moreover, an increase of OAE% was revealed in the group exposed to Zinc (2.5mg/kg) and l-NAME (80mg/kg) co-administration. Although, Two-way ANOVA showed no significant differences of anxiety indices in rats received drug+zinc chloride in compare to the zinc pretreated with saline group. Anxiolytic- like effect of zinc reversed by nitric oxide precursor l-arginine. Additionally, the synergistic effects of l-NAME and ZnCl 2 were shown in the EPM. Thus our findings suggest that at least in part the anxiolytic effects of zinc can be mediated through the nitric oxide system. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Inhibition of nitric oxide production and the effects of arginine and Lactobacillus administration in an acute liver injury model.

PubMed

Adawi, D; Molin, G; Jeppsson, B

1998-12-01

To study the effect of inhibiting nitric oxide production and the effects of arginine and lactobacilli administration in an acute liver injury (LI) model. Infectious complications caused by enteric bacteria are common in patients with liver diseases and those who have undergone liver surgery. Increased bacterial translocation has been proposed as one underlying mechanism. Lactobacilli constitute an integral part of the normal gastrointestinal microecology; they are involved in host metabolism and have many beneficial properties. Arginine has numerous roles in cellular metabolism and may be metabolized by lactobacilli in some cases. We have previously shown that rectal administration of Lactobacillus plantarum DSM 9843 (strain 299v), with and without arginine, in an acute LI model significantly reduces the extent of the LI and reduces bacterial translocation. To clarify the pathogenetic mechanisms, we studied the role of nitric oxide in the effects of L. plantarum and arginine in acute LI, as determined by bacterial translocation, ileal, cecal, and colonic nucleotides, RNA, and DNA. Male Sprague-Dawley rats were used. L. plantarum, 2% arginine, and/or N-nitro-L-arginine methyl ester (L-NAME), as appropriate, were administered rectally once daily for 8 days. Acute LI was induced on the eighth day by intraperitoneal injection of D-galactosamine (1.1 g/kg body weight), and samples were collected after 24 hours. Bacterial translocation was evaluated by culture of portal and arterial blood, mesenteric lymph nodes, and liver tissue. Liver enzymes and bilirubin were assayed in the serum. The bacterial load in the cecum and colon was determined. Ileal, cecal, and colonic mucosal nucleotides, RNA, and DNA were evaluated. The levels of liver enzymes and bilirubin were lower in liver-injured rats supplemented with arginine and Lactobacillus, and this effect was abolished by the addition of L-NAME. Inhibition of nitric oxide production (by L-NAME) increased bacterial translocation in many groups. L-NAME administration increased the cecal and colonic bacterial count and decreased the levels of mucosal nucleotides, RNA, and DNA. Inhibition of nitric oxide production modulated the effects of arginine and L. plantarum in this acute LI model. L-NAME potentiated the LI, as indicated by elevation of liver enzymes and bilirubin, and it also increased bacterial translocation and the cecal and colonic bacterial count. Increased bacterial translocation could be one of the mechanisms by which LI is potentiated.

Intrinsic nitric oxide regulates the taste response of the sugar receptor cell in the blowfly, Phormia regina.

PubMed

Murata, Yoshihiro; Mashiko, Masashi; Ozaki, Mamiko; Amakawa, Taisaku; Nakamura, Tadashi

2004-01-01

The taste organ in insects is a hair-shaped taste sensory unit having four functionally differentiated contact chemoreceptor cells. In the blowfly, Phormia regina, cGMP has been suggested to be a second messenger for the sugar receptor cell. Generally, cGMP is produced by membranous or soluble guanylyl cyclase (sGC), which can be activated by nitric oxide (NO). In the present paper, we electrophysiologically showed that an NO scavenger, 2-phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl (PTIO), an NO donor, 1-hydroxy-2-oxo-3-(N-methyl-3-aminopropyl)-3-methyl-1-triazene (NOC 7) or an NO synthase (NOS) inhibitor, NG-nitro-L-arginine methyl ester (L-NAME) specifically affected the response in the sugar receptor cell, but not in other receptor cells. PTIO, when introduced into the receptor cells in a sensillum aided by sodium deoxycholate (DOC, pH 7.2), depressed the response of sugar receptor cells to sucrose but did not affect those of the salt or water receptor cells. NOC 7, given extracellularly, latently induced the response of sugar receptor cells; and L-NAME, when introduced into the receptor cells, depressed the response of sugar receptor cells. The results clearly suggest that NO, which may be produced by intrinsic NOS in sugar receptor cells, participates in the transduction cascade of these cells in blowfly.

Antidepressant effect of pramipexole in mice forced swimming test: A cross talk between dopamine receptor and NMDA/nitric oxide/cGMP pathway.

PubMed

Ostadhadi, Sattar; Imran Khan, Muhammad; Norouzi-Javidan, Abbas; Dehpour, Ahmad-Reza

2016-07-01

Pramipexole is a dopamine D2 receptor agonist indicated for treating Parkinson disorder. This study was aimed to investigate the effect of pramipexole in forced swimming test (FST) in mice and the possible involvement of activation of D2 receptors and inhibition of N-methyl-d-aspartate (NMDA) receptors and nitric oxide-cyclic guanosine monophosphate (NO-cGMP) on this effect. Intraperitoneal administration of pramipexole (1-3mg/kg) reduced the immobility time in the FST similar to fluoxetine (20mg/kg, i.p.). This effect of pramipexole (1mg/kg, i.p.) was ceased when mice were pretreated with haloperidol (0.15mg/kg, i.p,) and sulpiride (5mg/kg, i.p) as D2 receptor antagonists, NMDA (75mg/kg,i.p.), l-arginine (750mg/kg, i.p., a substrate for nitric oxide synthase) or sildenafil (5mg/kg, i.p., a phosphodiesterase 5 inhibitor). The administration of MK-801 (0.05mg/kg, i.p., a NMDA receptor antagonist) l-NG-Nitro arginine methyl ester (l-NAME, 10mg/kg, i.p., a non-specific nitric oxide synthase (NOS) inhibitor), 7-nitroindazole (30mg/kg, i.p., a neuronal NOS inhibitor) and methylene blue (10mg/kg, i.p.), an inhibitor of both NOS and soluble guanylyl cyclase (sGC) in combination with the sub-effective dose of pramipexole (0.3mg/kg, i.p.) reduced the immobility. Altogether, our data suggest that the antidepressant-like effect of pramipexole is dependent on the activation of D2 receptor and inhibition of either NMDA receptors and/or NO-cGMP synthesis. These results contribute to the understanding of the mechanisms underlying the antidepressant-like effect of pramipexole and reinforce the role of D2 receptors, NMDA receptors and l-arginine-NO-GMP pathway in the antidepressant mechanism of this agent. Copyright © 2016. Published by Elsevier Masson SAS.

Protective effect of C-peptide on experimentally induced diabetic nephropathy and the possible link between C-peptide and nitric oxide.

PubMed

Elbassuoni, Eman A; Aziz, Neven M; El-Tahawy, Nashwa F

2018-06-01

Diabetic nephropathy one of the major microvascular diabetic complications. Besides hyperglycemia, other factors contribute to the development of diabetic complications as the proinsulin connecting peptide, C-peptide. We described the role of C-peptide replacement therapy on experimentally induced diabetic nephropathy, and its potential mechanisms of action by studying the role of nitric oxide (NO) as a mediator of C-peptide effects by in vivo modulating its production by N G -nitro-l-arginine methyl ester (L-NAME). Renal injury markers measured were serum urea, creatinine, tumor necrosis factor alpha, and angiotensin II, and malondialdehyde, total antioxidant, Bcl-2, and NO in renal tissue. In conclusion, diabetic induction resulted in islet degenerations and decreased insulin secretion with its metabolic consequences and subsequent renal complications. C-Peptide deficiencies in diabetes might have contributed to the metabolic and renal error, since C-peptide treatment to the diabetic rats completely corrected these errors. The beneficial effects of C-peptide are partially antagonized by L-NAME coadministration, indicating that NO partially mediates C-peptide effects.

Diminished contractile responses of isolated conduit arteries in two rat models of hypertension.

PubMed

Zemancíková, Anna; Török, Jozef

2013-08-31

Hypertension is accompanied by thickening of arteries, resulting in marked changes in their passive and active mechanical properties. The aim of this study was to demonstrate that the large conduit arteries from hypertensive individuals may not exhibit enhanced contractions in vitro, as is often claimed. Mechanical responses to vasoconstrictor stimuli were measured under isometric conditions using ring arterial segments isolated from spontaneously hypertensive rats, N(omega)-nitro-L-arginine methyl ester (L-NAME)-treated Wistar rats, and untreated Wistar rats serving as normotensive control. We found that thoracic aortas from both types of hypertensive rats had a greater sensitivity but diminished maximal developed tension in response to noradrenaline, when compared with that from normotensive rats. In superior mesenteric arteries, the sensitivity to noradrenaline was similar in all examined rat groups but in L-NAME-treated rats, these arteries exhibited decreased active force when stimulated with high noradrenaline concentrations, or with 100 mM KCl. These results indicate that hypertension leads to specific biomechanical alterations in diverse arterial types which are reflected in different modifications in their contractile properties.

Sildenafil Prevents Apoptosis of Human First-Trimester Trophoblast Cells Exposed to Oxidative Stress

PubMed Central

Bolnick, Jay M.; Kilburn, Brian A.; Bolnick, Alan D.; Diamond, Michael P.; Singh, Manvinder; Hertz, Michael; Dai, Jing

2015-01-01

Human first-trimester trophoblast cells proliferate at low O2, but survival is compromised by oxidative stress, leading to uteroplacental insufficiency. The vasoactive drug, sildenafil citrate (Viagra, Sigma, St Louis, Missouri), has proven useful in reducing adverse pregnancy outcomes. An important biological function of this pharmaceutical is its action as an inhibitor of cyclic guanosine monophosphate (cGMP) phosphodiesterase type 5 activity, which suggests that it could have beneficial effects on trophoblast survival. To investigate whether sildenafil can prevent trophoblast cell death, human first-trimester villous explants and the HTR-8/SVneo cytotrophoblast cell line were exposed to hypoxia and reoxygenation (H/R) to generate oxidative stress, which induces apoptosis. Apoptosis was optimally inhibited during H/R by 350 ng/mL sildenafil. Sildenafil-mediated survival was reversed by l-NG-nitro-l-arginine methyl ester hydrochloride or cGMP antagonist, indicating a dependence on both nitric oxide (NO) and cGMP. Indeed, either a cGMP agonist or an NO generator was cytoprotective independent of sildenafil. These findings suggest a novel intervention route for patients with recurrent pregnancy loss or obstetrical placental disorders. PMID:25431453

Estimation of total rate of formation of nitric oxide in the rat.

PubMed Central

Sakinis, A; Wennmalm, A

1998-01-01

Nitric oxide (NO) is a powerful mediator with important actions in several organ systems. NO is synthesized during the enzymatic conversion of l-arginine and molecular oxygen to L-citrulline. About 90% of the NO formed is degraded to nitrate. Utilizing this information we have developed a method for assessment of the total rate of formation of NO in the rat. Male Wistar rats were kept in a closed-cage system allowing controlled breathing of a mixture of 18O2 and 16O2 in N2 for up to 5h. Blood samples for mass spectrometric analysis of nitrate residues with varying numbers of 18O atoms incorporated were drawn before and during the exposure to 18O2. By comparing the relative incorporation of 18O into nitrate residues to the 16O2/18O2 ratio in the breathing gas mixture in the cage system it was possible to calculate the absolute rate of NO formation in the animal. The rate of formation of NO in anaesthetized rats ranged from 0.33 to 0.85 micromol.kg-1.h-1. The rate of formation did not differ significantly in rats which were awake during the experiment (range 0.36-0.72 micromol.kg-1.h-1). The L-arginine analogue Nomega-nitro-L-arginine methyl ester (L-NAME) dose-dependently inhibited the formation of NO, at a dose of 100mg/kg by more than 99%. The technique presented allows estimation of the total rate of formation of NO in vivo in rats. Application of the technique may yield important information about the physiological and pathophysiological roles of NO. It may also be utilized to evaluate the effect of pharmacological treatment on NO formation. PMID:9461552

B16-BL6 melanoma cells release inhibitory factor(s) of active pump activity in isolated lymph vessels.

PubMed

Nakaya, K; Mizuno, R; Ohhashi, T

2001-12-01

We investigated whether supernatant cultured with melanoma cell lines B16-BL6 and K1735 or the Lewis lung carcinoma cell line (LLC) can regulate lymphatic pump activity with bioassay preparations isolated from murine iliac lymph vessels. B16-BL6 and LLC supernatants caused significant dilation of lymph microvessels with cessation of pump activity. B16-BL6 supernatant produced dose-related cessation of lymphatic pump activity. There was no significant tachyphylaxis in the supernatant-mediated inhibitory response of lymphatic pump activity. Pretreatment with 3 x 10(-5) M N(omega)-nitro-L-arginine methyl ester (L-NAME) or 10(-7) M or 10(-6) M glibenclamide and 5 x 10(-4) M 5-hydroxydecanoic acid caused significant reduction of supernatant-mediated inhibitory responses. Simultaneous treatment with 10(-3) M L-arginine and 3 x 10(-5) M L-NAME significantly lessened L-NAME-induced inhibition of the supernatant-mediated response, suggesting that endogenous nitric oxide (NO) plays important roles in supernatant-mediated inhibitory responses. Chemical treatment dialyzed substances of <1,000 molecular weight (MW), producing complete reduction of the supernatant-mediated response. In contrast, pretreatment with heating or digestion with protease had no significant effect on supernatant-mediated response. These findings suggest that B16-BL6 cells may release nonpeptide substance(s) of <1,000 MW, resulting in significant cessation of lymphatic pump activity via production and release of endogenous NO and activation of mitochondrial ATP-sensitive K(+) channels.

Nitric oxide synthase inhibition reduces muscle inflammation and necrosis in modified muscle use

NASA Technical Reports Server (NTRS)

Pizza, F. X.; Hernandez, I. J.; Tidball, J. G.

1998-01-01

The objective of this study was to determine the role of nitric oxide in muscle inflammation, fiber necrosis, and apoptosis of inflammatory cells in vivo. The effects of nitric oxide synthase (NOS) inhibition on the concentrations of neutrophils, ED1+ and ED2+ macrophages, apoptotic inflammatory cells, and necrotic muscle fibers in rats subjected to 10 days of hindlimb unloading and 2 days of reloading were determined. Administration of NOS inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) significantly reduced the concentrations of neutrophils, ED1+ and ED2+ macrophages, and necrotic fibers in soleus muscle relative to water-treated controls. The concentration of apoptotic inflammatory cells was also significantly lower for L-NAME-treated animals compared with water-treated controls. However, the proportion of the inflammatory cell population that was apoptotic did not differ between L-NAME-treated and control animals, suggesting that L-NAME treatment did not decrease inflammatory cell populations by increasing the frequency of apoptosis. Thus, nitric oxide or one of its intermediates promotes muscle inflammation and fiber necrosis during modified muscle use and plays no more than a minor role in the resolution of muscle inflammation by inducing apoptosis of inflammatory cells.

Upregulation of Cyclooxygenase-2 Expression in Porcine Macula Densa With Chronic Nitric Oxide Synthase Inhibition

PubMed Central

Kommareddy, M.; McAllister, R. M.; Ganjam, V. K.; Turk, J. R.; Laughlin, M. Harold

2012-01-01

The objective of this study was to investigate the effects of chronic inhibition of nitric oxide synthase (NOS) on cyclooxygenase-2 (COX-2) expression in the macula densa (MD) of swine, as well as the effects on expression of related proteins. Adult female Yucatan swine were given either tap water (control, n = 6) or water with NG-nitro-l-arginine methyl ester (L-NAME, 100 mg/liter, n = 5) for a minimum of 30 days. Duplicate samples of kidney were fixed or snap frozen. There was a significant (P = .0082) upregulation of COX-2 mRNA expression in the MD of L-NAME, as well as an apparent increase in COX-2 protein. Plasma renin activity also increased with L-NAME treatment (control, 0.34 ± 0.08 ng/ml; L-NAME, 1.26 ± 0.03 ng/ml; P = .00000003). There were no differences between groups in expression of either inducible NOS or renin protein or in serum electrolyte concentrations. In conclusion, with chronic inhibition of NOS, COX-2 in MD is upregulated, perhaps to compensate for loss of nitric oxide. Increases in COX-2 products may counteract renal arteriolar constriction and sustain renin release. PMID:21160023

Upregulation of cyclooxygenase-2 expression in porcine macula densa with chronic nitric oxide synthase inhibition.

PubMed

Kommareddy, M; McAllister, R M; Ganjam, V K; Turk, J R; Laughlin, M Harold

2011-11-01

The objective of this study was to investigate the effects of chronic inhibition of nitric oxide synthase (NOS) on cyclooxygenase-2 (COX-2) expression in the macula densa (MD) of swine, as well as the effects on expression of related proteins. Adult female Yucatan swine were given either tap water (control, n = 6) or water with N (G)-nitro-L-arginine methyl ester (L-NAME, 100 mg/liter, n = 5) for a minimum of 30 days. Duplicate samples of kidney were fixed or snap frozen. There was a significant (P = .0082) upregulation of COX-2 mRNA expression in the MD of L-NAME, as well as an apparent increase in COX-2 protein. Plasma renin activity also increased with L-NAME treatment (control, 0.34 ± 0.08 ng/ml; L-NAME, 1.26 ± 0.03 ng/ml; P = .00000003). There were no differences between groups in expression of either inducible NOS or renin protein or in serum electrolyte concentrations. In conclusion, with chronic inhibition of NOS, COX-2 in MD is upregulated, perhaps to compensate for loss of nitric oxide. Increases in COX-2 products may counteract renal arteriolar constriction and sustain renin release.

Blockade of nitric oxide synthesis modulates rat immunoglobulin A.

PubMed

Budec, Mirela; Marković, Dragana; Djikić, Dragoslava; Mitrović, Olivera; Drndarević, Neda; Koko, Vesna; Todorović, Vera

2009-01-01

Nitric oxide (NO) is known as a regulator of inflammation and immunity. The purpose of this study was to investigate the influence of this signal molecule on the rat immunoglobulin A (IgA) system using Nomega-nitro-L-arginine-methyl ester (L-NAME), which inhibits the activity of all isoforms of NO synthase. The experiments were performed on adult female Wistar rats showing diestrus day 1 that were treated with L-NAME (30 or 50 mg/kg, s.c.). Untreated and saline-injected animals were used as controls. The rats were sacrificed 3 h following L-NAME or saline administration. The concentration of IgA in serum and intestinal extracts was determined by a sandwich enzyme-linked immunosorbent assay. The number of IgA-expressing cells per area unit of Peyer's patches and the intestinal lamina propria was evaluated using stereological analysis. The results showed that L-NAME decreased the level of IgA in serum and elevated its concentration in intestinal extracts. Additionally, the increased number of IgA+ cells was found in the intestinal lamina propria in both experimental groups. Obtained findings imply that endogenous NO may modulate the IgA system in the rat. Copyright 2009 S. Karger AG, Basel.

The role of N-methyl-D-aspartate receptors and nitric oxide in cochlear dopamine release.

PubMed

Halmos, G; Horváth, T; Polony, G; Fekete, A; Kittel, A; Vizi, E S; van der Laan, B F A M; Zelles, T; Lendvai, B

2008-06-23

Dopamine (DA) released from lateral olivocochlear (LOC) terminals may have a neuroprotective effect in the cochlea. To explore the role of N-methyl-d-aspartate (NMDA) receptors and nitric oxide (NO) in the modulation of a cochlear DA release, we measured the release of [3H]DA from isolated mouse cochlea in response to the application of NMDA. NMDA at 100 muM significantly increased the electrical-field stimulation-evoked and resting release of DA from the cochlea. The NO donor sodium nitroprusside enhanced the basal outflow of DA but failed to influence the evoked release. The administration of the nitric oxide synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME) alone was ineffective, but it significantly inhibited the initial phase of the NMDA-induced elevation of DA outflow, which suggested the role of NO in the NMDA-induced DA release. The DA uptake inhibitor nomifensine increased the electrically evoked release of DA. Nomifensine failed to change the effect of NMDA on the resting or electrically-evoked DA release, which suggested that the uptake mechanism does not play a role in NMDA-evoked and NO-mediated DA release. In summary, we provide evidence that NO can modulate the release of DA from the cochlea following NMDA receptor activation, but does not affect the uptake of DA.

Leptin improves membrane fluidity of erythrocytes in humans via a nitric oxide-dependent mechanism--an electron paramagnetic resonance investigation.

PubMed

Tsuda, Kazushi; Kimura, Keizo; Nishio, Ichiro

2002-09-27

Abnormalities in physical properties of the cell membranes may underlie the defects that are strongly linked to hypertension, stroke, and other cardiovascular diseases. Recently, there has been an indication that leptin, the product of the human obesity gene, actively participates not only in the metabolic regulations but also in the control of cardiovascular functions. In the present study, to assess the role of leptin in the regulation of membrane properties, the effects of leptin on membrane fluidity of erythrocytes in humans are examined. The membrane fluidity of erythrocytes in healthy volunteers by means of an electron paramagnetic resonance (EPR) and spin-labeling method is determined. In an in vitro study, leptin decreased the order parameter (S) for 5-nitroxide stearate (5-NS) and the peak height ratio (ho/h-1) for 16-NS obtained from EPR spectra of erythrocyte membranes in a dose-dependent manner in healthy volunteers. The finding indicated that leptin increased the membrane fluidity and improved the microviscosity of erythrocytes. The effect of leptin on the membrane fluidity was significantly potentiated by the nitric oxide (NO) donors, L-arginine and S-nitroso-N-acetylpenicillamine (SNAP), and a cyclic guanosine monophosphate (cGMP) analog, 8-bromo-cGMP. In contrast, the change evoked by leptin was significantly attenuated in the presence of the NO synthase inhibitors, N(G)-nitro-L-arginine-methyl-ester (L-NAME) and asymmetric dimethyl-L-arginine (ADMA). The results of the present study showed that leptin increased the membrane fluidity and improved the rigidity of cell membranes to some extent via an NO- and cGMP-dependent mechanism. Furthermore, the data also suggest that leptin might have a crucial role in the regulation of rheological behavior of erythrocytes and microcirculation in humans.

Modulation of haemostatic function and prevention of experimental thrombosis by red wine in rats: a role for increased nitric oxide production

PubMed Central

Wollny, Tomasz; Aiello, Luca; Di Tommaso, Donata; Bellavia, Vincenzo; Rotilio, Domenico; Donati, Maria Benedetta; de Gaetano, Giovanni; Iacoviello, Licia

1999-01-01

The effects of ethyl alcohol and wine (red and white) on haemostatic parameters and experimental thrombosis were studied in rats; NO was evaluated as a possible mediator of these effects. We found that red wine (12% alcohol) supplementation (8.4±0.4 ml d−1 in drinking water, for 10 days) induced a marked prolongation of ‘template' bleeding time (BT) (258±13 vs 132±13 s in controls; P<0.001), a decrease in platelet adhesion to fibrillar collagen (11.6±1.0 vs 32.2±1.3%; P<0.01) and a reduction in thrombus weight (1.45±0.33 vs 3.27±0.39 mg; P<0.01). Alcohol-free red wine showed an effect similar to red wine. In contrast, neither ethyl alcohol (12%) nor white wine (12% alcohol) affected these systems. All these effects were also observed after red wine i.v. injection (1 ml kg−1 of 1 : 4 dilution) 15 min before the experiments. The effects of red wine were prevented by the NO inhibitor, Nωnitro-L-arginine-methyl ester (L-NAME). L-arginine, not D-arginine, reversed the effect of L-NAME on red wine infusion. Red wine injection induced a 3 fold increase in total radical-trapping antioxidant parameter values of rat plasma with respect to controls, while white wine and alcohol did not show any effect. Our study provides evidence that red wine modulates primary haemostasis and prevents experimental thrombosis in rats, independently of its alcohol content, by a NO-mediated mechanism. PMID:10401566

Tachykinin-independent activity of capsaicin on in-vitro lamb detrusor.

PubMed

Tucci, Paolo; Evandri, Maria Grazia; Bolle, Paola

2002-08-01

The capsicum alkaloid capsaicin is an afferent fibre exciter. In the vesical bladder, capsaicin acts by releasing peptides stored in afferent fibres. The aim of this work was to verify the activity of capsaicin on in-vitro lamb urinary bladder and to ascertain whether this alkaloid evokes peptide release. Capsaicin relaxed about 80% of the lamb detrusor muscle preparations tested and contracted about 20%. Whereas neurokinin A and substance P antagonists, administered alone or together, left the contractile responses to capsaicin unchanged, atropine and tetrodotoxin totally inhibited contraction. Ruthenium red and indometacin abolished contractions and relaxation. The substance P and neurokinin A antagonists and the NO-synthesis inhibitor N omega-nitro-L-arginine methyl ester (L-NAME) left relaxation unchanged; conversely, the calcitonin gene-related peptide antagonist alpha h-CGRP (8-37) abolished this response. These results suggest that capsaicin relaxes lamb detrusor muscle not through tachykinins but by releasing CGRP from afferent fibres. Our observation that indometacin blocks the capsaicin response in in-vitro lamb urinary bladder also suggests a role of prostanoids.

Role of endothelium-derived relaxing factors in adrenomedullin-induced vasodilation in the rat kidney.

PubMed

Wangensteen, Rosemary; Quesada, Andrés; Sainz, Juan; Duarte, Juan; Vargas, Félix; Osuna, Antonio

2002-05-24

The present study aimed to evaluate the contributions of endothelium-derived hyperpolarizing factor (EDHF), the nitric oxide (NO)-cGMP pathway, and prostaglandins to adrenomedullin-induced vasodilation in isolated rat kidney. Inhibition of the NO-cGMP pathway with N(omega)-nitro-L-arginine methyl ester (L-NAME) or 1H-[1,2,4]oxadiazolo-[4,3a]quinoxalin-1-one (ODQ) reduced the maximal vasodilator response to adrenomedullin by approximately 50%. Pretreatment of the vessels with the potassium channel inhibitor, tetraethylammonium or increased extracellular K(+), also decreased the maximal response to adrenomedullin by approximately 50%. The simultaneous administration of blockers of both endothelium-derived relaxing factors had a combined effect that almost suppressed adrenomedullin-induced vasodilation. The administration of indomethacin did not modify the renal response to adrenomedullin. Our results suggest that the vasodilator response to adrenomedullin in the isolated perfused kidney of rats is mediated by EDHF and NO to a similar extent. Our data also provide evidence that prostaglandins play no role in the vasodilator response to adrenomedullin in the renal vasculature.

Renal tubular angiotensin converting enzyme is responsible for nitro-L-arginine methyl ester (L-NAME)-induced salt sensitivity

PubMed Central

Giani, Jorge F.; Eriguchi, Masahiro; Bernstein, Ellen A.; Katsumata, Makoto; Shen, Xiao Z.; Li, Liang; McDonough, Alicia A.; Fuchs, Sebastien; Bernstein, Kenneth E.; Gonzalez-Villalobos, Romer A.

2017-01-01

Renal parenchymal injury predisposes to salt-sensitive hypertension, but how this occurs is not known. Here we tested whether renal tubular angiotensin converting enzyme (ACE), the main site of kidney ACE expression, is central to the development of salt sensitivity in this setting. Two mouse models were used: it-ACE mice in which ACE expression is selectively eliminated from renal tubular epithelial cells; and ACE 3/9 mice, a compound heterozygous mouse model that makes ACE only in renal tubular epithelium from the ACE 9 allele, and in liver hepatocytes from the ACE 3 allele. Salt sensitivity was induced using a post L-NAME salt challenge. While both wild-type and ACE 3/9 mice developed arterial hypertension following three weeks of high salt administration, it-ACE mice remained normotensive with low levels of renal angiotensin II. These mice displayed increased sodium excretion, lower sodium accumulation, and an exaggerated reduction in distal sodium transporters. Thus, in mice with renal injury induced by L-NAME pretreatment, renal tubular epithelial ACE, and not ACE expression by renal endothelium, lung, brain, or plasma, is essential for renal angiotensin II accumulation and salt-sensitive hypertension. PMID:27988209

The effects of bupivacaine, L-nitro-L-arginine-methyl ester, and phenylephrine on cardiovascular adaptations to asphyxia in the preterm fetal lamb.

PubMed

Santos, A C; Yun, E M; Bobby, P D; Noble, G; Arthur, G R; Finster, M

1997-12-01

The preterm fetal lamb that is exposed to clinically relevant plasma concentrations of lidocaine loses its cardiovascular adaptations to asphyxia, and its condition deteriorates further. Nitric oxide (NO) is an important regulator of vascular tone, and local anesthetics are known to inhibit endothelium-dependent vasodilation. The purpose of the present study was to determine whether the adverse effects of lidocaine noted in the preterm fetal lamb also occur with bupivacaine and whether the inhibition of NO results in effects similar to those of bupivacaine. Thirty-two chronically prepared pregnant sheep were studied at 117-119 days' gestation. Maternal and fetal blood pressure, heart rate, and acid-base state were evaluated. Fetal organ blood flows were determined using 15-microM diameter dye-labeled microspheres. After a control period, mild to moderate asphyxia (fetal PaO2 15 mm Hg) was induced by partial umbilical cord occlusion and maintained throughout the experiment. Ewes in Group I (n = 13) were given a two-step intravenous infusion of bupivacaine for 180 min. Fetuses in Group II (n = 12) received an intravenous injection of L-nitro-L-arginine-methyl ester (L-NAME) (25 mg/kg), and measurements were taken 10 and 30 min after the injection. A third group (Group III) of fetuses (n = 7) were given an intravenous infusion of phenylephrine to mimic the blood pressure increases noted in L-NAME-treated fetuses. At 90 min of stable asphyxia, there was a significant decrease in fetal PaO2 and pHa and an increase in PaCO2 and mean arterial blood pressure. There was also an increase in blood flow to the adrenals, myocardium, and cerebral cortex, whereas blood flow to the placenta decreased. Administration of bupivacaine during asphyxia did not affect the changes in mean arterial blood pressure and acid-base state but did abolish the increases in blood flows to the myocardium and cerebral cortex. Injection of L-NAME to the asphyxiated fetus resulted in an increase in mean arterial blood pressure above the level noted at 90 min of cord occlusion, and an increase in fetal PaO2 toward control levels. This was accompanied by a reduction in organ blood flows to preasphyxia levels. In asphyxiated Group III fetuses, titration of the phenylephrine infusion to achieve blood pressure increases similar to those noted with L-NAME were also associated with an increase in fetal PaO2. These data indicate that bupivacaine abolishes some of the circulatory adaptations to mild to moderate asphyxia induced by partial cord occlusion in the preterm fetal lamb. It is not clear whether these effects of bupivacaine are due to inhibition of NO. In the preterm fetal lamb, clinically relevant plasma concentrations of bupivacaine achieved by intravenous infusion to the pregnant ewe (80% gestation) abolished some of the fetal cardiovascular adaptations to asphyxia induced by partial umbilical cord occlusion.

Chronic inhibition of nitric-oxide synthase potentiates endothelium-dependent contractions in the rat aorta by augmenting the expression of cyclooxygenase-2.

PubMed

Qu, Chen; Leung, Susan W S; Vanhoutte, Paul M; Man, Ricky Y K

2010-08-01

Acute inhibition of nitric-oxide synthase (NOS) unmasks the release of endothelium-derived contracting factors (EDCFs). The present study investigated whether chronic inhibition of NOS modulates endothelium-dependent contractions. Eighteen-week-old male Sprague-Dawley rats were treated by daily gavage for 6 weeks with the NOS inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) (60 mg/kg) or vehicle (distilled water; 1 ml/kg). Chronic treatment with L-NAME increased arterial blood pressure. Isometric tension was measured in aortic rings with or without endothelium. Endothelium-dependent relaxations to acetylcholine and the calcium ionophore 5-(methylamino)-2-[(2R,3R,6S,8S,9R,11R)-3,9,11-trimethyl-8-[(1S)-1-methyl-2-oxo-2-(1H-pyrrol-2-yl)-ethyl]-1,7-dioxaspiro[5.5]undec-2-yl]methyl]-4-benzoxazolecarboxylic acid (A23187) were reduced in preparations from L-NAME-treated rats. The reduction in relaxation to A23187 was partially reversed by L-arginine (1 mM). In quiescent aortic rings, A23187 caused contractions in the presence of L-NAME and intact endothelium. The A23187-induced contractions were greater in rings from the L-NAME-treated rats than in those from the control group. These contractions were abolished by the cyclooxygenase (COX)-2 inhibitor N-[2-cyclohexyloxy-4-nitrophenyl]methanesulfonamide (NS-398) and the thromboxane-prostanoid (TP) receptor antagonist 3-((6R)-6-{[(4-chlorophenyl)sulfonyl]amido}-2-methyl-5,6,7,8-tetrahydronaphthalen-1-yl)propanoate (S18886), but not by the COX-1 inhibitor 5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-(trifluoromethyl)-1H-pyrazole (SC-560). Chronic L-NAME treatment reduced the level of nitric oxide in the plasma but increased COX activity in the aortic rings. Western blotting and immunohistochemical staining showed that endothelial NOS expression was reduced in the aortae of the chronic L-NAME-treated group. COX-1 expression was augmented slightly, whereas COX-2 expression was up-regulated markedly. The TP receptor expression was comparable with control. These experiments demonstrate that chronic NOS inhibition increases endothelium-dependent contractions of the rat aorta by inducing COX-2 expression and augmenting the production of EDCF.

N-Methyl-D aspartate receptor-mediated effect on glucose transporter-3 levels of high glucose exposed-SH-SY5Y dopaminergic neurons.

PubMed

Engin, Ayse Basak; Engin, Evren Doruk; Karakus, Resul; Aral, Arzu; Gulbahar, Ozlem; Engin, Atilla

2017-11-01

High glucose and insulin lead to neuronal insulin resistance. Glucose transport into the neurons is achieved by regulatory induction of surface glucose transporter-3 (GLUT3) instead of the insulin. N-methyl-D aspartate (NMDA) receptor activity increases GLUT3 expression. This study explored whether an endogenous NMDA receptor antagonist, kynurenic acid (KynA) affects the neuronal cell viability at high glucose concentrations. SH-SY5Y neuroblastoma cells were exposed to 150-250 mg/dL glucose and 40 μU/mL insulin. In KynA and N-nitro-l-arginine methyl ester (L-NAME) supplemented cultures, oxidative stress, mitochondrial metabolic activity (MTT), nitric oxide as nitrite+nitrate (NOx) and GLUT3 were determined at the end of 24 and 48-h incubation periods. Viable cells were counted by trypan blue dye. High glucose-exposed SH-SY5Y cells showed two-times more GLUT3 expression at second 24-h period. While GLUT3-stimulated glucose transport and oxidative stress was increased, total mitochondrial metabolic activity was significantly reduced. Insulin supplementation to high glucose decreased NOx synthesis and GLUT3 levels, in contrast oxidative stress increased three-fold. KynA significantly reduced oxidative stress, and increased MTT by regulating NOx production and GLUT3 expression. KynA is a noteworthy compound, as an endogenous, specific NMDA receptor antagonist; it significantly reduces oxidative stress, while increasing cell viability at high glucose and insulin concentrations. Copyright © 2017 Elsevier Ltd. All rights reserved.

L-NAME, a nitric oxide synthase inhibitor, as a potential countermeasure to post-suspension hypotension in rats

NASA Technical Reports Server (NTRS)

Bayorh, M. A.; Socci, R. R.; Watts, S.; Wang, M.; Eatman, D.; Emmett, N.; Thierry-Palmer, M.

2001-01-01

A large number of astronauts returning from spaceflight experience orthostatic hypotension. This hypotension may be due to overproduction of vasodilatory mediators, such as nitric oxide (NO) and prostaglandins. To evaluate the role of the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) as a countermeasure against the post-suspension reduction in mean arterial pressure (MAP), we assessed the cardiovascular responses and vascular reactivity to 7-day 30 degrees tail-suspension and a subsequent 6 hr post-suspension period in conscious rats. After a pre-suspension reading, direct MAP and heart rate (HR) were measured daily and every 2 hrs post-suspension. The NO synthase inhibitor L-NAME (20 mg/kg, i.v.), or saline, were administered after the 7th day reading prior to release from suspension and at 2 and 4 hrs post-suspension. At 6 hrs post-suspension, vascular reactivity was assessed. While MAP did not change during the suspension period, it was reduced post-suspension. Heart rate was not significantly altered. L-NAME administration reversed the post-suspension reduction in MAP. In addition, the baroreflex sensitivity for heart rate was modified by L-NAME. Thus, the post-suspension reduction in MAP may be due to overproduction of NO and altered baroreflex activity.

The estrogen-dependent baroreflex dysfunction caused by nicotine in female rats is mediated via NOS/HO inhibition: Role of sGC/PI3K/MAPK{sub ERK}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fouda, Mohamed A.; El-Gowelli, Hanan M.; El-Gowilly, Sahar M.

We have previously reported that estrogen (E2) exacerbates the depressant effect of chronic nicotine on arterial baroreceptor activity in female rats. Here, we tested the hypothesis that this nicotine effect is modulated by nitric oxide synthase (NOS) and/or heme oxygenase (HO) and their downstream soluble guanylate cyclase (sGC)/phosphatidylinositol 3-kinase (PI3K)/mitogen-activated protein kinases (MAPKs) signaling. We investigated the effects of (i) inhibition or facilitation of NOS or HO on the interaction of nicotine (2 mg/kg/day i.p., 2 weeks) with reflex bradycardic responses to phenylephrine in ovariectomized (OVX) rats treated with E2 or vehicle, and (ii) central pharmacologic inhibition of sGC, PI3K,more » or MAPKs on the interaction. The data showed that the attenuation by nicotine of reflex bradycardia in OVXE2 rats was abolished after treatment with hemin (HO inducer) or L-arginine (NOS substrate). The hemin or L-arginine effect disappeared after inhibition of NOS (Nω-Nitro-L-arginine methyl ester hydrochloride, L-NAME) and HO (zinc protoporphyrin IX, ZnPP), respectively, denoting the interaction between the two enzymatic pathways. E2-receptor blockade (ICI 182,780) reduced baroreflexes in OVXE2 rats but had no effect on baroreflex improvement induced by hemin or L-arginine. Moreover, baroreflex enhancement by hemin was eliminated following intracisternal (i.c.) administration of wortmannin, ODQ, or PD98059 (inhibitors of PI3K, sGC, and extracellular signal-regulated kinases, MAPK{sub ERK}, respectively). In contrast, the hemin effect was preserved after inhibition of MAPK{sub p38} (SB203580) or MAPK{sub JNK} (SP600125). Overall, NOS/HO interruption underlies baroreflex dysfunction caused by nicotine in female rats and the facilitation of NOS/HO-coupled sGC/PI3K/MAPK{sub ERK} signaling might rectify the nicotine effect. - Highlights: • Hemin or L-arginine blunts baroreflex dysfunction caused by nicotine in OVXE2 rats. • NO/CO crosstalk mediates favorable baroreflex effect of hemin or L-arginine. • Central sGC/PI3K/MAPK{sub ERK} is required for hemin facilitation of baroreflexes. • The favorable baroreflex action of hemin is independent of estrogen receptors.« less

Effects of nitric oxide synthase inhibitor on cochlear blood flow.

PubMed

Hoshijima, Hideaki; Makimoto, Kazuo; Noi, Osamu; Ohinata, Yoshimitsu; Takenaka, Hiroshi

2002-09-01

We observed in rats the changes in cochlear blood flow (CoBF) and cutaneous blood flow of the abdominal wall (AbBF) after the administration of the NO synthase inhibitor, N-nitro-L-arginine-methyl ester (L-NAME). Ten minutes after i.v. infusion of L-NAME (0.2, 1, 5, 10 mg/kg), L-arginine, which is a substrate of NO, was infused (100 mg/kg) i.v. Employing a laser Doppler flowmeter, the changes in blood flow were recorded from the basal turn of the right cochlea or the abdominal wall and blood pressure (BP) was recorded from the left femoral artery simultaneously. Vascular conductance (VC) was calculated from CoBF/mean BP (cochlear VC) or AbBF/mean BP (abdominal VC). The findings in rats generally agreed with those in guinea pigs [Brechtelsbauer et al., Hear. Res. 77 (1994) 38-42]. Intravenous infusion of L-NAME produced a dose-dependent depression of cochlear VC at 0.2 mg/kg (-18.9), 1 mg/kg (-37.9%), 5 mg/kg (-45.8%) and 10 mg/kg (-48.3%). AbBF also decreased after infusion of L-NAME (5 mg/kg) but to a lesser degree (-41.1% in VC) with no significance compared to CoBF (5 mg/kg). Infusion of L-arginine partially reversed the CoBF decrease caused by L-NAME. The group of 0.2 mg/kg infusion of L-NAME showed the largest degree of recovery with L-arginine, while the 10 mg/kg group showed the smallest. The decrease in AbBF did not recover substantially with L-arginine, the degree being less than that of each group in the CoBF experiment. It was suggested that the NO/soluble guanylate cyclase/cGMP system is more active in the cochlear microcirculation. With the round window (RW) application of 1% L-NAME (2 microl), cochlear VC was decreased by 21.6%, which was closest to that of the 0.2 mg/kg group of L-NAME i.v. infusion. The cochlear VC depression after local application of L-NAME did not show any recovery (-0.3%) by RW application of 5% L-arginine (2 microl) 25 min after L-NAME application; a slight gradual increase was observed when a higher concentration (20%) of L-arginine was applied to the RW. We propose that i.v. infusions of L-NAME and L-arginine primarily affect the precapillary arteriole of the spiral modiolar artery which effectively regulates microcirculation as a resistance vessel, and that RW application affects the vessels of the lateral wall, not the spiral modiolar artery because of the difficulty of substance diffusion.

[Role of NO signal in ABA-induced phenolic acids accumulation in Salvia miltiorrhiza hairy roots].

PubMed

Shen, Lihong; Ren, Jiahui; Jin, Wenfang; Wang, Ruijie; Ni, Chunhong; Tong, Mengjiao; Liang, Zongsuo; Yang, Dongfeng

2016-02-01

To investigate roles of nitric oxide (NO) signal in accumulations of phenolic acids in abscisic.acid (ABA)-induced Salvia miltiorrhiza hairy roots, S. miltiorrhiza hairy roots were treated with different concentrations of sodium nitroprusside (SNP)-an exogenous NO donor, for 6 days, and contents of phenolic acids in the hairy roots are determined. Then with treatment of ABA and NO scavenger (2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylimidazoline-1- oxyl-3-oxide, c-PTIO) or NO synthase inhibitor (NG-nitro-L-arginine methyl ester, L-NAME), contents of phenolic acids and expression levels of three key genes involved in phenolic acids biosynthesis were detected. Phenolic acids production in S. miltiorrhiza hairy roots was most significantly improved by 100 µmoL/L SNP. Contents of RA and salvianolic acid B increased by 3 and 4 folds. ABA significantly improved transcript levels of PAL (phenylalanine ammonia lyase), TAT (tyrosine aminotransferase) and RAS (rosmarinic acid synthase), and increased phenolic acids accumulations. However, with treatments of ABA+c-PTIO or ABA+L-NAME, accumulations of phenolic acids and expression levels of the three key genes were significantly inhibited. Both NO and ABA can increase accumulations of phenolic acids in S. miltiorrhiza hairy roots. NO signal probably mediates the ABA-induced phenolic acids production.

Possible mechanism of acute effect of ethanol on intestinal IgA expression in rat.

PubMed

Budec, Mirela; Koko, Vesna; Todorović, Vera; Marković, Dragana; Postić, Marija; Drndarević, Neda; Spasić, Andelka; Mitrović, Olivera

2007-06-01

The purpose of this study was to investigate the possible mechanism of acute effect of ethanol on IgA expression in rat intestine. To this end, adult female Wistar rats showing diestrus day 1 were treated with (a) ethanol (2 or 4 g/kg, i.p.); (b) N omega-nitro-L-arginine-methyl ester (L-NAME), which inhibits the activity of all isoforms of nitric oxide synthase, (30 mg/kg, s.c.) followed by ethanol 3 h later; and (c) L-NAME (30 mg/kg, s.c.) followed by saline 3 h later. Saline-injected and untreated rats were used as controls. The animals were sacrificed 0.5 h after ethanol administration. Intestinal expression of IgA was evaluated by both immunohistochemistry and Western immunoblotting. Morphometric analysis showed that acute ethanol treatment increased the number of IgA-immunoreactive cells in a dose-dependent manner. Pretreatment with L-NAME abolished this action of alcohol. Injection of L-NAME followed by saline had no influence on the number of IgA+cells. The results, obtained by Western immunoblotting, paralleled our immunohistochemical findings. Taken together, these data suggest that acute effect of ethanol on intestinal IgA might be mediated by endogenous nitric oxide.

Dimethylarginine dimethylaminohydrolase 1 modulates endothelial cell growth through nitric oxide and Akt.

PubMed

Zhang, Ping; Hu, Xinli; Xu, Xin; Chen, Yingjie; Bache, Robert J

2011-04-01

Dimethylarginine dimethylaminohydrolase 1 (DDAH1) modulates NO production by degrading the endogenous nitric oxide (NO) synthase (NOS) inhibitors asymmetrical dimethylarginine (ADMA) and L-NG-monomethyl arginine (L-NMMA). This study examined whether, in addition to degrading ADMA, DDAH1 exerts ADMA-independent effects that influence endothelial function. Using selective gene silencing of DDAH1 with small interfering RNA and overexpression of DDAH1 in human umbilical vein endothelial cells, we found that DDAH1 acts to promote endothelial cell proliferation, migration, and tube formation by Akt phosphorylation, as well as through the traditional role of degrading ADMA. Incubation of human umbilical vein endothelial cells with the NOS inhibitors l-NG-nitro-arginine methyl ester (L-NAME) or ADMA, the soluble guanylyl cyclase inhibitor 1H-(1,2,4)oxadiazolo-(4,3-2)quinoxalin-1-one, or the cGMP analog 8-(4-Chlorophenylthio)-cGMP had no effect on phosphorylated (p)-Akt(Ser473), indicating that the increase in p-Akt(Ser473) produced by DDAH1 was independent of the NO-cGMP signaling pathway. DDAH1 formed a protein complex with Ras, and DDAH1 overexpression increased Ras activity. The Ras inhibitor manumycin-A or dominant-negative Ras significantly attenuated the DDAH1-induced increase in p-Akt(Ser473). Furthermore, DDAH1 knockout impaired endothelial sprouting from cultured aortic rings, and overexpression of constitutively active Akt or DDAH1 rescued endothelial sprouting in the aortic rings from these mice. DDAH1 exerts a unique role in activating Akt that affects endothelial function independently of degrading endogenous NOS inhibitors.

The involvement of neuronal nitric oxide synthase in antiepileptic action of alpha-asarone on pentylenetetrazol molding rats.

PubMed

Su, Jing; Zhu, Wenting; Liu, Jing; Yin, Jian; Qin, Wei; Jiang, Changbin

2014-01-01

The aim of the present study was to research the role of nitric oxide (NO) as a mediator of alpha (α)-asarone effect at the pentylenetetrazol (PTZ)-induced epileptiform discharge in rat. α-Asarone that was injected intraperitoneally twenty minutes before PTZ injection suppressed the clonic discharge effectively and the significant actions lasted for 30 min with no change of clonic amplitude. Administration of α-asarone did not influence interictal discharge. Four kinds of NO regulators were administered, including non-selective NG-nitro-L-arginine methyl ester (L-NAME), selective neuronal nitric oxide synthase (nNOS) inhibitor, 7-nitroindazole (7-NI), inducible nitric oxide synthase (iNOS) inhibitor, aminoguanidine (AG) and NO substrate, L-arginine (ARG) and their influence on the actions of α-asarone were studied, and all of the regulators were administered fifteen minutes before α-asarone injection. L-NAME and 7-NI reversed the anticlonic activity of α-asarone, and a significant increase of clonic activity was induced by L-NAME later in L-NAME +.α-asarone + PTZ group. There were no significant differences between AG + α-asarone + PTZ and α-asarone + PTZ group. L-ARG played a dual role in this study. It aggravated clonic discharge in the early stage but relieved interictal discharge in the late stage compared with PTZ group alone, and the beneficial effect of α-asarone was also reversed. All the above results suggest that nNOS/NO pathway mediates the anticonvulsant effect of α-asarone, and NO played a biphasic role in PTZ modeling process, while iNOS was unrelated to the inhibition effect of α-asarone on PTZ induced epileptiform activity.

Cinnamon polyphenols attenuate cell swelling and mitochondrial dysfunction following oxygen-glucose deprivation in glial cells.

PubMed

Panickar, Kiran S; Polansky, Marilyn M; Anderson, Richard A

2009-04-01

Astrocyte swelling is an integral component of cytotoxic brain edema in ischemic injury. While mechanisms underlying astrocyte swelling are likely multifactorial, oxidative stress and mitochondrial dysfunction are hypothesized to contribute to such swelling. We investigated the protective effects of cinnamon polyphenol extract (CPE) that has anti-oxidant and insulin-potentiating effects on cell swelling and depolarization of the inner mitochondrial membrane potential (DeltaPsi(m)) in ischemic injury. C6 glial cells were subjected to oxygen-glucose deprivation (OGD) and cell volume determined using the 3-O-methyl-[3H]-glucose method at 90 min after the end of OGD. When compared with controls, OGD increased cell volume by 34%. This increase was blocked by CPE or insulin but not by blockers of oxidative/nitrosative stress including vitamin E, resveratrol, N-nitro-L-arginine methyl ester (L-NAME) or uric acid. Mitochondrial dysfunction, a key component of ischemic injury, contributes to cell swelling. Changes in DeltaPsi(m) were assessed at the end of OGD with tetramethylrhodamine ethyl ester (TMRE), a potentiometric dye. OGD induced a 39% decline in DeltaPsi(m) and this decline was blocked by CPE as well as insulin. To test the involvement of the mitochondrial permeability transition (mPT), we used Cyclosporin A (CsA), an immunosuppressant and a blocker of the mPT pore. CsA blocked cell swelling and the decline in DeltaPsi(m) but FK506, an immunosuppressant that does not block the mPT, did not. Our results show that CPE reduces OGD-induced cell swelling as well as the decline in DeltaPsi(m) in cultures and some of its protective effects may be through inhibiting the mPT.

The relaxant actions of ethanolic extract of Tridax procumbens (Linn.) on rat corpus cavernosum smooth muscle contraction.

PubMed

Salahdeen, Hussein M; Idowu, Gbolahan O; Yemitan, Omoniyi K; Murtala, Babatunde A; Alada, Abdul Rasak A

2015-03-01

The effect of Tridax procumbens aqueous ethanolic extract on the rat corpus cavernosum smooth muscles was evaluated in the present study. Corpus cavernosum strips obtained from healthy, young, adult male Wistar albino rats (250-300 g) were precontracted with phenylephrine (10-7 M) or KCl (60 mM) and then treated with various concentrations of T. procumbens extract (0.15-1.05 mg/mL). The change in corpus cavernosum strip tension was recorded. The interactions between T. procumbens extract with acetylcholine and with sodium nitroprusside were also evaluated. The results indicated that corpus cavernosum strips relaxation induced by T. procumbens extract was concentration-dependent and this was significant (p<0.5). Pre-treatment with a nitric oxide synthase (NOS) inhibitor (N(1) nitro-L-arginine-methyl ester, l-NAME), did not completely inhibit the relaxation. However, T. procumbens extract (0.6 mg/mL) significantly (p<0.5) enhanced both acetylcholine- and sodium nitroprusside-induced corpus cavernosum strips relaxation. RESULTS suggest that T. procumbens extract has a concentration-dependent relaxant effect on the isolated rat corpus cavernosum. The mechanism of action of T. procumbens extract is complex. A part of its relaxing effect is mediated directly by the release of NO from endothelium which may improve erectile dysfunction.

Mechanism for substance P-induced relaxation of precontracted airway smooth muscle during development.

PubMed

Mhanna, M J; Dreshaj, I A; Haxhiu, M A; Martin, R J

1999-01-01

Release of substance P (SP) from sensory nerve endings of the tracheobronchial system modulates airway smooth muscle contraction and may cause relaxation of precontracted airways. We sought to elucidate the effect of postnatal maturation on SP-induced relaxation of precontracted airways and determine the roles of endogenously generated nitric oxide (NO) and prostaglandins (PGs). Cylindrical airway segments were isolated from the midtrachea of rats at four different ages, 1, 2, and 4 wk and 3 mo, and contracted to 50-75% of the maximum response induced by bethanechol. SP was then administered in the absence and presence of the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME), the PG inhibitor indomethacin, or both. Relaxation of airways with SP decreased significantly with advancing postnatal age. SP-induced tracheal relaxation was consistently attenuated by pretreatment with L-NAME, indomethacin, or both. In a different group of animals, L-NAME significantly attenuated the relaxant response of airways to PGE2 exposure, but indomethacin had no significant effect on the relaxant response to exogenous NO. We conclude that SP induces a relaxant effect on precontracted airway smooth muscle, which decreases with advancing age and is mediated via SP-induced release of NO and/or PG.

The difference in the effect of glutamate and NO synthase inhibitor on free calcium concentration and Na+, K+-ATPase activity in synaptosomes from various brain regions.

PubMed

Avrova, N F; Shestak, K I; Zakharova, I O; Sokolova, T V; Leont'ev, V G

1999-09-01

The significant increase of free calcium concentration ([Ca2+]i) was found in rat cerebral cortex synaptosomes and hippocampal crude synaptosomal fraction after their exposure to glutamate. But no change of [Ca2+]i was revealed in cerebellar synaptosomes, the slight increase of [Ca2+]i in striatal synaptosomes was not significant. The presence of Ng-nitro-L-arginine methyl ester (L-NAME) in the incubation medium practically prevented the increase of [Ca2+]i initiated by glutamate in cerebral cortex synaptosomes, but not in hippocampal ones. The significant diminution of [Ca2+]i in the presence of this inhibitor was shown in striatal synaptosomes exposed to glutamate. Na+,K+-ATPase activity is significantly lower in cerebral cortex, striatal and hippocampal synaptosomes exposed to glutamate. L-NAME prevented the inactivation of this enzyme by glutamate. In cerebellar synaptosomes the tendency to the decrease of enzymatic activity in the presence of L-NAME was on the contrary noticed. Thus, the data obtained provide evidence of the protective effect of NO synthase inhibitor in brain cortex and striatal synaptosomes, but not in cerebellar synaptosomes. Synaptosomes appear to be an adequate model to study the regional differences in the mechanism of toxic effect of excitatory amino acids.

Anti-hypertensive effects of the methanol/methylene chloride stem bark extract of Mammea africana in l-NAME-induced hypertensive rats.

PubMed

Nguelefack-Mbuyo, P E; Nguelefack, T B; Dongmo, A B; Afkir, S; Azebaze, A G B; Dimo, T; Legssyer, A; Kamanyi, A; Ziyyat, A

2008-05-22

The methanol/methylene chloride (CH(3)OH/CH(2)Cl(2)) extract from the stem bark of Mammea africana was showed to possess vasodilating effect in the presence and the absence of N(omega)-nitro-l-arginine methyl ester (l-NAME). The present study was designed to evaluate the effects of the methanol/methylene chloride from the stem bark of Mammea africana. The extract (200 mg/(kg day)) was administered orally in rats treated concurrently with l-NAME (40 mg/(kg day)). l-Arginine (100 mg/(kg day)) and captopril (20 mg/(kg day))were used as positive controls. Bodyweight, systolic arterial blood pressure and heart rate were measured weekly throughout the experiment period (28 days). At the end of treatment, animals were killed and the cardiac mass index evaluated. The aorta was used to evaluate the endothelium-dependant relaxation to carbachol. The aorta contraction induced by noradrenalin was also examined and expressed as a percentage of that induced by KCl. The extract neither affected the body weight nor the heart rate. The extract as captopril completely prevented the development of arterial hypertension. Both the substances failed to restore the endothelium-dependent vascular relaxation and increased the vascular contraction to norepinephrine in relation to KCl contraction. They also significantly reduced the left ventricular hypertrophy induced by l-NAME. These findings are in agreement with the traditional use of Mammea africana in the treatment of arterial hypertension and indicate that it may have a beneficial effect in patients with NO deficiency but will be unable to improve their endothelium-dependent vasorelaxation.

Involvement of nitric oxide in anticompulsive-like effect of agmatine on marble-burying behaviour in mice.

PubMed

Gawali, Nitin B; Chowdhury, Amrita A; Kothavade, Pankaj S; Bulani, Vipin D; Nagmoti, Dnyaneshwar M; Juvekar, Archana R

2016-01-05

In view of the reports that nitric oxide modulates the neurotransmitters implicated in obsessive-compulsive disorder (OCD), patients with OCD exhibit higher plasma nitrate levels, and drugs useful in OCD influence nitric oxide. Agmatine is a polyamine and widely distributed in mammalian brain which interacts with nitrergic systems. Hence, the present study was carried out to understand the involvement of nitrergic systems in the anticompulsive-like effect of agmatine. We used marble-burying behaviour (MBB) of mice as the animal model of OCD, and nitric oxide levels in hippocampus (HC) and cortex homogenate were measured. Results revealed that, agmatine (20 and 40mg/kg, i.p) significantly inhibited the MBB. Intraperitoneal administration of nitric oxide enhancers viz. nitric oxide precursor - l-arginine (l-ARG) (400mg/kg and 800mg/kg) increased MBB as well as brain nitrites levels, whereas treatment with N(G)-nitro-l-arginine methyl ester (l-NAME) neuronal nitric oxide synthase inhibitor (30mg/kg and 50mg/kg, i.p.) and 7-nitroindazole (7-NI) (20mg/kg and 40mg/kg) attenuated MBB and nitrites levels in brain. Further, in combination studies, the anticompulsive-like effect of agmatine (20mg/kg, ip) was exacerbated by prior administration of l-ARG (400mg/kg) and conversely l-NAME (15mg/kg) or 7-NI (10.0mg/kg) attenuated OCD-like behaviour with HC and cortex changes in the levels of NO. None of the above treatment had any significant influence on locomotor activity. In conclusion, Agmatine is effective in ameliorating the compulsive-like behaviour in mice which appears to be related to nitric oxide in brain. Copyright © 2015 Elsevier B.V. All rights reserved.

Dietary supplementation of tiger nut alters biochemical parameters relevant to erectile function in l-NAME treated rats.

PubMed

Olabiyi, Ayodeji A; Carvalho, Fabiano B; Bottari, Nathieli B; Lopes, Thauan F; da Costa, Pauline; Stefanelo, Naiara; Morsch, Vera M; Akindahunsi, Afolabi A; Oboh, Ganiyu; Schetinger, Maria Rosa

2018-07-01

Tiger nut tubers have been reportedly used for the treatment of erectile dysfunction (ED) in folk medicine without scientific basis. Hence, this study evaluated the effect of tiger nut on erectile dysfunction by assessing biochemical parameters relevant to ED in male rats by nitric oxide synthase (NOS) inhibitor, Nω-nitro-l-arginine methyl ester hydrochloride (l-NAME) treatment. Rats were divided into five groups (n = 10) each: Control group; l-NAME plus basal diet; l-NAME plus Sildenafil citrate; diet supplemented processed tiger nut (20%) plus l-NAME;diet supplemented raw tiger nut (20%) plus l-NAME. l-NAME pre-treatment (40 mg/kg/day) lasted for 14 days. Arginase, acetycholinesterase (AChE) and adenosine deaminase (ADA) activities as well as nitric oxide levels (NO) in serum, brain and penile tissue were measured. l-NAME increased the activity of arginase, AChE and ADA and reduced NO levels. However, dietary supplementation with tiger nut caused a reduction on the activities of the above enzymes and up regulated nitric oxide levels when compared to the control group. The effect of tiger nut supplemented diet may be said to prevent alterations of the activities of the enzymes relevant in erectile function. Quercetin was revealed to be the most active component of tiger nut tuber by HPLC finger printing. Copyright © 2018. Published by Elsevier Ltd.

Effect of losartan, an angiotensin II type 1 receptor antagonist on cardiac autonomic functions of rats during acute and chronic inhibition of nitric oxide synthesis.

PubMed

Chaswal, M; Das, S; Prasad, J; Katyal, A; Mishra, A K; Fahim, M

2012-01-01

We studied the effect of losartan on baroreflex sensitivity (BRS) and heart rate variability (HRV) of adult Wistar rats during acute and chronic inhibition of nitric oxide synthesis by N(G)-nitro-L-arginine methyl ester (L-NAME). Chronic L-NAME administration (50 mg/kg per day for 7 days, orally through gavage) increased mean arterial pressure (MAP), heart rate but significantly decreased BRS. In addition, a significant fall of standard deviation of normal RR intervals, total spectral power, high frequency spectral power and a rise of low frequency to high frequency (LF: HF) ratio was seen. Acute L-NAME administration (30 mg/kg, i.v. bolus dose) also raised MAP and impaired HRV but it was associated with augmented BRS for bradycardia reflex. Losartan treatment (10 mg/kg, i.v.) in both acute and chronic L-NAME treated rats, decreased MAP but the difference was not significant. On the other hand, losartan administration normalized depressed BRS for bradycardia reflex and significantly reduced LF to HF ratio in chronic L-NAME treated rats. But this improvement was not observed in acute L-NAME group. These results indicate importance of mechanisms other than renin-angiotensin system in the pressor response of both acute as well as chronic L-NAME. However, autonomic dysregulation especially following chronic L-NAME appears to be partly angiotensin dependent.

Antidepressant-like effect of atorvastatin in the forced swimming test in mice: the role of PPAR-gamma receptor and nitric oxide pathway.

PubMed

Shahsavarian, Arash; Javadi, Shiva; Jahanabadi, Samane; Khoshnoodi, Mina; Shamsaee, Javad; Shafaroodi, Hamed; Mehr, Shahram Ejtemaei; Dehpour, Ahmadreza

2014-12-15

Atorvastatin is a synthetic and lipophilic statin which has been reported to have a positive role in reducing depression. The potential antidepressant-like effects of atorvastatin and the possible involvement of peroxisome proliferator-activated receptor gamma (PPAR_γ) and nitric oxide system were determined using forced swimming test (FST) in mice was studied. Atorvastatin (0.01, 0.1 and 1 mg/kg, p.o.) was administered 1 h before FST. To assess the involvement of PPAR_γ in the possible antidepressant effect of atorvastatin, pioglitazone, a PPAR_γ agonist (5 mg/kg), and GW-9662, a specific PPAR_γ antagonist (2 mg/kg), was co-administered with atorvastatin (0.01 mg/kg, p.o.) and then FST was performed. The possible role of nitric oxide pathway was determined by using co-administration of a non-specific NOS inhibitor, N-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg, i.p.), and a NO precursor, L-arginine (750 mg/kg, i.p.) with sub-effective doses of atorvastatin and pioglitazone. Immobility time was significantly decreased after atorvastatin administration (0.1 and 1 mg/kg, p.o.). Administration of pioglitazone or L-NAME in combination with the sub-effective dose of atorvastatin (0.01 mg/kg, p.o.) reduced the immobility time in the FST compared to drugs alone, showing the participation of these pathways; while co-administration of non-effective doses of atorvastatin and pioglitazone with GW9662 or L-arginine reversed antidepressant-like effect of atorvastatin in FST. Data from concurrent use of GW9662 and atorvastatin also demonstrated that the antidepressant effect of atorvastatin was significantly reversed by GW9662. The antidepressant-like effect of atorvastatin on mice in the FST is mediated at least in part through PPAR_γ receptors and NO pathway. Copyright © 2014 Elsevier B.V. All rights reserved.

A calcium channel blocker, benidipine, improves cell membrane fluidity in human subjects via a nitric oxide-dependent mechanism. An electron paramagnetic resonance investigation.

PubMed

Tsuda, Kazushi; Nishio, Ichiro

2004-12-01

Recent studies have revealed that benidipine, a long-acting dihydropyridine-type of calcium (Ca) channel blocker, may exert its protective effect against vascular disorders by increasing nitric oxide (NO) production. The purpose of the present study was to investigate the effects of benidipine and NO on the membrane function in human subjects. We measured the membrane fluidity of erythrocytes by using an electron paramagnetic resonance (EPR) and spin-labeling method. Benidipine decreased the order parameter (S) for 5-nitroxide stearate (5-NS) and the peak height ratio (h(o)/h(-1)) for 16-NS obtained from EPR spectra of erythrocyte membranes in a dose-dependent manner in normotensive volunteers. The finding indicated that benidipine increased the membrane fluidity and improved the microviscosity of erythrocytes. The effect of benidipine was significantly potentiated by the NO donor, S-nitroso-n-acetylpenicillamine, and by the cyclic guanosine 3', 5'-monophosphate (cGMP) analog, 8-bromo-cGMP. In contrast, the change evoked by benidipine was counteracted by the NO synthase inhibitors, N(G)-nitro-L-arginine-methyl-ester and asymmetric dimethyl-L-arginine. These results demonstrated that benidipine increased the membrane fluidity of erythrocytes, at least in part, via the NO- and cGMP-dependent mechanism. Furthermore, the data strongly suggest that benidipine might have a beneficial effect on the rheologic behavior of erythrocytes and the improvement of the microcirculation in humans.

Ginsenosides Rb1 and Re decrease cardiac contraction in adult rat ventricular myocytes: role of nitric oxide

PubMed Central

Scott, Glenda I; Colligan, Peter B; Ren, Bonnie H; Ren, Jun

2001-01-01

Panax ginseng is used to enhance stamina and relieve fatigue as well as physical stress. Ginsenoside, the effective component of ginseng, regulates cardiovascular function. This study was to examine the effect of ginsenosides Rb1 and Re on cardiac contractile function at the cellular level. Ventricular myocytes were isolated from adult rat hearts and were stimulated to contract at 0.5 Hz. Contractile properties analysed included: peak shortening (PS), time-to-90%PS (TPS), time-to-90% relengthening (TR90), and fluorescence intensity change (ΔFFI). Nitric oxide synthase (NOS) activity was determined by the 3H-arginine to 3H-citrulline conversion assay. Both Rb1 and Re exhibited dose-dependent (1 – 1000 nM) inhibition in PS and ΔFFI, with maximal inhibitions between 20 – 25%. Concurrent application Rb1 and Re did not produce any additive inhibition on peak shortening amplitude (with a maximal inhibition of 24.9±6.1%), compared to Rb1 or Re alone. Pretreatment with the NOS inhibitor Nω-nitro-L-arginine methyl ester (L-NAME, 100 μM) abolished the effect of Rb1 and Re. Both Rb1 and Re significantly (P<0.05) stimulated NOS activity concentration-dependently. This study demonstrated a direct depressant action of ginsenosides on cardiomyocyte contraction, which may be mediated in part through increased NO production. PMID:11704635

Fluoxetine induces vasodilatation of cerebral arterioles by co-modulating NO/muscarinic signalling

PubMed Central

Ofek, Keren; Schoknecht, Karl; Melamed-Book, Naomi; Heinemann, Uwe; Friedman, Alon; Soreq, Hermona

2012-01-01

Ischaemic stroke patients treated with Selective Serotonin Reuptake Inhibitors (SSRI) show improved motor, cognitive and executive functions, but the underlying mechanism(s) are incompletely understood. Here, we report that cerebral arterioles in the rat brain superfused with therapeutically effective doses of the SSRI fluoxetine showed consistent, dose-dependent vasodilatation (by 1.2 to 1.6-fold), suppressible by muscarinic and nitric oxide synthase (NOS) antagonists [atropine, NG-nitro-l-arginine methyl ester (l-NAME)] but resistant to nicotinic and serotoninergic antagonists (mecamylamine, methylsergide). Fluoxetine administered 10–30 min. following experimental vascular photo-thrombosis increased arterial diameter (1.3–1.6), inducing partial, but lasting reperfusion of the ischaemic brain. In brain endothelial b.End.3 cells, fluoxetine induced rapid muscarinic receptor-dependent increases in intracellular [Ca2+] and promoted albumin- and eNOS-dependent nitric oxide (NO) production and HSP90 interaction. In vitro, fluoxetine suppressed recombinant human acetylcholinesterase (rhAChE) activity only in the presence of albumin. That fluoxetine induces vasodilatation of cerebral arterioles suggests co-promotion of endothelial muscarinic and nitric oxide signalling, facilitated by albumin-dependent inhibition of serum AChE. PMID:22697296

The light-induced reduction of horizontal cell receptive field size in the goldfish retina involves nitric oxide.

PubMed

Daniels, Bryan A; Baldridge, William H

2011-03-01

Horizontal cells of the vertebrate retina have large receptive fields as a result of extensive gap junction coupling. Increased ambient illumination reduces horizontal cell receptive field size. Using the isolated goldfish retina, we have assessed the contribution of nitric oxide to the light-dependent reduction of horizontal cell receptive field size. Horizontal cell receptive field size was assessed by comparing the responses to centered spot and annulus stimuli and from the responses to translated slit stimuli. A period of steady illumination decreased the receptive field size of horizontal cells, as did treatment with the nitric oxide donor (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (100 μM). Blocking the endogenous production of nitric oxide with the nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester (1 mM), decreased the light-induced reduction of horizontal cell receptive field size. These findings suggest that nitric oxide is involved in light-induced reduction of horizontal cell receptive field size. Copyright © Cambridge University Press, 2011

Vascular reactivity in arterioles from normal and alloxan-diabetic mice: studies on single perfused islets.

PubMed

Lai, En Yin; Jansson, Leif; Patzak, Andreas; Persson, A Erik G

2007-01-01

Pancreatic islets possess an autonomous mechanism of blood flow regulation, independent of that of the exocrine pancreas. To study islet vascular regulation without confounding effects of the exocrine blood vessels, we have developed a technique enabling us to isolate single pancreatic islets and then to perfuse them using their endogenous vasculature for distribution of the medium. This made it possible to directly study the vascular reactivity of islet arterioles to different substances. We confirmed that control of islet blood flow is mainly located at the precapillary level. As expected, administration of angiotensin II and l-nitro-arginine methyl ester contracted islet arterioles, whereas nitric oxide and adenosine dilated them. d-glucose, the main insulin secretagogue, had a selective dilating effect on smooth muscle in islet arterioles but not in glomerular afferent arterioles. The response to glucose was amplified in islet arterioles from diabetic animals, indicating enhanced islet blood perfusion in diabetes. This newly developed technique for perfusing isolated pancreatic islets will provide new insights into islet perfusion control and its possible contributions to the pathogenesis of type 2 diabetes.

Vasorelaxant effect of formononetin in the rat thoracic aorta and its mechanisms.

PubMed

Zhao, Yan; Chen, Bai-Nian; Wang, Shou-Bao; Wang, Shao-Hua; Du, Guan-Hua

2012-01-01

The purpose of the present study was to investigate the effect of formononetin and the related mechanisms on isolated rat thoracic aorta. Formononetin concentration dependently relaxed aortic rings precontracted with norepinephrine (NE, 1 μM) or KCl (80 mM). Pretreatment with formononetin noncompetitively inhibited contractile responses of aortas to NE and KCl. The vasorelaxant effect of formononetin partially relied on intact endothelia, which was significantly attenuated by incubation with N(ω)-nitro-L-arginine methyl ester (100 μM). In endothelium-denuded rings, glibenclamide (10 μM) and tetraethylammonium (5 mM) showed slight reduction in the vasorelaxant effect of formononetin. Moreover, formononetin reduced NE-induced transient contraction in Ca²⁺-free solution and inhibited the vasocontraction induced by increasing external calcium in medium plus 80 mM KCl. Our results suggested that formononetin induced relaxation in rat aortic rings through an endothelium-dependent manner via nitric oxide synthesis pathway, and also involving an endothelium-independent vasodilatation by the blockade of Ca²⁺ channels. The opening of K⁺ channels might also be one of the mechanisms of formononetin-induced vasorelaxation.

Ascending neural pathways in the rat ileum in vitro--effect of capsaicin and involvement of nitric oxide.

PubMed

Allescher, H D; Sattler, D; Piller, C; Schusdziarra, V; Classen, M

1992-07-07

The aim of the present study was to develop and characterize an in vitro model of the rat ileum in which activation of the orally projecting neural excitatory pathway of the myenteric reflex is produced by electrical field stimulation anally to the recording site. The motility of a 10-cm segment of rat ileum was recorded using a perfused manometric assembly with side holes 2 and 4 cm orally to the stimulation site. Electrical field stimulation caused a contractile response in the oral but not in the aboral direction of the stimulation site. The contractile response, which was maximal using low stimulus frequencies (3 or 5 pulses per second (pps)) and decreased with higher frequencies (10 or 20 pps), was blocked by atropine (10(-6) M) at all frequencies tested after acute and after prolonged (greater than 30 min) treatment. The maximal contractile response at 3 pps was abolished by hexamethonium (10(-4) M), tetrodotoxin (5 x 10(-7) M) and by complete transection of the muscular wall between the stimulation and the recording site. Acute administration of capsaicin (8 x 10(-7) M) to the bath reduced the lag between the start of the electrical stimulation and the onset of the contractile response. Higher concentrations of capsaicin (10(-5) M) reduced the contractile response, but this was partly due to an unspecific effect of capsaicin. Blockade of nitric oxide (NO) synthesis by L-NG-nitro-arginine-methyl ester (L-NAME) (3 x 10(-4) M) augmented the contractile response to anal stimulation by 222.4% and reduced the lag period by 54.5%, whereas the stereoisomer D-NAME had no significant effect. The potentiating effects of L-NAME were reversed in the presence of L-arginine (3 x 10(-3) M) but not in the presence of the stereoisomer D-arginine (3 x 10(-3) M). This model can be used to study ascending neural pathways in the rat small intestine. The ascending excitatory response is abolished by atropine and hexamethonium and is modulated by capsicin-sensitive fibers. The ascending pathway is under tonic inhibition of metabolites of the L-arginine-NO pathway.

Spironolactone differently influences remodeling of the left ventricle and aorta in L-NAME-induced hypertension.

PubMed

Simko, F; Matúsková, J; Lupták, I; Pincíková, T; Krajcírovicová, K; Stvrtina, S; Pomsár, J; Pelouch, V; Paulis, L; Pechánová, O

2007-01-01

Aldosterone receptor antagonist, spironolactone, has been shown to prevent remodeling of the heart in several models of left ventricular hypertrophy. The aim of the present study was to determine whether the treatment with spironolactone can prevent hypertension, reduction of tissue nitric oxide synthase activity and left ventricular (LV) and aortic remodeling in N(G)-nitro-L-arginine methyl ester (L-NAME)-induced hypertension. Four groups of rats were investigated: control, spironolactone (200 mg/kg), L-NAME (40 mg/kg) and L-NAME + spironolactone (in corresponding dosage). Animals were studied after 5 weeks of treatment. The decrease of NO-synthase activity in the LV and kidney was associated with the development of hypertension and LV hypertrophy, with increased DNA concentration in the LV, and remodeling of the aorta in the L-NAME group. Spironolactone prevented the inhibition of NO-synthase activity in the LV and kidney and partially attenuated hypertension and LVH development and the increase in DNA concentration. However, remodeling of the aorta was not prevented by spironolactone treatment. We conclude that the aldosterone receptor antagonist spironolactone improved nitric oxide production and partially prevented hypertension and LVH development without preventing hypertrophy of the aorta in NO-deficient hypertension. The reactive growth of the heart and aorta seems to be controlled by different mechanisms in L-NAME-induced hypertension.

Arginine reduces Cryptosporidium parvum infection in undernourished suckling mice involving both nitric oxide synthase and arginase

PubMed Central

Castro, Ibraim C.; Oliveira, Bruna B.; Slowikowski, Jacek J.; Coutinho, Bruna P.; Siqueira, Francisco Júlio W.S.; Costa, Lourrany B.; Sevilleja, Jesus Emmanuel; Almeida, Camila A.; Lima, Aldo A.M.; Warren, Cirle A.; Oriá, Reinaldo B.; Guerrant, Richard L.

2011-01-01

Objective This study investigated the role of L-arginine supplementation to undernourished and Cryptosporidium parvum-infected suckling mice. Methods The following regimens were initiated on the 4th day of life and given subcutaneously daily: either 200mM of L-arginine or PBS for the C. parvum-infected controls. L-arginine-treated mice were grouped to receive either 20mM of NG-nitroarginine-methyl-ester (L-NAME) or PBS. Infected mice received orally 106 excysted-C. parvum oocysts on day 6 and were euthanized on day 14th at the infection peak. Results L-arginine improved weight gain compared to the untreated infected controls. L-NAME profoundly impaired body weight gain as compared to all other groups. Cryptosporidiosis was associated with ileal crypt hyperplasia, villus blunting, and inflammation. L-arginine improved mucosal histology following infection. L-NAME abrogated these arginine-induced improvements. Infected control mice showed an intense arginase expression, which was even greater with L-NAME. L-arginine reduced parasite burden, an effect that was reversed by L-NAME. C. parvum infection increased urine NO3-/NO2- concentration when compared to uninfected controls, which was increased by L-arginine supplementation, an effect that was also reversed by L-NAME. Conclusion These findings show a protective role of L-arginine during C. parvum infection in undernourished mice with involvement of arginase I and nitric oxide synthase enzymatic actions. PMID:22261576

H2S protects against methionine-induced oxidative stress in brain endothelial cells.

PubMed

Tyagi, Neetu; Moshal, Karni S; Sen, Utpal; Vacek, Thomas P; Kumar, Munish; Hughes, William M; Kundu, Soumi; Tyagi, Suresh C

2009-01-01

Homocysteine (Hcy) causes cerebrovascular dysfunction by inducing oxidative stress. However, to date, there are no strategies to prevent Hcy-induced oxidative damage. Hcy is an H2S precursor formed from methionine (Met) metabolism. We aimed to investigate whether H2S ameliorated Met-induced oxidative stress in mouse brain endothelial cells (bEnd3). The bEnd3 cells were exposed to Met treatment in the presence or absence of NaHS (donor of H2S). Met-induced cell toxicity increased the levels of free radicals in a concentration-dependent manner. Met increased NADPH-oxidase-4 (NOX-4) expression and mitigated thioredxion-1(Trx-1) expression. Pretreatment of bEnd3 with NaHS (0.05 mM) attenuated the production of free radicals in the presence of Met and protected the cells from oxidative damage. Furthermore, NaHS enhanced inhibitory effects of apocynin, N-acetyl-l-cysteine (NAC), reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), Nomega-nitro-l-arginine methyl ester (L-NAME) on ROS production and redox enzymes levels induced by Met. In conclusion, the administration of H2S protected the cells from oxidative stress induced by hyperhomocysteinemia (HHcy), which suggested that NaHS/H2S may have therapeutic potential against Met-induced oxidative stress.

Tributyltin contributes in reducing the vascular reactivity to phenylephrine in isolated aortic rings from female rats.

PubMed

Rodrigues, Samya Mere L; Ximenes, Carolina F; de Batista, Priscila R; Simões, Fabiana V; Coser, Pedro Henrique P; Sena, Gabriela C; Podratz, Priscila L; de Souza, Leticia N G; Vassallo, Dalton V; Graceli, Jones B; Stefanon, Ivanita

2014-03-21

Organotin compounds such as tributyltin (TBT) are used as antifouling paints by shipping companies. TBT inhibits the aromatase responsible for the transformation of testosterone into estrogen. Our hypothesis is that TBT modulates the vascular reactivity of female rats. Female Wistar rats were treated daily (Control; CONT) or TBT (100 ng/kg) for 15 days. Rings from thoracic aortas were incubated with phenylephrine (PHE, 10(-10)-10(-4) M) in the presence and absence of endothelium, and in the presence of N(G)-Nitro-L-Arginine Methyl Ester (L-NAME), tetraethylammonium (TEA) and apocynin. TBT decreased plasma levels of estrogen and the vascular response to PHE. In the TBT group, the vascular reactivity was increased in the absence of endothelium, L-NAME and TEA. The decrease in PHE reactivity during incubation with apocynin was more evident in the TBT group. The sensitivity to acetylcholine (ACh) and sodium nitroprusside (SNP) was reduced in the TBT group. TBT increased collagen, reduced α1-smooth muscle actin. Female rats treated with TBT for 15 days showed morphology alteration of the aorta and decreased their vascular reactivity, probably due to mechanisms dependent on nitric oxide (NO) bioavailability, K(+) channels and an increase in oxidative stress. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Importance of Nitric Oxide for Local Increases of Blood Flow in Rat Cerebellar Cortex During Electrical Stimulation

NASA Astrophysics Data System (ADS)

Akgoren, Nuran; Fabricius, Martin; Lauritzen, Martin

1994-06-01

The endothelium-derived relaxing factor, probably nitric oxide (NO), is a potent vasodilator that regulates the vascular tone in several vascular beds, including the brain. We explored the possibility that NO might be of importance for the increase of cerebral blood flow (CBF) associated with activity of the well-defined neuronal circuits of the rat cerebellar cortex. Laser-Doppler flowmetry was used to measure increases of cerebellar blood flow evoked by trains of electrical stimulations of the dorsal surface. The evoked increases of CBF were frequency-dependent, being larger on than off the parallel fiber tracts, suggesting that conduction along parallel fibers and synaptic activation of target cells were important for the increase of CBF. This was verified experimentally since the evoked CBF increases were abolished by tetrodotoxin and reduced by 10 mM Mg2+ and selective antagonists for non-N-methyl-D-aspartate receptors. The cerebellar cortex contains high levels of NO synthase. This raised the possibility that NO was involved in the increase of CBF associated with neuronal activation. NO synthase inhibition by topical application of N^G-nitro-L-arginine attenuated the evoked CBF increase by about 50%. This effect was partially reversed by pretreatment with L-arginine, the natural substrate for the enzyme, while N^G-nitro-D-arginine, the inactive enantiomer, had no effect on the evoked CBF increases. Simultaneous blockade of non-N-methyl-D-aspartate receptors and NO synthase had no further suppressing effect on the blood flow increase than either substance alone, suggesting that the NO-dependent flow rise was dependent on postsynaptic mechanisms. These findings are consistent with the idea that local synthesis of NO is involved in the transduction mechanism between neuronal activity and increased CBF.

Contractile activity of ATP and diadenosine tetraphosphate on urinary bladder in the rat: role of A1- and P2X-purinoceptors and nitric oxide.

PubMed

Khattab, M M; Al-Hrasen, M N; El-Hadiyah, T M

2007-01-01

1. Both adenosine-5'-triphosphate (ATP) and diadenosine tetraphosphate (AP4A) produced a dose-dependent contraction of the isolated rat urinary bladder rings. AP(4)A dose-response curve was to the left of that of ATP, and maximum response was greater than that produced by ATP. 2. 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), the A1-purinergic receptor blocker (0.01 mm) significantly inhibited the ATP- and AP4A-induced contractions at the whole dose range. The inhibition was between 31-41%, and 15-25% for ATP and AP4A respectively. 3. Pyridoxal phosphate 6-azophenyl-2',4'-disulphonic acid (PPADS), the P2X-purinoceptor antagonist (0.01 mm) potently inhibited the bladder contractions in response to ATP and AP4A by around 75-80%. 4. The nitric oxide (NO) precursor L-arginine reduced the bladder contractile response to ATP by about 22-41% and that of AP4A to a lesser extent by around 20-32%. 5. The nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME, 0.1 mM), did not produce any significant effect on ATP except for a weak inhibition of about 14% at the lowest dose of ATP. The contractions in response to AP4A were only slightly reduced by L-NAME by about 20%. 6. In conclusion, the contractile response of the bladder to ATP and to the dinucleotide AP4A is mediated mainly through P2X-purinoceptors and A1-purinergic receptors. In the detrusor muscle, NO donation possesses an inhibitory effect on ATP-mediated contractility more than that produced by the dinucleotide AP4A.

Doxycycline reduces nitric oxide production in guinea pig inner ears.

PubMed

Helling, Kai; Wodarzcyk, Karl; Brieger, Jürgen; Schmidtmann, Irene; Li, Huige; Mann, Wolf J; Heinrich, Ulf-Rüdiger

2011-12-01

Gentamicin application is an important therapeutic option to control vertigo spells in Ménière's disease. However, even in the case of low-dose intratympanic application, gentamicin might contribute to a pathological NO-increase leading to cochlear damage and hearing impairment. The study was performed to evaluate the nitric oxide (NO) reducing capacity of doxycycline in the inner ear after NO-induction by gentamicin. In a prospective animal study, a single dose of gentamicin (10mg/kg body weight) was injected intratympanically into male guinea pigs (n=48). The auditory brainstem responses (ABRs) were recorded prior to application and 3, 5 and 7 days afterwards. The organ of Corti and the lateral wall of 42 animals were isolated after 7 days and incubated separately for 6h in cell culture medium. Doxycycline was adjusted to organ cultures of 5 animals. Two NOS inhibitors, N(G)-Nitro-l-arginine methyl ester (l-NAME) and NG-monomethyl-l-arginine monoacetate (l-NMMA), were applied in three different concentrations to the organ cultures of 30 animals in total (5 animals per concentration). As controls, seven animals received no further substance except gentamicin. The NO-production was quantified by chemiluminescence. Additional six gentamicin-treated animals were used for immunohistochemical studies. The ABRs declined continuously from the first to the seventh day after gentamicin application. Doxycycline reduced NO-production in the lateral wall by 54% (p=.029) comparable to the effect of the applied nitric oxide inhibitors. In the organ of Corti, NO-production was reduced by about 41% showing no statistical significance in respect to great inter-animal variations. The application of doxycycline might offer a new therapeutic approach to prevent NO-induced cochlea damage through ototoxic substances. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Construction of chiral ligand exchange capillary electrochromatography for d,l-amino acids enantioseparation and its application in glutaminase kinetics study.

PubMed

Zhao, Liping; Qiao, Juan; Zhang, Ke; Li, Dan; Zhang, Hongyi; Qi, Li

2018-05-04

A chiral ligand exchange capillary electrochromatography (CLE-CEC) protocol was designed and implemented for d,l-amino acids enantioseparation with poly(maleic anhydride-styrene-methacryloyl-l-arginine methyl ester) as the coating. The block copolymer was synthesized through the reversible addition fragmentation chain transfer reaction. In the constructed CLE-CEC system, poly (methacryloyl-l-arginine methyl ester) moiety of the block copolymer played the role as the immobilized chiral ligand and Zn (II) was used as the central ion. Key factors, including pH of buffer solution, ratio of Zn (II) to ligands, the mass ratio of monomers in the block copolymer, which affect the enantioresolution were investigated. Comparing with the bare capillary, the CLE-CEC enantioresolution was enhanced greatly with the coating one. 5 Pairs of d,l-amino acids enantiomers obtained baseline separation with 5 pairs partly separated. The mechanism of enhancement enantioresolution of the developed CLE-CEC system was explored briefly. Further, good linearities were achieved in the range of 25.0 μM-5.0 mM for quantitative analysis of d-glutamine (r 2  = 0.997) and l-glutamine (r 2  = 0.991). Moreover, the proposed CLE-CEC assay was successfully applied in the kinetics study of glutaminase by using l-glutamine as the substrate. Copyright © 2018 Elsevier B.V. All rights reserved.

Venlafaxine prevents morphine antinociceptive tolerance: The role of neuroinflammation and the l-arginine-nitric oxide pathway.

PubMed

Mansouri, Mohammad Taghi; Naghizadeh, Bahareh; Ghorbanzadeh, Behnam; Alboghobeish, Soheila; Amirgholami, Neda; Houshmand, Gholamreza; Cauli, Omar

2018-05-01

Opioid-induced neuroinflammation and the nitric oxide (NO) signal-transduction pathway are involved in the development of opioid analgesic tolerance. The antidepressant venlafaxine (VLF) modulates NO in nervous tissues, and so we investigated its effect on induced tolerance to morphine, neuroinflammation, and oxidative stress in mice. Tolerance to the analgesic effects of morphine were induced by injecting mice with morphine (50 mg/kg) once a day for three consecutive days; the effect of co-administration of VLF (5 or 40 mg/kg) with morphine was similarly tested in a separate group. To determine if the NO precursor l-arginine hydrochloride (l-arg) or NO are involved in the effects rendered by VLF, animals were pre-treated with l-arg (200 mg/kg), or the NO synthesis inhibitors N(ω)-nitro-l-arginine methyl ester (L-NAME; 30 mg/kg) or aminoguanidine hydrochloride (AG; 100 mg/kg), along with VLF (40 mg/kg) for three days before receiving morphine for another three days. Nociception was assessed with a hot-plate test on the fourth day, and the concentration of tumor necrosis factor alpha (TNF-α), interleukin-1beta (IL-1β), interleukin-6 (IL-6), interleukin-10, brain-derived neurotrophic factor, NO, and oxidative stress factors such as total thiol, malondialdehyde content, and glutathione peroxidase (GPx) activity in the brain was also determined. Co-administration of VLF with morphine attenuated morphine-induced analgesic tolerance and prevented the upregulation of proinflammatory cytokines (TNF-α, IL-1β, and IL-6), NO, and malondialdehyde in brains of mice with induced morphine tolerance; chronic VLF administration inhibited this decrease in brain-derived neurotrophic factor, total thiol, and GPx levels. Moreover, repeated administration of l-arg before receipt of VLF antagonized the effects induced by VLF, while L-NAME and AG potentiated these effects. VLF attenuates morphine-induced analgesic tolerance, at least partly because of its anti-inflammatory and antioxidative properties. VLF also appears to suppress the development of morphine-induced analgesic tolerance through an l-arg-NO-mediated mechanism. Copyright © 2018 Elsevier Inc. All rights reserved.

Antihypertensive Effects of Roselle-Olive Combination in L-NAME-Induced Hypertensive Rats

PubMed Central

Hessin, Alyaa F.; Abdelbaset, Marwan; Ogaly, Hanan A.; Abd-Elsalam, Reham M.; Hassan, Salah M.

2017-01-01

This study aimed to evaluate the antihypertensive efficacy of a new combination therapy of Hibiscus sabdariffa and Olea europaea extracts (2 : 1; Roselle-Olive), using N(G)-nitro-L-arginine-methyl ester- (L-NAME-) induced hypertensive model. Rats received L-NAME (50 mg/kg/day, orally) for 4 weeks. Concurrent treatment with Roselle-Olive (500, 250, and 125 mg/kg/day for 4 weeks) resulted in a dose-dependent decrease in both systolic and diastolic blood pressure, reversed the L-NAME-induced suppression in serum nitric oxide (NO), and improved liver and kidney markers, lipid profile, and oxidative status. Furthermore, Roselle-Olive significantly lowered the elevated angiotensin-converting enzyme activity (ACE) and showed a marked genoprotective effect against oxidative DNA damage in hypertensive rats. Roselle-Olive ameliorated kidney and heart lesions and reduced aortic media thickness. Real-time PCR and immunohistochemistry showed an enhanced endothelial nitric oxide synthase (eNOS) gene and protein expression in both heart and kidney of Roselle-Olive-treated rats. To conclude, our data revealed that Roselle-Olive is an effective combination in which H. sabdariffa and O. europaea synergistically act to control hypertension. These effects are likely to be mediated by antioxidant and genoprotective actions, ACE inhibition, and eNOS upregulation by Roselle-Olive constituents. These findings provide evidences that Roselle-Olive combination affords efficient antihypertensive effect with a broad end-organ protective influence. PMID:29201276

Antihypertensive Effects of Roselle-Olive Combination in L-NAME-Induced Hypertensive Rats.

PubMed

Abdel-Rahman, Rehab F; Hessin, Alyaa F; Abdelbaset, Marwan; Ogaly, Hanan A; Abd-Elsalam, Reham M; Hassan, Salah M

2017-01-01

This study aimed to evaluate the antihypertensive efficacy of a new combination therapy of Hibiscus sabdariffa and Olea europaea extracts (2 : 1; Roselle-Olive), using N(G)-nitro-L-arginine-methyl ester- (L-NAME-) induced hypertensive model. Rats received L-NAME (50 mg/kg/day, orally) for 4 weeks. Concurrent treatment with Roselle-Olive (500, 250, and 125 mg/kg/day for 4 weeks) resulted in a dose-dependent decrease in both systolic and diastolic blood pressure, reversed the L-NAME-induced suppression in serum nitric oxide (NO), and improved liver and kidney markers, lipid profile, and oxidative status. Furthermore, Roselle-Olive significantly lowered the elevated angiotensin-converting enzyme activity (ACE) and showed a marked genoprotective effect against oxidative DNA damage in hypertensive rats. Roselle-Olive ameliorated kidney and heart lesions and reduced aortic media thickness. Real-time PCR and immunohistochemistry showed an enhanced endothelial nitric oxide synthase (eNOS) gene and protein expression in both heart and kidney of Roselle-Olive-treated rats. To conclude, our data revealed that Roselle-Olive is an effective combination in which H. sabdariffa and O. europaea synergistically act to control hypertension. These effects are likely to be mediated by antioxidant and genoprotective actions, ACE inhibition, and eNOS upregulation by Roselle-Olive constituents. These findings provide evidences that Roselle-Olive combination affords efficient antihypertensive effect with a broad end-organ protective influence.

Dietary Supplementation of Ginger and Turmeric Rhizomes Modulates Platelets Ectonucleotidase and Adenosine Deaminase Activities in Normotensive and Hypertensive Rats.

PubMed

Akinyemi, Ayodele Jacob; Thomé, Gustavo Roberto; Morsch, Vera Maria; Bottari, Nathieli B; Baldissarelli, Jucimara; de Oliveira, Lizielle Souza; Goularte, Jeferson Ferraz; Belló-Klein, Adriane; Oboh, Ganiyu; Schetinger, Maria Rosa Chitolina

2016-07-01

Hypertension is associated with platelet alterations that could contribute to the development of cardiovascular complications. Several studies have reported antiplatelet aggregation properties of ginger (Zingiber officinale) and turmeric (Curcuma longa) with limited scientific basis. Hence, this study assessed the effect of dietary supplementation of these rhizomes on platelet ectonucleotidase and adenosine deaminase (ADA) activities in Nω-nitro-l-arginine methyl ester hydrochloride (l-NAME) induced hypertensive rats. Animals were divided into seven groups (n = 10): normotensive control rats; induced (l-NAME hypertensive) rats; hypertensive rats treated with atenolol (10 mg/kg/day); normotensive and hypertensive rats treated with 4% supplementation of turmeric or ginger, respectively. After 14 days of pre-treatment, the animals were induced with hypertension by oral administration of l-NAME (40 mg/kg/day). The results revealed a significant (p < 0.05) increase in platelet ADA activity and ATP hydrolysis with a concomitant decrease in ADP and AMP hydrolysis of l-NAME hypertensive rats when compared with the control. However, dietary supplementation with turmeric or ginger efficiently prevented these alterations by modulating the hydrolysis of ATP, ADP and AMP with a concomitant decrease in ADA activity. Thus, these activities could suggest some possible mechanism of the rhizomes against hypertension-derived complications associated to platelet hyperactivity. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Nitric oxide mediates angiogenesis induced in vivo by platelet-activating factor and tumor necrosis factor-alpha.

PubMed Central

Montrucchio, G.; Lupia, E.; de Martino, A.; Battaglia, E.; Arese, M.; Tizzani, A.; Bussolino, F.; Camussi, G.

1997-01-01

We evaluated the role of an endogenous production of nitric oxide (NO) in the in vitro migration of endothelial cells and in the in vivo angiogenic response elicited by platelet-activating factor (PAF), tumor necrosis factor-alpha (TNF), and basic fibroblast growth factor (bFGF). The NO synthase inhibitor, N omega-nitro-L-arginine-methyl ester (L-NAME), but not its enantiomer D-NAME, prevented chemotaxis of endothelial cells induced in vitro by PAF and by TNF. The motogenic activity of TNF was also inhibited by WEB 2170, a specific PAF-receptor antagonist. In contrast, chemotaxis induced by bFGF was not prevented by L-NAME or by WEB 2170. Angiogenesis was studied in vivo in a murine model in which Matrigel was used as a vehicle for the delivery of mediators. In this model, the angiogenesis induced by PAF and TNF was inhibited by WEB 2170 and L-NAME but not by D-NAME. In contrast, angiogenesis induced by bFGF was not affected by L-NAME or by WEB 2170. TNF, but not bFGF, induced PAF synthesis within Matrigel. These results suggest that NO mediates the angiogenesis induced by PAF as well as that induced by TNF, which is dependent on the production of PAF. In contrast, the angiogenic effect of bFGF appears to be both PAF and NO independent. Images Figure 3 Figure 4 PMID:9250168

Involvement of nitric oxide in the wound bed microcirculatory change during negative pressure wound therapy.

PubMed

Sano, Hitomi; Ichioka, Shigeru

2015-08-01

This study investigated the role of nitric oxide (NO) in the mechanism of blood flow increase in the wound bed during negative pressure wound therapy (NPWT). We developed an improved experimental model that allowed visualisation of the wound bed microcirculation under NPWT. Wounds were created on the mouse ear, taking care to preserve the subdermal vascular plexus, because the wound bed microcirculation was visualised using an intravital microscope system. We investigated whether application of a NO synthase inhibitor (N(G) -nitro-l-arginine methyl ester: L-NAME) might diminish the effect of the NPWT in increasing the wound blood flow. The experimental animals were divided into a negative pressure group (negative pressure of -125 mmHg applied to the wound for 5 minutes; n = 8), and a negative pressure plus L-NAME group (administration of L-NAME prior to application of the negative pressure; n = 8). In the negative pressure group, significant increase of blood flow was observed at 1 minute after the negative pressure application, which was sustained until 5 minutes. On the contrary, in the negative pressure plus L-NAME group, no significant changes were observed throughout the period of observation. These findings suggest that NO synthesis is involved in the wound bed microcirculatory change induced by NPWT. © 2013 The Authors. International Wound Journal © 2013 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

Protection from inorganic mercury effects on the in vivo dopamine release by ionotropic glutamate receptor antagonists and nitric oxide synthase inhibitors.

PubMed

Vidal, Lucía; Durán, Rafael; Faro, Lilian F; Campos, Francisco; Cervantes, Rosa C; Alfonso, Miguel

2007-09-05

The possible role of ionotropics glutamate receptors on the HgCl(2)-induced dopamine (DA) release from rat striatum was investigated by using in vivo brain microdialysis technique after administration of selective NMDA and AMPA/Kainate receptors antagonists dizocilpine (MK-801), D (-)-2-amino-5-phoshonopentanoic acid (AP5), and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). Moreover, we have also studied the effects of nitric oxide synthase (NOS) inhibitors L-nitro-arginine methyl ester (L-NAME) and 7-nitro-indazol (7-NI) on HgCl(2)-induced DA release. Intraestriatal infusion of 1mM HgCl(2) increased striatal DA to 1717.2+/-375.4% respect to basal levels. Infusion of 1mM HgCl(2) in 400 microM MK-801 pre-treated animals produced an increase on striatal DA levels 61% smaller than that induced in non-pre-treated animals. In the case of AP5, this treatment reduced 92% the increase produced by HgCl(2) as compared to non-pre-treated rats. Nevertheless, the administration of CNQX did not produce any effect on HgCl(2)-induced dopamine release. Intrastriatal infusion of 1mM HgCl(2) in 100 microM L-NAME pre-treated animals produced an increase on extracellular DA levels 82% smaller than produced by HgCl(2) alone. In addition, the pre-treatment with 7-NI reduced 90% the increase produced by infusion of HgCl(2) alone in rats. Thus, HgCl(2)-induced DA release could be produced at last in part, by overstimulation of NMDA receptors with NO production, since administration of NMDA receptor antagonists and NOS inhibitors protected against HgCl(2) effects on DA release.

Propolis reduces oxidative stress in l-NAME-induced hypertension rats.

PubMed

Selamoglu Talas, Zeliha

2014-03-01

The inhibition in the synthesis or bioavailability of nitric oxide (NO) has an important role in progress of hypertension. The blocking of nitric oxide synthase activity may cause vasoconstriction with the formation of reactive oxygen species (ROS). Propolis is a resinous substance collected by honey bees from various plants. Propolis has biological and pharmacological properties. The aim of this study was to examine the effect of propolis on catalase (CAT) activity, malondialdehyde (MDA) and NO levels in the testis tissues of hypertensive rats by Nω-nitro-l-arginine methyl ester (l-NAME). Rats have received nitric oxide synthase inhibitor (l-NAME, 40 mg kg(-1) , intraperitoneally) for 15 days to produce hypertension and propolis (200 mg kg(-1) , by gavage) during the last 5 days. MDA level in l-NAME-treated group significantly increased compared with control group (P < 0.01). MDA level of l-NAME + propolis-treated rats significantly reduced (P < 0.01) compared with l-NAME-treated group. CAT activity and NO level significantly reduced (P < 0.01) in l-NAME group compared with control group. There were no statistically significant increases in the CAT activity and NO level of the l-NAME + propolis group compared with the l-NAME-treated group (P > 0.01). These results suggest that propolis changes CAT activity, NO and MDA levels in testis of l-NAME-treated animals, and so it may modulate the antioxidant system. Copyright © 2013 John Wiley & Sons, Ltd.

Inhibitory effects of atropine and hexamethonium on the angiotensin II-induced contractions of rat anococcygeus smooth muscles.

PubMed

de Godoy, Márcio Augusto Fressatto; Accorsi-Mendonça, Daniela; de Oliveira, Ana Maria

2003-02-01

We have evaluated the interaction between angiotensin II (Ang II) and the cholinergic transmission in anococcygeus smooth muscles isolated from rats treated (sympathectomised group) or not (vehicle group) with reserpine and alpha-methyl-p-tyrosine. For this, we contracted the tissues with Ang II in the presence and absence of atropine and hexamethonium. Ang II induced concentration-dependent contractions, which did not undergo temporal changes in tissues isolated from both groups of rats. In the vehicle group, Ang II induced more potent contractions than in the sympathectomised group. In the sympathectomised rat group, atropine inhibited the contractions induced by Ang II in a concentration-dependent fashion with no decrease in E(max). Additionally, hexamethonium inhibited the contraction induced by Ang II in a concentration-dependent fashion with a decrease in E(max). Association of atropine and hexamethonium produced Ang II-induced curves with rightward shifts from the control curve with a decrease in E(max). Incubation with N(G)-nitro-L-arginine methyl ester (L-NAME) reversed the effects of atropine and hexamethonium association. Conversely, in the vehicle group of rats, atropine and hexamethonium did not produce any significant effect. However, in the presence of yohimbine, atropine shifted the Ang II-induced curves to the right of the control curve with no E(max) decrease. Results suggest that there is a positive interaction between Ang II and cholinergic transmission in the rat anococcygeus smooth muscle mediated by angiotensin receptors located on pre-ganglionic cells.

The use of propidium iodide to assess excitotoxic neuronal death in primary mixed cortical cultures.

PubMed

Lau, Anthony C; Cui, Hong; Tymianski, Michael

2007-01-01

Neurodegenerative disorders are subjects of intense scrutiny in biomedical research because of their often-debilitating effects. Currently, many laboratories are engaged in developing or testing drugs to prevent neuronal loss in a variety of these pathologies. A key to testing such drugs is the use of a fast, reliable, and easily reproducible model of neurodegeneration and neuroprotection. Our laboratory has previously used propidium iodide (PI) to assess the degree of neurodegeneration and neuroprotection under a variety of conditions. Ultimately, efforts are underway in the laboratory to prevent delayed neuronal loss following acute ischemic insults using drug therapies. It is now believed that a key mechanism of neurodegeneration following acute ischemia or anoxia is a result of excitotoxicity via N-methyl-D-aspartate receptors (NMDARs) and subsequent overproduction of nitric oxide via neuronal nitric oxide synthase (nNOS). Thus, for the purposes of this chapter, the insult used to induce cell death will be various concentrations of NMDA and the compound used to demonstrate neuroprotection will be the nonspecific NOS inhibitor No-nitro-L-arginine methyl ester (L-NAME). Assessment of neuronal death is accomplished by measuring changes in PI fluorescence using a fluorescent plate reader. This chapter will outline the necessary steps required to (1) produce primary mixed cortical cultures, (2) apply PT and NMDA to these cultures, (3) quantify the results obtained from these cultures, and (4) image these cultures in conjunction with Hoechst 33342 and immunocytochemistry using fluorescence microscopy.

Urothelium-dependent and urothelium-independent detrusor contractility mediated by nitric oxide synthase and cyclooxygenase inhibition.

PubMed

Santoso, Aneira Gracia Hidayat; Lo, Wan Ning; Liang, Willmann

2011-04-01

The urothelium has been implicated in regulating detrusor smooth muscle contractility but the identity of the putative urothelium-derived inhibitory factor remains unconfirmed. There was inconclusive evidence on the role of nitric oxide synthase (NOS) and cyclooxygenase (COX) in mediating detrusor contractions. This study examined varying regulation by NOS and COX in transverse and longitudinal carbachol (CCh)-induced and unstimulated phasic contractions. Rat detrusor strips with the urothelium-intact (+UE) and urothelium-denuded (-UE) were isolated in both transverse and longitudinal directions. Isometric tension of the detrusor strips was recorded both during stimulation with CCh and at the unstimulated state. In the unstimulated state, phasic contractile activity was measured. Tension recordings were made with and without the NOS inhibitor N(ω)-nitro-L-arginine methyl ester (L-NAME) and COX inhibitor indomethacin (Indo). Only transverse +UE strips responded convincingly to L-NAME and Indo treatment, generating larger CCh-induced contractions. In unstimulated tissues, L-NAME treatment increased phasic amplitude in -UE strips only. Indo treatment failed to elicit any change in the amplitude but suppressed frequency of the phasic activity in transverse +UE strips. There was no significant Indo-mediated change in other strips. The data suggested heterogeneity in the regulation of directional detrusor contractility via NOS- and COX-associated mechanisms. Copyright © 2011 Wiley-Liss, Inc.

Gallic Acid Enriched Fraction of Phyllanthus emblica Potentiates Indomethacin-Induced Gastric Ulcer Healing via e-NOS-Dependent Pathway

PubMed Central

Chatterjee, Ananya; Chatterjee, Sirshendu; Biswas, Angshuman; Bhattacharya, Sayanti; Chattopadhyay, Subrata; Bandyopadhyay, Sandip K.

2012-01-01

The healing activity of gallic acid enriched ethanolic extract (GAE) of Phyllanthus emblica fruits (amla) against the indomethacin-induced gastric ulceration in mice was investigated. The activity was correlated with the ability of GAE to alter the cyclooxygenase- (COX-) dependent healing pathways. Histology of the stomach tissues revealed maximum ulceration on the 3rd day after indomethacin (18 mg/kg, single dose) administration that was associated with significant increase in inflammatory factors, namely, mucosal myeloperoxidase (MPO) activity and inducible nitric oxide synthase (i-NOS) expression. Proangiogenic parameters such as the levels of prostaglandin (PG) E2, vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), von Willebrand Factor VIII, and endothelial NOS (e-NOS) were downregulated by indomethacin. Treatment with GAE (5 mg/kg/day) and omeprazole (3 mg/kg/day) for 3 days led to effective healing of the acute ulceration, while GAE could reverse the indomethacin-induced proinflammatory changes of the designated biochemical parameters. The ulcer healing activity of GAE was, however, compromised by coadministration of the nonspecific NOS inhibitor, N-nitro-L-arginine methyl ester (L-NAME), but not the i-NOS-specific inhibitor, L-N6-(1-iminoethyl) lysine hydrochloride (L-NIL). Taken together, these results suggested that the GAE treatment accelerates ulcer healing by inducing PGE2 synthesis and augmenting e-NOS/i-NOS ratio. PMID:22966242

Celecoxib aggravates cardiac apoptosis in L-NAME-induced pressure overload model in rats: Immunohistochemical determination of cardiac caspase-3, Mcl-1, Bax and Bcl-2.

PubMed

Mosaad, Sarah M; Zaitone, Sawsan A; Ibrahim, Abdelazim; El-Baz, Amani A; Abo-Elmatty, Dina M; Moustafa, Yasser M

2017-06-25

The mechanism of celecoxib cardiovascular adverse events was earlier investigated; yet in-depth investigations are needed to assess the involvement of its pro-apoptotic effect throughout this process. An in-vivo chronic rat model of pressure overload employing Nʷ-nitro-l-arginine methyl ester (L-NAME) was tested at different time intervals to ensure the occurrence of persistent myocardial apoptosis along with pressure overload. Seven groups of male Wistar rats were assigned as (i) distilled water; (ii-iv) L-NAME (60 mg/kg) for 6, 12 or 16 weeks; (v-vii) L-NAME [16 weeks] + celecoxib (25, 50 or 100 mg/kg), from week 13 to week 16. Treatment with L-NAME for 6, 12 or 16 weeks increased systolic blood pressure, serum level of creatine kinase-MB and lactate dehydrogenase. Further, it induced cardiac hypertrophy, detected in terms of greater heart weight index and cardiomyocyte cross-sectional area and produced interstitial and perivascular fibrosis. Moreover, administration of L-NAME increased cardiac immunostaining for activated caspase-3 and Bax/Bcl-2 ratio whereas; immunostaining for Mcl-1 was decreased. Administration of celecoxib (25, 50 or 100 mg/kg) aggravated the L-NAME-induced toxicity. The work results shed the light on the putative pro-apoptotic effect of celecoxib at a risk state of pressure overload comparable to the clinical condition of essential hypertension. Copyright © 2017 Elsevier B.V. All rights reserved.

Chronic inhibition of nitric oxide synthase augments the ACTH response to exercise

PubMed Central

Jankord, Ryan; McAllister, Richard M.; Ganjam, Venkataseshu K.; Laughlin, M. Harold

2009-01-01

Exercise can activate the hypothalamo-pituitary-adrenocortical (HPA) axis, and regular exercise training can impact how the HPA axis responds to stress. The mechanism by which acute exercise induces HPA activity is unclear. Therefore, the purpose of this study was to test the hypothesis that nitric oxide modulates the neuroendocrine component of the HPA axis during exercise. Female Yucatan miniature swine were treated with N-nitro-l-arginine methyl ester (l-NAME) to test the effect of chronic nitric oxide synthase (NOS) inhibition on the ACTH response to exercise. In addition, we tested the effect of NOS inhibition on blood flow to tissues of the HPA axis and report the effects of handling and treadmill exercise on the plasma concentrations of ACTH and cortisol. Chronic NOS inhibition decreased plasma NOx levels by 44%, increased mean arterial blood pressure by 46%, and increased expression of neuronal NOS in carotid arteries. Vascular conductance was decreased in the frontal cortex, the hypothalamus, and the adrenal gland. Chronic NOS inhibition exaggerated the ACTH response to exercise. In contrast, chronic NOS inhibition decreased the ACTH response to restraint, suggesting that the role of NO in modulating HPA activity is stressor dependent. These results demonstrate that NOS activity modulates the response of the neuroendocrine component of the HPA axis during exercise stress. PMID:19144752

Chronic inhibition of nitric oxide synthase augments the ACTH response to exercise.

PubMed

Jankord, Ryan; McAllister, Richard M; Ganjam, Venkataseshu K; Laughlin, M Harold

2009-03-01

Exercise can activate the hypothalamo-pituitary-adrenocortical (HPA) axis, and regular exercise training can impact how the HPA axis responds to stress. The mechanism by which acute exercise induces HPA activity is unclear. Therefore, the purpose of this study was to test the hypothesis that nitric oxide modulates the neuroendocrine component of the HPA axis during exercise. Female Yucatan miniature swine were treated with N-nitro-l-arginine methyl ester (l-NAME) to test the effect of chronic nitric oxide synthase (NOS) inhibition on the ACTH response to exercise. In addition, we tested the effect of NOS inhibition on blood flow to tissues of the HPA axis and report the effects of handling and treadmill exercise on the plasma concentrations of ACTH and cortisol. Chronic NOS inhibition decreased plasma NO(x) levels by 44%, increased mean arterial blood pressure by 46%, and increased expression of neuronal NOS in carotid arteries. Vascular conductance was decreased in the frontal cortex, the hypothalamus, and the adrenal gland. Chronic NOS inhibition exaggerated the ACTH response to exercise. In contrast, chronic NOS inhibition decreased the ACTH response to restraint, suggesting that the role of NO in modulating HPA activity is stressor dependent. These results demonstrate that NOS activity modulates the response of the neuroendocrine component of the HPA axis during exercise stress.

Selective nitrergic neurodegeneration in diabetes mellitus–a nitric oxide-dependent phenomenon

PubMed Central

Cellek, Selim; Rodrigo, José; Lobos, Edgar; Fernández, Patricia; Serrano, Julia; Moncada, Salvador

1999-01-01

In vitro and in vivo studies have demonstrated a dysfunctional nitrergic system in diabetes mellitus, thus explaining the origin of diabetic impotence. However, the mechanism of this nitrergic defect is not understood.In the penises of streptozotocin (STZ)-induced diabetic rats, here, we show by immunohistochemistry that nitrergic nerves undergo selective degeneration since the noradrenergic nerves which have an anti-erectile function in the penis remained intact.Nitrergic relaxation responses in vitro and erectile responses to cavernous nerve stimulation in vivo were attenuated in these animals, whereas noradrenergic responses were enhanced.Activity and protein amount of neuronal nitric oxide synthase (nNOS) were also reduced in the penile tissue of diabetic rats.We, thus, hypothesized that NO in the nitrergic nerves may be involved in the nitrergic nerve damage, since only the nerves which contain neuronal NO synthase underwent degeneration.We administered an inhibitor of NO synthase, NG-nitro-L-arginine methyl ester (L-NAME), in the drinking water of rats for up to 12 weeks following the establishment of diabetes with STZ.Here we demonstrate that this compound protected the nitrergic nerves from morphological and functional impairment. Our results show that selective nitrergic degeneration in diabetes is NO-dependent and suggest that inhibition of NO synthase is neuroprotective in this condition. PMID:10588937

Inhibition of choline acetyltransferase by excitatory amino acids as a possible mechanism for cholinergic dysfunction in the central nervous system.

PubMed

Loureiro-Dos-Santos, N E; Reis, R A; Kubrusly, R C; de Almeida, O M; Gardino, P F; de Mello, M C; de Mello, F G

2001-05-01

Choline acetyltransferase (ChAT) activity was reduced by more than 85% in cultured retina cells after 16 h treatment with 150 microM kainate (T(1/2) : 3.5 h). Glutamate, AMPA and quisqualate also inhibited the enzyme in equivalent proportion. Cell lesion measured by lactate dehydrogenase (LDH) release, 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide - thiazolyl blue (MTT) reduction and microscopic observation was not detected even after 48 h with kainate. Other retina neurochemical markers were not affected by kainate and full recovery of the enzyme was achieved 9 days after kainate removal. Moreover, hemicolinium-3 sensitive choline uptake and hemicolinium-3 binding sites were maintained intact after kainate treatment. The immunoblot and immunohistochemical analysis of the enzyme revealed that ChAT molecules were maintained in cholinergic neurons. The use of antagonists showed that ionotropic and group 1 metabotropic receptors mediated the effect of glutamate on ChAT inhibition, in a calcium dependent manner. The quisqualate mediated ChAT inhibition and part of the kainate effect (30%) was prevented by 5 mM N(G)-nitro-L-arginine methyl ester (L-NAME). Veratridine (3 microM) also reduced ChAT by a Ca(2+) dependent, but glutamate independent mechanism and was prevented by 1 microM tetrodotoxin.

Increased nitric oxide synthase activity is essential for electromagnetic-pulse-induced blood-retinal barrier breakdown in vivo.

PubMed

Lu, Lianjun; Xu, Hui; Wang, Xiaowu; Guo, Guozhen

2009-04-06

To examine whether electromagnetic pulses (EMPs) affected the permeability of the blood-retinal barrier (BRB), gene expression of occludin and activity of nitric oxide synthase (NOS). Sprague-Dawley (SD) rats were used and randomized into EMP and control groups. Retinas were removed immediately, and 2 h or 24 h after EMP radiation. BRB permeability was analyzed by transmission electron microscopy and Evans Blue staining. Retinal NOS activity and concentrations of nitrite and nitrate were measured. Occludin mRNA and protein levels were detected by RT-PCR and Western blotting. Exposure of SD rats to EMP resulted in increased BRB permeability, with the greatest decrease in occludin at 24 h. Moreover, this permeability defect was also correlated with significant increases in the formation of NO and induction of NOS activity in SD rats. Furthermore, we found that treatment with NOS inhibitor N-nitro-L-arginine methyl ester (L-NAME) blocked BRB breakdown and prevented the increase in NO formation and induction of NOS activity, as well as the decrease in occluding expression. Taken together, these results support the view that NOS-dependent NO production is an important factor that contributes to EMP-induced BRB dysfunction, and suggests that NOS induction may play an important role in BRB breakdown.

Time-dependent alterations in serum NO concentration after oral administration of l-arginine, l-NAME, and allopurinol in intestinal ischemia/reperfusion

PubMed Central

Yanni, Amalia E; Margaritis, Eleutherios; Liarakos, Nikolaos; Pantopoulou, Alkisti; Poulakou, Maria; Kostakis, Maria; Perrea, Despoina; Kostakis, Alkis

2008-01-01

Objective To study the effect of oral administration of a nitric oxide (NO) donor l-arginine (l-Arg), a NO synthase inhibitor NG-nitro-l-arginine methyl ester (l-NAME) and an inhibitor of xanthine oxidase, allopurinol (Allo), on serum NO concentration and catalase activity after intestinal ischemia/reperfusion (I/R) in rats. Methods Male Wistar rats received per os l-Arg (800 mg/kg) or l-NAME (50 mg/kg) or Allo (100 mg/kg) 24 hrs, 12 hrs and 1 hr before underwent 1 hr occlusion of superior mesenteric artery followed by 1 hr of reperfusion (l-Arg(IR1), l-NAME(IR1) and Allo(IR1) respectively) or 1 hr occlusion followed by 8 hrs of reperfusion (l-Arg(IR8), l-NAME(IR8) and Allo(IR8) respectively). There was one group underwent 1 hr occlusion (I), a group underwent 1 hr occlusion followed by 1 hr reperfusion (IR1), a group subjected to 1 hr occlusion followed by 8 hrs of reperfusion (IR8) and a last group that served as control (C). Serum NO concentration and catalase activity were measured. Results After 1 hr of reperfusion serum NO concentration was elevated in IR1 and l-Arg(IR1) groups compared with group C but not in l-NAME(IR1) and Allo(IR1) group. Catalase activity was enhanced in l-NAME(IR1) group. Interestingly, serum NO concentration was increased after 8 hrs of reperfusion in all groups (IR8, l-Arg(IR8), l-NAME(IR8) and Allo(IR8)) compared with control while catalase activity did not show significant difference in any group. Conclusions The results of the present study show that NO concentration is elevated in serum after intestinal I/R and the elevation sustained after administration of l-Arg but not after administration of l-NAME or Allo after 1 hr reperfusion. However, after 8 hrs of reperfusion NO concentration was increased in all groups studied, focusing attention on its possible important role in a complicated situation such as intestinal I/R that involves intestine and other organs. Serum catalase activity does not seem to be affected by per os supplementation of l-Arg or Allo in intestinal I/R. PMID:18561519

Subacute Zinc Administration and L-NAME Caused an Increase of NO, Zinc, Lipoperoxidation, and Caspase-3 during a Cerebral Hypoxia-Ischemia Process in the Rat

PubMed Central

Blanco-Alvarez, Victor Manuel; Lopez-Moreno, Patricia; Soto-Rodriguez, Guadalupe; Martinez-Fong, Daniel; Rubio, Hector; Gonzalez-Barrios, Juan Antonio; Piña-Leyva, Celia; Torres-Soto, Maricela; Gomez-Villalobos, María de Jesus; Hernandez-Baltazar, Daniel; Eguibar, José Ramon; Ugarte, Araceli; Cebada, Jorge

2013-01-01

Zinc or L-NAME administration has been shown to be protector agents, decreasing oxidative stress and cell death. However, the treatment with zinc and L-NAME by intraperitoneal injection has not been studied. The aim of our work was to study the effect of zinc and L-NAME administration on nitrosative stress and cell death. Male Wistar rats were treated with ZnCl2 (2.5 mg/kg each 24 h, for 4 days) and N-ω-nitro-L-arginine-methyl ester (L-NAME, 10 mg/kg) on the day 5 (1 hour before a common carotid-artery occlusion (CCAO)). The temporoparietal cortex and hippocampus were dissected, and zinc, nitrites, and lipoperoxidation were assayed at different times. Cell death was assayed by histopathology using hematoxylin-eosin staining and caspase-3 active by immunostaining. The subacute administration of zinc before CCAO decreases the levels of zinc, nitrites, lipoperoxidation, and cell death in the late phase of the ischemia. L-NAME administration in the rats treated with zinc showed an increase of zinc levels in the early phase and increase of zinc, nitrites, and lipoperoxidation levels, cell death by necrosis, and the apoptosis in the late phase. These results suggest that the use of these two therapeutic strategies increased the injury caused by the CCAO, unlike the alone administration of zinc. PMID:23997853

[N(omega)-nitro-L-arginine methyl ester inhibits the up-regulated expression of neuronal nitric oxide synthase/NMDA receptor in the morphine analgesia tolerance rats].

PubMed

Yu, Ling; Xue, Fu-Shan; Li, Cheng-Wen; Xu, Ya-Chao; Zhang, Guo-Hua; Liu, Kun-Peng; Liu, Yi; Sun, Hai-Tao

2006-12-25

The effect of systemic administration of nonspecific nitric oxide synthase inhibitor (N(omega)-nitro-L-arginine methyl ester, L-NAME) on morphine analgesia tolerance was observed by using the thermal tail-flick method, and the roles of NO and NMDA receptors in morphine analgesia tolerance were evaluated on the basis of the expressions of nNOS mRNA, NR1A mRNA and NR2A mRNA in spinal cord and midbrain. Thirty-six healthy adult Sprague-Dawley rats were randomly divided into six groups (6 rats per group). Group 1, control group, received a subcutaneous (s.c.) injection of normal saline (1 ml); Groups 2, 3, 4, 5 and 6, the treatment groups received s.c. injection of L-NAME 10 mg/kg, L-NAME 20 mg/kg, morphine 10 mg/kg, L-NAME 10 mg/kg + morphine 10 mg/kg, and L-NAME 20 mg/kg + morphine 10 mg/kg, respectively. All rats received s.c. injections twice per day (8:00 and 17:00). The tail-flick latency (TFL) was measured in each rat before the injection as a baseline value, and then TFL at 50 min after the 1st injection every day as the measuring values. The animals (except for groups 2 and 5) were decapitated at 80 min after the last injection on the 8th day. The spinal segments and midbrain were removed for analysis of nNOS mRNA, NR1A mRNA and NR2A mRNA expressions by the RT-PCR method. The results showed that TFL remained unchangeable in group 2 compared with baseline value during the 7-day observation, while increased significantly on the 7th day in group 3. In group 4, TFL was longest on the 1st day, then decreased gradually from the 2nd day to the 6th day, and restored to the baseline value on the 6th day. In group 5, TFL showed a decreasing tendency during the 7-day observation, but was still significantly longer than the baseline value on the 7th day. The changes of TFL obtained in group 6 were similar to those in group 5. The results of RT-PCR showed that as compared with group 1, nNOS mRNA expressions in spinal cord and midbrain were significantly down-regulated in group 3, but the expressions of the NR1A mRNA and NR2A mRNA in both groups were similar, while the nNOS mRNA, NR(1A) mRNA and NR(2A) mRNA expressions were all significantly up-regulated in group 4. As compared with group 4, the expressions of nNOS mRNA, NR(1A) mRNA and NR(2A) mRNA were significantly inhibited in group 6. These results suggest that the expressions of nNOS and NMDA receptors in spinal cord and midbrain were significantly up-regulated in the rats with morphine analgesia tolerance. Chronic co-administration of L-NAME could effectively inhibit the morphine-induced overexpressions of nNOS and NMDA receptors, and postpone the development of morphine analgesia tolerance. Based on the results of this study, it is concluded that NO/NMDA receptor in spinal cord and midbrain is closely related to the development of morphine analgesia tolerance.

INDUCTION OF 6-THIOGUANINE RESISTANCE IN SYNTHRONIZED HUMAN FIBROBLAST CELLS TREATED WITH METHYL METHANESULFONATE, N-ACETOXY-2-ACETHYLAMINOFLUORENE AND N-METHYL-N'-NITRO-N-NITROSOGUANIDINE

EPA Science Inventory

Chemical induction of 6-thioguanine resistance was studied in synchronized human fibroblast cells. Cells initially grown in a medium lacking arginine and glutamine for 24 h ceased DNA synthesis and failed to enter the S phase. After introduction of complete medium, the cells prog...

Synergistic Antihypertensive Effect of Carthamus tinctorius L. Extract and Captopril in l-NAME-Induced Hypertensive Rats via Restoration of eNOS and AT1R Expression

PubMed Central

Maneesai, Putcharawipa; Prasarttong, Patoomporn; Bunbupha, Sarawoot; Kukongviriyapan, Upa; Kukongviriyapan, Veerapol; Tangsucharit, Panot; Prachaney, Parichat; Pakdeechote, Poungrat

2016-01-01

This study examined the effect of Carthamus tinctorius (CT) extract plus captopril treatment on blood pressure, vascular function, nitric oxide (NO) bioavailability, oxidative stress and renin-angiotensin system (RAS) in Nω-Nitro-l-arginine methyl ester (l-NAME)-induced hypertension. Rats were treated with l-NAME (40 mg/kg/day) for five weeks and given CT extract (75 or 150 or 300 or 500 mg/kg/day): captopril (5 mg/kg/day) or CT extract (300 mg/kg/day) plus captopril (5 mg/kg/day) for two consecutive weeks. CT extract reduced blood pressure dose-dependently, and the most effective dose was 300 mg/kg/day. l-NAME-induced hypertensive rats showed abnormalities including high blood pressure, high vascular resistance, impairment of acetylcholine-induced vasorelaxation in isolated aortic rings and mesenteric vascular beds, increased vascular superoxide production and plasma malondialdehyde levels, downregulation of eNOS, low level of plasma nitric oxide metabolites, upregulation of angiotensin II type 1 receptor and increased plasma angiotensin II. These abnormalities were alleviated by treatment with either CT extract or captopril. Combination treatment of CT extract and captopril normalized all the abnormalities found in hypertensive rats except endothelial dysfunction. These data indicate that there are synergistic antihypertensive effects of CT extract and captopril. These effects are likely mediated by their anti-oxidative properties and their inhibition of RAS. PMID:26938552

Vascular wall function in insulin-resistant JCR:LA-cp rats: role of male and female sex.

PubMed

O'Brien, S F; Russell, J C; Dolphin, P J; Davidge, S T

2000-08-01

Vascular wall function was assessed in obese insulin-resistant (cp/cp) and lean normal (+/?), male and female, JCR:LA-cp rats. Both male and female cp/cp rats showed enhanced maximum contractility in response to norepinephrine; impaired smooth muscle in response to sodium nitroprusside, a nitric oxide (NO) donor; and impaired relaxation in response to acetylcholine (ACh), compared with their lean counterparts. The abnormalities were similar in male and female cp/cp rats. The NO synthase inhibitor, Nomega-nitro-L-arginine methyl ester (L-NAME), inhibited ACh-mediated relaxation significantly in male rats, both cp/cp and +/?. The inhibition of ACh-mediated relaxation by L-NAME in +/? females was less, with no reduction in maximal relaxation, and was absent in cp/cp females. These effects suggest that the relative importance of NO in the endothelial modulation of smooth muscle contractility is greater in male rats. The results are consistent with a decreased role for endothelial NO in the cp/cp rats of both sexes and a reduction in NO-independent cholinergic relaxation in the male cp/cp rat. This NO-independent mechanism is not affected in the female cp/cp rats. The relatively small differences between males and females in smooth muscle cell and vascular function may contribute to sex-related differences in the atherogenesis, vasospasm, and ischemic damage associated with the obese insulin-resistant state.

H2S Protects Against Methionine–Induced Oxidative Stress in Brain Endothelial Cells

PubMed Central

Tyagi, Neetu; Moshal, Karni S.; Sen, Utpal; Vacek, Thomas P.; Kumar, Munish; Hughes, William M.; Kundu, Soumi

2009-01-01

Abstract Homocysteine (Hcy) causes cerebrovascular dysfunction by inducing oxidative stress. However, to date, there are no strategies to prevent Hcy-induced oxidative damage. Hcy is an H2S precursor formed from methionine (Met) metabolism. We aimed to investigate whether H2S ameliorated Met-induced oxidative stress in mouse brain endothelial cells (bEnd3). The bEnd3 cells were exposed to Met treatment in the presence or absence of NaHS (donor of H2S). Met-induced cell toxicity increased the levels of free radicals in a concentration-dependent manner. Met increased NADPH-oxidase-4 (NOX-4) expression and mitigated thioredxion-1(Trx-1) expression. Pretreatment of bEnd3 with NaHS (0.05 mM) attenuated the production of free radicals in the presence of Met and protected the cells from oxidative damage. Furthermore, NaHS enhanced inhibitory effects of apocynin, N-acetyl-l-cysteine (NAC), reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), Nω-nitro-l-arginine methyl ester (L-NAME) on ROS production and redox enzymes levels induced by Met. In conclusion, the administration of H2S protected the cells from oxidative stress induced by hyperhomocysteinemia (HHcy), which suggested that NaHS/H2S may have therapeutic potential against Met-induced oxidative stress. Antioxid. Redox Signal. 11, 25–33. PMID:18837652

Central Antinociceptive and Mechanism of Action of Pereskia bleo Kunth Leaves Crude Extract, Fractions, and Isolated Compounds

PubMed Central

Guilhon, Carolina Carvalho; Abdul Wahab, Ikarastika Rahayu; Boylan, Fabio; Fernandes, Patricia Dias

2015-01-01

Pereskia bleo (Kunth) DC. (Cactaceae) is a plant commonly used in popular medicine in Malaysia. In this work, we evaluate the antinociceptive effect of P. bleo leaf extracts and isolated compounds in central antinociceptive model. Ethanol extract (E), hexane (H), ethyl acetate (EA), or butanol (B) fractions (30, 50, or 100 mg/kg, p.o.), sitosterol (from hexane) and vitexin (from ethyl acetate), were administered to mice. Antinociceptive effect was evaluated in the hot plate and capsaicin- or glutamate-induced licking models. Morphine (1 mg/kg, p.o.) was used as reference drug. Naloxone (1 mg/kg, i.p.), atropine (1 mg/kg, i.p.), and L-nitro arginine methyl ester (L-NAME, 3 mg/kg, i.p.) were administered 30 min earlier (100 mg/kg, p.o.) in order to evaluate the mechanism of the antinociceptive action. Higher dose of B developed an effect significantly superior to morphine-treated group. Naloxone prevented the antinociceptive effect of all fractions. L-NAME demonstrated effect against E, EA, and B. In all fractions, sitosterol and vitexin reduced the licking time after capsaicin injection. Glutamate-induced licking response was blocked by H, EA, and B. Our results indicate that Pereskia bleo fractions, sitosterol and vitexin, possessed a central antinociceptive effect. Part of this effect is mediated by opioid receptors and nitrergic pathway. PMID:26273315

Ex vivo relaxation effect of Cuscuta chinensis extract on rabbit corpus cavernosum.

PubMed

Sun, Kai; Zhao, Chen; Chen, Xiang-Feng; Kim, Hye-Kyung; Choi, Bo-Ram; Huang, Yi-Ran; Park, Jong-Kwan

2013-01-01

The effect of Cuscuta chinensis extract on the rabbit penile corpus cavernosum (PCC) was evaluated in the present study. Penises obtained from healthy male New Zealand white rabbits (2.5-3.0 kg) were precontracted with phenylephrine (Phe, 10 µmol l(-1)) and then treated with various concentrations of Cuscuta chinensis extract (1, 2, 3, 4 and 5 mg ml(-1)). The change in penile tension was recorded, and cyclic nucleotides in the PCC were measured by radioimmunoassay (RIA). The interaction between Cuscuta chinensis and sildenafil was also evaluated. The result indicated that the PCC relaxation induced by Cuscuta chinensis extract was concentration-dependent. Pre-treatment with an nitric oxide synthase (NOS) inhibitor (Nω nitro-L-arginine-methyl ester, L-NAME), a guanylyl cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, ODQ), or a protein kinase A inhibitor (KT 5720) did not completely inhibit the relaxation. Incubation of penile cavernous tissue with the Cuscuta chinensis extract significantly increased cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) in the PCC. Moreover, the Cuscuta chinensis extract significantly enhanced sildenafil-induced PCC relaxation. In conclusion, the Cuscuta chinensis extract exerts a relaxing effect on penile cavernous tissue in part by activating the NO-cGMP pathway, and it may improve erectile dysfunction (ED), which does not completely respond to sildenafil citrate.

Relaxation by urocortin of rat renal arteries: effects of diabetes in males and females.

PubMed

Sanz, Elena; Fernández, Nuria; Monge, Luis; Climent, Belén; Diéguez, Godofredo; García-Villalón, Angel Luis

2003-06-01

Urocortin is a peptide structurally related to corticotropin releasing factor (CRF), and the present study was performed to examine the effects of diabetes mellitus on the relaxation by urocortin of renal arteries from males and females. The response to urocortin was studied in isolated segments, 2 mm long, from renal arteries, from male and female, control (normoglycemic) and streptozotocin-induced diabetic rats. In the renal arterial segments precontracted with endothelin-1, urocortin produced concentration-dependent relaxation, that was not different between males and females. Diabetes reduced the relaxation in renal arteries from females but not in those from males. The potassium channel blocker charybdotoxin (10(-7) M) reduced the relaxation to urocortin of renal arteries from normoglycemic males and females. The cyclooxygenase inhibitor meclofenamate did not modify the relaxation to urocortin in renal arteries from normoglycemic males or females. The inhibitor of nitric oxide synthesis N(W)-nitro-L-arginine methyl ester (L-NAME, 10(-4) M) reduced the relaxation to urocortin in renal arteries from normoglycemic females, but not in renal arteries from normoglycemic males. Neither charybdotoxin, L-NAME or meclofenamate modified the relaxation to urocortin of renal arteries from diabetic females. These results suggest that urocortin produces a marked vasodilation of renal arteries, which may be mediated by nitric oxide in females and by activation of potassium channels in both genders, and is reduced by diabetes in renal arteries from females.

Ferulic acid alleviates symptoms of preeclampsia in rats by upregulating vascular endothelial growth factor.

PubMed

Gong, Weiyan; Wan, Jipeng; Yuan, Qing; Man, Quanzhan; Zhang, Xiaojing

2017-10-01

Preeclampsia is a complication affecting pregnant women worldwide, which leads to maternal and fetal morbidity and mortality. In this study, we evaluated the efficacy of ferulic acid (FA) on an N ω -nitro-L-arginine methyl ester hydrochloride (L-NAME) induced rat model of preeclampsia. L-NAME was administered to pregnant rats to induce preeclampsia. 48 rats were divided into three experimental groups (n=16 each): control group, preeclampsia group and preeclampsia with FA treatment (preeclampsia+FA). Physiological characteristics such as urine volume, total urine protein and blood pressure were assessed. Expressions levels of urinary nephrin and podocin mRNAs were analyzed by RT-PCR. Levels of renal vascular endothelial growth factor (VEGF), renal soluble fms-like tyrosine kinase-1 (sFlt-1) and serum placenta growth factor (PlGF) were also examined. Urine volume, total urine protein and blood pressure were markedly increased in preeclampsia group rats compared to control (P<.05), which were then significantly reduced in preeclampsia+FA group (P<.05). Expressions of urinary nephrin and podocin mRNAs, levels of VEGF, sFlt-1 and PlGF were also reversed in preeclampsia+FA group compared to preeclampsia rats (P<.05). We hereby report for the first time, FA alleviates preeclampsia symptoms in a rat preeclampsia model, supporting its potential value in treating preeclampsia. © 2017 John Wiley & Sons Australia, Ltd.

Uncaria rhynchophylla (miq) Jack plays a role in neuronal protection in kainic acid-treated rats.

PubMed

Tang, Nou-Ying; Liu, Chung-Hsiang; Su, Shan-Yu; Jan, Ya-Min; Hsieh, Ching-Tou; Cheng, Chin-Yi; Shyu, Woei-Cherng; Hsieh, Ching-Liang

2010-01-01

Uncaria rhynchophylla (Miq) Jack (UR) is one of many Chinese herbs. Our previous studies have shown that UR has both anticonvulsive and free radical-scavenging activities in kainic acid (KA)-treated rats. The aim of the present study was to use the effect of UR on activated microglia, nitric oxide synthase, and apoptotic cells to investigate its function in neuroproction in KA-treated rats. UR of 1.0 or 0.5 g/kg was orally administered for 3 days (first day, second day, and 30 min prior to KA administration on the third day), or 10 mg/kg (intraperitoneal injection, i.p.) N-nitro-L-arginine methyl ester (L-NAME) 30 min prior to KA (2 microg/2 microl) was injected into the right hippocampus region of Sprague-Dawly rats. ED1 (mouse anti rat CD68), neuronal nitric oxide synthase (nNOS), inducible nitric oxide synthase (iNOS) immunoreactive cells and apoptotic cells were observed in the hippocampus region. The results indicated that 1.0 g/kg, 0.5 g/kg of UR and 10 mg/kg of L-NAME reduced the counts of ED1, nNOS, iNOS immunoreactive cells and apoptotic cells in KA-treated rats. This study demonstrates that UR can reduce microglia activation, nNOS, iNOS and apoptosis, suggesting that UR plays a neuro-protective role against neuronal damage in KA-treated rats.

Mechanisms mediating substance P-induced contraction in the rat iris in vitro.

PubMed

Grumann-Júnior, A; Dias, M A; Alves, R V; Boteon, J E; Calixto, J B

2000-06-01

To determine some of the mechanisms by which substance P (SP) induces contraction in the isolated rat iris. Rings of rat iris were mounted in a 5-ml organ chamber containing Krebs solution at 37 degrees C under basal tension of 75 mg, and isometric tension was recorded. Substance P produced graded contraction in the rat iris, being approximately 40-fold more potent than carbachol. Peptidase inhibitors (captopril, phosphoramidon, thiorphan) did not affect the SP response. The SP contraction was dependent on external Ca2+ by a mechanism resistant to both nifedipine and omega-conotoxin GVIA. Atropine and tetrodotoxin significantly shifted the SP response to the right (three- and fivefold, respectively). Neither phorbol nor genistein altered the SP-induced contraction, whereas staurosporine caused a weak inhibition. Indomethacin, pyrilamine, guanethidine, 8-37 calcitonin gene-related peptide (CGRP) fragment, and NG-nitro-L-arginine methyl ester had no effect on SP response. All the natural tachykinin agonists caused concentration-dependent contraction in rat iris with similar maximal responses. The NK3 selective agonist senktide caused graded contraction, being approximately 150-fold more active than the NK2 selective agonist [beta-ala] NKA. The NK1 selective agonist SP methyl ester induced a small contraction. The NK3 and NK2 antagonists SR 142801 and SR 48968 shifted the SP response to the right. Schilds plots gave pA2 (negative logarithm of the molar concentration of antagonist causing a twofold rightward displacement of the concentration response curves) values of 9.37 and 7.97 and slopes of 0.70 and 1.02, respectively. Substance P produces a potent contraction in the isolated rat iris that seems to depend on the neural release of acetylcholine by tetrodotoxin-sensitive mechanisms. Its response relies largely on external Ca2+, through mechanisms independent of activation of L- or N-type Ca2+ channels, and is probably mediated via activation of NK3 and NK2 receptors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tirapelli, Carlos R.; De Andrade, Claudia R.; Lieberman, Marcel

We aimed to investigate the mechanisms underlying the vascular effects induced by phylloquinone (Vitamin K{sub 1}; VK{sub 1}). Vascular reactivity experiments, using standard muscle bath procedures, showed that VK{sub 1} (5 and 50 {mu}M) enhances the contractile response of endothelium-intact, but not denuded, rat carotid rings to phenylephrine. Similarly, maximal contraction induced by phenylephrine was enhanced in the presence of the nitric oxide (NO) synthase inhibitor N {sup G}-nitro-L-arginine methyl ester (L-NAME). The combination of L-NAME and VK{sub 1} did not produce any further additional effect. Pre-incubation of intact-rings with VK{sub 1} reduced both acetylcholine- and bradykinin-induced relaxation. VK{sub 1}more » induced an increment in tension on carotid rings submaximally pre-contracted with phenylephrine. VK{sub 1}-induced increment in tension was completely abolished by endothelial removal or incubation of intact rings with L-NAME and L-NNA. Conversely, 7-nitroindazole, 1400 W, or indomethacin did not affect VK{sub 1}-induced contraction. Moreover, VK{sub 1} reduced L-arginine-induced relaxation in endothelium-intact rings. Lucigenin-amplified chemiluminescence assays showed that VK{sub 1} induced an increase in the level of superoxide anions in endothelium-intact but not denuded rings. Measurement of nitrite and nitrate generation showed that VK{sub 1} did not alter nitrate formation but strongly inhibited the generation of nitrite. Finally, the superoxide anions scavenger tiron prevented the endothelial vasomotor dysfunction caused by VK{sub 1} on phenyleprine-induced contraction and acetylcholine or bradykinin-induced relaxation. In conclusion, our data show that VK{sub 1} disrupts the vasomotor function of rat carotid. Our results suggest that VK{sub 1}-induced oxidative stress through production of superoxide anion is interfering with the NO pathway, which in turn is responsible for the altered vascular reactivity induced by VK{sub 1}.« less

17α-ethinyl estradiol attenuates depressive-like behavior through GABAA receptor activation/nitrergic pathway blockade in ovariectomized mice.

PubMed

Saeedi Saravi, Seyed Soheil; Arefidoust, Alireza; Yaftian, Rahele; Saeedi Saravi, Seyed Sobhan; Dehpour, Ahmad Reza

2016-04-01

This study was performed to investigate the antidepressant-like effect of 17α-ethinyl estradiol (EE2) in ovariectomized (OVX) mice and the possible role of nitrergic and gamma aminobutyric acid (GABA)ergic pathways in this paradigm. Bilateral ovariectomy was performed in female mice, and different doses of EE2 were intraperitoneally injected either alone or combined with GABAA agonist, diazepam, GABAA antagonist, flumazenil, non-specific nitric oxide synthase (NOS) inhibitor, N(ω)-nitro-L-arginine methyl ester (L-NAME), specific nNOS inhibitor, 7-nitroindazole (7-NI), a nitric oxide (NO) precursor, L-arginine, and selective PDE5I, sildenafil. After locomotion assessment, immobility times were recorded in the forced swimming test (FST) and tail suspension test (TST). Moreover, hippocampal nitrite concentrations were measured in the examined groups. Ten days after ovariectomy, a significant prolonged immobility times were observed. EE2 (0.3 and 1μg/kg and 0.03, 0.1, and 1mg/kg) caused antidepressant-like activity in OVX mice in FST and TST. Diazepam (1 and 5mg/kg), L-NAME (30mg/kg), and 7-NI (100mg/kg) significantly reduced the immobility times. Co-administration of minimal and sub-effective doses of EE2 and diazepam (0.3μg/kg and 0.5mg/kg, respectively) exerted a significant antidepressant-like effect. The same effect was observed in combination of minimal and sub-effective doses of EE2 and either L-NAME or 7-NI. Moreover, combination of minimal and sub-effective doses of EE2, diazepam either L-NAME, or 7-NI emphasized the significant robust antidepressant-like activity. The study has demonstrated that lowest dose of EE2 exerts a significant antidepressant-like behavior. It is suggested that suppression of NO system, as well as GABAA activation, may be responsible for antidepressant-like activity of EE2 in OVX mice. Moreover, GABAA activation may inhibit nitrergic pathway.

Effect of N-acetylarginine, a metabolite accumulated in hyperargininemia, on parameters of oxidative stress in rats: protective role of vitamins and L-NAME.

PubMed

Sasso, Simone; Dalmedico, Leticia; Delwing-Dal Magro, Débora; Wyse, Angela T S; Delwing-de Lima, Daniela

2014-08-01

In the present investigation, we initially evaluated the in vitro effect of N-acetylarginine on thiobarbituric acid-reactive substances (TBA-RS), total sulfhydryl content and on the activities of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in the blood, kidney and liver of rats. Results showed that N-acetylarginine, at a concentration of 5.0 μM, decreased the activity of CAT in erythrocytes, enhanced TBA-RS in the renal cortex, decreased CAT and SOD activities in the renal medulla and decreased CAT and increased SOD and GSH-Px activities in the liver of 60-day-old rats. Furthermore, we tested the influence of the antioxidants, trolox and ascorbic acid, as well as of the N(ω) -nitro-L-arginine methyl ester (L-NAME) on the effects elicited by N-acetylarginine on the parameters tested. Antioxidants and L-NAME prevented most of the alterations caused by N-acetylarginine on the oxidative stress parameters evaluated. Data indicate that oxidative stress induction is probably mediated by the generation of NO and/or ONOO(-) and other free radicals because L-NAME and antioxidants prevented the effects caused by N-acetylarginine in the blood, renal tissues and liver of rats. Our findings lend support to a potential therapeutic strategy for this condition, which may include the use of appropriate antioxidants for ameliorating the damage caused by N-acetylarginine. Copyright © 2014 John Wiley & Sons, Ltd.

Antihypertensive mechanisms of chronic captopril or N-acetylcysteine treatment in L-NAME hypertensive rats.

PubMed

Zicha, Josef; Dobesová, Zdenka; Kunes, Jaroslav

2006-12-01

Hypertension due to chronic inhibition of NO synthase (NOS) by Nomega-nitro-L-arginine methyl ester (L-NAME) administration is characterized by both impaired NO-dependent vasodilation and enhanced sympathetic vasoconstriction. The aim of our study was to evaluate changes in the participation of major vasoactive systems in L-NAME-treated rats which were subjected to simultaneous antihypertensive (captopril) or antioxidant (N-acetylcysteine, NAC) treatment. Three-month-old Wistar males treated with L-NAME (60 mg/kg/day) for 5 weeks were compared to rats in which L-NAME treatment was combined with simultaneous chronic administration of captopril or NAC. Basal blood pressure (BP) and its acute responses to consecutive i.v. injections of captopril (10 mg/kg), pentolinium (5 mg/kg), L-NAME (30 mg/kg), tetraethylammonium (TEA, 16 mg/kg) and nitroprusside (NP, 20 microg/kg) were determined in conscious rats at the end of the study. The development of L-NAME hypertension was prevented by captopril treatment, whereas NAC treatment caused only a moderate BP reduction. Captopril treatment normalized the sympathetic BP component and significantly reduced residual BP (measured at full NP-induced vasodilation). In contrast, chronic NAC treatment did not modify the sympathetic BP component or residual BP, but significantly enhanced NO-dependent vasodilation. Neither captopril nor NAC treatment influenced the compensatory increase of TEA-sensitive vasodilation mediated by endothelium-derived hyperpolarizing factor in L-NAME-treated rats. Chronic captopril treatment prevented L-NAME hypertension by lowering of sympathetic tone, whereas chronic NAC treatment attenuated L-NAME hypertension by reduction in the vasodilator deficit due to enhanced NO-dependent vasodilation.

Rapid tachyphylaxis to hemodynamic effects of PACAP-27 after inhibition of nitric oxide synthesis

NASA Technical Reports Server (NTRS)

Whalen, E. J.; Travis, M. D.; Johnson, A. K.; Lewis, S. J.

1999-01-01

The vasodilator effects of pituitary adenylate cyclase-activating polypeptide (PACAP)-27 are subject to tachyphylaxis in rats treated with the nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME). We examined whether this tachyphylaxis could be prevented by administration of the putative endothelium-derived nitrosyl factor S-nitroso-L-cysteine (L-SNC) and whether L-SNC may exert its effects via increases in cGMP levels in vascular smooth muscle. Five doses of PACAP-27 (2 nmol/kg iv) produced pronounced vasodilator responses in saline-treated rats. These responses were not subject to tachyphylaxis. The first injection of PACAP-27 (2 nmol/kg iv) in L-NAME-treated (50 micromol/kg iv) rats produced vasodilator responses similar to those in saline-treated rats, whereas subsequent injections produced progressively smaller responses. The injection of L-SNC (1,200 nmol/kg iv) before each injection of PACAP-27 prevented tachyphylaxis to the Gs protein-coupled receptor agonist in L-NAME-treated rats, whereas equihypotensive doses of the NO donor sodium nitroprusside (100 micrograms/kg iv) did not. The injection of the membrane-permeant cGMP analog 8-(4-chlorophenylthio)guanosine 3',5'-cyclic monophosphate (8-CPT-cGMP; 30 micromol/kg iv) to L-NAME-treated rats restored resting hemodynamic values to pre-L-NAME levels but did not prevent the development of tachyphylaxis to PACAP-27. These results suggest that nitrosyl factors prevent the development of tachyphylaxis to the hemodynamic actions of PACAP-27. These nitrosyl factors may act independently of their ability to generate cGMP in vascular smooth muscle.

Mechanism whereby nitric oxide (NO) infused chronically intrauterine in ewes is antiluteolytic rather than being luteolytic.

PubMed

Weems, Y S; Lennon, E; Uchima, T; Raney, A; Goto, K; Ong, A; Zaleski, H; Weems, C W

2008-02-01

Nitric oxide (NO) has been reported to be luteolytic in vitro and in vivo in cows. However, an NO donor reversed PGF2alpha-induced inhibition of rat luteal progesterone secretion in vitro and an NO donor or endothelin-1 stimulated bovine luteal tissue secretion of prostaglandins E (PGE; PGE1, PGE2) in vitro without affecting progesterone or PGF2alpha secretion. In addition, chronic infusion of an NO donor into the interstitial tissue of the ovarian vascular pedicle adjacent the luteal-containing ovary prevented the decline in circulating progesterone, while a nitric oxide synthase (NOS) inhibitor did not affect luteolysis. The objective of this experiment was to determine whether an NO donor or NOS inhibitor infused chronically intrauterine adjacent to the luteal-containing ovary during the ovine estrous cycle was luteolytic or antiluteolytic. Ewes were treated either with vehicle (N=5), diethylenetriamine (DETA-control for DETANONOate; N=5), (Z)-1-[2-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETANONOate-long acting NO donor; N=6), l-arginine (N=5), l-nitro-arginine methyl ester (l-NAME-NOS inhibitor; N=6), or NG-monomethyl-l-arginine acetate (l-NMMA; NOS inhibitor; N=5) every 6h from 2400h (0h) on day 8 through 1800h on day 18 of the estrous cycle. Jugular venous blood and inferior vena cava plasma via a saphenous vein cathether 5cm anterior to the juncture of the ovarian vein and inferior vena cava were collected every 6h for analysis for progesterone and PGF2alpha and PGE, respectively, by RIA. Corpora lutea were collected at 1800h on day 18 and weighed. Weights of corpora lutea were heavier (P< or =0.05) in DETANONOate-treated ewes when compared to vehicle, DETA, l-arginine, l-NAME, or l-NMMA-treated ewes, l-arginine luteal weights were heavier than vehicle, DETA, l-arginine, l-NAME, or l-NMMA-treated ewes, and luteal weights of vehicle, DETA, l-NAME, or l-NMMA-treated ewes did not differ amongst each other (P> or =0.05). Profiles of progesterone in jugular venous blood on days 8-18 differed (P< or =0.05) in DETANONOate-treated ewes when compared to vehicle, DETA, l-arginine, l-NMMA or l-NAME-treated ewes, which did not differ (P> or =0.05) amongst each other. The PGE:PGF2alpha ratio profile in inferior vena cava plasma of DETANONOate-treated ewes was increased (P< or =0.05) when compared to all other treatment groups. In a second experiment, conversion of [3H PGE2] to [3H PGF2alpha] by day 15 ovine caruncular endometrium in vitro was determined in vehicle, DETA, or DETANONOate-treatment groups. Conversion of [3H PGE2] to [3H PGF2alpha] was decreased (P< or =0.05) only by DETANONOate. It is concluded that NO is not luteolytic during the ovine estrous cycle, but may instead be antiluteolytic and prevent luteolysis by altering the PGE:PGF2alpha ratio secreted by the uterus.

Effect of streptavidin-biotin on endothelial vasoregulation and leukocyte adhesion.

PubMed

Chan, Bernard P; Reichert, William M; Truskey, George A

2004-08-01

The current study examines whether the adhesion promoting arginine-glycine-aspartate-streptavidin mutant (RGD-SA) also affects two important endothelial cell (EC) functions in vitro: vasoregulation and leukocyte adhesion. EC adherent to surfaces via fibronectin (Fn) or Fn plus RGD-SA were subjected to laminar shear flow and media samples were collected over a period of 4h to measure the concentration of nitric oxide (NO), prostacyclin (PGI(2)), and endothelin-1 (ET-1). Western blot analysis was used to quantify the levels of endothelial-derived nitric oxide synthase (eNOS) and cyclooxygenase II (COX II). In a separate set of experiments, fluorescent polymorphonuclear leukocyte (PMN) adhesion to EC was quantified for EC with and without exposure to flow preconditioning. When cell adhesion was supplemented with the SA-biotin system, flow-induced production of NO and PGI(2) increased significantly relative to cells adherent on Fn alone. Previous exposure of EC to shear flow also significantly decreased PMN attachment to SA-biotin supplemented EC, but only after 2h of exposure to shear flow. The observed decrease in PMN-EC adhesion was negated by NG-nitro-L-arginine methyl ester (L-NAME), an antagonist of NO synthesis, but not by indomethacin, an inhibitor to PGI(2) synthesis, indicating the induced effect of PMN-EC interaction is primarily NO-dependent. Results from this study suggest that the use of SA-biotin to supplement EC adhesion encourages vasodilation and PMN adhesion in vitro under physiological shear-stress conditions. We postulate that the presence of SA-biotin more efficiently transmits the shear-stress signal and amplifies the downstream events including the NO and PGI(2) release and leukocyte-EC inhibition. These results may have ramifications for reducing thrombus-induced vascular graft failure.

Nitric oxide production contributes to Bacillus anthracis edema toxin-associated arterial hypotension and lethality: ex vivo and in vivo studies in the rat

PubMed Central

Li, Yan; Cui, Xizhong; Xu, Wanying; Ohanjanian, Lernik; Sampath-Kumar, Hanish; Suffredini, Dante; Moayeri, Mahtab; Leppla, Stephen; Fitz, Yvonne

2016-01-01

We showed previously that Bacillus anthracis edema toxin (ET), comprised of protective antigen (PA) and edema factor (EF), inhibits phenylephrine (PE)-induced contraction in rat aortic rings and these effects are diminished in endothelial-denuded rings. Therefore, employing rat aortic ring and in vivo models, we tested the hypothesis that nitric oxide (NO) contributes to ET's arterial effects. Compared with rings challenged with PA alone, ET (PA + EF) reduced PE-stimulated maximal contractile force (MCF) and increased the PE concentration producing 50% MCF (EC50) (P < 0.0001). Compared with placebo, l-nitro-arginine methyl-ester (l-NAME), an NO synthase (NOS) inhibitor, reduced ET's effects on MCF and EC50 in patterns that approached or were significant (P = 0.06 and 0.03, respectively). In animals challenged with 24-h ET infusions, l-NAME (0.5 or 1.0 mg·kg−1·h−1) coadministration increased survival to 17 of 28 animals (60.7%) compared with 4 of 27 (14.8%) given placebo (P = 0.01). Animals receiving l-NAME but no ET all survived. Compared with PBS challenge, ET increased NO levels at 24 h and l-NAME decreased these increases (P < 0.0001). ET infusion decreased mean arterial blood pressure (MAP) in placebo and l-NAME-treated animals (P < 0.0001) but l-NAME reduced decreases in MAP with ET from 9 to 24 h (P = 0.03 for the time interaction). S-methyl-l-thiocitrulline, a selective neuronal NOS inhibitor, had effects in rings and, at a high dose in vivo models, comparable to l-NAME, whereas N′-[3-(aminomethyl)benzyl]-acetimidamide, a selective inducible NOS inhibitor, did not. NO production contributes to ET's arterial relaxant, hypotensive, and lethal effects in the rat. PMID:27448553

Different effect of l-NAME treatment on susceptibility to decompression sickness in male and female rats.

PubMed

Mazur, Aleksandra; Buzzacott, Peter; Lambrechts, Kate; Wang, Qiong; Belhomme, Marc; Theron, Michael; Popov, Georgi; Distefano, Giovanni; Guerrero, Francois

2014-11-01

Vascular bubble formation results from supersaturation during inadequate decompression contributes to endothelial injuries, which form the basis for the development of decompression sickness (DCS). Risk factors for DCS include increased age, weight-fat mass, decreased maximal oxygen uptake, chronic diseases, dehydration, and nitric oxide (NO) bioavailability. Production of NO is often affected by diving and its expression-activity varies between the genders. Little is known about the influence of sex on the risk of DCS. To study this relationship we used an animal model of Nω-nitro-l-arginine methyl ester (l-NAME) to induce decreased NO production. Male and female rats with diverse ages and weights were divided into 2 groups: treated with l-NAME (in tap water; 0.05 mg·mL(-1) for 7 days) and a control group. To control the distribution of nitrogen among tissues, 2 different compression-decompression protocols were used. Results showed that l-NAME was significantly associated with increased DCS in female rats (p = 0.039) only. Weight was significant for both sexes (p = 0.01). The protocol with the highest estimated tissue pressures in the slower compartments was 2.6 times more likely to produce DCS than the protocol with the highest estimated tissue pressures in faster compartments. The outcome of this study had significantly different susceptibility to DCS after l-NAME treatment between the sexes, while l-NAME per se had no effect on the likelihood of DCS. The analysis also showed that for the appearance of DCS, the most significant factors were type of protocol and weight.

Role of nitric oxide in in vitro contractile activity of the third compartment of the stomach in llamas.

PubMed

Van Hoogmoed, L; Rakestraw, P C; Snyder, J R; Harmon, F A

1998-09-01

To determine the role of nitric oxide and an apamin-sensitive nonadrenergic-noncholinergic inhibitory transmitter in in vitro contractile activity of the third compartment in llamas. Isolated strips of third compartment of the stomach from 5 llamas. Strips were mounted in tissue baths containing oxygenated Kreb's buffer solution and connected to a polygraph chart recorder to measure contractile activity. Atropine, guanethidine, and indomethacin were added to tissue baths to inhibit muscarinic receptors, adrenoreceptors, and prostaglandin synthesis. Responses to electrical field stimulation following addition of the nitric oxide antagonist Nwo-nitro-L-arginine methyl ester (L-NAME) and apamin were evaluated. Electrical field stimulation (EFS) resulted in a reduction in the amplitude and frequency of contractile activity, followed by rebound contraction when EFS was stopped. Addition of L-NAME resulted in a significant reduction in inhibition of contractile activity. Addition of apamin also resulted in a significant reduction in inhibitory contractile activity at most stimulation frequencies. The combination of L-NAME and apamin resulted in a significant reduction in inhibition at all frequencies. Nitric oxide and a transmitter acting via an apamin-sensitive mechanism appear to be involved in inhibition of contractile activity of the third compartment in llamas. Results suggest that nitric oxide plays an important role in mediating contractile activity of the third compartment in llamas. Use of nitric oxide synthase inhibitors may have a role in the therapeutic management of llamas with lesions of the third compartment.

Effects of calcium dobesilate on the synthesis of endothelium-dependent relaxing factors in rabbit isolated aorta

PubMed Central

Ruiz, E; Lorente, R; Tejerina, T

1997-01-01

Some cardiovascular disturbances which occur in diabetics are a consequence of alterations in vascular contractility as well as in endothelium-dependent relaxation. Calcium dobesilate (DOBE) is a drug used in diabetic retinopathy and its mechanism of action is not yet understood. The aim of this study was to investigate the effects of DOBE on synthesis and release of endothelium-dependent relaxing factor (EDRF) and endothelium-dependent hyperpolarizing factor (EDHF) in rabbit isolated aorta. Endothelium-dependent relaxation induced by acetylcholine (ACh) (10−8–10−5 M) increased in the presence of DOBE 10−5 M only when vascular endothelium was kept intact. NG-nitro-L-arginine methyl ester (L-NAME; 10−8–10−4 M progressively decreased the enhancing effect of DOBE on endothelium-dependent relaxation whereas it was progressively increased by L-Arg. DOBE 10−5 M increased in a non-significant manner endothelium-dependent relaxation induced by ACh when the arteries were incubated with both L-NAME 10−4 M and indomethacin 10−6 M. DOBE (10−6 M and 10−5 M) was able to scavenge superoxide anion radicals generated by the hypoxanthine/xanthine oxidase reaction. These results provide evidence that DOBE is able to affect the vascular disorders associated with diabetes mellitus since it enhances the synthesis of endothelium-dependent relaxing factors. PMID:9208138

Lactate dilates cochlear capillaries via type V fibrocyte-vessel coupling signaled by nNOS.

PubMed

Dai, Min; Yang, Yue; Shi, Xiaorui

2011-10-01

Transduction of sound in the inner ear demands tight control over delivery of oxygen and glucose. However, the mechanisms underlying the control of regional blood flow are not yet fully understood. In this study, we report a novel local control mechanism that regulates cochlear blood flow to the stria vascularis, a high energy-consuming region of the inner ear. We found that extracellular lactate had a vasodilatory effect on the capillaries of the spiral ligament under both in vitro and in vivo conditions. The lactate, acting through monocarboxylate transporter 1 (MCT1), initiated neuronal nitric oxide (NO) synthase (nNOS) and catalyzed production of NO for the vasodilation. Blocking MCT1 with the MCT blocker, α-cyano-4-hydroxycinnamate (CHC), or a suppressing NO production with either the nonspecific inhibitor of NO synthase, N(G)-nitro-L-arginine methyl ester (L-NAME), or either of two selective nNOS inhibitors, 3-bromo-7-nitroindazole or (4S)-N-(4-amino-5[aminoethyl]aminopentyl)-N'-nitroguanidine (TFA), totally abolished the lactate-induced vasodilation. Pretreatment with the selective endothelial NO synthase inhibitor, L-N(5)-(1-iminoethyl)ornithine (L-NIO), eliminated the inhibition of lactate-induced vessel dilation. With immunohistochemical labeling, we found the expression of MCT1 and nNOS in capillary-coupled type V fibrocytes. The data suggest that type V fibrocytes are the source of the lactate-induced NO. Cochlear microvessel tone, regulated by lactate, is mediated by an NO-signaled coupling of fibrocytes and capillaries.

Damage-associated molecular pattern activated Toll-like receptor 4 signalling modulates blood pressure in L-NAME-induced hypertension.

PubMed

Sollinger, Daniel; Eißler, Ruth; Lorenz, Steffen; Strand, Susanne; Chmielewski, Stefan; Aoqui, Cristiane; Schmaderer, Christoph; Bluyssen, Hans; Zicha, Josef; Witzke, Oliver; Scherer, Elias; Lutz, Jens; Heemann, Uwe; Baumann, Marcus

2014-03-01

Recent publications have shed new light on the role of the adaptive and innate immune system in the pathogenesis of hypertension. However, there are limited data whether receptors of the innate immune system may influence blood pressure. Toll-like receptor 4 (TLR4), a pattern recognition receptor, is a key component of the innate immune system, which is activated by exogenous and endogenous ligands. Hypertension is associated with end-organ damage and thus might lead to the release of damage-associated molecular patterns (DAMPs), which are endogenous activators of TLR4 receptors. The present study aimed to elucidate whether TLR4 signalling is able to modulate vascular contractility in an experimental model of hypertension thus contributing to blood pressure regulation. NG-nitro-l-arginine methyl ester (l-NAME)-induced hypertension was blunted in TLR4(-/-) when compared with wild-type mice. Treatment with l-NAME was associated with a release of DAMPs, leading to reactive oxygen species production of smooth muscle cells in a TLR4-dependent manner. As oxidative stress leads to an impaired function of the NO-sGC-cyclic GMP (cGMP) pathway, we were able to demonstrate that TLR4(-/-) was protected from sGC inactivation. Consequently, arterial contractility was reduced in TLR4(-/-). Cell damage-associated TLR4 signalling might act as a direct mediator of vascular contractility providing a molecular link between inflammation and hypertension.

Effects of One Resistance Exercise Session on Vascular Smooth Muscle of Hypertensive Rats

PubMed Central

da Silva, Tharciano Luiz Teixeira Braga; Mota, Marcelo Mendonça; Fontes, Milene Tavares; Araújo, João Eliakim dos Santos; Carvalho, Vitor Oliveira; Bonjardim, Leonardo Rigoldi; Santos, Márcio Roberto Viana

2015-01-01

Background Hypertension is a public health problem and increases the incidence of cardiovascular diseases. Objective To evaluate the effects of a resistance exercise session on the contractile and relaxing mechanisms of vascular smooth muscle in mesenteric arteries of NG-nitro L-arginine methyl ester (L-NAME)-induced hypertensive rats. Methods Wistar rats were divided into three groups: control (C), hypertensive (H), and exercised hypertensive (EH). Hypertension was induced by administration of 20 mg/kg of L-NAME for 7 days prior to experimental protocols. The resistance exercise protocol consisted of 10 sets of 10 repetitions and intensity of 40% of one repetition maximum. The reactivity of vascular smooth muscle was evaluated by concentration‑response curves to phenylephrine (PHEN), potassium chloride (KCl) and sodium nitroprusside (SNP). Results Rats treated with L-NAME showed an increase (p < 0.001) in systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) compared to the initial period of induction. No difference in PHEN sensitivity was observed between groups H and EH. Acute resistance exercise reduced (p < 0.001) the contractile response induced by KCl at concentrations of 40 and 60 mM in group EH. Greater (p < 0.01) smooth muscle sensitivity to NPS was observed in group EH as compared to group H. Conclusion One resistance exercise session reduces the contractile response induced by KCl in addition to increasing the sensitivity of smooth muscle to NO in mesenteric arteries of hypertensive rats. PMID:26107814

Effects of one resistance exercise session on vascular smooth muscle of hypertensive rats.

PubMed

Silva, Tharciano Luiz Teixeira Braga da; Mota, Marcelo Mendonça; Fontes, Milene Tavares; Araújo, João Eliakim Dos Santos; Oliveira Carvalho, Vitor; Bonjardim, Leonardo Rigoldi; Santos, Márcio Roberto Viana

2015-08-01

Hypertension is a public health problem and increases the incidence of cardiovascular diseases. To evaluate the effects of a resistance exercise session on the contractile and relaxing mechanisms of vascular smooth muscle in mesenteric arteries of NG-nitro L-arginine methyl ester (L-NAME)-induced hypertensive rats. Wistar rats were divided into three groups: control (C), hypertensive (H), and exercised hypertensive (EH). Hypertension was induced by administration of 20 mg/kg of L-NAME for 7 days prior to experimental protocols. The resistance exercise protocol consisted of 10 sets of 10 repetitions and intensity of 40% of one repetition maximum. The reactivity of vascular smooth muscle was evaluated by concentration‑response curves to phenylephrine (PHEN), potassium chloride (KCl) and sodium nitroprusside (SNP). Rats treated with L-NAME showed an increase (p < 0.001) in systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) compared to the initial period of induction. No difference in PHEN sensitivity was observed between groups H and EH. Acute resistance exercise reduced (p < 0.001) the contractile response induced by KCl at concentrations of 40 and 60 mM in group EH. Greater (p < 0.01) smooth muscle sensitivity to NPS was observed in group EH as compared to group H. One resistance exercise session reduces the contractile response induced by KCl in addition to increasing the sensitivity of smooth muscle to NO in mesenteric arteries of hypertensive rats.

Peritoneal dialysis solution attenuates microvascular leukocyte adhesion induced by nitric oxide synthesis inhibition.

PubMed

White, R; Ram, S

1996-01-01

In the mesenteric microcirculation, inhibition of nitric oxide (NO) synthesis results in an inflammatory response through increased leukocyte adherence to the microvascular postcapillary venular endothelium. Recent studies have demonstrated that elevated concentrations of endogenous NO synthesis inhibitors are present in renal failure. How peritoneal dialysis solutions may affect leukocyte-endothelial interactions during inflammation induced by NO synthesis inhibition has been previously unknown. Using in vivo intravital microscopy of the rat mesenteric postcapillary venules, microvascular leukocyte adherence was quantitated during baseline conditions in which the mesentery was superfused with a buffer solution, followed by the superfusion of a NO synthesis inhibitor NG-nitro-L-ARGININE methyl ester (L-NAME) added to the buffer, followed by 4.25% Dianeal (4.25% D). When compared to baseline, L-NAME increased the mean number of adherent leukocytes by fivefold (2.2 +/- 0.9 vs 11.6 +/- 3.6 leukocytes/100 microns venule/10 min, p < 0.05), while 4.25% D quickly reversed the L-NAME-induced inflammatory response, returning the number of adherent leukocytes back to baseline values (11.6 +/- 3.6 vs 2.4 +/- 1.3 leukocytes/100 microns venule/ 10 min, p < 0.05). These results confirm that NO synthesis inhibition induces inflammation in mesenteric postcapillary venules. Superfusion of 4.25% D reverses leukocyte adhesion induced by NO synthesis inhibition. Thus, a standard peritoneal dialysis solution (4.25% D) reverses the leukocyte-adhesive effects of NO synthesis inhibition in the mesenteric microcirculation.

Evidence for a specific influence of the nitrergic pathway on the peripheral pulse waveform in rabbits.

PubMed

Nier, B A; Harrington, L S; Carrier, M J; Weinberg, P D

2008-04-01

The height of the dicrotic notch between the systolic and diastolic peaks of the peripheral pulse wave, expressed as a fraction of the overall amplitude of the wave, is sensitive to nitric oxide (NO) bioactivity. This phenomenon might form the basis of a simple, non-invasive method for determining endothelial function in vivo. We assessed whether the phenomenon is specific to the NO pathway or whether other vasoactive agents have similar effects. The relative height of the dicrotic notch (RHDN) was determined by photoplethysmography in the rabbit ear. It was dose-dependently decreased by acetylcholine, a stimulator of endothelial NO synthesis, and increased by N(G)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO synthesis. There was no effect on RHDN of the alpha-adrenergic blocker phentolamine or the beta-adrenergic blocker propranolol. The cyclo-oxygenase inhibitor indomethacin dose-dependently decreased RHDN but this effect was blocked by L-NAME, suggesting it was mediated by cross-talk with the NO pathway. Changes in RHDN appeared to be independent of heart rate and of the delay between the systolic peak and the notch, but were associated with changes in the slope of the dicrotic limb. Both L-NAME and phentolamine produced multiple diastolic peaks, indicative of wave reflections in the vasculature. These data support the view that changes in RHDN are specific to the NO pathway and provide additional information about the mechanisms involved.

The acute effect of ethanol on adrenal cortex in female rats--possible role of nitric oxide.

PubMed

Dikić, Dragoslava; Budeč, Mirela; Vranješ-Durić, Sanja; Koko, Vesna; Vignjević, Sanja; Mitrović, Olivera

2011-01-01

The present study was designed to investigate a possible role of endogenous nitric oxide (NO) in the adrenal response to an acute alcohol administration in female rats. To this end, N(ω)-nitro-L-arginine-methyl ester (L-NAME), a competitive inhibitor of all isoforms of NO synthase, was used. Adult female Wistar rats showing diestrus Day 1 were treated with: (a) ethanol (2 or 4 g/kg, intraperitoneally); (b) L-NAME (30 or 50 mg/kg, subcutaneously) followed by either ethanol or saline 3 h later. Untreated and saline-injected rats were used as controls. The animals were killed 30 min after last injection. Adrenal cortex was analyzed morphometrically, and plasma levels of adrenocorticotropic hormone (ACTH) and serum concentrations of corticosterone were determined. Acute ethanol treatment enhanced the levels of ACTH and corticosterone in a dose-dependent manner. Stereological analysis revealed that acute alcohol administration induced a significant increase in absolute volume of the cortex and the zona fasciculata (ZF). In addition, ethanol at a dose of 4 g/kg increased volume density and length of the capillaries in the ZF. However, other stereological parameters were unaffected by alcohol exposure. Pretreatment with both doses of L-NAME had no effect on ethanol-induced changes. Obtained findings indicate that acute ethanol treatment stimulates the activity of the adrenal cortex and that this effect is not mediated by endogenous NO in female rats under these experimental conditions.

[Effects of Nomega-nitro-L-arginine on photoreceptor apoptosis in inherited retinal degeneration of RCS rats].

PubMed

Li, Ai-jun; Fang, Jun; Zhu, Xiu-an

2004-08-18

To investigate inducible nitric oxide synthase(iNOS) activity of retina and the effects of N(omega)-nitro-L-arginine(N-Arg) on photoreceptor apoptosis in inherited retinal degeneration of Royal College of Surgeons (RCS) rats. iNOS activity was assayed in the whole retinal homogenates of RCS rats and Wistar rats by monitoring the conversion rate of (3)H-arginine to (3)H-citrulline. Intravitreal injection of the NOS inhibitor, N(omega)-nitro-L-arginine(N-Arg), in one lateral eye on postnatal days 17 (P17), P22, P27 and P32 was performed, while the other lateral eye was treated with PBS by intravitreal injection as controls. Then the retinas of the RCS rats were studied by TdT-mediated biotin-dUTP nick-end labeling (TUNEL) for apoptosis on P38. The enzymatic activity of iNOS was elevated in RCS rat retinas on P25. In RCS rats on P38, the percent area of apoptotic photoreceptor nuclei and the thickness of rod and cone layer in the treated group were significantly reduced compared with the controls, while the thickness of outer nuclear layer (ONL) was increased. The inhibitor of NOS might supply a potential medicine for inherited retinal degeneration.

Tachyphylaxis to PACAP-27 after inhibition of NO synthesis: a loss of adenylate cyclase activation

NASA Technical Reports Server (NTRS)

Whalen, E. J.; Johnson, A. K.; Lewis, S. J.

1999-01-01

The vasodilator effects of pituitary adenylate cyclase activating polypeptide (PACAP-27) are subject to tachyphylaxis in rats treated with the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). This study examined whether this tachyphylaxis is due to the loss of vasodilator potency of cAMP generated by activation of the G(s) protein-coupled PACAP receptors. Five successive treatments with PACAP-27 (2 nmol/kg iv) produced pronounced vasodilator responses in saline-treated rats that were not subject to tachyphylaxis. The first injection of PACAP-27 (2 nmol/kg iv) in L-NAME (50 micromol/kg iv)-treated rats produced vasodilator responses of similar magnitude to those in saline-treated rats, whereas four subsequent injections produced progressively and markedly smaller responses. The hemodynamic effects of the membrane-permeable cAMP analog 8-(4-chlorophenylthiol)-cAMP (8-CPT-cAMP; 5-15 micromol/kg iv) were similar in L-NAME-treated rats and in L-NAME-treated rats that had received the five injections of PACAP-27. In addition, five injections of 8-CPT-cAMP (10 micromol/kg iv) produced pronounced vasodilator responses in saline- and L-NAME-treated rats that were not subject to the development of tachyphylaxis. These results suggest that a loss of biological potency of cAMP is not responsible for tachyphylaxis to PACAP-27 in L-NAME-treated rats. This tachyphylaxis may be due to the inability of the G(s) protein-coupled PACAP receptor to activate adenylate cyclase.

Curcumin attenuates cardiomyocyte hypertrophy induced by high glucose and insulin via the PPARγ/Akt/NO signaling pathway.

PubMed

Chen, Rongchun; Peng, Xiaofeng; Du, Weimin; Wu, Yang; Huang, Bo; Xue, Lai; Wu, Qin; Qiu, Hongmei; Jiang, Qingsong

2015-05-01

To investigate the potential effect of curcumin on cardiomyocyte hypertrophy and a possible mechanism involving the PPARγ/Akt/NO signaling pathway in diabetes. The cardiomyocyte hypertrophy induced by high glucose (25.5mmol/L) and insulin (0.1μmol/L) (HGI) and the antihypertrophic effect of curcumin were evaluated in primary culture by measuring the cell surface area, protein content and atrial natriuretic factor (ANF) mRNA expression. The mRNA and protein expressions were assayed by reverse transcription PCR and Western blotting, whereas the NO concentration and endothelial NO synthase (eNOS) activity were determined using nitrate reduction and ELISA methods, respectively. The cardiomyocyte hypertrophy induced by HGI was characterized by increasing ANF mRNA expression, total protein content, and cell surface area, with downregulated mRNA and protein expressions of both PPARγ and Akt, which paralleled the declining eNOS mRNA expression, eNOS content, and NO concentration. The effects of HGI were inhibited by curcumin (1, 3, 10μmol/L) in a concentration-dependent manner. GW9662 (10μmol/L), a selective PPARγ antagonist, could abolish the effects of curcumin. LY294002 (20μmol/L), an Akt blocker, and N(G)-nitro-l-arginine-methyl ester (100μmol/L), a NOS inhibitor, could also diminish the effects of curcumin. The results suggested that curcumin supplementation can improve HGI-induced cardiomyocytes hypertrophy in vitro through the activation of PPARγ/Akt/NO signaling pathway. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Minocycline Attenuates Depressive-Like Behaviour Induced by Rat Model of Testicular Torsion: Involvement of Nitric Oxide Pathway.

PubMed

Saravi, Seyed Soheil Saeedi; Mousavi, Seyyedeh Elaheh; Saravi, Seyed Sobhan Saeedi; Dehpour, Ahmad Reza

2016-04-01

Testicular torsion/detorsion (T/D) can induce depression in pre- and post-pubertal patients. This study was conducted to investigate the psychological impact of testicular torsion and mechanism underlying its depressive-like behaviour, as well as antidepressant-like activity of minocycline and possible involvement of nitric oxide (NO)/cyclic GMP pathway in this paradigm in male rats undergoing testicular T/D. Unilateral T/D was performed in 36 male adult Wistar rats, and different doses of minocycline were injected alone or combined with N(ω) -nitro-l-arginine methyl ester (l-NAME), non-specific NO synthase (NOS) inhibitor; aminoguanidine (AG), specific inducible NOS inhibitor; l-arginine, an NO precursor; and selective PDE5I, sildenafil. After assessment of locomotor activity in open-field test, immobility times were recorded in the forced swimming test (FST). Moreover, 30 days after testicular T/D, testicular venous testosterone and serum nitrite concentrations were measured. A correlation was observed between either a decrease in plasma testosterone or an increase in serum nitrite concentrations with prolongation in immobility time in the testicular T/D-operated rats FST. Minocycline (160 mg/kg) exerted the highest significant antidepressant-like effect in the operated rats in the FST (p < 0.001). Furthermore, combination of subeffective doses of minocycline (80 mg/kg) and either l-NAME (10 mg/kg) or AG (50 mg/kg) demonstrated a significant robust antidepressant-like activity in T/D group (p < 0.01). Consequently, NO/cGMP pathway was involved in testicular T/D-induced depressive-like behaviour and antidepressant-like activity of minocycline in the animal model. Moreover, a contribution was observed between either decreased testosterone or elevated serum nitrite levels and depressive-like behaviour following testicular T/D. © 2015 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

Mechanisms underlying the biphasic effect of vitamin K1 (phylloquinone) on arterial blood pressure.

PubMed

Tirapelli, Carlos R; Resstel, Leonardo B M; de Oliveira, Ana M; Corrêa, Fernando M A

2008-07-01

Phylloquinone (vitamin K(1), VK(1)) is widely used therapeutically and intravenous administration of this quinone can induce hypotension. We aimed to investigate the mechanisms underlying the effects induced by VK(1) on arterial blood pressure. With this purpose a catheter was inserted into the abdominal aorta of male Wistar rats for blood pressure and heart rate recording. Bolus intravenous injection of VK(1) (0.5-20 mgkg(-1)) produced a transient increase in blood pressure followed by a fall. Both the pressor and depressor response induced by VK(1) were dose-dependent. On the other hand, intravenous injection of VK(1) did not alter heart rate. The nitric oxide synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME, 10 and 20 mgkg(-1)) reduced both the increase and decrease in blood pressure induced by VK(1) (5 mgkg(-1)). On the other hand, indometacin (10 mg kg(-1)), a non-selective cyclooxygenase inhibitor, did not alter the increase in mean arterial pressure (MAP) induced by VK(1). However, VK(1)-induced fall in MAP was significantly attenuated by indometacin. We concluded that VK(1) induces a dose-dependent effect on blood pressure that consists of an acute increase followed by a more sustained decrease in MAP. The hypotension induced by VK(1) involves the activation of the nitric oxide (NO) pathway and the release of vasodilator prostanoid(s).

Ex vivo relaxation effect of Cuscuta chinensis extract on rabbit corpus cavernosum

PubMed Central

Sun, Kai; Zhao, Chen; Chen, Xiang-Feng; Kim, Hye-Kyung; Choi, Bo-Ram; Huang, Yi-Ran; Park, Jong-Kwan

2013-01-01

The effect of Cuscuta chinensis extract on the rabbit penile corpus cavernosum (PCC) was evaluated in the present study. Penises obtained from healthy male New Zealand white rabbits (2.5–3.0 kg) were precontracted with phenylephrine (Phe, 10 µmol l−1) and then treated with various concentrations of Cuscuta chinensis extract (1, 2, 3, 4 and 5 mg ml−1). The change in penile tension was recorded, and cyclic nucleotides in the PCC were measured by radioimmunoassay (RIA). The interaction between Cuscuta chinensis and sildenafil was also evaluated. The result indicated that the PCC relaxation induced by Cuscuta chinensis extract was concentration-dependent. Pre-treatment with an nitric oxide synthase (NOS) inhibitor (Nω nitro-L-arginine-methyl ester, L-NAME), a guanylyl cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, ODQ), or a protein kinase A inhibitor (KT 5720) did not completely inhibit the relaxation. Incubation of penile cavernous tissue with the Cuscuta chinensis extract significantly increased cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) in the PCC. Moreover, the Cuscuta chinensis extract significantly enhanced sildenafil-induced PCC relaxation. In conclusion, the Cuscuta chinensis extract exerts a relaxing effect on penile cavernous tissue in part by activating the NO-cGMP pathway, and it may improve erectile dysfunction (ED), which does not completely respond to sildenafil citrate. PMID:23147465

Vasodilating effect of norethisterone and its 5 alpha metabolites: a novel nongenomic action.

PubMed

Perusquía, Mercedes; Villalón, Carlos M; Navarrete, Erika; García, Gustavo A; Pérez-Palacios, Gregorio; Lemus, Ana E

2003-08-15

Estrogens are generally administered in hormone replacement therapy in combination with synthetic progestins. Studies of cardiovascular risk factors in postmenopausal women have shown a variety of responses according to the molecular structure of the progestin used in hormone replacement therapy schemes. The present study sets out to determine the vasoactive effects of norethisterone and its 5alpha-dihydro (5alpha-norethisterone) and -tetrahydro (3alpha,5alpha-norethisterone and 3beta,5alpha-norethisterone) metabolites in isolated precontracted rat thoracic aorta. The addition of norethisterone and 3alpha,5alpha-norethisterone in rat aorta exhibited a potent, concentration-response inhibition of noradrenaline-induced contraction, while 5alpha- and 3beta,5alpha-norethisterone had very little, if any, vasorelaxing effect. Relaxation to norethisterone and 3alpha,5alpha-norethisterone had very rapid time-courses and it was neither affected by the absence of endothelium nor by the inhibitor of nitric oxide synthase, Nomega-nitro-L-arginine methyl ester (L-NAME). The addition of specific anti-androgen, anti-progestin and anti-estrogen compounds and protein synthesis inhibitors did not preclude the vasorelaxing effect of norethisterone and its 3alpha,5alpha-reduced metabolite. The results strongly suggest that these effects are not mediated by nuclear sex steroid hormone receptors. The overall data document a novel nongenomic endothelium-independent vasorelaxing action of a 19-nor synthetic progestin and one of its A-ring-reduced derivatives.

Modulation of cGMP by human HO-1 retrovirus gene transfer in pulmonary microvessel endothelial cells.

PubMed

Abraham, Nader G; Quan, Shuo; Mieyal, Paul A; Yang, Liming; Burke-Wolin, Theresa; Mingone, Christopher J; Goodman, Alvin I; Nasjletti, Alberto; Wolin, Michael S

2002-11-01

Carbon monoxide (CO) stimulates guanylate cyclase (GC) and increases guanosine 3',5'-cyclic monophosphate (cGMP) levels. We transfected rat-lung pulmonary endothelial cells with a retrovirus-mediated human heme oxygenase (hHO)-1 gene. Pulmonary cells that expressed hHO-1 exhibited a fourfold increase in HO activity associated with decreases in the steady-state levels of heme and cGMP without changes in soluble GC (sGC) and endothelial nitric oxide synthase (NOS) proteins or basal nitrite production. Heme elicited significant increases in CO production and intracellular cGMP levels in both pulmonary endothelial and pulmonary hHO-1-expressing cells. N(omega)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NOS, significantly decreased cGMP levels in heme-treated pulmonary endothelial cells but not heme-treated hHO-1-expressing cells. In the presence of exogenous heme, CO and cGMP levels in hHO-1-expressing cells exceeded the corresponding levels in pulmonary endothelial cells. Acute exposure of endothelial cells to SnCl2, which is an inducer of HO-1, increased cGMP levels, whereas chronic exposure decreased heme and cGMP levels. These results indicate that prolonged overexpression of HO-1 ultimately decreases sGC activity by limiting the availability of cellular heme. Heme activates sGC and enhances cGMP levels via a mechanism that is largely insensitive to NOS inhibition.

Semipurified Ethyl Acetate Partition of Methanolic Extract of Melastoma malabathricum Leaves Exerts Gastroprotective Activity Partly via Its Antioxidant-Antisecretory-Anti-Inflammatory Action and Synergistic Action of Several Flavonoid-Based Compounds

PubMed Central

Ismail Suhaimy, Noor Wahida; Noor Azmi, Ahmad Khusairi; Mohtarrudin, Norhafizah; Cheema, Manraj Singh

2017-01-01

Recent study has demonstrated the gastroprotective activity of crude methanolic extract of M. malabathricum leaves. The present study evaluated the gastroprotective potential of semipurified extracts (partitions): petroleum ether, ethyl acetate (EAMM), and aqueous obtained from the methanolic extract followed by the elucidation of the gastroprotective mechanisms of the most effective partition. Using the ethanol-induced gastric ulcer assay, all partitions exerted significant gastroprotection, with EAMM being the most effective partition. EAMM significantly (i) reduced the volume and acidity (free and total) while increasing the pH of gastric juice and enhanced the gastric wall mucus secretion when assessed using the pylorus ligation assay, (ii) increased the enzymatic and nonenzymatic antioxidant activity of the stomach tissue, (iii) lost its gastroprotective activity following pretreatment with N-omega-nitro-L-arginine methyl ester (L-NAME; NO blocker) or carbenoxolone (CBXN; NP-SH blocker), (iv) exerted antioxidant activity against various in vitro oxidation assays, and (v) showed moderate in vitro anti-inflammatory activity via the LOX-modulated pathway. In conclusion, EAMM exerts a remarkable NO/NP-SH-dependent gastroprotective effect that is attributed to its antisecretory and antioxidant activities, ability to stimulate the gastric mucus production and endogenous antioxidant system, and synergistic action of several gastroprotective-induced flavonoids. PMID:28168011

Orthostatic responses to nitric oxide synthase inhibition in persons with tetraplegia.

PubMed

Wecht, Jill M; Radulovic, Miroslav; Lafountaine, Michael F; Rosado-Rivera, Dwindally; Zhang, Run-Lin; Bauman, William A

2009-08-01

To determine the effects of 1.0 mg/kg nitro-L-arginine methyl ester (L-NAME) on orthostatic mean arterial pressure (MAP), serum aldosterone, and plasma renin concentrations in persons with chronic tetraplegia compared with nonspinal cord-injured controls. Prospective placebo-controlled intervention study. James J. Peters Veterans Affairs Medical Center. Patients (n=5) with tetraplegia and controls (n=7) participated. The groups were matched for age, height, and weight; the average duration of injury in the tetraplegia group was 22+/-14 years. Subjects with tetraplegia visited the laboratory twice, receiving placebo on day 1 and L-NAME (1.0 mg/kg) on day 2. The agents were infused via an intravenous catheter over 60 minutes with the patient in the supine position. Data were collected during the infusion and then during head-up tilt to 45 degrees for 30 minutes. Control subjects visited the laboratory once for placebo infusion and the head-up tilt maneuver. Orthostatic MAP. Orthostatic MAP was reduced after placebo infusion in subjects with tetraplegia compared with controls (69+/-11 vs 89+/-9 mmHg, respectively; P<.01) and compared with L-NAME infusion (90+/-16 mmHg; P<.01). Orthostatic MAP did not differ when comparing the tetraplegia group with controls after L-NAME infusion. Orthostatic aldosterone levels were increased after placebo compared with L-NAME infusion in persons with tetraplegia; plasma renin levels did not differ among the groups. These data suggest that nitric oxide synthase inhibition may have clinical potential for treatment of orthostatic hypotension in persons with chronic tetraplegia.

Renal ischemia induces an increase in nitric oxide levels from tissue stores.

PubMed

Salom, Miguel G; Arregui, Begoña; Carbonell, Luis F; Ruiz, Fernando; González-Mora, José Luis; Fenoy, Francisco J

2005-11-01

Tissue nitric oxide (NO) levels increase dramatically during ischemia, an effect that has been shown to be partially independent from NO synthases. Because NO is stored in tissues as S-nitrosothiols and because these compounds could release NO during ischemia, we evaluated the effects of buthionine sulfoximine (BSO; an intracellular glutathione depletor), light stimulation (which releases NO, decomposing S-nitrosothiols), and N-acetyl-L-cysteine (a sulfhydryl group donor that repletes S-nitrosothiols stores) on the changes in outer medullary NO concentration produced during 45 min of renal artery occlusion in anesthetized rats. Renal ischemia increased renal tissue NO concentration (+223%), and this effect was maintained along 45 min of renal arterial blockade. After reperfusion, NO concentration fell below preischemic values and remained stable for the remainder of the experiment. Pretreatment with 10 mg/kg nitro-L-arginine methyl ester (L-NAME) decreased significantly basal NO concentration before ischemia, but it did not modify the rise in NO levels observed during ischemia. In rats pretreated with 4 mmol/kg BSO and L-NAME, ischemia was followed by a transient increase in renal NO concentration that fell to preischemic values 20 min before reperfusion. A similar response was observed when the kidney was illuminated 40 min before the ischemia. The coadministration of 10 mg/kg iv N-acetyl-L-cysteine with BSO + L-NAME restored the increase in NO levels observed during renal ischemia and prevented the depletion of renal thiol groups. These results demonstrate that the increase in renal NO concentration observed during ischemia originates from thiol-dependent tissue stores.

Effects of carvedilol or amlodipine on target organ damage in L-NAME hypertensive rats: their relationship with blood pressure variability.

PubMed

Del Mauro, Julieta S; Prince, Paula D; Donato, Martín; Fernandez Machulsky, Nahuel; Morettón, Marcela A; González, Germán E; Bertera, Facundo M; Carranza, Andrea; Gorzalczany, Susana B; Chiappetta, Diego A; Berg, Gabriela; Morales, Celina; Gelpi, Ricardo J; Taira, Carlos A; Höcht, Christian

2017-04-01

The aim of the study was to compare the effects of chronic oral treatment with carvedilol or amlodipine on blood pressure, blood pressure variability and target organ damage in N-nitro-l-arginine methyl ester (L-NAME) hypertensive rats. Wistar rats were treated with L-NAME administered in the drinking water for 8 weeks together with oral administration of carvedilol 30 mg/kg (n = 6), amlodipine 10 mg/kg (n = 6), or vehicle (n = 6). At the end of the treatment, echocardiographic evaluation, blood pressure, and short-term variability measurements were performed. Left ventricular and thoracic aortas were removed to assess activity of metalloproteinase 2 and 9 and expression levels of transforming growth factor β, tumor necrosis factor α, and interleukin 6. Histological samples were prepared from both tissues. Carvedilol and amlodipine induced a comparable reduction of systolic and mean arterial pressure and its short-term variability in L-NAME rats. The expression of transforming growth factor β, tumor necrosis factor α, and interleukin 6 decreased in both organs after carvedilol or amlodipine treatment and the activity of metalloproteinase was reduced in aortic tissue. Treatment with carvedilol or amlodipine completely prevented left ventricular collagen deposition and morphometric alterations in aorta. Oral chronic treatment with carvedilol or amlodipine significantly attenuates blood pressure variability and reduces target organ damage and biomarkers of tissue fibrosis and inflammation in L-NAME hypertensive rats. Copyright © 2017 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.

The effects of sildenafil citrate on uterine angiogenic status and serum inflammatory markers in an L-NAME rat model of pre-eclampsia.

PubMed

Soobryan, Nerolen; Murugesan, Saravanakumar; Phoswa, Wendy; Gathiram, Prem; Moodley, Jagidesa; Mackraj, Irene

2017-01-15

Pre-eclampsia (PE), a hypertensive disorder of pregnancy, is detrimental to both mother and foetus. There is currently no effective treatment, but we have shown that Sildenafil Citrate (SC) improve various foetal outcomes in N ω -nitro-L arginine methyl ester (L-NAME) rat model of PE. Therefore, we aimed to investigate the effects of SC on a uterine angiogenic status and serum inflammatory markers in an L-NAME rat model of PE. One hundred and twenty adult nulliparous pregnant female Sprague-Dawley rats were used for the study. These were divided into five equal groups; the pregnant control, early and late onset PE and respective SC treated animals. Hypertension was manifested by considerably increased systolic blood pressure and placental lipid peroxidative marker (thiobarbituric acid reactive substances) and also we assessed the activities of plasma nitric oxide level, serum inflammatory marker (TGF-β and IFN-γ) and uterine angiogenic status (VEGF and sFlt-1) at two stages of PE. The administration of SC decreased systolic blood pressure, placental lipid peroxidation product and altered uterine angiogenic status; increased plasma nitric oxide levels in an early and late onset L-NAME model of PE. In addition, histological findings of SC treated preeclamptic rat placenta support the biochemical findings of this study. Our findings revealed that SC enhanced plasma NO levels and uterine angiogenic status in an L-NAME model of PE at two gestational stages. Copyright © 2016 Elsevier B.V. All rights reserved.

Nitric oxide synthase and oxidative-nitrosative stress play a key role in placental infection by Trypanosoma cruzi.

PubMed

Triquell, María Fernanda; Díaz-Luján, Cintia; Romanini, María Cristina; Ramirez, Juan Carlos; Paglini-Oliva, Patricia; Schijman, Alejandro Gabriel; Fretes, Ricardo Emilio

2018-03-25

The innate immune response of the placenta may participate in the congenital transmission of Chagas disease through releasing reactive oxygen and nitrogen intermediates. Placental explants were cultured with 1 × 10 6 and 1 × 10 5 trypomastigotes of Tulahuen and Lucky strains and controls without parasites, and with the addition of nitric oxide synthase inhibitor Nω-Nitro-l-arginine methyl ester (l-NAME) and N-acetyl cysteine (NAC) as the reactive oxygen species (ROS) scavenger. Detachment of the syncytiotrophoblast (STB) was examined by histological analysis, and the nitric oxide synthase, endothelial (eNOS), and nitrotyrosine expressions were analyzed by immunohistochemistry, as well as the human chorionic gonadotrophin (hCG) levels in the culture supernatant through ELISA assays. Parasite load with qPCR using Taqman primers was quantified. The higher number of T. cruzi (10 6 ) increased placental infection, eNOS expression, nitrosative stress, and STB detachment, with the placental barrier being injured by oxidative stress. The higher number of parasites caused deleterious consequences to the placental barrier, and the inhibitors (l-NAME and NAC) prevented the damage caused by trypomastigotes in placental villi but not that of the infection. Moreover, trophoblast eNOS played a key role in placental infection with the highest inoculum of Lucky, demonstrating the importance of the enzyme and nitrosative-oxidative stress in Chagas congenital transmission. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Opposing actions of TRPV4 channel activation in the lung vasculature.

PubMed

Ke, Sun-Kui; Chen, Lan; Duan, Hong-Bing; Tu, Yuan-Rong

2015-12-01

Transient receptor potential vanilloid 4 (TRPV4) calcium channels are known to promote endothelium-dependent relaxation of mouse mesenteric arteries but TRPV4's role in the pulmonary vasculature is uncertain. Thus, we characterized TRPV4 channel vascular tone regulation in mouse main pulmonary artery rings and in the isolated perfused pulmonary circulation and studied possible mechanisms behind these characterizations. Using myography and a TRPV4 specific agonist GSK1016790A in a C57BL/6 WT mouse model of isolated constant-flow lung perfusion, we studied vascular tone regulation in arterial rings from the main left and right pulmonary arteries and vascular resistance of the intra-pulmonary circulation beyond the second branches of the pulmonary arteries. Removal of the endothelium confirmed endothelial dependence. GSK1016790A relaxed the main pulmonary artery (EC50 4 × 10(-8)mol/L), which was inhibited by removal of the endothelium from main pulmonary artery rings. GSK1016790A significantly increased vascular resistance of the pulmonary circulation in isolated perfused lungs, but these effects were inhibited by a TRPV4 antagonist AB159908. A nitric oxide inhibitor NG-nitro-L-arginine methyl ester (L-NAME) and K(+) channel blockers apamin plus charybdotoxin (ChTx) significantly inhibited GSK1016790A in the main pulmonary artery and in an isolated perfused lung in vitro. Activated TRPV4 channels increase pulmonary vascular resistance and vasodilate the main pulmonary artery. Copyright © 2015 Elsevier B.V. All rights reserved.

Folic Acid Promotes Recycling of Tetrahydrobiopterin and Protects Against Hypoxia-Induced Pulmonary Hypertension by Recoupling Endothelial Nitric Oxide Synthase.

PubMed

Chalupsky, Karel; Kračun, Damir; Kanchev, Ivan; Bertram, Katharina; Görlach, Agnes

2015-11-10

Nitric oxide (NO) derived from endothelial NO synthase (eNOS) has been implicated in the adaptive response to hypoxia. An imbalance between 5,6,7,8-tetrahydrobiopterin (BH4) and 7,8-dihydrobiopterin (BH2) can result in eNOS uncoupling and the generation of superoxide instead of NO. Dihydrofolate reductase (DHFR) can recycle BH2 to BH4, leading to eNOS recoupling. However, the role of DHFR and eNOS recoupling in the response to hypoxia is not well understood. We hypothesized that increasing the capacity to recycle BH4 from BH2 would improve NO bioavailability as well as pulmonary vascular remodeling (PVR) and right ventricular hypertrophy (RVH) as indicators of pulmonary hypertension (PH) under hypoxic conditions. In human pulmonary artery endothelial cells and murine pulmonary arteries exposed to hypoxia, eNOS was uncoupled as indicated by reduced superoxide production in the presence of the nitric oxide synthase inhibitor, L-(G)-nitro-L-arginine methyl ester (L-NAME). Concomitantly, NO levels, BH4 availability, and expression of DHFR were diminished under hypoxia. Application of folic acid (FA) restored DHFR levels, NO bioavailability, and BH4 levels under hypoxia. Importantly, FA prevented the development of hypoxia-induced PVR, right ventricular pressure increase, and RVH. FA-induced upregulation of DHFR recouples eNOS under hypoxia by improving BH4 recycling, thus preventing hypoxia-induced PH. FA might serve as a novel therapeutic option combating PH.

Manganese enhances peroxynitrite and leukotriene E4 formation in bovine aortic endothelial cells exposed to arsenic.

PubMed

Bunderson, Melisa; Pereira, Flavia; Schneider, Mark C; Shaw, Pamela K; Coffin, J Douglas; Beall, Howard D

2006-01-01

Long-term exposure to arsenic in drinking water has been linked to cancer and other health effects, including cardiovascular disease. Arsenic in the environment is found in combination with a range of metals that could influence its toxicity. Manganese, in particular, is a metal that is typically found in conjunction with arsenic in contaminated groundwater. Peroxynitrite is a powerful oxidant formed from the reaction between nitric oxide and superoxide anion. Arsenic has been shown to increase the formation of peroxynitrite in bovine aortic endothelial cells (BAECs) and promote the formation of 3-nitrotyrosine (3-NY) in the atherosclerotic plaque of ApoE-/-/LDLr-/- mice. Arsenic exposure also increases leukotriene E4 (LTE4) formation in both the mice and BAECs, an effect that is partially reversed by the addition of Nomega-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase (NOS) inhibitor. In the present study, we investigated the effect of adding nontoxic concentrations of manganese along with arsenic to BAEC cultures. Manganese increased arsenic toxicity and enhanced peroxynitrite, 3-NY, and LTE4 formation in BAECs. Addition of LNAME reduced 3-NY formation induced by arsenic/manganese mixtures, but in contrast to its effect on arsenic alone, L-NAME actually increased LTE4 synthesis in BAECs treated with the arsenic/manganese combination. Overall, these data suggest that manganese may exacerbate the toxic effects of arsenic on the vascular system.

5-HT4 receptor agonists enhance both cholinergic and nitrergic activities in human isolated colon circular muscle.

PubMed

Cellek, S; John, A K; Thangiah, R; Dass, N B; Bassil, A K; Jarvie, E M; Lalude, O; Vivekanandan, S; Sanger, G J

2006-09-01

Previous studies have demonstrated mixed inhibitory and facilitatory effects of 5-hydroxytryptamine-4 (5-HT(4)) receptor agonists on electrical field stimulation (EFS)-induced responses in human isolated colon. Here we report three types of responses to EFS in human isolated colon circular muscle: monophasic cholinergic contraction during EFS, biphasic response (nitrergic relaxation during EFS followed by cholinergic contraction after termination of EFS) and triphasic response (cholinergic contraction followed by nitrergic relaxation during EFS and a tachykininergic contraction after EFS). The effects of two 5-HT(4) receptor agonists, prucalopride and tegaserod were then investigated on monophasic responses only. Each compound inhibited contractions during EFS in a concentration-dependent manner. In the presence of N(omega)-nitro-l-arginine methyl ester (l-NAME) however, prucalopride and tegaserod enhanced the contractions in a concentration-dependent manner. In strips where the tone was elevated with substance-P and treated with scopolamine, EFS-induced relaxations were enhanced by the two agonists. The above observed effects by the two agonists were abolished by 5-HT(4) receptor antagonist SB-204070. The two agonists did not alter the tone raised by substance-P in the presence of scopolamine and l-NAME and did not affect carbachol-induced contractions in the presence of tetrodotoxin. These results suggest that in the circular muscle of human colon, 5-HT(4) receptor agonists simultaneously facilitate the activity of neurones which release the inhibitory and excitatory neurotransmitters, nitric oxide and acetylcholine respectively.

Role of nitric oxide in pheromone-mediated intraspecific communication in mice.

PubMed

Agustín-Pavón, Carmen; Martínez-Ricós, Joana; Martínez-García, Fernando; Lanuza, Enrique

2009-12-07

Nitric oxide is known to take part in the control of sexual and agonistic behaviours. This is usually attributed to its role in neural transmission in the hypothalamus and other structures of the limbic system. However, socio-sexual behaviours in rodents are mainly directed by chemical signals detected by the vomeronasal system, and nitric oxide is abundant in key structures along the vomeronasal pathway. Thus, here we check whether pharmacological treatments interfering with nitrergic transmission could affect socio-sexual behaviour by impairing the processing of chemical signals. Treatment with an inhibitor of nitric oxide synthesis (Nomega-Nitro-l-arginine methyl ester hydrochloride, L-NAME, 100mg/kg) blocks the innate preference displayed by female mice for sexual pheromones contained in male-soiled bedding, with a lower dose of the drug (50mg/kg) having no effect. Animals treated with the high dose of L-NAME show no reduction of olfactory discrimination of male urine in a habituation-dishabituation test, thus suggesting that the effect of the drug on the preference for male pheromones is not due to an inability to detect male urine. Alternatively, it may result from an alteration in processing the reinforcing value of pheromones as sexual signals. These results add a new piece of evidence to our understanding of the neurochemistry of intraspecific chemical communication in rodents, and suggest that the role of nitric oxide in socio-sexual behaviours should be re-evaluated taking into account the involvement of this neuromodulator in the processing of chemical signals.

Hypotensive effect of Gentiana floribunda is mediated through Ca++ antagonism pathway

PubMed Central

2012-01-01

Background Gentiana floribunda was investigated for the possible hypotensive and vasodilator activities in an attempt to rationalize its traditional use in hypertension. Methods The crude extract of Gentiana floribunda (Gf.Cr) was studied in anaesthetized rats and isolated thoracic aorta tissues. Results Gf.Cr which tested positive for presence of flavonoids, saponins, sterols, tannins and terpenes caused dose-dependent (3.0-100 mg/kg) fall in arterial blood pressure (BP) of rats under anaesthesia. In rat aortic ring preparations denuded of endothelium, Gf.Cr at concentration range of 1.0-10 mg/mL relaxed high K+ (80 mM) and phenylephrine (PE, 1 μM)-induced contractions and shifted Ca++ dose–response curves to right, similar to that caused by verapamil. It also suppressed PE (1 μM) control peak responses at 0.3-1.0 mg/mL, obtained in Ca++-free medium, as exhibited by verapamil. Pre-treatment of tissues with Gf.Cr produced rightward non-parallel shift of PE-curves with decline of maximum contractile response. The vasodilator effect of Gf.Cr was endothelial-independent, as it was not blocked by Nω-nitro-L-arginine methyl ester hydrochloride, atropine and indomethacin in endothelium-intact aortic tissues. Conclusions These data indicate that BP-lowering action of Gentiana floribunda occurred via Ca++ antagonism (inhibition of Ca++ ingress and release from intracellular stores), which provides pharmacological basis to justify its effectiveness in hypertension. PMID:22883710

Continuous light and L-NAME-induced left ventricular remodelling: different protection with melatonin and captopril.

PubMed

Simko, Fedor; Pechanova, Olga; Pelouch, Vaclav; Krajcirovicova, Kristina; Celec, Peter; Palffy, Roland; Bednarova, Kristina; Vrankova, Stanislava; Adamcova, Michaela; Paulis, Ludovit

2010-09-01

Blood pressure enhancement induced by continuous light exposure represents an attractive but rarely investigated model of experimental hypertension. The aim of this study was to show whether the combination of continuous light (24 h/day) exposure and chronic N-nitro-L-arginine-methyl ester (L-NAME) treatment induces remodelling of the left ventricle and whether captopril or melatonin can modify these potential alterations. Six groups of 3-month-old Wistar rats (nine per group) were treated for 6 weeks: control (untreated), L-NAME (40 mg/kg per day), exposed to continuous light, L-NAME treated and exposed to continuous light (L24), L24 rats treated with either captopril 100 mg/kg per day, or melatonin (10 mg/kg/24 h). Systolic blood pressure (SBP), relative weights of the left ventricle, endothelial nitric oxide synthase (eNOS) and angiotensin-converting enzyme (ACE) expression in tissues, malondialdehyde and advanced oxidation protein product concentrations in the plasma and hydroxyproline levels in collagenous protein fractions were measured. The continuous light and L-NAME treatment led to hypertension, left ventricular hypertrophy (LVH) and fibrosis. An increase in SBP was completely prevented by captopril and partly by melatonin in the L24 group. Both drugs reduced oxidative damage and attenuated enhanced expression of ACE in the myocardium. Neither of the drugs prevented the attenuation of eNOS expression in the combined hypertensive model. Only captopril reduced LVH development in L24, whereas captopril and melatonin reduced left ventricular hydroxyproline concentrations in soluble and insoluble collagen, respectively. The total hydroxyproline concentration was reduced only by melatonin. In hypertension induced by a combination of continuous light and L-NAME treatment, melatonin and captopril protect the heart against pathological left ventricular remodelling differently.

A selective estrogen receptor modulator, tamoxifen, and membrane fluidity of erythrocytes in normotensive and hypertensive postmenopausal women: an electron paramagnetic resonance investigation.

PubMed

Tsuda, Kazushi; Nishio, Ichiro

2005-08-01

Recent studies have shown that tamoxifen, which belongs to a group called selective estrogen receptor modulators (SERM), may exert protective effects against cardiovascular diseases and stroke in postmenopausal women. On the other hand, abnormalities in physical properties of the cell membranes may underlie the defects that are strongly linked to hypertension, stroke, and other cardiovascular diseases. The present study was performed to investigate the effects of tamoxifen on cell membrane fluidity (a reciprocal value of membrane microviscosity) in normotensive and hypertensive postmenopausal women. We used an electron paramagnetic resonance (EPR) and spin-labeling method. Tamoxifen significantly decreased the order parameter (S) for 5-nitroxide stearate (5-NS) and the peak height ratio (h(o)/h(-1)) for 16-NS obtained from EPR spectra of erythrocyte membranes in normotensive postmenopausal women (mean +/- SEM, order parameter value; control 0.719 +/- 0.002, n = 41; tamoxifen 1 x 10(-7) mol/L 0.704 +/- 0.002, n = 41, P < .0001; tamoxifen 1 x 10(-6) mol/L 0.696 +/- 0.002, n = 41, P < .0001; tamoxifen 1 x 10(-5) mol/L 0.692 +/- 0.002, n = 41, P < .0001). The finding indicated that tamoxifen increased the membrane fluidity and improved the membrane microviscosity of erythrocytes. The membrane action of tamoxifen was antagonized by the estrogen receptor antagonist ICI 182,780. The effect of tamoxifen was significantly potentiated by the nitric oxide (NO) donors, l-arginine and S-nitroso-N-acetylpenicillamine, and a cGMP analog 8-bromo-cGMP. In contrast, the change evoked by tamoxifen was counteracted by the NO synthase inhibitors N(G)-nitro-l-arginine-methyl-ester and asymmetric dimethyl-l-arginine. In hypertensive postmenopausal women, the membrane fluidity of erythrocytes was significantly lower than in normotensive postmenopausal women. The effect of tamoxifen on the membrane fluidity was more pronounced in hypertensive postmenopausal women than in normotensive postmenopausal women. These results showed that tamoxifen increased the membrane fluidity of erythrocytes and improved the rigidity of cell membranes in postmenopausal women, to some extent, through the NO- and cGMP-dependent mechanisms. Furthermore, the greater effect of tamoxifen in hypertensive postmenopausal women suggests that tamoxifen could have a beneficial effect in regulating the blood rheologic behavior and in the improvement of the microcirculation in hypertension.

Blood flow of the right and left submandibular gland during unilateral carotid artery occlusion in rat: role of nitric oxide.

PubMed

Vág, J; Hably, C; Fazekas, A; Bartha, J

1999-01-01

The aim of the present study was to investigate the effect of unilateral carotid artery occlusion on the blood flow of submandibular gland in anesthetized rats and identify the role of nitric oxide (NO) in blood flow changes after the artery occlusion. L-NAME (N omega-nitro-L-arginine-methyl-ester; 10 mg/kg/day, per os) dissolved in tap water was used to block nitric oxide synthase. Glandular blood flow was measured using Sapirstein's indicator (86Rb) distribution technique. In the control animals the blood flow of left (ligated side) submandibular gland was lower than in the right (unligated side) one (right: 76.4+/-15.4 ml/min/100 g, 64.1+/-13.4 ml/min/100 g, p<0.01). The blood flow of submandibular glands decreased in NOS blocked group versus control. The vascular resistance after L-NAME treatment was elevated (control: 11+/-2.3 R/kg, L-NAME: 17.5+/-4.1 R/kg, p<0.001). In L-NAME group the difference between blood flow value of the left and right submandibular gland was significantly lower than in the control group (control: -16%, NAME: -8%, p<0.01). The maintenance of the blood flow in the left submandibular gland during ligation of the left common carotid artery could be due to the good vascular anastomotic system at these regions and adaptation of the submandibular vessels to the decreased perfusion pressure. Nitric oxide may have a role in the regulation of blood flow tinder this condition.

Pyridostigmine prevents peripheral vascular endothelial dysfunction in rats with myocardial infarction.

PubMed

Qin, Fangfang; Lu, Yi; He, Xi; Zhao, Ming; Bi, Xueyuan; Yu, Xiaojiang; Liu, Jinjun; Zang, Weijin

2014-03-01

1. Myocardial infarction (MI) is characterized by the withdrawal of vagal activity and increased sympathetic activity. We have shown previously that pyridostigmine (PYR), an acetylcholinesterase inhibitor, was able to improve vagal activity and ameliorate cardiac dysfunction following MI. However, the effect of PYR on endothelial dysfunction in peripheral arteries after MI remains unclear. 2. In the present study, MI was induced by coronary artery ligation in adult Sprague-Dawley rats. Rats were treated intragastrically with saline or PYR (approximately 31 mg/kg per day) for 2 weeks, at which time haemodynamic and parasympathetic parameters and the vascular reactivity of isolated mesenteric arteries were measured and the ultrastructure of the endothelium evaluated. 3. Compared with the MI group, PYR not only improved cardiac function, vagal nerve activity and endothelial impairment, but also reduced intravascular superoxide anion and malondialdehyde. In addition, in the PYR-treated MI group, nitric oxide (NO) bioavailability was increased and attenuated endothelium-dependent relaxations were improved, whereas restored vasodilator responses were inhibited by N(G)-nitro-L-arginine methyl ester. 4. Based on our results, PYR is able to attenuate the impairment of peripheral endothelial function and maintain endothelial ultrastructural integrity in MI rats by inhibiting reactive oxygen species production, enhancing NO bioavailability and improving vagal activity. © 2014 Wiley Publishing Asia Pty Ltd.

Hypotensive and vasorelaxant effects of citronellol, a monoterpene alcohol, in rats.

PubMed

Bastos, Joana F A; Moreira, Italo J A; Ribeiro, Thaís P; Medeiros, Isac A; Antoniolli, Angelo R; De Sousa, Damião P; Santos, Márcio R V

2010-04-01

Citronellol is an essential oil constituent from the medicinal plants Cymbopogon citratus, Cymbopogon winterianus and Lippia alba which are thought to possess antihypertensive properties. Citronellol-induced cardiovascular effects were evaluated in this study. In rats, citronellol (1-20 mg/kg, i.v.) induced hypotension, which was not affected by pre-treatment with atropine, hexamethonium, N(omega)-nitro-L-arginine methyl ester hydrochloride or indomethacin, and tachycardia, which was only attenuated by pre-treatment with atropine and hexamethonium. These responses were less than those obtained for nifedipine, a reference drug. In intact rings of rat mesenteric artery pre-contracted with 10 microM phenylephrine, citronellol induced relaxations (pD(2) = 0.71 +/- 0.11; E(max) = 102 +/- 5%; n = 6) that were not affected by endothelium removal, after tetraethylamonium in rings without endothelium pre-contracted with KCl 80 mM. Citronellol strongly antagonized (maximal inhibition = 97 +/- 4%; n = 6) the contractions induced by CaCl(2) (10(-6) to 3 x 10(-3 )M) and did not induce additional effects on the maximal response of nifedipine (10 microM). Finally, citronellol inhibited the contractions induced by 10 microM phenylephrine or 20 mM caffeine. The present results suggest that citronellol lowers blood pressure by a direct effect on the vascular smooth muscle leading to vasodilation.

Contractile responses of human deferential artery and vas deferens to vasopressin.

PubMed

Medina, P; Martínez, M C; Aldasoro, M; Vila, J M; Chuan, P; Lluch, S

1996-04-11

We studied the effects of vasopressin on isolated rings of human deferential artery and vas deferens (prostatic portion) obtained from patients undergoing radical cystectomy (n = 11) or prostatectomy (n = 10). Ring segments of artery or vas deferens were studied in organ bath experiments at optimal resting tension. In artery rings, vasopressin produced concentration-dependent, endothelium-independent contractions with an EC50 of 4.5 x 10(-10) M. The presence of NG-nitro-L-arginine methyl ester hydrochloride (10(-4) M), an inhibitor of nitric oxide synthase, did not change significantly (P > 0.05) the vasopressin-induced contraction. In ring preparations of the prostatic part of the vas deferens, vasopressin induced phasic contractions with an EC50 of 7.0 x 10(-9) M. The vasopressin V1 receptor antagonist, d(CH2)5Tyr(Me)AVP (10(-8) and 10(-6)), displaced to the right in parallel the control curve to vasopressin in artery and vas deferens rings. These results indicate that vasopressin exerts a powerful constrictor action on human deferential artery and vas deferens by direct stimulation of V1 receptors. It is concluded that the deferential artery may dampen the passage of blood to the vas deferens in circumstances characterized by increased plasma vasopressin levels.

Paramecium caudatum as a source of nitric oxide: Chemiluminescent detection based on Bluestar® Forensic reagent connected with microdialysis.

PubMed

Bancirova, Martina

2017-11-01

Nitric oxide (NO) chemistry inside the body is the most interesting part of its behavior. NO is involved in controlling blood pressure, and in transmitting nerve signals and a variety of other signaling processes. To explain the behavior of NO, it is necessary to determine its immediate concentration or observe time-dependent changes in its concentration. In Paramecium caudatum, NO is formed by calcium-dependent nNOS (NOS1)-like protein, which is distributed in the cytoplasm. NO synthesis affects the ciliary beat and consequent motility of cells and blocked NO synthesis reduces the ability of cells to move. The possibility of online coupling of microdialysis (of P. caudatum solution) with NO detection is demonstrated. Direct measurement of NO is carried out using dilute Bluestar ® Forensic reagent (luminol-H 2 O 2 system; one of the NO detections is based upon the chemiluminescent reaction between NO and the luminol-H 2 O 2 system, which is specifically reactive to NO). The effect of a nitric oxide synthase inhibitor, NG-nitro-l-arginine methyl ester was observed. NO production was inhibited and the movement of P. caudatum was restricted. These effects were time dependent and after a specific time were reversed. Copyright © 2017 John Wiley & Sons, Ltd.

Vasodilatory effects and underlying mechanisms of the ethyl acetate extracts from Gastrodia elata.

PubMed

Dai, Rong; Wang, Ting; Si, Xiaoqin; Jia, Yuanyuan; Wang, Lili; Yuan, Yan; Lin, Qing; Yang, Cui

2017-05-01

The objective of this study was to assess the ethyl acetate extracts of Gastrodia elata Blume (GEB) on vascular tone and the mechanisms involved. GEB was extracted with 95% EtOH followed by a further extraction with ethyl acetate. The effects of GEB and its ingredients on the isometric tensions of the aortic rings from rats were measured. The ethyl acetate extract of GEB induced a vasodilatory effect on rat aorta, which was partially dependent on endothelium. Four chemical compounds isolated from GEB were identified as 3,4-dihydroxybenzaldehyde (DB), 4-hydroxybenzaldehyde (HB), 4-methoxybenzyl alcohol (MA), and 4,4'-dihydroxydiphenyl methane (DM), respectively. All of these compounds induced vasodilatations, which were dependent on the endothelium to different degrees. After pretreatment with N ω -nitro-l-arginine methyl ester, indomethacin, or methylene blue, the vasodilatations induced by DB, HB, and MA were significantly decreased. In addition, the contractions of the rat aortic rings due to Ca 2+ influx and intracellular Ca 2+ release were also inhibited by DM. Furthermore, the administration of DB significantly enhanced the productions of nitric oxide (NO) and the activities of the endothelial NO synthase in aorta and in endothelial cells. Thus, GEB may play an important role in the amelioration of hypertension by modulating vascular tones.

Contribution of cytochrome P450 1B1 to hypertension and associated pathophysiology: a novel target for antihypertensive agents.

PubMed

Malik, Kafait U; Jennings, Brett L; Yaghini, Fariborz A; Sahan-Firat, Seyhan; Song, Chi Young; Estes, Anne M; Fang, Xiao R

2012-08-01

The aim of this review is to discuss the contribution of cytochrome P450 (CYP) 1B1 in vascular smooth muscle cell growth, hypertension, and associated pathophysiology. CYP1B1 is expressed in cardiovascular and renal tissues, and mediates angiotensin II (Ang II)-induced activation of NADPH oxidase and generation of reactive oxygen species (ROS), and vascular smooth muscle cell migration, proliferation, and hypertrophy. Moreover, CYP1B1 contributes to the development and/or maintenance of hypertension produced by Ang II-, deoxycorticosterone (DOCA)-salt-, and N(ω)-nitro-L-arginine methyl ester-induced hypertension and in spontaneously hypertensive rats. The pathophysiological changes, including cardiovascular hypertrophy, increased vascular reactivity, endothelial and renal dysfunction, injury and inflammation associated with Ang II- and/or DOCA-salt induced hypertension in rats, and Ang II-induced hypertension in mice are minimized by inhibition of CYP1B1 activity with 2,4,3',5'-tetramethoxystilbene or by Cyp1b1 gene disruption in mice. These pathophysiological changes appear to be mediated by increased production of ROS via CYP1B1-dependent NADPH oxidase activity and extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase, and c-Src. Copyright © 2011 Elsevier Inc. All rights reserved.

Contribution of Cytochrome P450 1B1 to Hypertension and Associated Pathophysiology: A Novel Target for Antihypertensive Agents

PubMed Central

Malik, Kafait U.; Jennings, Brett L.; Yaghini, Fariborz A.; Sahan-Firat, Seyhan; Song, Chi Young; Estes, Anne M.; Fang, Xiao R.

2012-01-01

The aim of this review is to discuss the contribution of cytochrome P450 (CYP) 1B1 in vascular smooth muscle cell growth, hypertension, and associated pathophysiology. CYP1B1 is expressed in cardiovascular and renal tissues, and mediates angiotensin II (Ang II)-induced activation of NADPH oxidase and generation of reactive oxygen species (ROS), and vascular smooth muscle cell migration, proliferation, and hypertrophy. Moreover, CYP1B1 contributes to the development and/or maintenance of hypertension produced by Ang II-, deoxycorticosterone Nω-nitro-(DOCA)-salt-, and L-arginine methyl ester-induced hypertension and in spontaneously hypertensive rats. The pathophysiological changes, including cardiovascular hypertrophy, increased vascular reactivity, endothelial and renal dysfunction, injury and inflammation associated with Ang II- and/or DOCA-salt induced hypertension in rats, and Ang II-induced hypertension in mice are minimized by inhibition of CYP1B1 activity with 2,4,3′,5′-tetramethoxystilbene or by Cyp1b1 gene disruption in mice. These pathophysiological changes appear to be mediated by increased production of ROS via CYP1B1-dependent NADPH oxidase activity and extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase, and c-Src. PMID:22210049

Dillapiole, isolated from Peperomia pellucida, shows gastroprotector activity against ethanol-induced gastric lesions in Wistar rats.

PubMed

Rojas-Martínez, Raúl; Arrieta, Jesús; Cruz-Antonio, Leticia; Arrieta-Baez, Daniel; Velázquez-Méndez, Antonio Magdiel; Sánchez-Mendoza, María Elena

2013-09-13

Peperomia pellucida is a plant used in traditional medicine to treat gastric ulcers. Although this gastroprotective activity was reported, the active compounds have not been identified. Therefore, the aim herein was to identify the most active compound in the gastroprotective activity of P. pellucida using an ethanol-induced gastric ulcer experimental rat model. A gastroprotective effect was observed when the hexane and dichloromethane extracts were tested, with the higher effect being obtained with the dichloromethane extract (82.3 ± 5.6%) at 100 mg/kg. Dillapiole was identified as the most active compound in this extract. Although there have been previous reports on dillapiole, this is the first on its gastroprotective activity. Rats treated with this compound at 3, 10, 30 and 100 mg/kg showed 23.1, 56.1, 73.2 and 85.5% gastroprotection, respectively. The effect elicited by dillapiole at 100 mg/kg was not attenuated by pretreatment with indomethacin (10 mg/kg, s.c.), a prostaglandin synthesis blocker, NG-nitro-l-arginine methyl ester (70 mg/kg, i.p.), a nitric oxide (NO) synthase inhibitor, or N-ethylmaleimide (10 mg/kg, s.c.), a blocker of sulfhydryl groups. This suggests that the gastroprotective mechanism of action of dillapiole does not involve prostaglandins, NO or sulfhydryl groups.

Blockade of nitric oxide formation enhances thermal and behavioral responses in rats during turpentine abscess.

PubMed

Soszynski, D

2000-01-01

The purpose of this study was to investigate the role of nitric oxide (NO) during the development of fever and other symptoms of sickness behavior (i.e. anorexia, cachexia) in response to localized tissue inflammation caused by injection of turpentine in freely moving biotelemetered rats. To determine the role of NO in turpentine-induced fever, we injected the NO synthase (NOS) inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) intraperitoneally simultaneously or 5 h after turpentine injection. Rats responded with fever to intramuscular injection of 20 microl of turpentine that commenced 6 h after injection and reached peak values 11 h after injection. Although turpentine did not significantly alter food and water intake, it caused a drop in body weight. Rats injected with turpentine and treated with L-NAME responded with a substantial rise in fever, independently of the time of L-NAME injection. The rise in body temperature (T(b)) due to turpentine injection began slightly sooner and reached the maximal T(b) value faster in rats treated with L-NAME than in the ones treated with saline (control for L-NAME). The enhanced decrease in food and water intake in rats treated with a combination of L-NAME and turpentine was also observed. As a result, L-NAME-injected rats responded with a profound drop in body mass due to turpentine, independently of the time of L-NAME injection. L-NAME alone did not affect food and water intake, but slightly suppressed the gain of body mass. These results indirectly indicate that NO is involved in pyrogenic and behavioral responses in rats during turpentine abscess. Copyright 2001 S. Karger AG, Basel.

Effect of Sildenafil on Pre-Eclampsia-Like Mouse Model Induced By L-Name.

PubMed

Motta, C; Grosso, C; Zanuzzi, C; Molinero, D; Picco, N; Bellingeri, R; Alustiza, F; Barbeito, C; Vivas, A; Romanini, M C

2015-08-01

N(omega)-nitro-L-arginine methyl ester (L-NAME) decreases the vasodilator effect of nitric oxide (NO) and induces pre-eclampsia in mouse. Sildenafil inhibits the degradation of nitric oxide and increases vasodilation. This study aimed to determine the effects of sildenafil citrate on angiogenesis and oxidative stress at the maternal foetal interface on pre-eclampsia-like mouse model induced by L-NAME. Twenty pregnant mice were divided into four groups: (i) vehicle control; (ii) L-NAME; (iii) sildenafil; (4) L-NAME+sildenafil. L-NAME was administered from day 7 of pregnancy and sildenafil from day 8 until day 16; animals were euthanized on day 17. Placental and foetal sizes and weights were measured; lipid peroxide levels and catalase activity in placental homogenates were determined, and placental vascular endothelia were identified by lectin-histochemistry using BSA-I lectin. Western blot analysis was used to determine VEGF expression in placental homogenates. No changes were seen in placental and foetal development in mice with normal pregnancies treated with sildenafil. Treatments with L-NAME reduced significantly the placental weight and average height and decreased the percentage of the endothelial surface. These alterations may be mediated by the reduction of NO levels in trophoblastic cells, due to the inhibitory effect of L-NAME on nitric oxide synthase (NOS) synthesis. This effect was offset by the treatment with sildenafil, with an increase in the percentage of the endothelial surface. In conclusion, our results indicate that treatment with sildenafil on pre-eclampsia mouse model can be used without adverse effects on the concept and its use in the treatment of pre-eclampsia is promising. © 2015 Blackwell Verlag GmbH.

Cardiac-specific overexpression of metallothionein attenuates myocardial remodeling and contractile dysfunction in l-NAME-induced experimental hypertension: Role of autophagy regulation.

PubMed

Yang, Lifang; Gao, Jian-Yuan; Ma, Jipeng; Xu, Xihui; Wang, Qiurong; Xiong, Lize; Yang, Jian; Ren, Jun

2015-09-02

Hypertension is an independent risk factor for heart disease and is responsible for the increased cardiac morbidity and mortality. Oxidative stress plays a key role in hypertensive heart diseases although the precise mechanism remains unclear. This study was designed to examine the effect of cardiac-specific overexpression of metallothionein, a cysteine-rich antioxidant, on myocardial contractile and intracellular Ca(2+) anomalies in N(G)-nitro-l-arginine methyl ester (l-NAME)-induced experimental hypertension and the mechanism involved with a focus on autophagy. Our results revealed that l-NAME treatment (14 days) led to hypertension and myocardial anomalies evidenced by interstitial fibrosis, cardiomyocyte hypertrophy, increased LV end systolic and diastolic diameters (LVESD and LVEDD) along with suppressed fractional shortening. l-NAME compromised cardiomyocyte contractile and intracellular Ca(2+) properties manifested as depressed peak shortening, maximal velocity of shortening/relengthening, electrically-stimulated rise in intracellular Ca(2+), elevated baseline and peak intracellular Ca(2+). These l-NAME-induced histological and mechanical changes were attenuated or reconciled by metallothionein. Protein levels of autophagy markers LC3B and p62 were decreased and increased, respectively. Autophagy signaling molecules AMPK, TSC2 and ULK1 were inactivated while those of mTOR and p70s6K were activated by l-NAME, the effects of which were ablated by metallothionein. Autophagy induction mimicked whereas autophagy inhibition nullified the beneficial effect of metallothionein against l-NAME. These findings suggested that metallothionein protects against l-NAME-induced myocardial anomalies possibly through restoration of autophagy. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Effects of nitric oxide synthase inhibition with or without cyclooxygenase-2 inhibition on resting haemodynamics and responses to exendin-4

PubMed Central

Gardiner, S M; March, J E; Kemp, P A; Bennett, T

2006-01-01

Background and purpose: Interactions between the NO system and the cyclooxygenase systems may be important in cardiovascular regulation. Here we measured the effects of acute cyclooxygenase-2 inhibition (with parecoxib), alone and in combination with NOS inhibition (with N G-nitro-L-arginine methyl ester (L-NAME)), on resting cardiovascular variables and on responses to the glucagon-like peptide 1 agonist, exendin-4, which causes regionally-selective vasoconstriction and vasodilatation. Experimental approach: Rats were instrumented with flow probes and intravascular catheters to measure regional haemodynamics in the conscious, freely moving state. L-NAME was administered as a primed infusion 180 min after administration of parecoxib or vehicle, and exendin-4 was given 60 min after the onset of L-NAME infusion. Key results: Parecoxib had no effect on resting cardiovascular variables or on responses to L-NAME. Exendin-4 caused a pressor response accompanied by tachycardia, mesenteric vasoconstriction and hindquarters vasodilatation. Parecoxib did not affect haemodynamic responses to exendin-4, but L-NAME inhibited its hindquarters vasodilator and tachycardic effects. When combined, L-NAME and parecoxib almost abolished the hindquarters vasodilatation while enhancing the pressor response. Conclusions and implications: Cyclooxygenase-2-derived products do not affect basal haemodynamic status in conscious normotensive rats, or influence the NO system acutely. The inhibitory effects of L-NAME on the hindquarters vasodilator and tachycardic effects of exendin-4 are consistent with a previous study that showed those events to be β-adrenoceptor mediated. The additional effect of parecoxib on responses to exendin-4 in the presence of L-NAME, is consistent with other evidence for enhanced involvement of vasodilator prostanoids when NO production is reduced. PMID:17016494

Interferon Gamma potentiates the injury caused by MPP(+) on SH-SY5Y cells, which is attenuated by the nitric oxide synthases inhibition.

PubMed

Titze-de-Almeida, Simoneide S; Lustosa, Cátia Faria; Horst, Camila Hillesheim; Bel, Elaine Del; Titze-de-Almeida, Ricardo

2014-12-01

This study examined whether the cytokine interferon (IFN) gamma plays a role in the injury of SH-SY5Y cells caused by MPP(+) (1-methyl-4-phenylpyridinium). First of all, IFN-gamma sensitized cells to the neurotoxin MPP(+), as determined by MTT (3-(4,5-dimethylthiazol-2-y1)-2,5-diphenyltetrazolium bromide) assay. MPP(+)-injured cells showed higher reactive oxygen species (ROS) levels, which was reinforced by IFN-gamma. The injury triggered a marked expression of the neuronal NOS (nNOS) enzyme. L-NAME [N(ω)-nitro-L-arginine methyl ester, a non-specific NOS inhibitor] reestablished the cell viability after IFN-gamma challenging, and recovered cells from MPP(+) injury (95.0 vs. 84.7 %; P < 0.05). Seven-NI (7-nitroindazole, a nNOS inhibitor) protected cells against the injury by MPP(+) co-administered with IFN-gamma. Both inhibitors restrained the apoptosis of SH-SY5Y cells caused by MPP(+)/IFN-gamma. Regarding oxidative stress, L-NAME and 7-NI attenuated the increase in ROS levels caused by MPP(+) (45.3 or 48.4 vs. 87.9 %, P < 0.05). Indeed, L-NAME was more effective than 7-NI for reducing oxidative stress caused by MPP(+) under IFN-gamma exposition. The nNOS gene silencing by small-interfering RNAs recovered cells challenged by IFN-gamma (24 h), or MPP(+) (8 h). In conclusion, IFN-gamma sensitizes cells to MPP(+)-induced injury, also causing an increase in ROS levels. Pretreating cells with L-NAME or 7-NI reverts both the oxidative stress and apoptosis triggered by the neurotoxin MPP(+). Taking together, our data reinforce that IFN-gamma and NOS enzymes play a role in oxidative stress and dopaminergic cell death triggered by MPP(+).

The influence of a novel pentadecapeptide, BPC 157, on N(G)-nitro-L-arginine methylester and L-arginine effects on stomach mucosa integrity and blood pressure.

PubMed

Sikirić, P; Seiwerth, S; Grabarević, Z; Rucman, R; Petek, M; Jagić, V; Turković, B; Rotkvić, I; Mise, S; Zoricić, I; Konjevoda, P; Perović, D; Jurina, L; Separović, J; Hanzevacki, M; Artuković, B; Bratulić, M; Tisljar, M; Gjurasin, M; Miklić, P; Stancić-Rokotov, D; Slobodnjak, Z; Jelovac, N; Marović, A

1997-07-30

The known effects of a novel stomach pentadecapeptide BPC157 (10 microg or 10 ng/kg), namely its salutary activity against ethanol (96%, i.g.)-induced gastric lesions (simultaneously applied i.p.) and in blood pressure maintenance (given i.v.), were investigated in rats challenged with a combination of N(G)-nitro-L-arginine methylester (L-NAME) (5 mg/kg i.v.), a competitive inhibitor of endothelium nitric oxide (NO)-generation and NO precursor, L-arginine (200 mg/kg i.v.) (D-arginine was ineffective). In the gastric lesions assay, NO agents were given 5 min before ethanol injury and BPC 157 medication. Given alone, BPC157 had an antiulcer effect, as did L-arginine, but L-NAME had no effect. L-NAME completely abolished the effect of L-arginine, whereas it only attenuated the effect of BPC 157. After application of the combination of L-NAME + L-arginine, the BPC157 effect was additionally impaired. In blood pressure studies, compared with L-arginine, pentadecapeptide BPC 157 (without effect on basal normal values) had both a mimicking effect (impaired L-NAME-blood pressure increase, when applied prophylactically and decreased already raised L-NAME values, given at the time of the maximal L-NAME-blood pressure increase (i.e., 10 min after L-NAME)) and preventive activity (L-arginine-induced moderate blood pressure decrease was prevented by BPC 157 pretreatment). When BPC 157 was given 10 min after L-NAME + L-arginine combination, which still led to a blood pressure increase, its previously clear effect (noted in L-NAME treated rats) disappeared. In vitro, in gastric mucosa from rat stomach tissue homogenates, BPC 157, given in the same dose (100 microM) as L-arginine, induced a comparable generation of NO. But, BPC 157 effect could not be inhibited by L-NAME, even when L-NAME was given in a tenfold (100 versus 1000 microM) higher dose than that needed for inhibition of the L-arginine effect. NO synthesis was blunted when the pentadecapeptide BPC 157 and L-arginine were combined. In summary, BPC 157 could interfere with the effects of NO on both gastric mucosal integrity and blood pressure maintenance in a specific way, especially with L-arginine, having a more prominent and/or particularly different effect from that of NO.

Development of High-Throughput Method for Measurement of Vascular Nitric Oxide Generation in Microplate Reader.

PubMed

Abd El-Hay, Soad S; Colyer, Christa L

2017-01-13

Despite the importance of nitric oxide (NO) in vascular physiology and pathology, a high-throughput method for the quantification of its vascular generation is lacking. By using the fluorescent probe 4-amino-5-methylamino-2',7'-difluorofluorescein (DAF-FM), we have optimized a simple method for the determination of the generation of endothelial nitric oxide in a microplate format. A nitric oxide donor was used (3-morpholinosydnonimine hydrochloride, SIN-1). Different factors affecting the method were studied, such as the effects of dye concentration, different buffers, time of reaction, gain, and number of flashes. Beer's law was linear over a nanomolar range (1-10 nM) of SIN-1 with wavelengths of maximum excitation and emission at 495 and 525 nm; the limit of detection reached 0.897 nM. Under the optimized conditions, the generation of rat aortic endothelial NO was measured by incubating DAF-FM with serial concentrations (10-1000 µM) of acetylcholine (ACh) for 3 min. To confirm specificity, N ω -Nitro-l-arginine methyl ester (l-NAME)-the standard inhibitor of endothelial NO synthase-was found to inhibit the ACh-stimulated generation of NO. In addition, vessels pre-exposed for 1 h to 400 µM of the endothelial damaging agent methyl glyoxal showed inhibited NO generation when compared to the control stimulated by ACh. The capability of the method to measure micro-volume samples makes it convenient for the simultaneous handling of a very large number of samples. Additionally, it allows samples to be run simultaneously with their replicates to ensure identical experimental conditions, thus minimizing the effect of biological variability.

Effects of Mutations and Ligands on the Thermostability of the l-Arginine/Agmatine Antiporter AdiC and Deduced Insights into Ligand-Binding of Human l-Type Amino Acid Transporters

PubMed Central

Ilgü, Hüseyin; Jeckelmann, Jean-Marc; Colas, Claire; Ucurum, Zöhre; Schlessinger, Avner; Fotiadis, Dimitrios

2018-01-01

The l-arginine/agmatine transporter AdiC is a prokaryotic member of the SLC7 family, which enables pathogenic enterobacteria to survive the extremely acidic gastric environment. Wild-type AdiC from Escherichia coli, as well as its previously reported point mutants N22A and S26A, were overexpressed homologously and purified to homogeneity. A size-exclusion chromatography-based thermostability assay was used to determine the melting temperatures (Tms) of the purified AdiC variants in the absence and presence of the selected ligands l-arginine (Arg), agmatine, l-arginine methyl ester, and l-arginine amide. The resulting Tms indicated stabilization of AdiC variants upon ligand binding, in which Tms and ligand binding affinities correlated positively. Considering results from this and previous studies, we revisited the role of AdiC residue S26 in Arg binding and proposed interactions of the α-carboxylate group of Arg exclusively with amide groups of the AdiC backbone. In the context of substrate binding in the human SLC7 family member l-type amino acid transporter-1 (LAT1; SLC7A5), an analogous role of S66 in LAT1 to S26 in AdiC is discussed based on homology modeling and amino acid sequence analysis. Finally, we propose a binding mechanism for l-amino acid substrates to LATs from the SLC7 family. PMID:29558430

Effects of Mutations and Ligands on the Thermostability of the l-Arginine/Agmatine Antiporter AdiC and Deduced Insights into Ligand-Binding of Human l-Type Amino Acid Transporters.

PubMed

Ilgü, Hüseyin; Jeckelmann, Jean-Marc; Colas, Claire; Ucurum, Zöhre; Schlessinger, Avner; Fotiadis, Dimitrios

2018-03-20

The l-arginine/agmatine transporter AdiC is a prokaryotic member of the SLC7 family, which enables pathogenic enterobacteria to survive the extremely acidic gastric environment. Wild-type AdiC from Escherichia coli, as well as its previously reported point mutants N22A and S26A, were overexpressed homologously and purified to homogeneity. A size-exclusion chromatography-based thermostability assay was used to determine the melting temperatures ( T m s) of the purified AdiC variants in the absence and presence of the selected ligands l-arginine (Arg), agmatine, l-arginine methyl ester, and l-arginine amide. The resulting T m s indicated stabilization of AdiC variants upon ligand binding, in which T m s and ligand binding affinities correlated positively. Considering results from this and previous studies, we revisited the role of AdiC residue S26 in Arg binding and proposed interactions of the α-carboxylate group of Arg exclusively with amide groups of the AdiC backbone. In the context of substrate binding in the human SLC7 family member l-type amino acid transporter-1 (LAT1; SLC7A5), an analogous role of S66 in LAT1 to S26 in AdiC is discussed based on homology modeling and amino acid sequence analysis. Finally, we propose a binding mechanism for l-amino acid substrates to LATs from the SLC7 family.

Relaxation of human isolated mesenteric arteries by vasopressin and desmopressin.

PubMed Central

Martínez, M C; Vila, J M; Aldasoro, M; Medina, P; Flor, B; Lluch, S

1994-01-01

1. The effects of vasopressin and deamino-8-D-arginine vasopressin (DDAVP, desmopressin) were studied in artery rings (0.8-1 mm in external diameter) obtained from portions of human omentum during the course of abdominal operations (27 patients). 2. In arterial rings under resting tension, vasopressin produced concentration-dependent, endothelium-independent contractions with an EC50 of 0.59 +/- 0.12 nM. The V1 antagonist d(CH2)5Tyr(Me)AVP (1 microM) and the mixed V1-V2 antagonist desGly-d(CH2)5D-Tyr(Et)ValAVP (0.01 microM) displaced the control curve to vasopressin to the right in a parallel manner without differences in the maximal responses. In the presence of indomethacin (1 microM) the contractile response to vasopressin was significantly increased (P < 0.01). 3. In precontracted arterial rings, previously treated with the V1 antagonist, d(CH2)5Tyr(Me)AVP (1 microM), vasopressin produced endothelium-dependent relaxation. This relaxation was reduced significantly (P < 0.05) by indomethacin (1 microM) and unaffected by the V1-V2 receptor antagonist desGly-d(CH2)5D-Tyr(Et)ValAVP (1 microM) or by NG-nitro-L-arginine methyl ester (L-NAME, 0.1 mM). 4. The selective V2 receptor agonist, DDAVP, caused endothelium-independent, concentration-dependent relaxations in precontracted arterial rings that were inhibited by the mixed V1-V2 receptor antagonist, but not by the V1 receptor antagonist or by pretreatment with indomethacin or L-NAME. 5. Results from this study suggest that vasopressin is primarily a constrictor of human mesenteric arteries by V1 receptor stimulation; vasopressin causes dilatation only during V1 receptor blockade. The relaxation appears to be mediated by the release of vasodilator prostaglandins from the endothelial cell layer and is independent of V2 receptor stimulation or release of nitric oxide.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7834191

Effects of tumor necrosis factor alpha antagonist, platelet activating factor antagonist, and nitric oxide synthase inhibitor on experimental otitis media with effusion.

PubMed

Kim, Dong-Hyun; Park, Yong-Soo; Jeon, Eun-Ju; Yeo, Sang-Won; Chang, Ki-Hong; Lee, Seung Kyun

2006-08-01

We studied the inflammatory responses in otitis media with effusion induced by lipopolysaccharide (LPS) in rats, and compared the preventive effects of tumor necrosis factor (TNF) soluble receptor type I (sTNFRI, a TNF-alpha antagonist), platelet activating factor antagonist, and the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). We used 2 control groups of Sprague Dawley rats (untreated and saline-treated) and 4 experimental groups, which all received an intratympanic injection of LPS, followed in 3 groups by experimental treatment of the same ear. The LPS group had no additional treatment. The L-NAME group received intraperitoneal injection of L-NAME and was reinjected after 12 hours. The A-85783 group was first given an intraperitoneal injection of A-85783. The sTNFRI group was first given an intratympanic injection of sTNFRI. Twenty-four hours after the initial intratympanic injection of LPS, temporal bones from each group were examined histopathologically and the vascular permeability of the middle ear mucosa was measured by Evans blue vital dye staining. The L-NAME, A-85783, and sTNFRI groups showed significantly reduced capillary permeability, subepithelial edema, and infiltration of inflammatory cells in comparison with the LPS group. There were no differences in capillary permeability, subepithelial edema, or infiltration of inflammatory cells between the A-85783 and sTNFRI groups. The L-NAME group showed no difference in vascular permeability or subepithelial edema in comparison with the A-85783 and sTNFRI groups, but showed more infiltration of inflammatory cells. We conclude that sTNFRI, A-85783, and L-NAME can be proposed as alternative future treatments for otitis media with effusion. However, L-NAME may be the least effective of these agents.

Nitric oxide synthesis-promoting effects of valsartan in human umbilical vein endothelial cells via the Akt/adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway.

PubMed

Zhao, Yingshuai; Wang, Liuyi; He, Shanshan; Wang, Xiaoyan; Shi, Weili

2017-05-20

Valsartan (VAL), an antagonist of angiotensin II receptor type 1, has antihypertensive and multiple cardiovascular protective effects. The pleiotropic functions of VAL are related to the increased synthesis and biological activity of intravascular nitric oxide (NO). In this study, the role and mechanisms of VAL in the synthesis of NO were examined in human umbilical vein endothelial cells (HUVECs). Ten µmol/L of VAL was used to treat EA.hy926 cells for 30 minutes, 1, 3, 6, 12, and 24 hours, and three concentrations of VAL (i.e., 10, 1, and 0.1 µmol/L) were used to treat EA.hy926 cells for 24 hours. The cells were divided into five groups: control, VAL, VAL + Compound C (adenosine monophosphate-activated protein kinase [AMPK] inhibitor, 1 µmol/L), VAL + LY294002 (Akt [protein kinase B] inhibitor, 10 µmol/L), and VAL + L-nitro-arginine methyl ester (L-NAME, endothelial NO synthase [eNOS] inhibitor, 500 µmol/L) groups. The NO content in the VAL-treated HUVEC line (EA.hy926) was detected using the nitrate reductase method, and western blot was used to detect the phosphorylation of Akt, AMPK, and eNOS, as well as the changes in total protein levels. VAL increased NO synthesis in EA.hy926 cells in time- and dose-dependent manners (p < 0.05) and the intracellular phosphorylation levels of Akt, AMPK, and eNOS at the corresponding time points. LY294002, Compound C, and L-NAME could inhibit the VAL-promoted NO synthesis. VAL activated Akt, AMPK, and eNOS, thus promoting NO synthesis and playing a protective role in endothelial cells. These results partially explained the mechanisms underlying the cardiovascular protective effects of VAL.

The effect of pre-eclampsia-like syndrome induced by L-NAME on learning and memory and hippocampal glucocorticoid receptor expression: A rat model.

PubMed

Zhu, Hao; Zhu, Weimin; Hu, Rong; Wang, Huijun; Ma, Duan; Li, Xiaotian

2017-02-01

We aimed to study the impacts of pre-eclampsia on the cognitive and learning capabilities of adolescent rat offspring and to explore the possible underlying mechanisms at the molecular level. Pregnant rats were subcutaneously injected with saline solution (control) (n = 16) or NG-nitro-L-arginine methyl ester (L-NAME) (n = 16) from the 13th day of gestation until parturition. The brain tissues from fetal rats delivered by cesarean section were examined in both groups with hematoxylin and eosin (H&E) staining. Rats born vaginally in both groups were subjected to the Morris water maze test when 8-week-old and their hippocampi were analyzed for glucocorticoid receptor (GR) expression. A pre-eclampsia-like model was successfully built in pregnant rats by infusion of the NO synthase inhibitor L-NAME, including phenotypes as maternal hypertension and proteinuria, high stillbirth rate, and fetal growth retardation. Neuroepithelial cell proliferation was found in the hippocampus of fetal rats in the L-NAME group. Grown to 8-week-old, the L-NAME group showed significantly longer escape latency than the control group in the beginning as well as in the end of navigation trials. At the same time, the swimming distance achieved by the L-NAME group was significantly longer than that of the control group. Such differences in cognitive and learning capabilities between the two groups were not gender dependent. Besides, the 8-week-old rats in the L-NAME group had increased GR expression in the hippocampus than the control group. Pre-eclampsia would impair cognitive and learning capabilities in adolescent offspring, and the upregulated expression of hippocampal GR may be involved in the underlying mechanisms.

Antihypertensive and cardioprotective effects of pumpkin seed oil.

PubMed

El-Mosallamy, Aliaa E M K; Sleem, Amany A; Abdel-Salam, Omar M E; Shaffie, Nermeen; Kenawy, Sanaa A

2012-02-01

Pumpkin seed oil is a natural product commonly used in folk medicine for treatment of prostatic hypertrophy. In the present study, the effects of treatment with pumpkin seed oil on hypertension induced by the nitric oxide synthase inhibitor N(ω)-nitro-L-arginine methyl ester hydrochloride (L-NAME) (50 mg /kg/day) in rats were studied and compared with those of the calcium channel blocker amlodipine. Pumpkin seed oil (40 or 100 mg/kg), amlodipine (0.9 mg/kg), or vehicle (control) was given once daily orally for 6 weeks. Arterial blood pressure (BP), heart rate, electrocardiogram (ECG) changes, levels of serum nitric oxide (NO) (the concentrations of nitrite/nitrate), plasma malondialdehyde (MDA), blood glutathione, and erythrocytic superoxide dismutase activity were measured. Histopathological examination of heart and aorta was conducted as well. L-NAME administration resulted in a significant increase in BP starting from the second week. Pumpkin seed oil or amlodipine treatment significantly reduced the elevation in BP by L-NAME and normalized the L-NAME-induced ECG changes-namely, prolongation of the RR interval, increased P wave duration, and ST elevation. Both treatments significantly decreased the elevated levels of MDA and reversed the decreased levels of NO metabolites to near normal values compared with the L-NAME-treated group. Amlodipine also significantly increased blood glutathione content compared with normal (but not L-NAME-treated) rats. Pumpkin seed oil as well as amlodipine treatment protected against pathological alterations in heart and aorta induced by L-NAME. In conclusion, this study has shown that pumpkin seed oil exhibits an antihypertensive and cardioprotective effects through a mechanism that may involve generation of NO.

Lysine Methylation of Nuclear Co-repressor Receptor Interacting Protein 140

PubMed Central

Huq, MD Mostaqul; Ha, Sung Gil; Barcelona, Helene; Wei, Li-Na

2009-01-01

Receptor interacting protein 140 (RIP140) undergoes extensive posttranslational modifications (PTMs), including phosphorylation, acetylation, arginine methylation, and pyridoxylation. PTMs affect its sub-cellular distribution, protein-protein interaction, and biological activity in adipocyte differentiation. Arginine methylation on Arg240, Arg650, and Arg948 suppresses the repressive activity of RIP140. Here we find that endogenous RIP140 in differentiated 3T3-L1 cells is also modified by lysine methylation. Three lysine residues, Lys591, Lys653, and Lys757 are mapped as potential methylation sites by mass spectrometry. Site-directed mutagenesis study shows that lysine methylation enhances its gene repressive activity. Mutation of lysine methylation sites enhances arginine methylation, while mutation on arginine methylation sites has little effect on its lysine methylation, suggesting a relationship between lysine methylation and arginine methylation. Kinetic analysis of PTMs of endogenous RIP140 in differentiated 3T3-L1 cells demonstrates sequential modifications on RIP140, initiated from constitutive lysine methylation, followed by increased arginine methylation later in differentiation. This study reveals a potential hierarchy of modifications, at least for lysine and arginine methylation, which bi-directionally regulate the functionality of a non-histone protein. PMID:19216533

New dicyclopeptides from Dianthus chinensis.

PubMed

Han, Jing; Wang, Zhe; Zheng, Yu-Qing; Zeng, Guang-Zhi; He, Wen-Jun; Tan, Ning-Hua

2014-05-01

One new dicyclopeptide cyclo-(L-N-methyl Glu-L-N-methyl Glu) (1), together with one new natural dicyclopeptide cyclo-(L-methyl Glu ester-L-methyl Glu ester) (2), and two known dicyclopeptides cyclo-(L-methyl Glu ester-L-Glu) (3), and cyclo-(L-Glu-L-Glu) (4), were isolated from the aerial parts of Dianthus chinensis L. Their structures were determined by spectroscopic analyses and chemical methods.

TDAE strategy in the benzoxazolone series: synthesis and reactivity of a new benzoxazolinonic anion.

PubMed

Nadji-Boukrouche, Aïda R; Khoumeri, Omar; Terme, Thierry; Liacha, Messaoud; Vanelle, Patrice

2015-01-14

We describe an original pathway to produce new 5-substituted 3-methyl-6-nitro-benzoxazolones by the reaction of aromatic carbonyl and α-carbonyl ester derivatives with a benzoxazolinonic anion formed exclusively via the TDAE strategy.

The structure and mechanism of stem bromelain. Evaluation of the homogeneity of purified stem bromelain, determination of the molecular weight and kinetic analysis of the bromelain-catalysed hydrolysis of N-benzyloxycarbonyl-l-phenylalanyl-l-serine methyl ester

PubMed Central

Wharton, Christopher W.

1974-01-01

1. Purified stem bromelain (EC 3.4.22.4) was eluted from Sephadex G-100 as a single peak. The specific activity across the elution peak was approximately constant towards p-nitrophenyl hippurate but increased with elution volume with N2-benzoyl-l-arginine ethyl ester as substrate. 2. The apparent molecular weight, determined by elution analysis on Sephadex G-100, is 22500±1500, an anomalously low value. 3. Purified stem bromelain was eluted from CM-cellulose CM-32 as a single peak and behaved as a single species during column electrophoresis on Sephadex G-100. 4. Purified stem bromelain migrates as a single band during polyacrylamide-gel electrophoresis under a wide variety of conditions. 5. The molecular weight determined by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate is 28500±1000. 6. Sedimentation-velocity and equilibrium-ultracentrifugation experiments, under a variety of conditions, indicate that bromelain is an apparently homogeneous single peptide chain of mol.wt. 28400±1400. 7. The N-terminal amino acid composition is 0.64±0.04mol of valine and 0.36±0.04mol of alanine per mol of enzyme of mol.wt. 28500. (The amino acid recovery of the cyanate N-terminal amino acid analysis was standardized by inclusion of carbamoyl-norleucine at the cyclization stage.) 8. The pH-dependence of the Michaelis parameters of the bromelain-catalysed hydrolysis of N-benzyloxycarbonyl-l-phenylalanyl-l-serine methyl ester was determined. 9. The magnitude and pH-dependence of the Michaelis parameters have been interpreted in terms of the mechanism of the enzyme. 10. The enzyme is able to bind N-benzyloxycarbonyl-l-phenylalanyl-l-serine methyl ester relatively strongly but seems unable to make use of the binding energy to promote catalysis. PMID:4462742

Circadian variation in the effects of nitric oxide synthase inhibitors on body temperature, feeding and activity in rats.

PubMed

Kamerman, Peter; Mitchell, Duncan; Laburn, Helen

2002-02-01

We have investigated whether there is circadian variation in the effects of nitric oxide synthase inhibitors on body temperature, physical activity and feeding. We used nocturnally active Sprague-Dawley rats, housed at approximately 24 degrees C with a 12:12 h light:dark cycle (lights on 07:00 hours) and provided with food and water ad libitum. Nitric oxide synthesis was inhibited by intraperitoneal injection of the unspecific nitric oxide synthase inhibitor N-nitro- L-arginine methyl ester ( L-NAME, 100, 50, 25, 10 mg/kg), or the relatively selective inducible nitric oxide synthase inhibitor aminoguanidine (100, 50 mg/kg), during the day ( approximately 09:00 hours) or night ( approximately 21:00 hours). Body temperature and physical activity were measured using radiotelemetry, while food intake was calculated by weighing each animal's food before as well as 12 and 24 h after each injection. We found that daytime injection of L-NAME and aminoguanidine had no effect on daytime body temperature. However, daytime injection of both drugs did decrease nocturnal food intake ( P<0.05) and activity ( P<0.05). When injected at night, L-NAME reduced night-time body temperature ( P<0.01), activity ( P<0.05) and food intake ( P<0.05) in a dose-dependent manner, but night-time injection of aminoguanidine inhibited only night-time activity ( P<0.05). The effects of nitric oxide synthase inhibition on body temperature, feeding and activity therefore are primarily a consequence of inhibiting constitutively expressed nitric oxide synthase, and are subject to circadian variation.

Analysis of responses to valerian root extract in the feline pulmonary vascular bed.

PubMed

Fields, Aaron M; Richards, Todd A; Felton, Jason A; Felton, Shaili K; Bayer, Erin Z; Ibrahim, Ikhlass N; Kaye, Alan David

2003-12-01

This study was undertaken to investigate pulmonary vascular response to valerian (Valeriana officinalis) in the feline pulmonary vasculature under constant flow conditions. In separate experiments, the effects of NG-L-nitro-L-arginine methyl ester (L-NIO), a nitric oxide synthase inhibitor, glibenclamide, an adenosine triphosphate (ATP)-sensitive potassium (K+) channel blocker, meclofenamate, a nonselective cyclooxygenase (COX) inhibitor, bicuculline, a GABA(A) receptor antagonist, and saclofen, a GABA(B) antagonist, were investigated on pulmonary arterial responses to various agonists in the feline pulmonary vascular bed. These agonists included valerian, muscimol, a GABA(A) agonist, SKF-97541 a GABA(B) agonist, acetylcholine (ACh), and bradykinin, both inducers of nitric oxide synthase, arachidonic acid, a COX substrate, and pinacidil, an ATP-sensitive K+ channel activator, during increased tone conditions induced by the thromboxane A2 mimic, U46619. Laboratory investigation. Mongrel cats of either gender. Injections of the abovementioned agonists and antagonists were given. Baseline pulmonary tone, responses to the agonists, and responses to the agonists after injections of antagonists were all measured via a pulmonary catheter transducer and recorded. Valerian root extract is a potent smooth muscle dilator in the feline pulmonary vascular bed. The vasodilatory effects of valerian root extract were unchanged after the administration of L-NIO, glibenclamide, and meclofenamate. These effects were ablated, however, by both saclofen and bicuculline. The ability of saclofen and bicuculline to modulate the dilatory effects of valerian root extract was not statistically different. The vasodilatory effects of valerian root extract are mediated by a nonselective GABA mechanism.

Continuously measured renal blood flow does not increase in diabetes if nitric oxide synthesis is blocked.

PubMed

Bell, Tracy D; DiBona, Gerald F; Biemiller, Rachel; Brands, Michael W

2008-11-01

This study used 16 h/day measurement of renal blood flow (RBF) and arterial pressure (AP) to determine the role of nitric oxide (NO) in mediating the renal vasodilation caused by onset of type 1 diabetes. The AP and RBF power spectra were used to determine the autoregulatory efficiency of the renal vasculature. Rats were instrumented with artery and vein catheters and a Transonic flow probe on the left renal artery and were divided randomly into four groups: control (C), diabetes (D), control plus nitro-L-arginine methyl ester (L-NAME; CL), and diabetes plus L-NAME (DL). Mean AP averaged 90 +/- 1 and 121 +/- 1 mmHg in the D and DL groups, respectively, during the control period, and RBF averaged 5.9 +/- 1.2 and 5.7 +/- 0.7 ml/min, respectively. Respective C and CL groups were not different. Onset of diabetes (streptozotocin 40 mg/kg iv) in D rats increased RBF gradually, but it averaged 55% above control by day 14. In DL rats, on the other hand, RBF remained essentially constant, tracking with RBF in the nondiabetic C and CL groups for the 2-wk period. Diabetes did not change mean AP in any group. Transfer function analysis revealed impaired dynamic autoregulation of RBF overall, including the frequency range of tubuloglomerular feedback (TGF), and L-NAME completely prevented those changes as well. These data strongly support a role for NO in causing renal vasodilation in diabetes and suggest that an effect of NO to blunt RBF autoregulation may play an important role.

Continuously measured renal blood flow does not increase in diabetes if nitric oxide synthesis is blocked

PubMed Central

Bell, Tracy D.; DiBona, Gerald F.; Biemiller, Rachel; Brands, Michael W.

2008-01-01

This study used 16 h/day measurement of renal blood flow (RBF) and arterial pressure (AP) to determine the role of nitric oxide (NO) in mediating the renal vasodilation caused by onset of type 1 diabetes. The AP and RBF power spectra were used to determine the autoregulatory efficiency of the renal vasculature. Rats were instrumented with artery and vein catheters and a Transonic flow probe on the left renal artery and were divided randomly into four groups: control (C), diabetes (D), control plus nitro-l-arginine methyl ester (l-NAME; CL), and diabetes plus l-NAME (DL). Mean AP averaged 90 ± 1 and 121 ± 1 mmHg in the D and DL groups, respectively, during the control period, and RBF averaged 5.9 ± 1.2 and 5.7 ± 0.7 ml/min, respectively. Respective C and CL groups were not different. Onset of diabetes (streptozotocin 40 mg/kg iv) in D rats increased RBF gradually, but it averaged 55% above control by day 14. In DL rats, on the other hand, RBF remained essentially constant, tracking with RBF in the nondiabetic C and CL groups for the 2-wk period. Diabetes did not change mean AP in any group. Transfer function analysis revealed impaired dynamic autoregulation of RBF overall, including the frequency range of tubuloglomerular feedback (TGF), and l-NAME completely prevented those changes as well. These data strongly support a role for NO in causing renal vasodilation in diabetes and suggest that an effect of NO to blunt RBF autoregulation may play an important role. PMID:18753304

Temporal characteristics of nitric oxide-, prostaglandin-, and EDHF-mediated components of endothelium-dependent vasodilation in the kidney.

PubMed

Dautzenberg, Marcel; Just, Armin

2013-11-01

Endothelium-dependent vasodilation is mediated by nitric oxide (NO), prostaglandins (PG), and endothelium-derived hyperpolarizing factor (EDHF). We studied the contributions and temporal characteristics of these components in the renal vasodilator responses to acetylcholine (ACh) and bradykinin (BK) and in the buffering of vasoconstrictor responses to norepinephrine (NE) and angiotensin II (ANG II). Renal blood flow (RBF) and vascular conductance (RVC) were studied in anesthetized rats in response to renal arterial bolus injections before and after inhibition of NO-synthase (N(G)-nitro-L-arginine methyl ester, L-NAME), cyclooxygenase (indomethacin, INDO), or both. ACh increased RVC peaking at maximal time (tmax) = 29 s. L-NAME (n = 8) diminished the integrated response and made it substantially faster (tmax = 18 s). The point-by-point difference caused by L-NAME (= NO component) integrated to 74% of control and was much slower (tmax = 38 s). INDO (n = 9) reduced the response without affecting tmax (36 vs. 30 s). The difference (= PG) reached 21% of the control with tmax = 25 s. L-NAME+INDO (n = 17) reduced the response to 18% and markedly accelerated tmax to 16s (= EDHF). Results were similar for BK with slightly more PG and less NO contribution than for ACh. Constrictor responses to NE and ANG II were augmented and decelerated by L-NAME and L-NAME+INDO. The calculated difference (= buffering by NO or NO+PG) was slower than the constriction. It is concluded that NO, PG, and EDHF contribute >50%, 20-40%, and <20% to the renal vasodilator effect of ACh and BK, respectively. EDHF acts substantially faster and less sustained (tmax = 16 s) than NO and PG (tmax = 30 s). Constrictor buffering by NO and PG is not constant over time, but renders the constriction less sustained.

Antihypertensive activity of blueberries fermented by Lactobacillus plantarum DSM 15313 and effects on the gut microbiota in healthy rats.

PubMed

Ahrén, Irini Lazou; Xu, Jie; Önning, Gunilla; Olsson, Crister; Ahrné, Siv; Molin, Göran

2015-08-01

The aim of the present animal study was to examine the anti-hypertensive capacity of two probiotic products combining blueberries and the tannase producing probiotic bacteria Lactobacillus plantarum DSM 15313 and to investigate if such an effect is linked to a change in the gut microbiota. Male Sprague Dawley rats were randomly divided into six groups of nine each. Three groups of the animals were treated with N(G)-nitro-L-arginine methyl ester (L-NAME) in the drinking water (40 mg/L) to induce a hypertensive state, and the other three groups were not treated with L-NAME (healthy rats). Two blueberry products differing in their phenolic acid content were tested and each rat received 2 g/day of the fermented blueberry powders for 4 weeks. The effects of the study products on the blood pressure, blood lipids, inflammatory markers, organ weights as well as caecal microbiota of the healthy (non-L-NAME-treated) rats were analyzed. After four weeks, healthy rats consuming freeze dried fermented blueberries with probiotics had a significant reduction in blood pressure compared to the control rats. In rats with L-NAME induced hypertension there was a significant reduction of the blood pressure after two weeks treatment. The probiotic product with a higher content of phenolic acids reduced ALAT in the healthy rats. Furthermore, ingestion of the probiotic blueberry products resulted in changes of the gut microbiota in the healthy rats. Blueberries fermented with the tannase producing bacteria L. plantarum DSM 15313 have anti-hypertensive properties and may reduce the risk for cardiovascular diseases. Copyright © 2014 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

The role of phosphatidylinositol-3-OH-kinase (PI3-kinase) and respiratory burst enzymes in the [omim][BF4]-mediated toxic mode of action in mussel hemocytes.

PubMed

Belavgeni, Alexia; Dailianis, Stefanos

2017-09-01

The present study investigates the role of phosphatidylinositol-3-OH-kinase (PI3-kinase) and respiratory burst enzymes, NADPH oxidase and NO synthase, in the 1-methyl-3-octylimidazolium tetrafluoroborate ([omim][BF 4 ])-mediated toxic mode of action in mussel hemocytes. Specifically, cell viability (using the neutral red uptake assay) was primarily tested in hemocytes treated with different concentrations of [omim][BF 4 ] (0.1-10 mg L -1 ) and thereafter [omim][BF 4 ]-mediated oxidative (in terms of superoxide anions/O 2 - and nitric oxide/NO generation, as well as the enhancement of lipid peroxidation by-products, in terms of malondialdehyde/MDA) and genotoxic (in terms of DNA damage) effects were determined in hemocytes treated with 1 mg L -1 [omim][BF 4 ]. Moreover, in order to investigate, even indirectly and non-entirely specific, the role of PI3-kinase, NADPH oxidase and NO synthase, the [omim][BF 4 ]-mediated effects were also investigated in hemocytes pre-incubated with wortmannin (50 nM), diphenyleneiodonium chloride (DPI 10 μM) and N G -nitro- l -arginine methyl ester (l-NAME 10 μM), respectively. The results showed that [omim][BF 4 ] ability to enhance O 2 - , NO, MDA and DNA damage, via its interaction with cellular membranes, was significantly attenuated in the presence of each inhibitor in almost all cases. The current findings revealed for the first time that certain signaling molecules, such as PI3-kinase, as well as respiratory burst enzymes activation, such as NADPH oxidase and NO synthase, could merely attribute to the [omim][BF 4 ]-mediated mode of action, thus enriching our knowledge for the molecular mechanisms of ILs toxicity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Affinity analysis and application of dipeptides derived from l-tyrosine in plasmid purification.

PubMed

Ferreira, Soraia; Carvalho, Josué; Valente, Joana F A; Corvo, Marta C; Cabrita, Eurico J; Sousa, Fani; Queiroz, João A; Cruz, Carla

2015-12-01

The developments in the use of plasmid DNA (pDNA) in gene therapy and vaccines have motivated the search and improvement of optimized purification processes. In this context, dipeptides l-tyrosine-l-tyrosine and l-tyrosine-l-arginine are synthetized to explore their application as affinity ligands for supercoiled (sc) plasmid DNA (pDNA) purification. The synthesis is based on the protection of N-Boc-l-tyrosine, followed by condensation with l-tyrosine or l-arginine methyl esters in the presence of dicyclohexylcarbodiimide (DCC), which after hydrolysis and acidification give the afforded dipeptides. The supports are then obtained by coupling l-tyrosine, l-tyrosine-l-tyrosine and l-tyrosine-l-arginine to epoxy-activated Sepharose and are characterized by high resolution magic angle spinning (HR-MAS) NMR and Fourier transform infrared spectroscopy (FTIR). Surface plasmon resonance (SPR) biosensor is used to establish the promising ligand to be used in the chromatographic experiments and ascertain experimental conditions. Sc isoform showed the highest affinity to the dipeptides, followed by linear (ln) pDNA, being the open circular (oc) the one that promoted the lowest affinity to l-tyrosine-l-arginine. Saturation transfer difference (STD)-NMR experiments show that the interaction is mainly hydrophobic with the majority of the 5'-mononucleotides, except for 5'-GMP with l-tyrosine-l-arginine Sepharose that is mainly electrostatic. The support l-tyrosine Sepharose used in chromatographic experiments promotes the separation of native pVAX1-LacZ and pcDNA3-FLAG-p53 samples (oc+sc) by decreasing the salt concentration. The results suggest that it is possible to purify different plasmids with the l-tyrosine Sepharose, with slight adjustments in the gradient conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

Serotonin depletion can enhance the cerebrovascular responses induced by cortical spreading depression via the nitric oxide pathway.

PubMed

Saengjaroentham, Chonlawan; Supornsilpchai, Weera; Ji-Au, Wilawan; Srikiatkhachorn, Anan; Maneesri-le Grand, Supang

2015-02-01

Serotonin (5-HT) is an important neurotransmitter involved in the control of neural and vascular responses. 5-HT depletion can induce several neurological disorders, including migraines. Studies on a cortical spreading depression (CSD) migraine animal model showed that the cortical neurons sensitivity, vascular responses, and nitric oxide (NO) production were significantly increased in 5-HT depletion. However, the involvement of NO in the cerebrovascular responses in 5-HT depletion remains unclear. This study aimed to investigate the role of NO in the CSD-induced alterations of cerebral microvessels in 5-HT depletion. Rats were divided into four groups: control, control with L-NAME treatment, 5-HT depleted, and 5-HT depleted with L-NAME treatment. 5-HT depletion was induced by intraperitoneal injection with para-chlorophenylalanine (PCPA) 3 days before the experiment. The CSD was triggered by KCl application. After the second wave of CSD, N-nitro-l-arginine methyl ester (L-NAME) or saline was intravenously injected into the rats with or without L-NAME treatment groups, respectively. The intercellular adhesion molecules-1 (ICAM-1), cell adhesion molecules-1 (VCAM-1), and the ultrastructural changes of the cerebral microvessels were examined. The results showed that 5-HT depletion significantly increased ICAM-1 and VCAM-1 expressions in the cerebral cortex. The number of endothelial pinocytic vesicles and microvilli was higher in the 5-HT depleted group when compared to the control. Interestingly, L-NAME treatment significantly reduced the abnormalities observed in the 5-HT depleted group. The results of this study demonstrated that an increase of NO production is one of the mechanisms involved in the CSD-induced alterations of the cerebrovascular responses in 5-HT depletion.

Effects of altered nitric oxide availability on rat muscle microvascular oxygenation during contractions.

PubMed

Ferreira, L F; Padilla, D J; Williams, J; Hageman, K S; Musch, T I; Poole, D C

2006-03-01

To explore the role of nitric oxide (NO) in controlling microvascular O2 pressure (P(O2)mv) at rest and during contractions (1 Hz). We hypothesized that at the onset of contractions sodium nitroprusside (SNP) would raise P(O2)mv and slow the kinetics of P(O2)mv change whereas l-nitro arginine methyl ester (L-NAME) would decrease P(O2)mv and speed its kinetics. We superfused the spinotrapezius muscle of female Sprague-Dawley rats (n = 7, body mass = 298 +/- 10 g) with SNP (300 microM) and L-NAME (1.5 mm) and measured P(O2)mv (phosphorescence quenching) during contractions. SNP decreased mean arterial pressure (92 +/- 5 mmHg) below that of control (CON, 124 +/- 4 mmHg) and L-NAME (120 +/- 4 mmHg) conditions. SNP did not raise P(O2)mv at rest but it did elevate the P(O2)mv-to-MAP ratio (50% increase, P < 0.05) and slow the kinetics by lengthening the time-delay (TD, 14.0 +/- 5.0 s) and time constant (tau, 24.0 +/- 10.0 s) of the response compared with CON (TD, 8.4 +/- 3.3 s; tau, 16.0 +/- 4.5 s, P < 0.05 vs. SNP). L-NAME decreased P(O2)mv at rest and tended to speed tau (10.1 +/- 3.8 s, P = 0.1), while TD (8.1 +/- 1.0 s) was not significantly different. L-NAME also caused P(O2)mv to fall transiently below steady-state contracting values. These results indicate that NO availability can significantly affect P(O2)mv at rest and during contractions and suggests that P(O2)mv derangements in ageing and chronic disease conditions may potentially result from impairments in NO availability.

Chronic nitric oxide synthase inhibition blunts endothelium-dependent function of conduit coronary arteries, not arterioles

PubMed Central

Ingram, David G.; Newcomer, Sean C.; Price, Elmer M.; Eklund, Kevin E.; McAllister, Richard M.; Laughlin, M. Harold

2009-01-01

Current literature suggests that chronic nitric oxide synthase (NOS) inhibition has differential effects on endothelium-dependent dilation (EDD) of conduit arteries vs. arterioles. Therefore, we hypothesized that chronic inhibition of NOS would impair EDD of porcine left anterior descending (LAD) coronary arteries but not coronary arterioles. Thirty-nine female Yucatan miniature swine were included in the study. Animals drank either tap water or water with NG-nitro-L-arginine methyl ester (L-NAME; 100 mg/l), resulting in control and chronic NOS inhibition (CNI) groups, respectively. Treatment was continued for 1–3 mo (8.3 ± 0.6 mg · kg−1 · day−1). In vitro EDD of coronary LADs and arterioles was assessed via responses to ADP (LADs only) and bradykinin (BK), and endothelium-independent function was assessed via responses to sodium nitroprusside (SNP). Chronic NOS inhibition diminished coronary artery EDD to ADP and BK. Incubating LAD rings with L-NAME decreased relaxation responses of LADs from control pigs but not from CNI pigs such that between-group differences were abolished. Neither indomethacin (Indo) nor sulfaphenazole incubation significantly affected relaxation responses of LAD rings to ADP or BK. Coronary arteries from CNI pigs showed enhanced relaxation responses to SNP. In contrast to coronary arteries, coronary arterioles from CNI pigs demonstrated preserved EDD to BK and no increase in dilation responses to SNP. L-NAME, Indo, and L-NAME + Indo incubation did not result in significant between-group differences in arteriole dilation responses to BK. These results suggest that although chronic NOS inhibition diminishes EDD of LAD rings, most likely via a NOS-dependent mechanism, it does not affect EDD of coronary arterioles. PMID:17259441

The Mechanism of Helium-Induced Preconditioning: A Direct Role for Nitric Oxide in Rabbits

PubMed Central

Pagel, Paul S.; Krolikowski, John G.; Pratt, Phillip F.; Shim, Yon Hee; Amour, Julien; Warltier, David C.; Weihrauch, Dorothee

2008-01-01

BACKGROUND Helium produces preconditioning against myocardial infarction by activating prosurvival signaling, but whether nitric oxide (NO) generated by endothelial NO synthase plays a role in this phenomenon is unknown. We tested the hypothesis that NO mediates helium-induced cardioprotection in vivo. METHODS Rabbits (n = 62) instrumented for hemodynamic measurement were subjected to a 30-min left anterior descending coronary artery occlusion and 3 h reperfusion, and received 0.9% saline (control) or three cycles of 70% helium–30% oxygen administered for 5 min interspersed with 5 min of an air–oxygen mixture before left anterior descending coronary artery occlusion in the absence or presence of pretreatment with the nonselective NOS inhibitor N-nitro-l-arginine methyl ester (L-NAME; 10 mg/kg), the selective inducible NOS inhibitor aminoguanidine hydrochloride (AG; 300 mg/kg), or selective neuronal NOS inhibitor 7-nitroindazole (7-NI; 50 mg/kg). In additional rabbits, the fluorescent probe 4,5-diaminofluroscein diacetate (DAF-2DA) and confocal laser microscopy were used to detect NO production in the absence or presence of helium with or without L-NAME pretreatment. RESULTS Helium reduced (P < 0.05) infarct size (24% ± 4% of the left ventricular area at risk; mean ± sd) compared with control (46% ± 3%). L-NAME, AG, and 7-NI did not alter myocardial infarct size when administered alone. L-NAME, but not 7-NI or AG, abolished helium-induced cardioprotection. Helium enhanced DAF-2DA fluorescence compared with control (26 ± 8 vs 15 ± 5 U, respectively). Pretreatment with L-NAME abolished these helium-induced increases in DAF-2DA fluorescence. CONCLUSIONS The results indicate that cardioprotection by helium is mediated by NO that is probably generated by endothelial NOS in vivo. PMID:18713880

Review of Vaccinia Virus and Baculovirus Viability Versus Virucides

DTIC Science & Technology

2008-03-01

21 disinfectant. Sugimoto and Toyoshima (1979) reported on the inactivation of VACV by Na-Cocoyi-L-Arginine Ethyl Ester, DL- Pyroglutamic Acid Salt...12, pp 473-475. Sugimoto, Y.; Toyoshima, S. N"-Cocoyi-L-Arginine Ethyl Ester, DL- Pyroglutamic Acid Salt, as an Inactivator of Hepatitis B Surface...20 5.1.3 Ascorbic Acid ....................................................................... 20 5.1.4 Dithiothreitol Reducing Agent

Resveratrol protects rats from Aβ-induced neurotoxicity by the reduction of iNOS expression and lipid peroxidation.

PubMed

Huang, Tai-Chun; Lu, Kwok-Tung; Wo, Yu-Yuan Peter; Wu, Yao-Ju; Yang, Yi-Ling

2011-01-01

Alzheimer disease (AD) is an age-dependent neurodegenerative disease characterized by the formation of β-amyloid (Aβ)-containing senile plaque. The disease could be induced by the administration of Aβ peptide, which was also known to upregulate inducible nitric oxide synthase (iNOS) and stimulate neuronal apoptosis. The present study is aimed to elucidate the cellular effect of resveratrol, a natural phytoestrogen with neuroprotective activities, on Aβ-induced hippocampal neuron loss and memory impairment. On adult Sprague-Dawley rats, we found the injection of Aβ could result in a significant impairment in spatial memory, a marked increase in the cellular level of iNOS and lipid peroxidation, and an apparent decrease in the expression of heme oxygenase-1 (HO-1). By combining the treatment with Aβ, resveratrol was able to confer a significant improvement in spatial memory, and protect animals from Aβ-induced neurotoxicity. These neurological protection effects of resveratrol were associated with a reduction in the cellular levels of iNOS and lipid peroxidation and an increase in the production of HO-1. Moreover, the similar neurological and cellular response were also observed when Aβ treatment was combined with the administration of a NOS inhibitor, N(G)-nitro-L-arginine methyl ester hydrochloride (L-NAME). These findings strongly implicate that iNOS is involved in the Aβ-induced lipid peroxidation and HO-1 downregulation, and resveratrol protects animals from Aβ-induced neurotoxicity by suppressing iNOS production.

Resveratrol Protects Rats from Aβ-induced Neurotoxicity by the Reduction of iNOS Expression and Lipid Peroxidation

PubMed Central

Wo, Yu-Yuan Peter; Wu, Yao-Ju; Yang, Yi-Ling

2011-01-01

Alzheimer disease (AD) is an age-dependent neurodegenerative disease characterized by the formation of β–amyloid (Aβ)-containing senile plaque. The disease could be induced by the administration of Aβ peptide, which was also known to upregulate inducible nitric oxide synthase (iNOS) and stimulate neuronal apoptosis. The present study is aimed to elucidate the cellular effect of resveratrol, a natural phytoestrogen with neuroprotective activities, on Aβ-induced hippocampal neuron loss and memory impairment. On adult Sprague-Dawley rats, we found the injection of Aβ could result in a significant impairment in spatial memory, a marked increase in the cellular level of iNOS and lipid peroxidation, and an apparent decrease in the expression of heme oxygenase-1 (HO-1). By combining the treatment with Aβ, resveratrol was able to confer a significant improvement in spatial memory, and protect animals from Aβ-induced neurotoxicity. These neurological protection effects of resveratrol were associated with a reduction in the cellular levels of iNOS and lipid peroxidation and an increase in the production of HO-1. Moreover, the similar neurological and cellular response were also observed when Aβ treatment was combined with the administration of a NOS inhibitor, N(G)-nitro-L-arginine methyl ester hydrochloride (L-NAME). These findings strongly implicate that iNOS is involved in the Aβ-induced lipid peroxidation and HO-1 downregulation, and resveratrol protects animals from Aβ-induced neurotoxicity by suppressing iNOS production. PMID:22220203

Scanning electron microscopy study of neutrophil membrane tubulovesicular extensions (cytonemes) and their role in anchoring, aggregation and phagocytosis. The effect of nitric oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galkina, Svetlana I.; Molotkovsky, Julian G.; Ullrich, Volker

2005-04-01

We have shown that human neutrophils develop dynamic thin and very long tubulovesicular extensions (cytonemes) upon adhesion to fibronectin, if cell spreading was blocked by Na{sup +}-free medium or by 4-bromophenacyl bromide, N-ethylmaleimide, 7-chloro-4-nitrobenz-2-oxa-1,3-diazole and cytochalasin D (S. I. Galkina, G. F. Sud'ina and V. Ullrich (2001). Exp. Cell Res. 266, 222-228). In the present work we found that similar in size and behavior tubulovesicular extensions were formed on the neutrophil cell bodies upon adhesion to fibronectin-coated substrata in the presence of the nitric oxide donor diethylamine NONOate. In the presence of the nitric oxide synthase inhibitor N-{omega}-nitro-L-arginine methyl ester,more » neutrophils were well spread and had no microextensions. Using scanning electron microscopy, we demonstrated that tubulovesicular extensions of neutrophils executed long-range adhesion and binding objects for phagocytosis, such as serum-opsonized zymosan particles and erythrocytes. Tubulovesicular extensions anchored neutrophils to substrata in a {beta}1 and {beta}2 integrin-independent, but L-selectin-dependent manner. BODIPY-sphingomyelin impaired development of tubulovesicular extension, and heparitinase 1 played a role in their destruction. Membrane tubulovesicular extensions are supposed to represent protrusions of an intracellular exocytotic traffic and serve as cellular sensory and adhesive organelles. Nitric oxide seems to play a role in regulation of tubulovesicular extensions formation, thus affecting neutrophil adhesive interactions and phagocytosis.« less

Aging impairs smooth muscle-mediated regulation of aortic stiffness: a defect in shock absorption function?

PubMed Central

Gao, Yuan Z.; Saphirstein, Robert J.; Yamin, Rina; Suki, Bela

2014-01-01

Increased aortic stiffness is an early and independent biomarker of cardiovascular disease. Here we tested the hypothesis that vascular smooth muscle cells (VSMCs) contribute significantly to aortic stiffness and investigated the mechanisms involved. The relative contributions of VSMCs, focal adhesions (FAs), and matrix to stiffness in mouse aorta preparations at optimal length and with confirmed VSMC viability were separated by the use of small-molecule inhibitors and activators. Using biomechanical methods designed for minimal perturbation of cellular function, we directly quantified changes with aging in aortic material stiffness. An alpha adrenoceptor agonist, in the presence of NG-nitro-l-arginine methyl ester (l-NAME) to remove interference of endothelial nitric oxide, increases stiffness by 90–200% from baseline in both young and old mice. Interestingly, increases are robustly suppressed by the Src kinase inhibitor PP2 in young but not old mice. Phosphotyrosine screening revealed, with aging, a biochemical signature of markedly impaired agonist-induced FA remodeling previously associated with Src signaling. Protein expression measurement confirmed a decrease in Src expression with aging. Thus we report here an additive model for the in vitro biomechanical components of the mouse aortic wall in which 1) VSMCs are a surprisingly large component of aortic stiffness at physiological lengths and 2) regulation of the VSMC component through FA signaling and hence plasticity is impaired with aging, diminishing the aorta's normal shock absorption function in response to stressors. PMID:25128168

Changes in nitric oxide release in vivo in response to vasoactive substances.

PubMed Central

Nava, E.; Wiklund, N. P.; Salazar, F. J.

1996-01-01

1. Changes in the release of nitric oxide (NO) in vivo were studied in rats following the administration of endothelium-dependent and -independent vasodilators as well as the NO synthesis inhibitor, NG-nitro-L-arginine methyl ester (L-NAME). NO production was assessed by measuring variations of nitrate in plasma by capillary ion analysis. 2. Intravenous administration of the endothelium-dependent vasodilators, bradykinin (2 and 10 micrograms kg-1 min-1) or substance P (0.3-3 micrograms kg-1 min-1) caused a transient dose-dependent hypotension followed by an increase in plasma nitrate concentration (maximal increments: 33 +/- 5% and 38 +/- 6%, for bradykinin and substance P, respectively). Prior administration of L-NAME (10 mg kg-1 min-1) inhibited the hypotension and increase in plasma nitrate caused by these substances. Intravenous administration of sodium nitrate (200 micrograms kg-1) also produced a transitory elevation in plasma nitrate which was similar in magnitude as that caused by the vasodilators. A rapid and transitory increment in plasma nitrate was observed after i.v. administration of authentic NO (400 micrograms kg-1). 3. Rats receiving the endothelium-dependent vasodilators, prostacyclin (0.6 micrograms kg-1 min-1) or adenosine (3 mg kg-1 min-1) intravenously showed a drop in blood pressure paralleled by a decrease in plasma nitrate (maximal decreases: 34 +/- 5% and 24 +/- 4%, for prostacyclin and adenosine, respectively). A similar effect on the plasmatic concentration of nitrate was observed when L-NAME (10 mg kg-1 min-1, i.v.) was administered to the animals. 4. This study demonstrates that (i) changes in plasma nitrate can be detected in vivo after stimulation or inhibition of NO synthase, (ii) an increased production of NO, measured as plasma nitrate, is related to the hypotension caused by bradykinin and substance P and (iii) a diminished concentration of plasmatic nitrate is associated to the hypotension induced by adenosine or prostacyclin (endothelium-independent vasodilators), suggesting that the L-arginine: NO pathway is capable of rapid down-regulation in response to a fall in blood pressure. PMID:8937725

A nitric oxide donor reduces brain injury and enhances recovery of cerebral blood flow after hypoxia-ischemia in the newborn rat.

PubMed

Wainwright, Mark S; Grundhoefer, Dava; Sharma, Shruti; Black, Stephen M

2007-03-26

Nitric oxide (NO) released in response to hypoxia-ischemia (HI) in the newborn brain may mediate both protective and pathologic responses. We sought to determine whether pharmacologic increase of NO using an NO donor would reduce neurologic injury resulting from HI in the postnatal day 7 rat. We measured NO levels and CBF in the presence of either a NOS inhibitor, N-nitro-l-arginine methyl ester (L-NAME) or an NO donor (Z)-1-[N-(2-amino-ethyl)-N-(2-ammonio-ethyl)amino]diazen-1-ium-1,2-diolate (DETANONOate). Both inhibition of NOS and administration of an NO donor reduced neuropathologic injury after 7-day recovery. NO levels decreased in both ischemic and contralateral hemispheres during HI. This response was prevented by treatment with DETANONOate. Despite the decrease in NO, CBF increased during ischemia in the contralateral hemisphere but decreased when combined with brief hypoxia. Treatment with L-NAME abolished these increases, which were not altered by DETANONOate. Reduction of cellular metabolism by mild hypothermia also reduced both NO and CBF. Following prolonged HI, CBF remained decreased in the ischemic hemisphere up to 24-h recovery. This decrease was prevented by treatment with DETANONOate. These data show that administration of an NO donor reduces neurologic injury following HI in the newborn rat. This mechanism of this protection, in part, is due to an increase in the rate of recovery of CBF compared to vehicle-treated animals. Augmentation of NO-dependent increases in CBF may serve to improve neurologic outcome after perinatal asphyxia.

A NITRIC OXIDE DONOR REDUCES BRAIN INJURY AND ENHANCES RECOVERY OF CEREBRAL BLOOD FLOW AFTER HYPOXIA-ISCHEMIA IN THE NEWBORN RAT

PubMed Central

Wainwright, Mark S.; Grundhoefer, Dava; Sharma, Shruti; Black, Stephen M.

2007-01-01

Nitric oxide (NO) released in response to hypoxia-ischemia (HI) in the newborn brain may mediate both protective and pathologic responses. We sought to determine whether pharmacologic increase of NO using an NO donor would reduce neurologic injury resulting from HI in the postnatal day 7 rat. We measured NO levels and CBF in the presence of either a NOS inhibitor, N-nitro-L-arginine methyl ester (L-NAME) or an NO donor (Z)-1-[N-(2aminoethyl)-N-(2-ammonio-ethyl)amino]diazen-1-ium-1,2-diolate (DETANONOate). Both inhibition of NOS and administration of an NO donor reduced neuropathologic injury after 7-day recovery. NO levels decreased in both ischemic and contralateral hemispheres during HI. This response was prevented by treatment with DETANONOate. Despite the decrease in NO, CBF increased during ischemia in the contralateral hemisphere but decreased when combined with brief hypoxia. Treatment with L-NAME abolished these increases, which were not altered by DETANONOate. Reduction of cellular metabolism by mild hypothermia also reduced both NO and CBF. Following prolonged HI, CBF remained decreased in the ischemic hemisphere up to 24-hour recovery. This decrease was prevented by treatment with DETANONOate. These data show that administration of an NO donor reduces neurologic injury following HI in the newborn rat. This mechanism of this protection, in part, is due to an increase in the rate of recovery of CBF compared to vehicle-treated animals. Augmentation of NO-dependent increases in CBF may serve to improve neurologic outcome after perinatal asphyxia. PMID:17270345

Resistin impairs endothelium-dependent dilation to bradykinin, but not acetylcholine, in the coronary circulation.

PubMed

Dick, Gregory M; Katz, Paige S; Farias, Martin; Morris, Michael; James, Jeremy; Knudson, Jarrod D; Tune, Johnathan D

2006-12-01

Elevated plasma levels of fat-derived signaling molecules are associated with obesity, vascular endothelial dysfunction, and coronary heart disease; however, little is known about their direct coronary vascular effects. Accordingly, we examined mechanisms by which one adipokine, resistin, affects coronary vascular tone and endothelial function. Studies were conducted in anesthetized dogs and isolated coronary artery rings. Resistin did not change coronary blood flow, mean arterial pressure, or heart rate. Resistin had no effect on acetylcholine-induced relaxation of artery rings; however, resistin did impair bradykinin-induced relaxation. Selective impairment was also observed in vivo, as resistin attenuated vasodilation to bradykinin but not to acetylcholine. Resistin had no effect on dihydroethidium fluorescence, an indicator of superoxide (O(2)(-)) production, and the inhibitory effect of resistin on bradykinin-induced relaxation persisted in the presence of Tempol, a superoxide dismutase mimetic. To determine whether resistin impaired production of and/or responses to nitric oxide (NO) or prostaglandins (e.g., prostacyclin; PGI(2)), we performed experiments with N(omega)-nitro-L-arginine methyl ester (L-NAME) and indomethacin. The effect of resistin to attenuate bradykinin-induced vasodilation persisted in the presence of L-NAME or indomethacin, suggesting resistin may act at a cell signaling point upstream of NO or PGI(2) production. Resistin-induced endothelial dysfunction is not generalized, and it is not consistent with effects mediated by O(2)(-) or interference with NO or PGI(2) signaling. The site of the resistin-induced impairment is unknown but may be at the bradykinin receptor or a closely associated signal transduction machinery proximal to NO synthase or cyclooxygenase.

Copper induces vasorelaxation and antagonizes noradrenaline-induced vasoconstriction in rat mesenteric artery.

PubMed

Wang, Yu-Chun; Hu, Chao-Wei; Liu, Ming-Yu; Jiang, Hong-Chao; Huo, Rong; Dong, De-Li

2013-01-01

Copper is an essential trace element for normal cellular function and contributes to critical physiological or pathological processes. The aim of the study was to investigate the effects of copper on vascular tone of rat mesenteric artery and compare the effects of copper on noradrenaline (NA) and high K(+) induced vasoconstriction. The rat mesenteric arteries were isolated and the vessel tone was measured by using multi wire myograph system in vitro. Blood pressure of carotid artery in rabbits was measured by using physiological data acquisition and analysis system in vivo. Copper dose-dependently blunted NA-induced vasoconstriction of rat mesenteric artery. Copper-induced vasorelaxation was inhibited when the vessels were pretreated with NG-nitro-L-arginine methyl ester (L-NAME). Copper did not blunt high K(+)-induced vasoconstriction. Copper preincubation inhibited NA-evoked vasoconstriction and the inhibition was not affected by the presence of L-NAME. Copper preincubation showed no effect on high K(+)-evoked vasoconstriction. Copper chelator diethyldithiocarbamate trihydrate (DTC) antagonized the vasoactivity induced by copper in rat mesenteric artery. In vivo experiments showed that copper injection (iv) significantly decreased blood pressure of rabbits and NA or DTC injection (iv) did not rescue the copper-induced hypotension and animal death. Copper blunted NA but not high K(+)-induced vasoconstriction of rat mesenteric artery. The acute effect of copper on NA-induced vasoconstriction was depended on nitric oxide (NO), but the effect of copper pretreatment on NA-induced vasoconstriction was independed on NO, suggesting that copper affected NA-induced vasoconstriction by two distinct mechanisms. © 2013 S. Karger AG, Basel.

Post-resistance exercise hypotension in spontaneously hypertensive rats is mediated by nitric oxide.

PubMed

Lizardo, J H F; Silveira, E A A; Vassallo, D V; Oliveira, E M

2008-07-01

1. Postexercise hypotension (PEH) plays an important role in the non-pharmacological treatment of hypertension. It is characterized by a decrease in blood pressure (BP) after a single bout of exercise in relation to pre-exercise levels. 2. The present study investigated the effect of a single session of resistance exercise, as well as the effect of nitric oxide (NO) and the autonomic nervous system (ANS), in PEH in spontaneously hypertensive rats (SHR). 3. Catheters were inserted into the left carotid artery and left jugular vein of male SHR (n = 37) for the purpose of measuring BP or heart rate (HR) and drug or vehicle administration, respectively. Haemodynamic measurements were made before and after acute resistance exercise. The roles of NO and the ANS were investigated by using N(G)-nitro-L-arginine methyl ester (L-NAME; 15 mg/kg, i.v.) and hexamethonium (20 mg/kg, i.v.) after a session of acute resistance exercise. 4. Acute resistance exercise promoted a pronounced reduction in systolic and diastolic BP (-37 +/- 1 and -8 +/- 1 mmHg, respectively; P < 0.05), which was suppressed after treatment with L-NAME. The reduction in systolic BP caused by exercise (-37 +/- 1 mmHg) was not altered by the administration of hexamethonium (-38 +/- 2 mmHg; P > 0.05). After exercise, the decrease in diastolic BP was greater with hexamethonium (-26 +/- 1 mmHg; P < 0.05) compared with the decrease caused by exercise alone. 5. The results suggest that acute resistance exercise has an important hypotensive effect on SHR and that NO plays a crucial role in this response.

Folic Acid Promotes Recycling of Tetrahydrobiopterin and Protects Against Hypoxia-Induced Pulmonary Hypertension by Recoupling Endothelial Nitric Oxide Synthase

PubMed Central

Chalupsky, Karel; Kračun, Damir; Kanchev, Ivan; Bertram, Katharina

2015-01-01

Abstract Aims: Nitric oxide (NO) derived from endothelial NO synthase (eNOS) has been implicated in the adaptive response to hypoxia. An imbalance between 5,6,7,8-tetrahydrobiopterin (BH4) and 7,8-dihydrobiopterin (BH2) can result in eNOS uncoupling and the generation of superoxide instead of NO. Dihydrofolate reductase (DHFR) can recycle BH2 to BH4, leading to eNOS recoupling. However, the role of DHFR and eNOS recoupling in the response to hypoxia is not well understood. We hypothesized that increasing the capacity to recycle BH4 from BH2 would improve NO bioavailability as well as pulmonary vascular remodeling (PVR) and right ventricular hypertrophy (RVH) as indicators of pulmonary hypertension (PH) under hypoxic conditions. Results: In human pulmonary artery endothelial cells and murine pulmonary arteries exposed to hypoxia, eNOS was uncoupled as indicated by reduced superoxide production in the presence of the nitric oxide synthase inhibitor, L-(G)-nitro-L-arginine methyl ester (L-NAME). Concomitantly, NO levels, BH4 availability, and expression of DHFR were diminished under hypoxia. Application of folic acid (FA) restored DHFR levels, NO bioavailability, and BH4 levels under hypoxia. Importantly, FA prevented the development of hypoxia-induced PVR, right ventricular pressure increase, and RVH. Innovation: FA-induced upregulation of DHFR recouples eNOS under hypoxia by improving BH4 recycling, thus preventing hypoxia-induced PH. Conclusion: FA might serve as a novel therapeutic option combating PH. Antioxid. Redox Signal. 23, 1076–1091. PMID:26414244

Onset of diabetes modulates the airway smooth muscle reactivity of guinea pigs: role of epithelial mediators.

PubMed

Saidullah, Bano; Muralidhar, Kambadur; Fahim, Mohammad

2014-01-01

Diabetes induces lung dysfunction, leading to alteration in the pulmonary functions. Our aim was to investigate whether the early stage of diabetes alters the epithelium-dependent bronchial responses and whether nitric oxide (NO), KATP channels and cyclooxygenase (COX) pathways contribute in this effect. Guinea pigs were treated with a single injection of streptozotocin (180 mg/kg, i.p.) for induction of diabetes. Airway conductivity was assessed by inhaled histamine, using a non-invasive body plethysmography. The contractile responses of tracheal rings induced by acetylcholine (ACh) and relaxant responses of precontracted rings, induced by isoproterenol (IP) were compared in the presence and absence of the epithelium. Effects of N(ω)-Nitro-L-arginine methyl ester (L-NAME, a nitric oxide synthase inhibitor), glybenclamide (a KATP channel inhibitor) and indomethacin (a COX inhibitor) were also assessed in diabetic guinea pigs. Early stage diabetes did not alter the airway conductivity. ACh-induced bronchoconstriction in epithelium intact tracheal rings was not affected by the onset of diabetes, however a reduction in the increased ACh responses due to epithelium removal, to L-NAME or to indomethacin was observed. The relaxation response to IP was impaired in trachea from guinea pigs in which diabetes had just developed. Early diabetes significantly reduced the IP response to glybenclamide and to indomethacin. Our results demonstrate that the early stage of diabetes, modulate the bronchial reactivity to both ACh and IP by disrupting the NO, KATP channels and COX pathways, without affecting the airway conductivity in guinea pigs.

Endothelin-like action of Pausinystalia yohimbe aqueous extract on vascular and renal regional hemodynamics in Sprague Dawley rats.

PubMed

Ajayi, A A; Newaz, M; Hercule, H; Saleh, M; Bode, C O; Oyekan, A O

2003-12-01

The bark of the African tree Pausinystalia yohimbe has been used as a food additive with aphrodisiac and penile erection enhancing properties. The effect of an aqueous extract of P. yohimbe (CCD-X) on renal circulation was assessed in order to test the hypothesis that it possesses additional effects on nitric oxide production and/or endothelin-1 (ET-1)-like actions. In vivo studies with CCD-X in Sprague Dawley rats demonstrated a dose-dependent (1-1000 ng/kg) increase in mean blood pressure (p < 0.001) and an increase in medullary blood flow (MBF) (p < 0.001). Both the pressor action and renal medullary vasodilation were blocked by endothelinA (ETA) receptor antagonist BMS182874 and endothelinB (ETB) receptor antagonist BQ788 in combination. L-Nomega-nitro-l-arginine methyl ester (L-NAME; 10 mg/kg) also inhibited the increase in MBF induced by CCD-X. In vitro studies in isolated perfused kidney and in pressurized renal microvessels confirmed the dose-dependent vasoconstrictor action of this extract. ETA receptor antagonist BQ610 and ETB receptor antagonist BQ788 separately and significantly attenuated the renal vasoconstrictor actions of the extract (p < 0.001 ANOVA). These preliminary observations indicate that, in addition to the alpha-adrenergic antagonist actions that characterize yohimbine, CCD-X possesses endothelin-like actions and affects nitric oxide (NO) production in renal circulation. These findings suggest a strong possibility of post-receptor cross-talk between alpha2-adrenoceptors and endothelin, as well as a direct effect of alpha2-adrenoceptors on renal NO production. (c) 2003 Prous Science

Mechanisms underlying the antinociceptive effect of mangiferin in the formalin test.

PubMed

Izquierdo, Teresa; Espinosa de los Monteros-Zuñiga, Antonio; Cervantes-Durán, Claudia; Lozada, María Concepción; Godínez-Chaparro, Beatriz

2013-10-15

The purpose of this study was to investigate the possible antinociceptive effect of mangiferin, a glucosylxanthone present in Mangifera indica L., in inflammatory pain. Furthermore, we sought to investigate the possible mechanisms action that contributes to these effects. The ipsilateral local peripheral (1-30 µg/paw), intrathecal (1-30 µg/rat) and oral (1-30 mg/kg) administration of mangiferin produced a dose-dependent reduction in formalin-induced nociception. The antinociceptive effect of this drug was similar to that induced by diclofenac after oral and local peripheral administration. Furthermore, mangiferin was also able to reduce 0.1% capsaicin- and serotonin-induced nociceptive behavior. The local peripheral antinociceptive effect of mangiferin in the formalin test was blocked by naloxone (50 μg/paw), naltrindole (1 μg/paw), 5-guanidinonaltrindole (5-GNTI, 1 μg/paw), N(G)-L-nitro-arginine methyl ester (L-NAME, 100 µg/paw), 1H-(1,2,4)-oxadiazolo [4,2-a]quinoxalin-1-one (ODQ, 50 µg/paw) and glibenclamide (50 μg/paw), but not by methiothepin (30 μg/paw). These results suggest that the antinociceptive effects induced by mangiferin are mediated by the peripheral opioidergic system involving the activation of δ, κ, and probably µ, receptors, but not serotonergic receptors. Data also suggests that mangiferin activates the NO-cyclic GMP-ATP-sensitive K(+) channels pathway in order to produce its local peripheral antinociceptive effect in the formalin test. Mangiferin may prove to be effective in treating inflammatory pain in humans. © 2013 Elsevier B.V. All rights reserved.

Effects of NOS inhibition on the cardiopulmonary system and brain microvascular markers after intermittent hypoxia in rats.

PubMed

Barer, G R; Fairlie, J; Slade, J Y; Ahmed, S; Laude, E A; Emery, C J; Thwaites-Bee, D; Oakley, A E; Barer, D H; Kalaria, R N

2006-07-07

We previously demonstrated that rats subjected to intermittent hypoxia (IH) by exposure to 10% O(2) for 4 h daily for 56 days in a normobaric chamber, developed pulmonary hypertension, right ventricular hypertrophy and wall-thickening in pulmonary arterioles, compared with normoxic (N) controls. These changes were greater in rats subjected to continuous hypoxia (CH breathing 10% O(2) for 56 days). Cerebral angiogenesis was demonstrated by immunostaining with glucose transporter 1 (GLUT1) antibody, in viable vessels, in CH and to a lesser degree in IH. In this study, adult Wistar rats were subjected to the same hypoxic regimes and given the nitric oxide synthase (NOS) inhibitor N(6)-nitro-L-arginine methyl ester (L-NAME) in drinking water (NLN, IHLN and CHLN regimes) to induce hypertension. There was significant systemic hypertension in NLN and IHLN rats, compared with N and IH, but surprisingly not in CHLN compared with CH. Hematocrit rose in all hypoxic groups (up to 79% in CHLN). There was no significant pulmonary hypertension in IHLN versus NLN rats, although there was asymmetric wall thickening in pulmonary arterioles. Cerebral GLUT1 immunoreactivity increased with L-NAME, with or without hypoxia, especially in CHLN rats, but conspicuously there was no evidence of angiogenesis in brains of IHLN compared with NLN rats. NOS blockade may attenuate the cerebral and pulmonary vascular changes of IH while augmenting cerebral angiogenesis in continuous hypoxia. However, whether cerebral effects are due to systemic hypertension or changes in cerebral nitric oxide production needs to be evaluated.

Characteristics of the pulse waveform during altered nitric oxide synthesis in the rabbit.

PubMed

Weinberg, P D; Habens, F; Kengatharan, M; Barnes, S E; Matz, J; Anggård, E E; Carrier, M J

2001-06-01

Nitrovasodilators produce characteristic changes in the shape of the peripheral pulse wave. Similar changes might also be caused by alteration of endogenous NO activity, which would allow such activity to be assessed in vivo. We investigated whether manipulation of the NO pathway influences the pulse waveform, and the mechanisms involved. The pulse wave in the ear of normal rabbits was examined by reflectance photoplethysmography before and during infusion of vasoactive agents. Pulse wave velocity was assessed by using an additional sensor on the rear foot. A diastolic peak was observed in the ear pulse; its timing was consistent with it being a reflection of the systolic peak from the lower body. The height of the dicrotic notch marking the start of this diastolic wave was decreased by acetylcholine or an NO donor, and further decreased by a phosphodiesterase type V inhibitor. The acetylcholine-induced decreases were blocked by inhibiting NO synthesis with N(G)-nitro-L-arginine methyl ester (L-NAME) but were unaffected by the inactive enantiomer D-NAME. These data demonstrate that NO influences the height of the notch in the pulse wave. Heart rate and blood pressure were altered during acetylcholine or L-NAME infusion, but there were no changes in pulse wave amplitude or velocity, or in the timing of the diastolic peak or dicrotic notch. The slope of the pulse wave between the systolic peak and notch changed substantially. These effects are most convincingly explained by changes in wave reflection, not only from the lower body but also from more proximal sites.

Characteristics of the pulse waveform during altered nitric oxide synthesis in the rabbit

PubMed Central

Weinberg, P D; Habens, F; Kengatharan, M; Barnes, S E; Matz, J; Änggård, E E; Carrier, M J

2001-01-01

Nitrovasodilators produce characteristic changes in the shape of the peripheral pulse wave. Similar changes might also be caused by alteration of endogenous NO activity, which would allow such activity to be assessed in vivo. We investigated whether manipulation of the NO pathway influences the pulse waveform, and the mechanisms involved. The pulse wave in the ear of normal rabbits was examined by reflectance photoplethysmography before and during infusion of vasoactive agents. Pulse wave velocity was assessed by using an additional sensor on the rear foot. A diastolic peak was observed in the ear pulse; its timing was consistent with it being a reflection of the systolic peak from the lower body. The height of the dicrotic notch marking the start of this diastolic wave was decreased by acetylcholine or an NO donor, and further decreased by a phosphodiesterase type V inhibitor. The acetylcholine-induced decreases were blocked by inhibiting NO synthesis with NG-nitro-L-arginine methyl ester (L-NAME) but were unaffected by the inactive enantiomer D-NAME. These data demonstrate that NO influences the height of the notch in the pulse wave. Heart rate and blood pressure were altered during acetylcholine or L-NAME infusion, but there were no changes in pulse wave amplitude or velocity, or in the timing of the diastolic peak or dicrotic notch. The slope of the pulse wave between the systolic peak and notch changed substantially. These effects are most convincingly explained by changes in wave reflection, not only from the lower body but also from more proximal sites. PMID:11375252

Effects of nitric oxide synthase inhibition on sympathetically-mediated tachycardia

NASA Technical Reports Server (NTRS)

Whalen, E. J.; Johnson, A. K.; Lewis, S. J.

1999-01-01

The aim of the present study was to determine whether inhibition of nitric oxide (NO) synthesis directly alters the tachycardia produced by sympathetically-derived norepinephrine. The NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME; 50 micromol/kg, i.v.), produced a marked rise in mean arterial blood pressure. This pressor response was associated with a fall in heart rate which involved the withdrawal of cardiac sympathetic nerve activity. The NO-donor, sodium nitroprusside (5 microg/kg, i.v.), produced a pronounced fall in mean arterial blood pressure but only a minor increase in heart rate. The beta-adrenoceptor agonist, isoproterenol (0.5 micromol/kg, i.v.), and the membrane-permeable cAMP analogue, 8-(4-chlorophenylthiol)-cAMP (10 micromol/kg, i.v.), produced falls in mean arterial blood pressure and pronounced increases in heart rate. The indirectly acting sympathomimetic agent, tyramine (0.5 mg/kg, i.v.), produced a pressor response and a tachycardia. The effects of sodium nitroprusside, tyramine, isoproterenol and 8-(4-chlorophenylthiol)-cAMP on mean arterial blood pressure were not markedly affected by L-NAME. However, the tachycardia produced by these agents was considerably exaggerated in the presence of this NO synthesis inhibitor. These findings suggest that L-NAME potentiates the tachycardia produced by sympathetically-derived norepinephrine. The increased responsiveness to norepinephrine may involve (i) a rapid up-regulation of cardiac beta1-adrenoceptors and cAMP signaling in cardiac pacemaker cells due to the loss of the inhibitory influence of cardiac NO, and (ii) the up-regulation of beta1-adrenoceptor-mediated signal transduction processes in response to the L-NAME-induced withdrawal of cardiac sympathetic nerve activity.

Use-dependent loss of active sympathetic neurogenic vasodilation after nitric oxide synthase inhibition in conscious rats. Evidence for the presence of preformed stores of nitric oxide-containing factors

NASA Technical Reports Server (NTRS)

Davisson, R. L.; Shaffer, R. A.; Johnson, A. K.; Lewis, S. J.

1996-01-01

In this study, we examined whether air-jet stress-induced active sympathetic hindlimb vasodilation in conscious rats involves the release of preformed stores of nitric oxide-containing factors. We determined the effects of repeated episodes of air-jet stress (six episodes given 5 minutes apart) on mean arterial pressure and vascular resistances in the mesenteric bed and intact and sympathetically denervated hindlimb beds of conscious rats treated with saline or the nitric oxide synthesis inhibitor N omega-nitro-L-arginine methyl ester (L-NAME, 25 mumol/kg IV). In saline-treated rats, air-jet stress produced alerting behavior, minor changes in blood pressure, pronounced mesenteric vaso-constriction, and immediate and marked vasodilation in the sympathetically intact hindlimb but a minor vasodilation in the sympathetically denervated hindlimb. Each air-jet stress produced virtually identical responses. In L-NAME-treated rats, the first air-jet stress produced vasodilator responses in the sympathetically intact and sympathetically denervated hindlimbs that were similar to those in the saline-treated rats. However, each subsequent air-jet stress produced progressively smaller vasodilator responses in the sympathetically intact but not the sympathetically denervated hindlimb. There was no loss of air-jet stress-induced alerting behavior or mesenteric vasoconstriction, suggesting that L-NAME did not interfere with the central processing of the air-jet or the resultant changes in autonomic nerve activity. The progressive diminution of air-jet stress-induced vasodilation in the intact hindlimb of L-NAME-treated rats may be due to the use-dependent depletion of preformed stores of nitric oxide-containing factors that cannot be replenished in the absence of nitric oxide synthesis.

Edematogenic activity of a sulfated galactan from the red marine algae Gelidium crinale.

PubMed

Assreuy, Ana Maria Sampaio; Amorim, Renata Morais Ferreira; Brizeno, Luiz André Cavalcante; de Paulo Pereira, Lívia; de Sousa, Albertina Antonielly Sydney; Aragão, Gislei Frota; Pereira, Maria Gonçalves

2012-09-01

The red algae Gelidium crinale (Turner) Gaillon (Gelidiaceae), encountered along the Southeast and Northeast Brazilian sea coast, contains a sulfated galactan presenting a similar saccharide backbone compared to λ carrageenan. Inflammatory effects of other galactans were reported, but not for that obtained from G. crinale (SG-Gc). To investigate the in vivo edematogenic effect of SG-Gc in comparison to λ carrageenan. SG-Gc was isolated by ion exchange chromatography. Paw edema was induced by subcutaneous (s.c.) intraplantar injection of SG-Gc or λ carrageenan and evaluated by hydroplethysmometry. Data were expressed as the increase in paw volume subtracted from the basal volume or area under curve-AUC. To investigate the participation of early and late-phase inflammatory mediators, rats were treated with pyrilamine, compound 48/80, indomethacin, NG-nitro-L-arginine methyl ester (L-NAME), or pentoxifylline before SG-Gc. SG-Gc edematogenic effect was initiated at 0.5 h, peaked at 2 h (1.26 ± 0.05 mL) and lasted until 6 h (0.21 ± 0.03 mL), whereas the carrageenan-induced edema started at 1 h. The first phase (1-3 h) of SG-Gc-induced edema was 176 ± 15 (AUC) versus carrageenan (114.5 ± 14), whereas the second phase (3-5 h) was 95 ± 12 (AUC) versus carrageenan (117.5 ± 11). Treatment with compound 48/80, pyrilamine, indomethacin, L-NAME, and pentoxifylline inhibited the effect of SG-Gc by 32, 40, 69, 72, and 49%, respectively. SG-Gc and λ carrageenan induce different profile of inflammatory response in the paw edema model, that involves histamine, cytokines, prostaglandins, and nitric oxide (NO), but with different degree of participation.

Leptin receptors are expressed in coronary arteries, and hyperleptinemia causes significant coronary endothelial dysfunction.

PubMed

Knudson, Jarrod D; Dincer, U Deniz; Zhang, Cuihua; Swafford, Albert N; Koshida, Ryoji; Picchi, Andrea; Focardi, Marta; Dick, Gregory M; Tune, Johnathan D

2005-07-01

Obesity is associated with marked increases in plasma leptin concentration, and hyperleptinemia is an independent risk factor for coronary artery disease. As a result, the purpose of this investigation was to test the following hypotheses: 1) leptin receptors are expressed in coronary endothelial cells; and 2) hyperleptinemia induces coronary endothelial dysfunction. RT-PCR analysis revealed that the leptin receptor gene is expressed in canine coronary arteries and human coronary endothelium. Furthermore, immunocytochemistry demonstrated that the long-form leptin receptor protein (ObRb) is present in human coronary endothelium. The functional effects of leptin were determined using pressurized coronary arterioles (<130 microm) isolated from Wistar rats, Zucker rats, and mongrel dogs. Leptin induced pharmacological vasodilation that was abolished by denudation and the nitric oxide synthase inhibitor N(omega)-nitro-l-arginine methyl ester and was absent in obese Zucker rats. Intracoronary leptin dose-response experiments were conducted in anesthetized dogs. Normal and obese concentrations of leptin (0.1-3.0 microg/min ic) did not significantly change coronary blood flow or myocardial oxygen consumption; however, obese concentrations of leptin significantly attenuated the dilation to graded intracoronary doses of acetylcholine (0.3-30.0 microg/min). Additional experiments were performed in canine coronary rings, and relaxation to acetylcholine (6.25 nmol/l-6.25 micromol/l) was significantly attenuated by obese concentrations of leptin (625 pmol/l) but not by physiological concentrations of leptin (250 pmol/l). The major findings of this investigation were as follows: 1) the ObRb is present in coronary arteries and coupled to pharmacological, nitric oxide-dependent vasodilation; and 2) hyperleptinemia produces significant coronary endothelial dysfunction.

Insulin restores gestational diabetes mellitus-reduced adenosine transport involving differential expression of insulin receptor isoforms in human umbilical vein endothelium.

PubMed

Westermeier, Francisco; Salomón, Carlos; González, Marcelo; Puebla, Carlos; Guzmán-Gutiérrez, Enrique; Cifuentes, Fredi; Leiva, Andrea; Casanello, Paola; Sobrevia, Luis

2011-06-01

To determine whether insulin reverses gestational diabetes mellitus (GDM)-reduced expression and activity of human equilibrative nucleoside transporters 1 (hENT1) in human umbilical vein endothelium cells (HUVECs). Primary cultured HUVECs from full-term normal (n = 44) and diet-treated GDM (n = 44) pregnancies were used. Insulin effect was assayed on hENT1 expression (protein, mRNA, SLC29A1 promoter activity) and activity (initial rates of adenosine transport) as well as endothelial nitric oxide (NO) synthase activity (serine(1177) phosphorylation, l-citrulline formation). Adenosine concentration in culture medium and umbilical vein blood (high-performance liquid chromatography) as well as insulin receptor A and B expression (quantitative PCR) were determined. Reactivity of umbilical vein rings to adenosine and insulin was assayed by wire myography. Experiments were in the absence or presence of l-N(G)-nitro-l-arginine methyl ester (l-NAME; NO synthase inhibitor) or ZM-241385 (an A(2A)-adenosine receptor antagonist). Umbilical vein blood adenosine concentration was higher, and the adenosine- and insulin-induced NO/endothelium-dependent umbilical vein relaxation was lower in GDM. Cells from GDM exhibited increased insulin receptor A isoform expression in addition to the reported NO-dependent inhibition of hENT1-adenosine transport and SLC29A1 reporter repression, and increased extracellular concentration of adenosine and NO synthase activity. Insulin reversed all these parameters to values in normal pregnancies, an effect blocked by ZM-241385 and l-NAME. GDM and normal pregnancy HUVEC phenotypes are differentially responsive to insulin, a phenomenon where insulin acts as protecting factor for endothelial dysfunction characteristic of this syndrome. Abnormal adenosine plasma levels, and potentially A(2A)-adenosine receptors and insulin receptor A, will play crucial roles in this phenomenon in GDM.

The hyperthermia mediated by 3,4-methylenedioxymethamphetamine (MDMA, Ecstasy) is sensitive to sex differences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wyeth, Richard P.; Division of Physiology, Virginia College of Osteopathic Medicine, Blacksburg, VA 24060; Mills, Edward M.

Female subjects have been reported to be less sensitive to the hyperthermic effects of 3,4-methylenedioxymethamine (MDMA) than males. Studies were designed to examine the cellular mechanisms involved in these sex sensitive differences. Gonadectomized female and male rats were treated with a 200 {mu}g 100 {mu}L{sup -1} of estrogen or 100 {mu}g 100 {mu}L{sup -1} of testosterone respectively every 5 days for a total of three doses. Rats were then challenged with either saline or MDMA (20 mg kg{sup -1}, sc). Rats were then euthanized and aortas were constricted, in vitro, by serial phenylephrine (Phe) addition with or without the inhibitormore » of nitric oxide (NO) synthase, g-nitro-L-Arginine-Methyl Ester (L-NAME). Skeletal muscle uncoupling protein-3 (UCP3) expression was measured as well as plasma norepinephrine (NE) levels. All males but no females developed hyperthermia following MDMA treatment. The EC{sub 50} for Phe dose response curves increased only in the females treated with MDMA and T{sub max} for Phe increased following L-NAME only in the females. Both males and females demonstrated an increase in plasma NE following MDMA treatment; however, males displayed a significantly greater NE concentration. Skeletal muscle UCP3 expression was 80% less in females than in males. These results suggest that the inability of MDMA to induce a thermogenic response in the female subjects may be due to four sex-specific mechanisms: 1) Female subjects have reduced sympathetic activation following MDMA challenge; 2) Female vasculature is less sensitive to {alpha}{sub 1}-AR stimulation following MDMA challenge; 3) Female vasculature has an increased sensitivity to NO; 4) UCP3 expression in skeletal muscle is less in females.« less

SIMVASTATIN RESTORES ISCHEMIC PRECONDITIONING IN THE PRESENCE OF HYPERGLYCEMIA THROUGH A NITRIC OXIDE-MEDIATED MECHANISM

PubMed Central

Gu, Weidong; Kehl, Franz; Krolikowski, John G.; Pagel, Paul S.; Warltier, David C.; Kersten, Judy R.

2015-01-01

Background A growing body of evidence indicates that statins decrease perioperative cardiovascular risk and that these drugs may be particularly efficacious in diabetes. Diabetes or hyperglycemia abolish the cardioprotective effects of ischemic preconditioning (IPC). We tested the hypothesis that simvastatin restores the beneficial effects of IPC during hyperglycemia through a nitric oxide (NO)-mediated mechanism. Methods Myocardial infarct size was measured in dogs (n=76) subjected to coronary artery occlusion and reperfusion in the presence or absence of hyperglycemia (300 mg/dl) with or without IPC in separate groups. Additional dogs received simvastatin (20 mg orally daily for 3 days) in the presence or absence of IPC and hyperglycemia. Other dogs were pretreated with N-nitro-L-arginine methyl ester (L-NAME; 30 mg intracoronary) with or without IPC, hyperglycemia and simvastatin. Results IPC significantly (P<0.05) reduced infarct size (n=7, 7±2%) as compared to control (n=7, 29±3%). Hyperglycemia (n=7), simvastatin (n=7) and L-NAME alone (n=7), and simvastatin with hyperglycemia (n=6) did not alter infarct size. Hyperglycemia (n=7, 24±2%), but not L-NAME (n=5, 10±1%), blocked the protective effects of IPC. Simvastatin restored the protective effects of IPC in the presence of hyperglycemia (n=7, 14±1%), and this beneficial action was blocked by L-NAME (n=7, 29±4%). Conclusions The results indicate that simvastatin restored the cardioprotective effects of IPC during hyperglycemia by NO-mediated signaling. The results also suggest that enhanced cardioprotective signaling could be a mechanism for statin-induced decreases in perioperative cardiovascular risk. PMID:18362595

Nitric oxide modulates cadmium influx during cadmium-induced programmed cell death in tobacco BY-2 cells.

PubMed

Ma, Wenwen; Xu, Wenzhong; Xu, Hua; Chen, Yanshan; He, Zhenyan; Ma, Mi

2010-07-01

Nitric oxide (NO) is a bioactive gas and functions as a signaling molecule in plants exposed to diverse biotic and abiotic stresses including cadmium (Cd(2+)). Cd(2+) is a non-essential and toxic heavy metal, which has been reported to induce programmed cell death (PCD) in plants. Here, we investigated the role of NO in Cd(2+)-induced PCD in tobacco BY-2 cells (Nicotiana tabacum L. cv. Bright Yellow 2). In this work, BY-2 cells exposed to 150 microM CdCl(2) underwent PCD with TUNEL-positive nuclei, significant chromatin condensation and the increasing expression of a PCD-related gene Hsr203J. Accompanied with the occurring of PCD, the production of NO increased significantly. The supplement of NO by sodium nitroprusside (SNP) had accelerated the PCD, whereas the NO synthase inhibitor Nomega-nitro-L-arginine methyl ester hydrochloride (L-NAME) and NO-specific scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) alleviated this toxicity. To investigate the mechanism by which NO exerted its function, Cd(2+) concentration was measured subsequently. SNP led more Cd(2+) content than Cd(2+) treatment alone. By contrast, the prevention of NO by L-NAME decreased Cd(2+) accumulation. Using the scanning ion-selective electrode technique, we analyzed the pattern and rate of Cd(2+) fluxes. This analysis revealed the promotion of Cd(2+) influxes into cells by application of SNP, while L-NAME and cPTIO reduced the rate of Cd(2+) uptake or even resulted in net Cd(2+) efflux. Based on these founding, we concluded that NO played a positive role in CdCl(2)-induced PCD by modulating Cd(2+) uptake and thus promoting Cd(2+) accumulation in BY-2 cells.

Renal cytochrome P450 omega-hydroxylase and epoxygenase activity are differentially modified by nitric oxide and sodium chloride.

PubMed

Oyekan, A O; Youseff, T; Fulton, D; Quilley, J; McGiff, J C

1999-10-01

Renal function is perturbed by inhibition of nitric oxide synthase (NOS). To probe the basis of this effect, we characterized the effects of nitric oxide (NO), a known suppressor of cytochrome P450 (CYP) enzymes, on metabolism of arachidonic acid (AA), the expression of omega-hydroxylase, and the efflux of 20-hydroxyeicosatetraenoic acid (20-HETE) from the isolated kidney. The capacity to convert [(14)C]AA to HETEs and epoxides (EETs) was greater in cortical microsomes than in medullary microsomes. Sodium nitroprusside (10-100 microM), an NO donor, inhibited renal microsomal conversion of [(14)C]AA to HETEs and EETs in a dose-dependent manner. 8-bromo cGMP (100 microM), the cell-permeable analogue of cGMP, did not affect conversion of [(14)C]AA. Inhibition of NOS with N(omega)-nitro-L-arginine-methyl ester (L-NAME) significantly increased conversion of [(14)C]AA to HETE and greatly increased the expression of omega-hydroxylase protein, but this treatment had only a modest effect on epoxygenase activity. L-NAME induced a 4-fold increase in renal efflux of 20-HETE, as did L-nitroarginine. Oral treatment with 2% sodium chloride (NaCl) for 7 days increased renal epoxygenase activity, both in the cortex and the medulla. In contrast, cortical omega-hydroxylase activity was reduced by treatment with 2% NaCl. Coadministration of L-NAME and 2% NaCl decreased conversion of [(14)C]AA to HETEs without affecting epoxygenase activity. Thus, inhibition of NOS increased omega-hydroxylase activity, CYP4A expression, and renal efflux of 20-HETE, whereas 2% NaCl stimulated epoxygenase activity.

Increase in neurokinin-1 receptor-mediated colonic motor response in a rat model of irritable bowel syndrome.

PubMed

La, Jun-Ho; Kim, Tae-Wan; Sung, Tae-Sik; Kim, Hyn-Ju; Kim, Jeom-Yong; Yang, Il-Suk

2005-01-14

Irritable bowel syndrome (IBS) is a functional bowel disorder. Its major symptom is bowel dysmotility, yet the mechanism of the symptom is poorly understood. Since the neurokinin-1 receptor (NK1R)-mediated signaling in the gut is important in the control of normal bowel motor function, we aimed to investigate whether the NK1R-mediated bowel motor function was altered in IBS, using a rat IBS model that was previously reported to show colonic dysmotility in response to restraint stress. IBS symptoms were produced in male Sprague-Dawley rats by inducing colitis with acetic acid. Rats were left to recover from colitis for 6 d, and used for experiments 7 d post-induction of colitis. Motor activities of distal colon were recorded in vitro. The contractile sensitivity of isolated colon to a NK1R agonist (Sar9,Met(O2)11)-substance P (1-30 nmol/L) was higher in IBS rats than that in normal rats. After the enteric neurotransmission was blocked by tetrodotoxin (TTX, 1 micromol/L), the contractile sensitivity to the NK1R agonist was increased in normal colon but not in IBS rat colon. The NK1R agonist-induced contraction was not different between the two groups when the agonist was challenged to the TTX-treated colon or the isolated colonic myocytes. A nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME, 100 micromol/L) augmented the NK1R agonist-induced contraction only in normal rat colon. These results suggest that the NK1R-meidated colonic motor response is increased in IBS rats, due to the decrease in the nitrergic inhibitory neural component.

Melatonin mediates vasodilation through both direct and indirect activation of BKCa channels.

PubMed

Zhao, T; Zhang, H; Jin, C; Qiu, F; Wu, Y; Shi, L

2017-10-01

Melatonin, synthesized primarily by the pineal gland, is a neuroendocrine hormone with high membrane permeability. The vascular effects of melatonin, including vasoconstriction and vasodilation, have been demonstrated in numerous studies. However, the mechanisms underlying these effects are not fully understood. Large-conductance Ca 2+ -activated K + (BK Ca ) channels are expressed broadly on smooth muscle cells and play an important role in vascular tone regulation. This study explored the mechanisms of myocyte BK Ca channels and endothelial factors underlying the action of melatonin on the mesenteric arteries (MAs). Vascular contractility and patch-clamp studies were performed on myocytes of MAs from Wistar rats. Melatonin induced significant vasodilation on MAs. In the presence of N ω -nitro-l-arginine methyl ester (l-NAME), a potent endothelial oxide synthase (eNOS) inhibitor, melatonin elicited concentration-dependent relaxation, with lowered pIC 50 The effect of melatonin was significantly attenuated in the presence of BK Ca channel blocker iberiotoxin or MT1/MT2 receptor antagonist luzindole in both (+) l-NAME and (-) l-NAME groups. In the (+) l-NAME group, iberiotoxin caused a parallel rightward shift of the melatonin concentration-relaxation curve, with pIC 50 lower than that of luzindole. Both inside-out and cell-attached patch-clamp recordings showed that melatonin significantly increased the open probability, mean open time and voltage sensitivity of BK Ca channels. In a cell-attached patch-clamp configuration, the melatonin-induced enhancement of BK Ca channel activity was significantly suppressed by luzindole. These findings indicate that in addition to the activation of eNOS, melatonin-induced vasorelaxation of MAs is partially attributable to its direct (passing through the cell membrane) and indirect (via MT1/MT2 receptors) activation of the BK Ca channels on mesenteric arterial myocytes. © 2017 Society for Endocrinology.

Angiotensin II activates collagen type I gene in the renal vasculature of transgenic mice during inhibition of nitric oxide synthesis: evidence for an endothelin-mediated mechanism.

PubMed

Boffa, J J; Tharaux, P L; Placier, S; Ardaillou, R; Dussaule, J C; Chatziantoniou, C

1999-11-02

Hypertension is frequently associated with renal vascular fibrosis. The purpose of this study was to investigate whether angiotensin II (Ang II) is involved in this fibrogenic process. Experiments were performed on transgenic mice harboring the luciferase gene under the control of the collagen I-alpha(2) chain promoter [procolalpha(2)(I)]. Hypertension was induced by chronic inhibition of NO synthesis (N(G)-nitro-L-arginine methyl ester, L-NAME). Procolalpha(2)(I) activity started to increase in the renal vasculature after 4 weeks of L-NAME treatment (P<0.01) and at 14 weeks reached 3- and 8-fold increases over control in afferent arterioles and glomeruli, respectively (P<0.001). Losartan, an AT(1) receptor antagonist, given simultaneously with L-NAME prevented the increase of procolalpha(2)(I) levels and attenuated the development of renal vascular fibrosis without normalizing systolic pressure increase. Because we found previously that endothelin mediated renal vascular fibrosis in the L-NAME model, the interaction between Ang II, endothelin, and procolalpha(2)(I) was investigated in ex vivo and short-term in vivo experiments. In both conditions, the Ang II-induced activation of procolalpha(2)(I) in renal cortex was blocked by an endothelin receptor antagonist. During chronic inhibition of NO, the collagen I gene becomes activated, leading to the development of renal vascular fibrosis. Ang II is a major player in this fibrogenic process, and its effect on collagen I gene is independent of systemic hemodynamics and is at least partly mediated by the profibrogenic action of endothelin.

The effects of sildenafil citrate on urinary podocin and nephrin mRNA expression in an L-NAME model of pre-eclampsia.

PubMed

Baijnath, Sooraj; Murugesan, Saravanakumar; Mackraj, Irene; Gathiram, Prem; Moodley, Jagidesa

2017-03-01

We investigated the effects of sildenafil citrate (SC) on podocyturia in N ω -nitro-L-arginine methyl ester hydrochloride (L-NAME) model of pre-eclampsia (PE). One hundred and twenty Sprague-Dawley rats (SDR) were divided into five groups like pregnant control (PC), early-onset PE (EOPE), late-onset PE(LOPE), early and late-onset PE with SC-treated groups [EOPE (SC); LOPE (SC)]. PE was induced in SDR by oral administration of L-NAME in drinking water for 4-8 days for EOPE and 8-14 day for LOPE. The blood pressure, urine volume and total urine protein were increased in EOPE and LOPE groups when compared to PC, and all the above parameters decreased in EOPE (SC) and LOPE (SC) groups when compared to EOPE and LOPE groups, respectively. The EOPE and LOPE groups showed an increase in urinary nephrin mRNA and podocin mRNA levels compared to PC group. Increases in serum and renal soluble fms-like tyrosine kinase-1 (sFlt-1) expression levels and decreases in renal vascular endothelial growth factor (VEGF) expression and serum placenta growth factor (PlGF) levels were observed in EOPE and LOPE groups when compared to PC group. In addition, decreases in serum and renal sFlt-1 expression levels and increases in renal VEGF expression and serum PlGF levels were observed in EOPE (SC) and LOPE (SC) groups when compared to EOPE and LOPE groups, respectively. The light microscopy showed that the renal tissue of L-NAME-treated rats had extensive glomerular damage, tubular damage and infiltration by mononuclear cells when compared to PC group. Therefore, SC ameliorated podocyturia through its effects on the antiangiogenic/angiogenic status in this animal model.

Beneficial effects of Acer okamotoanum sap on L-NAME-induced hypertension-like symptoms in a rat model.

PubMed

Yang, Hyun; Hwang, Inho; Koo, Tae-Hyoung; Ahn, Hyo-Jin; Kim, Sun; Park, Mi-Jin; Choi, Won-Sil; Kang, Ha-Young; Choi, In-Gyu; Choi, Kyung-Chul; Jeung, Eui-Bae

2012-02-01

The sap of Acer okamotoanum has been termed 'bone-benefit-water' in Korea owing to its mineral and sugar content. In particular, the calcium (Ca) and potassium (K) concentrations of the sap of Acer okamotoanum are 40- and 20-times higher, respectively, than commercial spring water. In the present study, we examined whether Acer okamotoanum sap improves or prevents hypertension-like symptoms in a rat model. Male Sprague-Dawley rats (8-weeks-old) were provided commercial spring water supplemented with 25, 50 or 100% Acer okamotoanum sap, 3% potassium ions (K+) or captopril, and treated daily for 2 weeks with NG-nitro-L-arginine methyl ester (L-NAME; 100 mg/kg/day) by subcutaneous injection, in order to induce hypertensive symptoms. Rats were euthanized 6 h following the final injection. To assess the effect of the sap on hypertension-like symptoms, we examined the mean blood pressure (BP), protein levels and localization of endothelial nitric oxide synthase (eNOS) in the descending aorta of the rats. BP levels were significantly lower in hypertensive rats received 25, 50 and 100% sap compared with rats who were administered only commercial spring water. Protein levels of eNOS were repressed in L-NAME-only-treated rats, but were elevated in the descending aorta of rats administered captopril, K+ water and Acer okamotoanum sap (25, 50 and 100%) up to the level of the sham group provided commercial spring water, and then injected with dimethyl sulfoxide for the same period of time. Localized eNOS protein was abundantly expressed in the perivascular descending aorta adipose tissue of the rats. Taken together, these results demonstrated that the sap of Acer okamotoanum ameliorated high BP induced by L-NAME treatment in a rat model.

Arrest of B16 Melanoma Cells in the Mouse Pulmonary Microcirculation Induces Endothelial Nitric Oxide Synthase-Dependent Nitric Oxide Release that Is Cytotoxic to the Tumor Cells

PubMed Central

Qiu, Hongming; Orr, F.William; Jensen, Derrek; Wang, Hui Helen; McIntosh, Alan R.; Hasinoff, Brian B.; Nance, Dwight M.; Pylypas, Susan; Qi, Ke; Song, Chun; Muschel, Ruth J.; Al-Mehdi, Abu-Bakr

2003-01-01

Metastatic cancer cells seed the lung via blood vessels. Because endothelial cells generate nitric oxide (NO) in response to shear stress, we postulated that the arrest of cancer cells in the pulmonary microcirculation causes the release of NO in the lung. After intravenous injection of B16F1 melanoma cells, pulmonary NO increased sevenfold throughout 20 minutes and approached basal levels by 4 hours. NO induction was blocked by NG-nitro-l-arginine methyl ester (L-NAME) and was not observed in endothelial nitric oxide synthase (eNOS)-deficient mice. NO production, visualized ex vivo with the fluorescent NO probe diaminofluorescein diacetate, increased rapidly at the site of tumor cell arrest, and continued to increase throughout 20 minutes. Arrested tumor cells underwent apoptosis with apoptotic counts more than threefold over baseline at 8 and 48 hours. Neither the NO signals nor increased apoptosis were seen in eNOS knockout mice or mice pretreated with L-NAME. At 48 hours, 83% of the arrested cells had cleared from the lungs of wild-type mice but only ∼55% of the cells cleared from eNOS-deficient or L-NAME pretreated mice. eNOS knockout and L-NAME-treated mice had twofold to fivefold more metastases than wild-type mice, measured by the number of surface nodules or by histomorphometry. We conclude that tumor cell arrest in the pulmonary microcirculation induces eNOS-dependent NO release by the endothelium adjacent to the arrested tumor cells and that NO is one factor that causes tumor cell apoptosis, clearance from the lung, and inhibition of metastasis. PMID:12547699

Systemic blockage of nitric oxide synthase by L-NAME increases left ventricular systolic pressure, which is not augmented further by Intralipid®.

PubMed

Shin, Il-Woo; Hah, Young-Sool; Kim, Cheol; Park, Jungchul; Shin, Heewon; Park, Kyeong-Eon; Ok, Seong-Ho; Lee, Heon-Keun; Chung, Young-Kyun; Shim, Haeng Seon; Lim, Dong Hoon; Sohn, Ju-Tae

2014-01-01

Intravenous lipid emulsions (LEs) are effective in the treatment of toxicity associated with various drugs such as local anesthetics and other lipid soluble agents. The goals of this study were to examine the effect of LE on left ventricular hemodynamic variables and systemic blood pressure in an in vivo rat model, and to determine the associated cellular mechanism with a particular focus on nitric oxide. Two LEs (Intralipid(®) 20% and Lipofundin(®) MCT/LCT 20%) or normal saline were administered intravenously in an in vivo rat model following induction of anesthesia by intramuscular injection of tiletamine/zolazepam and xylazine. Left ventricular systolic pressure (LVSP), blood pressure, heart rate, maximum rate of intraventricular pressure increase, and maximum rate of intraventricular pressure decrease were measured before and after intravenous administration of various doses of LEs or normal saline to an in vivo rat with or without pretreatment with the non-specific nitric oxide synthase inhibitor N(ω)-nitro-L-arginine-methyl ester (L-NAME). Administration of Intralipid(®) (3 and 10 ml/kg) increased LVSP and decreased heart rate. Pretreatment with L-NAME (10 mg/kg) increased LSVP and decreased heart rate, whereas subsequent treatment with Intralipid(®) did not significantly alter LVSP. Intralipid(®) (10 ml/kg) increased mean blood pressure and decreased heart rate. The increase in LVSP induced by Lipofundin(®) MCT/LCT was greater than that induced by Intralipid(®). Intralipid(®) (1%) did not significantly alter nitric oxide donor sodium nitroprusside-induced relaxation in endothelium-denuded rat aorta. Taken together, systemic blockage of nitric oxide synthase by L-NAME increases LVSP, which is not augmented further by intralipid(®).

Acute pancreatitis associated with administration of a nitric oxide synthase inhibitor in tumor-bearing dogs.

PubMed

Poulson, J M; Dewhirst, M W; Gaskin, A A; Vujaskovic, Z; Samulski, T V; Prescott, D M; Meyer, R E; Page, R L; Thrall, D E

2000-01-01

Nitric oxide synthase (NOS) inhibitors have been investigated as potential cytotoxic agents to treat tumors lacking p53 function. Furthermore, their ability to reduce tumor blood flow can be combined with drugs that are specifically designed to kill cells that are hypoxic or to improve temperatures during local heat (hyperthermia) treatment of tumors. This paper reports the unexpected development of acute pancreatitis in two tumor-bearing pet dogs that were treated with the NOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME) during administration of local hyperthermia. Prior to the use of L-NAME in tumor-bearing dogs, purpose-bred beagles were studied. Following induction of inhalation anesthesia, local hyperthermia was applied to either normal thigh muscle (beagles) or tumors (tumor-bearing dogs). Once a thermal steady state was achieved, L-NAME was administered and temperature monitoring continued. Animals were observed after treatment for evidence of toxicity. The beagles tolerated the treatment well, with no side effects noted either clinically or by routine CBC or blood chemistry analyses. In contrast, the first two tumor-bearing dogs accrued onto the phase I study developed acute pancreatitis in the immediate post-treatment period which necessitated hospitalization and intensive care. The trial was stopped. Both dogs had intercurrent risk factors which predisposed them to development of pancreatitis, although neither had a history of symptoms of pancreatitis at the time the hyperthermia + L-NAME treatment was given. We conclude that caution should be exercised when considering NOS inhibition for cancer treatment. Careful evaluation of history and health status as well as recognition of potential risk factors may be key in avoiding potentially fatal complications. This study demonstrates the value of performing potentially harmful treatments in tumor-bearing dogs prior to introduction into the human clinic.

Effect of Blockade of Nitric Oxide Synthesis on the Renin Secretory Response to Frusemide in Conscious Rabbits

NASA Technical Reports Server (NTRS)

Reid, Ian A.; Chou, Lance

1995-01-01

The enzyme nitric oxide synthase is present in the macula densa and may participate in the control of renin secretion by the adjacent juxtagiomerular cells. In the present study, we investigated the effect of inhibiting nitric oxide synthase on the renin secretory response to frusemide, which stimulates renin secretion by blocking Na(+)-K(+)-2Cl(-) co-transport in the macula densa. Injection of frusemide in 12 conscious rabbits elicited a transient increase in mean arterial pressure from 84 +/- 2 to 92 +/-3 mm Hg at 5 min (P less than 0.01) and a sustained increase in heart rate from 246 +/- 6 to 281 +/- 10 beats/min at 45 min (P less than 0.01). Plasma renin activity increased from 8.0 +/- 1.2 to 14.3 +/- 1.8, 12.4 +/- 1.6 and 11.6 +/- 1.5 pmol/2h ml at 15, 30 and 45min respectively (P less than 0.01). There were no changes in plasma sodium and potassium concentrations or osmoiality. Inhibition of nitric oxide synthase with N(sup G)-nitro-L- arginine methyl ester increased mean arterial pressure by 9 mm Hg, decreased heart rate and plasma renin activity, and markedly suppressed the renin response to frusemide (from 4.6 +/- 0.7 to 7.6 +/- 1.7, 4.7 +/- 1.0 and 4.6 +/- 0.7pmol/2h ml at 15, 30 and 45 min respectively). By contrast, infusion of an equipressor dose of phenylephrine did not suppress the renin response to frusemide. Histochemical studies with the NADPH diaphorase technique confirmed the presence of nitric oxide synthase in the macula densa, and suggested that enzyme activity is increased by treatment with frusemide. These results are consistent with a role for the L- arginine-nitric oxide pathway in the modulation of renin secretion by the macula densa.

Endothelial nitric oxide synthase is dynamically expressed during bone marrow stem cell differentiation into endothelial cells.

PubMed

Liu, Zhenguo; Jiang, Yuehua; Hao, Hong; Gupta, Kalpna; Xu, Jian; Chu, Ling; McFalls, Edward; Zweier, Jay; Verfaillie, Catherine; Bache, Robert J

2007-09-01

This study was designed to investigate the developmental expression of endothelial nitric oxide synthase (eNOS) during stem cell differentiation into endothelial cells and to examine the functional status of the newly differentiated endothelial cells. Mouse adult multipotent progenitor cells (MAPCs) were used as the source of stem cells and were induced to differentiate into endothelial cells with vascular endothelial growth factor (VEGF) in serum-free medium. Expression of eNOS in the cells during differentiation was evaluated with real-time PCR, nitric oxide synthase (NOS) activity, and Western blot analysis. It was found that eNOS, but no other NOS, was present in undifferentiated MAPCs. eNOS expression disappeared in the cells immediately after induction of differentiation. However, eNOS expression reoccurred at day 7 during differentiation. Increasing eNOS mRNA, protein content, and activity were observed in the cells at days 14 and 21 during differentiation. The differentiated endothelial cells formed dense capillary networks on growth factor-reduced Matrigel. VEGF-stimulated phosphorylation of extracellular signal-regulated kinase (ERK)-1 and ERK-2 occurred in these cells, which was inhibited by NOS inhibitor N(G)-nitro-L-arginine methyl ester. In conclusion, these data demonstrate that eNOS is present in MAPCs and is dynamically expressed during the differentiation of MAPCs into endothelial cells in vitro.

Simulated microgravity upregulates an endothelial vasoconstrictor prostaglandin

NASA Technical Reports Server (NTRS)

Sangha, D. S.; Han, S.; Purdy, R. E.

2001-01-01

Endothelial nitric oxide contributes to the vascular hyporesponsiveness to norepinephrine (NE) observed in carotid arteries from rats exposed to simulated microgravity. The goal of the present study was to determine whether a cyclooxygenase product of arachidonic acid also influences vascular responsiveness in this setting. Microgravity was simulated in rats by hindlimb unweighting (HU). After 20 days of HU, carotid arteries were isolated from control and HU-treated rats, and vascular rings were mounted in tissue baths for the measurement of isometric contraction. Two cyclooxygenase inhibitors, indomethacin and ibuprofen, and the selective thromboxane A(2) prostanoid-receptor antagonist, SQ-29548, had no effect on the contraction to NE in control vessels but markedly reduced contraction to NE in HU vessels. When the endothelium was removed, indomethacin no longer had any effect on the NE-induced contraction in HU vessels. In endothelium-intact vessels in the presence of indomethacin, the addition of the nitric oxide synthase inhibitor, N(G)-L-nitro-arginine methyl ester, to the medium bathing HU vessels increased the contraction to NE to the level of that of the control vessels. These results indicate that HU treatment induced two endothelial changes in carotid artery that opposed each other. Nitric oxide activity was increased and was responsible for the vascular hyporesponsiveness to NE. The activity of a vasoconstrictor prostaglandin was also increased, and attenuated the vasodilating effect of nitric oxide.

Impaired pulmonary artery contractile responses in a rat model of microgravity: role of nitric oxide

NASA Technical Reports Server (NTRS)

Nyhan, Daniel; Kim, Soonyul; Dunbar, Stacey; Li, Dechun; Shoukas, Artin; Berkowitz, Dan E.

2002-01-01

Vascular contractile hyporesponsiveness is an important mechanism underlying orthostatic intolerance after microgravity. Baroreceptor reflexes can modulate both pulmonary resistance and capacitance function and thus cardiac output. We hypothesized, therefore, that pulmonary vasoreactivity is impaired in the hindlimb-unweighted (HLU) rat model of microgravity. Pulmonary artery (PA) contractile responses to phenylephrine (PE) and U-46619 (U4) were significantly decreased in the PAs from HLU vs. control (C) animals. N(G)-nitro-L-arginine methyl ester (10(-5) M) enhanced the contractile responses in the PA rings from both C and HLU animals and completely abolished the differential responses to PE and U4 in HLU vs. C animals. Vasorelaxant responses to ACh were significantly enhanced in PA rings from HLU rats compared with C. Moreover, vasorelaxant responses to sodium nitroprusside were also significantly enhanced. Endothelial nitric oxide synthase (eNOS) and soluble guanlyl cyclase expression were significantly enhanced in PA and lung tissue from HLU rats. In marked contrast, the expression of inducible nitric oxide synthase was unchanged in lung tissue. These data support the hypothesis that vascular contractile responsiveness is attenuated in PAs from HLU rats and that this hyporesponsiveness is due at least in part to increased nitric oxide synthase activity resulting from enhanced eNOS expression. These findings may have important implications for blood volume distribution and attenuated stroke volume responses to orthostatic stress after microgravity exposure.

Impairment of the vascular relaxation and differential expression of caveolin-1 of the aorta of diabetic +db/+db mice.

PubMed

Lam, Tze Yan; Seto, Sai Wang; Lau, Yee Man; Au, Lai Shan; Kwan, Yiu Wa; Ngai, Sai Ming; Tsui, Kwong Wing

2006-09-28

In this study, we compared the endothelium-dependent and -independent relaxation of the isolated thoracic aorta of control (+db/+m) and diabetic (+db/+db) (C57BL/KsJ) mice. The gene expression (mRNA and protein) level of the muscarinic M(3) receptors, endothelial nitric oxide synthase (eNOS) and caveolin-1 of the aorta was also evaluated. Acetylcholine caused a concentration-dependent, N(G)-nitro-L-arginine methyl-ester (20 microM)-sensitive relaxation, with approximately 100% relaxation at 10 microM, in +db/+m mice. In +db/+db mice, the acetylcholine-induced relaxation was significantly smaller (maximum relaxation: approximately 80%). The sodium nitroprusside-mediated relaxation was slightly diminished in +db/+db mice, compared to +db/+m mice. However, there was no significant difference in the isoprenaline- and cromakalim-induced relaxation observed in both species. The mRNA and protein expression levels of caveolin-1 were significantly higher in the aorta of +db/+db mice. In contrast, there was no difference in the mRNA and protein expression levels of eNOS and muscarinic M(3) receptors between these mice. Our results demonstrate that the impairment of the acetylcholine-induced, endothelium-dependent aortic relaxation observed in +db/+db mice was probably associated with an enhanced expression of caveolin-1 mRNA and protein.

Dynamics of enhanced mitochondrial respiration in female compared with male rat cerebral arteries.

PubMed

Rutkai, Ibolya; Dutta, Somhrita; Katakam, Prasad V; Busija, David W

2015-11-01

Mitochondrial respiration has never been directly examined in intact cerebral arteries. We tested the hypothesis that mitochondrial energetics of large cerebral arteries ex vivo are sex dependent. The Seahorse XFe24 analyzer was used to examine mitochondrial respiration in isolated cerebral arteries from adult male and female Sprague-Dawley rats. We examined the role of nitric oxide (NO) on mitochondrial respiration under basal conditions, using N(ω)-nitro-l-arginine methyl ester, and following pharmacological challenge using diazoxide (DZ), and also determined levels of mitochondrial and nonmitochondrial proteins using Western blot, and vascular diameter responses to DZ. The components of mitochondrial respiration including basal respiration, ATP production, proton leak, maximal respiration, and spare respiratory capacity were elevated in females compared with males, but increased in both male and female arteries in the presence of the NOS inhibitor. Although acute DZ treatment had little effect on mitochondrial respiration of male arteries, it decreased the respiration in female arteries. Levels of mitochondrial proteins in Complexes I-V and the voltage-dependent anion channel protein were elevated in female compared with male cerebral arteries. The DZ-induced vasodilation was greater in females than in males. Our findings show that substantial sex differences in mitochondrial respiratory dynamics exist in large cerebral arteries and may provide the mechanistic basis for observations that the female cerebral vasculature is more adaptable after injury. Copyright © 2015 the American Physiological Society.

Cyclooxygenase inhibition improves endothelial vasomotor dysfunction of visceral adipose arterioles in human obesity

PubMed Central

Farb, Melissa G.; Tiwari, Stephanie; Karki, Shakun; Ngo, Doan TM; Carmine, Brian; Hess, Donald T.; Zuriaga, Maria A.; Walsh, Kenneth; Fetterman, Jessica L.; Hamburg, Naomi M.; Vita, Joseph A.; Apovian, Caroline M.; Gokce, Noyan

2013-01-01

Objective The purpose of this study was to determine whether cyclooxygenase inhibition improves vascular dysfunction of adipose microvessels from obese humans. Design and Methods In 20 obese subjects (age 37±12 yrs, BMI 47±8 kg/m2) we collected subcutaneous and visceral fat during bariatric surgery and characterized adipose depot-specific gene expression, endothelial cell phenotype, and microvascular function. Vasomotor function was assessed in response to endothelium-dependent agonists using videomicroscopy of small arterioles from fat. Results Arterioles from visceral fat exhibited impaired endothelium-dependent, acetylcholine-mediated vasodilation, compared to the subcutaneous depot (p<0.001). Expression of mRNA transcripts relevant to the cyclooxygenase pathway were upregulated in visceral compared to subcutaneous fat. Pharmacological inhibition of cyclooxygenase with indomethacin improved endothelium-dependent vasodilator function of arterioles from visceral fat by 2-fold (p=0.01), whereas indomethacin had no effect in the subcutaneous depot. Indomethacin increased activation via serine-1177 phosphorylation of endothelial nitric oxide synthase in response to acetylcholine in endothelial cells from visceral fat. Inhibition of endothelial nitric oxide synthase with Nω-nitro-L-arginine methyl ester abrogated the effects of cyclooxygenase-inhibition suggesting that vascular actions of indomethacin were related to increased nitric oxide bioavailability. Conclusions Our findings suggest that cyclooxygenase-mediated vasoconstrictor prostanoids partly contribute to endothelial dysfunction of visceral adipose arterioles in human obesity. PMID:23640904

Microinjection of l-glutamate into the nucleus ambiguus partially inhibits gastric motility through the NMDA receptor - nitric oxide pathway.

PubMed

Sun, Hong-Zhao; Zhao, Shu-Zhen; Ai, Hong-Bin

2014-06-01

We have previously reported that both l-glutamate (l-Glu) and nitric oxide (NO) modulate gastric motility in the nucleus ambiguus (NA). The aim of this study is to explore the potential correlation between the l-Glu and NO. A latex balloon connected to a pressure transducer was inserted into the pylorus through the fundus of anesthetized male Wistar rats to continuously record changes in gastric smooth muscle contractile curves. Pretreatment with the NO-synthase inhibitor N-nitro-l-arginine methylester (l-NAME) did not completely abolish the inhibitory effect of l-Glu on gastric motility, but intravenous injection of the ganglionic blocker hexamethonium bromide (Hb) did. By using a specific N-methyl-d-aspartic acid (NMDA) receptor antagonist, we blocked the inhibitory effect of the NO-donor sodium nitroprusside (SNP) on gastric motility. These results suggest that microinjections of l-Glu into the NA inhibits gastric motility by activating the cholinergic preganglionic neurons, partially through the NMDA receptor - NO pathway.

Trapping Phyllophaga spp. (Coleoptera: Scarabaeidae: Melolonthinae) in the United States and Canada using sex attractants.

PubMed Central

Robbins, Paul S.; Alm, Steven R.; Armstrong, Charles. D.; Averill, Anne L.; Baker, Thomas C.; Bauernfiend, Robert J.; Baxendale, Frederick P.; Braman, S. Kris; Brandenburg, Rick L.; Cash, Daniel B.; Couch, Gary J.; Cowles, Richard S.; Crocker, Robert L.; DeLamar, Zandra D.; Dittl, Timothy G.; Fitzpatrick, Sheila M.; Flanders, Kathy L.; Forgatsch, Tom; Gibb, Timothy J.; Gill, Bruce D.; Gilrein, Daniel O.; Gorsuch, Clyde S.; Hammond, Abner M.; Hastings, Patricia D.; Held, David W.; Heller, Paul R.; Hiskes, Rose T.; Holliman, James L.; Hudson, William G.; Klein, Michael G.; Krischik, Vera L.; Lee, David J.; Linn, Charles E.; Luce, Nancy J.; MacKenzie, Kenna E.; Mannion, Catherine M.; Polavarapu, Sridhar; Potter, Daniel A.; Roelofs, Wendell L.; Royals, Brian M.; Salsbury, Glenn A.; Schiff, Nathan M.; Shetlar, David J.; Skinner, Margaret; Sparks, Beverly L.; Sutschek, Jessica A.; Sutschek, Timothy P.; Swier, Stanley R.; Sylvia, Martha M.; Vickers, Neil J.; Vittum, Patricia J.; Weidman, Richard; Weber, Donald C.; Williamson, R. Chris; Villani, Michael G

2006-01-01

The sex pheromone of the scarab beetle, Phyllophaga anxia, is a blend of the methyl esters of two amino acids, L-valine and L-isoleucine. A field trapping study was conducted, deploying different blends of the two compounds at 59 locations in the United States and Canada. More than 57,000 males of 61 Phyllophaga species (Coleoptera: Scarabaeidae: Melolonthinae) were captured and identified. Three major findings included: (1) widespread use of the two compounds [of the 147 Phyllophaga (sensu stricto) species found in the United States and Canada, males of nearly 40% were captured]; (2) in most species intraspecific male response to the pheromone blends was stable between years and over geography; and (3) an unusual pheromone polymorphism was described from P. anxia. Populations at some locations were captured with L-valine methyl ester alone, whereas populations at other locations were captured with L-isoleucine methyl ester alone. At additional locations, the L-valine methyl ester-responding populations and the L-isoleucine methyl ester-responding populations were both present, producing a bimodal capture curve. In southeastern Massachusetts and in Rhode Island, in the United States, P. anxia males were captured with blends of L-valine methyl ester and L-isoleucine methyl ester. PMID:19537965

Possible involvement of endothelium-derived hyperpolarizing factor (EDHF) in the depressor responses to platelet activating factor (PAF) in rats

PubMed Central

Tanaka, Yoshio; Hayakawa, Sachiko; Imai, Toshiyasu; Akutsu, Aya; Hirano, Haruko; Tanaka, Hikaru; Nakahara, Tsutomu; Ishii, Kunio; Shigenobu, Koki

2000-01-01

In anaesthetized rats, platelet activating factor (PAF; 1 μg kg−1) decreased mean arterial blood pressure by around 60 mmHg (n=18). This depressor response was completely blocked by the PAF antagonist, CV-6209 (1 mg kg−1), indicating the role of PAF-specific receptor in the response.NG-nitro-L-arginine methyl ester (L-NAME; 50 mg kg−1), an NO synthase inhibitor, profoundly elevated systemic blood pressure (n=19), indicating an important role of NO in the basal blood pressure regulation. The depressor response to PAF (1 μg kg−1) normalized against that to sodium nitroprusside (SNP) (10 μg kg−1) was not substantially different between rats treated without and with L-NAME (n=4). In contrast, the depressor effect of acetylcholine (0.03–1.0 μg kg−1) normalized against that of SNP (10 μg kg−1) was significantly attenuated by L-NAME (n=5).Charybdotoxin (0.4 mg kg−1) plus apamin (0.2 mg kg−1) significantly attenuated the depressor response to PAF (1 μg kg−1) (n=5) without affecting the blood pressure change due to SNP (1 mg kg−1) (n=3). Charybdotoxin (0.4 mg kg−1) (n=4) or apamin (0.2 mg kg−1) (n=4) alone did not affect the PAF-induced depressor response.These findings suggest that EDHF may make a significant contribution to the depressor response to PAF in rats. Although NO plays the determinant role in the basal blood pressure regulation, its contribution to PAF-produced depressor response seems to be less as compared with that to the depressor response to acetylcholine. PMID:11082118

Effect of nitric oxide on boar sperm motility, membrane integrity, and acrosomal status during semen storage.

PubMed

Jovicić, M; Pintus, E; Fenclova, T; Simonik, O; Chmelikova, E; Ros-Santaella, J L; Sedmikova, M

2018-03-01

Nitric oxide (NO) is a major gasotransmitter involved in several physiological processes of male reproduction. There is, nevertheless, little information concerning the role of NO during semen storage. The aim of this study was to evaluate the effect of NO on boar semen stored at 17oC for 72 h. For this purporse, sperm samples were treated with 0.625, 1.25, 2.5, 5, and 10 mM aminoguanidine (AG) or Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME), a selective and non-selective NO synthase (NOS) inhibitor, respectively. Moreover, sodium nitroprusside (SNP), a NO donor, was used at the dose of 18.75, 37.5, 75, and 150 μM. Sperm motility, membrane integrity, and acrosomal status were evaluated at 0, 4, 24, 48, and 72 h of semen storage. A significant increase of the amplitude of lateral sperm head displacement (ALH), and both curvilinear and straight-line velocity (VCL and VSL, respectively) was observed at 72 h of semen storage in samples treated with 0.625 mM AG, probably because of the antioxidant properties of this NOS inhibitor. Contrarily, 0.625 mM L-NAME showed no effect on boar sperm parameters during the entire period of semen storage. Moreover, AG and L-NAME at 10 mM negatively affected sperm kinetics and acrosome integrity, which may provide further support to the notion that low NO levels are necessary for a normal sperm function. The concentrations of SNP used in this study had mostly no or negative effects on boar sperm parameters during semen storage. In conclusion, the results from this study increase the understanding of the role of NO on boar sperm physiology. Copyright© by the Polish Academy of Sciences.

Selective inhibition of iNOS attenuates trauma-hemorrhage/resuscitation-induced hepatic injury.

PubMed

Kan, Wen-Hong; Hsu, Jun-Te; Schwacha, Martin G; Choudhry, Mashkoor A; Raju, Raghavan; Bland, Kirby I; Chaudry, Irshad H

2008-10-01

Although trauma-hemorrhage produces tissue hypoxia, systemic inflammatory response and organ dysfunction, the mechanisms responsible for these alterations are not clear. Using a potent selective inducible nitric oxide (NO) synthase inhibitor, N-[3-(aminomethyl) benzyl]acetamidine (1400W), and a nonselective NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME), we investigated whether inducible NO synthase plays any role in producing hepatic injury, inflammation, and changes of protein expression following trauma-hemorrhage. To investigate this, male Sprague-Dawley rats were subjected to midline laparotomy and hemorrhagic shock (mean blood pressure 35-40 mmHg for approximately 90 min) followed by fluid resuscitation. Animals were treated with either vehicle (DMSO) or 1400W (10 mg/kg body wt ip), or L-NAME (30 mg/kg iv), 30 min before resuscitation and killed 2 h after resuscitation. Trauma-hemorrhage/resuscitation induced a marked hypotension and increase in markers of hepatic injury (i.e., plasma alpha-glutathione S-transferase, tissue myeloperoxidase activity, and nitrotyrosine formation). Hepatic expression of iNOS, hypoxia-inducible factor-1alpha, ICAM-1, IL-6, TNF-alpha, and neutrophil chemoattractant (cytokine-induced neutrophil chemoattractant-1 and macrophage inflammatory protein-2) protein levels were also markedly increased following trauma-hemorrhage/resuscitation. Administration of the iNOS inhibitor 1400W significantly attenuated hypotension and expression of these mediators of hepatic injury induced by trauma-hemorrhage/resuscitation. However, administration of L-NAME could not attenuate hepatic dysfunction and tissue injury mediated by trauma-hemorrhage, although it improved mean blood pressure as did 1400W. These results indicate that increased expression of iNOS following trauma-hemorrhage plays an important role in the induction of hepatic damage under such conditions.

The effects of dietary fish oil on exercising skeletal muscle vascular and metabolic control in chronic heart failure rats.

PubMed

Holdsworth, Clark T; Copp, Steven W; Hirai, Daniel M; Ferguson, Scott K; Sims, Gabrielle E; Hageman, Karen S; Stebbins, Charles L; Poole, David C; Musch, Timothy I

2014-03-01

Impaired vasomotor control in chronic heart failure (CHF) is due partly to decrements in nitric oxide synthase (NOS) mediated vasodilation. Exercising muscle blood flow (BF) is augmented with polyunsaturated fatty acid (PUFA) supplementation via fish oil (FO) in healthy rats. We hypothesized that FO would augment exercising muscle BF in CHF rats via increased NO-bioavailability. Myocardial infarction (coronary artery ligation) induced CHF in Sprague-Dawley rats which were subsequently randomized to dietary FO (20% docosahexaenoic acid, 30% eicosapentaenoic acid, n = 15) or safflower oil (SO, 5%, n = 10) for 6-8 weeks. Mean arterial pressure (MAP), blood [lactate], and hindlimb muscles BF (radiolabeled microspheres) were determined at rest, during treadmill exercise (20 m·min(-1), 5% incline) and exercise + N(G)-nitro-l-arginine-methyl-ester (l-NAME) (a nonspecific NOS inhibitor). FO did not change left ventricular end-diastolic pressure (SO: 14 ± 2; FO: 11 ± 1 mm Hg, p > 0.05). During exercise, MAP (SO: 128 ± 3; FO: 132 ± 3 mm Hg) and blood [lactate] (SO: 3.8 ± 0.4; FO: 4.6 ± 0.5 mmol·L(-1)) were not different (p > 0.05). Exercising hindlimb muscle BF was lower in FO than SO (SO: 120 ± 11; FO: 93 ± 4 mL·min(-1)·100 g(-1), p < 0.05) but was not differentially affected by l-NAME. Specifically, 17 of 28 individual muscle BF's were lower (p < 0.05) in FO demonstrating that PUFA supplementation with FO in CHF rats does not augment muscle BF during exercise but may lower metabolic cost.

Cascade Bioassay Evidence for the Existence of Urothelium-Derived Inhibitory Factor in Guinea Pig Urinary Bladder

PubMed Central

Guan, Na N.; Thor, Anna; Hallén, Katarina; Wiklund, N. Peter; Gustafsson, Lars E.

2014-01-01

Our aim was to investigate whether guinea pig urothelium-derived bioactivities compatible with the existence of urothelium-derived inhibitory factor could be demonstrated by in vitro serial bioassay and whether purinergic P1 receptor agonists, nitric oxide, nitrite or prostaglandins might explain observed activities. In a cascade superfusion system, urothelium-denuded guinea pig ureters were used as bioassay tissues, recording their spontaneous rhythmic contractions in presence of scopolamine. Urothelium-intact or -denuded guinea pig urinary bladders were used as donor tissues, stimulated by intermittent application of carbachol before or during the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME), the adenosine/P1 nucleoside receptor antagonist 8-(p-sulfophenyl)theophylline (8-PST) or the cyclo-oxygenase inhibitor diclofenac infused to bath donor and bioassay tissues. The spontaneous contractions of bioassay ureters were unaltered by application of carbachol 1–5 µM in the presence of scopolamine 5–30 µM. When carbachol was applied over the urothelium-denuded bladder, the assay ureter contraction rate was unaltered. Introducing carbachol over the everted urothelium-intact bladder significantly inhibited the contraction frequency of the assay ureter, suggesting the transfer of an inhibitory activity from the bladder to the assay ureter. The transmissible inhibitory activity was not markedly antagonized by L-NAME, 8-PST or diclofenac, while L-NAME nearly abolished nitrite release from the urothelium-intact bladder preparations. We suggest that urothelium-derived inhibitory factor is a transmissible entity over a significant distance as demonstrated in this novel cascade superfusion assay and seems less likely to be nitric oxide, nitrite, an adenosine receptor agonist or subject to inhibition by administration of a cyclo-oxygenase inhibitor. PMID:25084114

Cascade bioassay evidence for the existence of urothelium-derived inhibitory factor in Guinea pig urinary bladder.

PubMed

Guan, Na N; Thor, Anna; Hallén, Katarina; Wiklund, N Peter; Gustafsson, Lars E

2014-01-01

Our aim was to investigate whether guinea pig urothelium-derived bioactivities compatible with the existence of urothelium-derived inhibitory factor could be demonstrated by in vitro serial bioassay and whether purinergic P1 receptor agonists, nitric oxide, nitrite or prostaglandins might explain observed activities. In a cascade superfusion system, urothelium-denuded guinea pig ureters were used as bioassay tissues, recording their spontaneous rhythmic contractions in presence of scopolamine. Urothelium-intact or -denuded guinea pig urinary bladders were used as donor tissues, stimulated by intermittent application of carbachol before or during the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME), the adenosine/P1 nucleoside receptor antagonist 8-(p-sulfophenyl)theophylline (8-PST) or the cyclo-oxygenase inhibitor diclofenac infused to bath donor and bioassay tissues. The spontaneous contractions of bioassay ureters were unaltered by application of carbachol 1-5 µM in the presence of scopolamine 5-30 µM. When carbachol was applied over the urothelium-denuded bladder, the assay ureter contraction rate was unaltered. Introducing carbachol over the everted urothelium-intact bladder significantly inhibited the contraction frequency of the assay ureter, suggesting the transfer of an inhibitory activity from the bladder to the assay ureter. The transmissible inhibitory activity was not markedly antagonized by L-NAME, 8-PST or diclofenac, while L-NAME nearly abolished nitrite release from the urothelium-intact bladder preparations. We suggest that urothelium-derived inhibitory factor is a transmissible entity over a significant distance as demonstrated in this novel cascade superfusion assay and seems less likely to be nitric oxide, nitrite, an adenosine receptor agonist or subject to inhibition by administration of a cyclo-oxygenase inhibitor.

Investigation of neurogenic excitatory and inhibitory motor responses and their control by 5-HT(4) receptors in circular smooth muscle of pig descending colon.

PubMed

Priem, Evelien K V; Lefebvre, Romain A

2011-09-30

The aim of this study was to investigate whether the pig colon descendens might be a good model for the responses mediated via the different locations of human colonic 5-HT(4) receptors. The intrinsic excitatory and inhibitory motor neurotransmission in pig colon descendens was therefore first characterized. In circular smooth muscle strips, electrical field stimulation (EFS) at basal tone induced only in the combined presence of the NO synthase inhibitor N(ω)-nitro-L-arginine methyl ester hydrochloride (L-NAME) and the SK channel blocker apamin voltage-dependent on-contractions. These on-contractions were largely reduced by the neuronal conductance blocker tetrodotoxin (TTX) and by the muscarinic receptor antagonist atropine, illustrating activation of cholinergic neurons. The 5-HT(4) receptor agonist prucalopride facilitated submaximal EFS-evoked cholinergic contractions and this effect was prevented by the 5-HT(4) receptor antagonist GR113808, supporting the presence of facilitating 5-HT(4) receptors on the cholinergic nerve endings innervating circular muscle in pig colon descendens. Relaxations were induced by EFS in strips pre-contracted with substance P in the presence of atropine. The responses at lower stimulation voltages were abolished by TTX. L-NAME or apamin alone did not influence or only moderately reduced the relaxations, but L-NAME plus apamin abolished the relaxations at lower stimulation voltages, suggesting that NO and ATP act as inhibitory neurotransmitters in a redundant way. Prucalopride did not influence the EFS-induced relaxations at lower stimulation voltage, nor did it per se relax contracted circular muscle strips. No evidence for relaxing 5-HT(4) receptors, either on inhibitory neurons or on the muscle cells was thus obtained in pig colon descendens circular muscle. Copyright © 2011 Elsevier B.V. All rights reserved.

Penile Erection Induced by Scoparone from Artemisia capillaris through the Nitric Oxide-Cyclic Guanosine Monophosphate Signaling Pathway.

PubMed

Choi, Bo Ram; Kim, Hye Kyung; Park, Jong Kwan

2017-12-01

The objective of this study was to evaluate the relaxant effect of scoparone from Artemisia capillaris on rabbit penile corpus cavernosum smooth muscle (PCCSM) and to elucidate the mechanism of action of scoparone for the treatment of erectile dysfunction (ED). PCCSM that had been precontracted with phenylephrine was treated with 3 Artemisia herbs (A. princeps, A. capillaris, and A. iwayomogi) and 3 fractions (n-hexane, ethyl acetate, and n-butanol) with different concentrations (0.1, 0.5, 1.0, and 2.0 mg/mL). Four components (esculetin, scopoletin, capillarisin, and scoparone) isolated from A. capillaris were also evaluated. The PCCSM was preincubated with Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME) and 1H-[1,2,4] oxadiazolo [4,3-a]quinoxalin-1-one (ODQ). Cyclic nucleotides in the perfusate were measured by a radioimmunoassay. The interactions of scoparone with udenafil and rolipram were also evaluated. A. capillaris extract relaxed PCCSM in a concentration-dependent manner. Scoparone had the highest relaxant effect on PCCSM among the 4 components (esculetin, scopoletin, capillarisin, and scoparone) isolated from the ethyl acetate fraction. The application of scoparone on PCCSM pretreated with L-NAME and ODQ led to significantly less relaxation. Scoparone also increased the cyclic guanosine monophosphate (cGMP) levels in the perfusate in a concentration-dependent manner. Furthermore, scoparone enhanced udenafil- and rolipram-induced relaxation of the PCCSM. Scoparone relaxed the PCCSM mainly by activating the nitric oxide-cGMP signaling pathway, and it may be a new promising treatment for ED patients who do not completely respond to udenafil. Copyright © 2017 Korean Society for Sexual Medicine and Andrology

Penile Erection Induced by Scoparone from Artemisia capillaris through the Nitric Oxide-Cyclic Guanosine Monophosphate Signaling Pathway

PubMed Central

2017-01-01

Purpose The objective of this study was to evaluate the relaxant effect of scoparone from Artemisia capillaris on rabbit penile corpus cavernosum smooth muscle (PCCSM) and to elucidate the mechanism of action of scoparone for the treatment of erectile dysfunction (ED). Materials and Methods PCCSM that had been precontracted with phenylephrine was treated with 3 Artemisia herbs (A. princeps, A. capillaris, and A. iwayomogi) and 3 fractions (n-hexane, ethyl acetate, and n-butanol) with different concentrations (0.1, 0.5, 1.0, and 2.0 mg/mL). Four components (esculetin, scopoletin, capillarisin, and scoparone) isolated from A. capillaris were also evaluated. The PCCSM was preincubated with Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME) and 1H-[1,2,4] oxadiazolo [4,3-a]quinoxalin-1-one (ODQ). Cyclic nucleotides in the perfusate were measured by a radioimmunoassay. The interactions of scoparone with udenafil and rolipram were also evaluated. Results A. capillaris extract relaxed PCCSM in a concentration-dependent manner. Scoparone had the highest relaxant effect on PCCSM among the 4 components (esculetin, scopoletin, capillarisin, and scoparone) isolated from the ethyl acetate fraction. The application of scoparone on PCCSM pretreated with L-NAME and ODQ led to significantly less relaxation. Scoparone also increased the cyclic guanosine monophosphate (cGMP) levels in the perfusate in a concentration-dependent manner. Furthermore, scoparone enhanced udenafil- and rolipram-induced relaxation of the PCCSM. Conclusions Scoparone relaxed the PCCSM mainly by activating the nitric oxide-cGMP signaling pathway, and it may be a new promising treatment for ED patients who do not completely respond to udenafil. PMID:29164835

Local nitric oxide synthase inhibition reduces skeletal muscle glucose uptake but not capillary blood flow during in situ muscle contraction in rats.

PubMed

Ross, Renee M; Wadley, Glenn D; Clark, Michael G; Rattigan, Stephen; McConell, Glenn K

2007-12-01

We have previously shown in humans that local infusion of a nitric oxide synthase (NOS) inhibitor into the femoral artery attenuates the increase in leg glucose uptake during exercise without influencing total leg blood flow. However, rodent studies examining the effect of NOS inhibition on contraction-stimulated skeletal muscle glucose uptake have yielded contradictory results. This study examined the effect of local infusion of an NOS inhibitor on skeletal muscle glucose uptake (2-deoxyglucose) and capillary blood flow (contrast-enhanced ultrasound) during in situ contractions in rats. Male hooded Wistar rats were anesthetized and one hindleg electrically stimulated to contract (2 Hz, 0.1 ms) for 30 min while the other leg rested. After 10 min, the NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) (arterial concentration of 5 micromol/l) or saline was infused into the epigastric artery of the contracting leg. Local NOS inhibition had no effect on blood pressure, heart rate, or muscle contraction force. Contractions increased (P < 0.05) skeletal muscle NOS activity, and this was prevented by L-NAME infusion. NOS inhibition caused a modest significant (P < 0.05) attenuation of the increase in femoral blood flow during contractions, but importantly there was no effect on capillary recruitment. NOS inhibition attenuated (P < 0.05) the increase in contraction-stimulated skeletal muscle glucose uptake by approximately 35%, without affecting AMP-activated protein kinase (AMPK) activation. NOS inhibition attenuated increases in skeletal muscle glucose uptake during contraction without influencing capillary recruitment, suggesting that NO is critical for part of the normal increase in skeletal muscle fiber glucose uptake during contraction.

NMDA inhibits oxotremorine-induced acid secretion via the NO-dependent cyclic GMP system in rat stomach.

PubMed

Tsai, L H; Lee, Y J

2001-12-31

The mechanism of N-methyl-D-aspartate (NMDA) inhibits oxotremorine-induced acid secretion was examined in rat stomach, in relation to the cyclic GMP system. NMDA (10(-7) M) did not affect the spontaneous acid secretion from the everted preparations of isolated rat stomach, but inhibited the acid secretion stimulated by oxotremorine, and this effect of NMDA was antagonized by 2-amino-5-phosphonovaleric acid (AP-5), (+/-)3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP) or N(G)-nitro-L-arginine (L-NNA). NMDA also elevated the cyclic GMP content of mucosal slices from rat stomach, and this effect of NMDA was antagonized by L-NNA. These results indicate that NMDA receptors are present in the rat stomach and regulate the gastric acid secretion. The mechanism underlying the effect of NMDA inhibits oxotremorine-induced acid secretion may be mediated by the NO-dependent cyclic GMP system.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaehler, Christian; Guenther, Anika; Uhlich, Anja

Arginine methylation is a posttranslational modification that is of importance in diverse cellular processes. Recent proteomic mass spectrometry studies reported arginine methylation of ataxin-2-like (ATXN2L), the paralog of ataxin-2, a protein that is implicated in the neurodegenerative disorder spinocerebellar ataxia type 2. Here, we investigated the methylation state of ATXN2L and its significance for ATXN2L localization. We first confirmed that ATXN2L is asymmetrically dimethylated in vivo, and observed that the nuclear localization of ATXN2L is altered under methylation inhibition. We further discovered that ATXN2L associates with the protein arginine-N-methyltransferase 1 (PRMT1). Finally, we showed that neither mutation of the arginine–glycine-richmore » motifs of ATXN2L nor methylation inhibition alters ATXN2L localization to stress granules, suggesting that methylation of ATXN2L is probably not mandatory. - Highlights: • ATXN2L is asymmetrically dimethylated in vivo. • ATXN2L interacts with PRMT1 under normal and stress conditions. • PRMT1-mediated dimethylation of ATXN2L controls its nuclear localization. • ATXN2L localization to stress granules appears independent of its methylation state.« less

Beta-adrenoceptor dysfunction after inhibition of NO synthesis

NASA Technical Reports Server (NTRS)

Whalen, E. J.; Johnson, A. K.; Lewis, S. J.

2000-01-01

G(s) protein-coupled beta-adrenoceptors rapidly desensitize on exposure to agonists in reconstituted membrane preparations, whereas rapid tachyphylaxis to beta-adrenoceptor-mediated vasodilation does not readily occur in vivo. This study examined the possibility that endothelium-derived nitrosyl factors prevent the rapid desensitization of beta-adrenoceptors in the vascular smooth muscle of resistance arteries in pentobarbital-anesthetized rats. The fall in mean arterial blood pressure and in hindquarter vascular resistance produced by the beta-adrenoceptor agonist isoproterenol (ISO, 0.1 to 10 microg/kg IV) was slightly but significantly smaller in rats treated with the NO synthase inhibitor N:(G)-nitro-L-arginine methyl ester (L-NAME, 100 micromol/kg IV) than in saline-treated rats. The ISO-induced fall in mesenteric resistance was similar in L-NAME-treated and in saline-treated rats. The fall in hindquarter vascular resistance and in mesenteric resistance produced by ISO (8 x 10 microg/kg IV) was subject to tachyphylaxis on repeated injection in rats treated with L-NAME (100 micromol/kg IV) but not in rats treated with saline. Injections of L-S:-nitrosocysteine (1200 nmol/kg IV), a lipophobic S:-nitrosothiol, before each injection of ISO (10 microg/kg IV) prevented tachyphylaxis to ISO in L-NAME-treated rats. The vasodilator effects of ISO (0.1 to 10 microg/kg IV) in L-NAME-treated rats that received 8 injections of ISO (10 microg/kg IV) were markedly smaller than in L-NAME-treated rats that received 8 injections of saline. These results indicate that (1) the vasodilator actions of ISO in pentobarbital-anesthetized rats only minimally involve the release of endothelium-derived nitrosyl factors, (2) the effects of ISO are subject to development of tachyphylaxis in L-NAME-treated rats, and (3) tachyphylaxis to ISO is prevented by L-S:-nitrosocysteine. These findings suggest that endothelium-derived nitrosyl factors may prevent desensitization of beta-adrenoceptors in vivo.

Role of Angiotensin II type 1 receptor on renal NAD(P)H oxidase, oxidative stress and inflammation in nitric oxide inhibition induced-hypertension.

PubMed

Rincón, J; Correia, D; Arcaya, J L; Finol, E; Fernández, A; Pérez, M; Yaguas, K; Talavera, E; Chávez, M; Summer, R; Romero, F

2015-03-01

Activation of the renin-angiotensin system (RAS), renal oxidative stress and inflammation are constantly present in experimental hypertension. Nitric oxide (NO) inhibition with N(w)-nitro-L-arginine methyl ester (L-NAME) has previously been reported to produce hypertension, increased expression of Angiotensin II (Ang II) and renal dysfunction. The use of Losartan, an Ang II type 1 receptor (AT1R) antagonist has proven to be effective reducing hypertension and renal damage; however, the mechanism by which AT1R blockade reduced kidney injury and normalizes blood pressure in this experimental model is still complete unknown. The current study was designed to test the hypothesis that AT1R activation promotes renal NAD(P)H oxidase up-regulation, oxidative stress and cytokine production during L-NAME induced-hypertension. Male Sprague-Dawley rats were distributed in three groups: L-NAME, receiving 70 mg/100ml of L-NAME, L-NAME+Los, receiving 70 mg/100ml of L-NAME and 40 mg/kg/day of Losartan; and Controls, receiving water instead of L-NAME or L-NAME and Losartan. After two weeks, L-NAME induced high blood pressure, renal overexpression of AT1R, NAD(P)H oxidase sub-units gp91, p22 and p47, increased levels of oxidative stress, interleukin-6 (IL-6) and interleukin-17 (IL-17). Also, we found increased renal accumulation of lymphocytes and macrophages. Losartan treatment abolished the renal expression of gp91, p22, p47, oxidative stress and reduced NF-κB activation and IL-6 expression. These findings indicate that NO induced-hypertension is associated with up-regulation of NADPH oxidase, oxidative stress production and overexpression of key inflammatory mediators. These events are associated with up-regulation of AT1R, as evidenced by their reversal with AT1R blocker treatment. Copyright © 2015 Elsevier Inc. All rights reserved.

NO-dependent blood pressure regulation in RGS2-deficient mice

PubMed Central

Obst, Michael; Tank, Jens; Plehm, Ralph; Blumer, Kendall J.; Diedrich, Andrè; Jordan, Jens; Luft, Friedrich C.; Gross, Volkmar

2009-01-01

The regulator of G protein signaling (RGS) 2, a GTPase-activating protein, is activated via the nitric oxide (NO)-cGMP pathway and thereby may influence blood pressure regulation. To test that notion, we measured mean arterial blood pressure (MAP) and heart rate (HR) with telemetry in Nω-nitro-L-arginine methyl ester (L-NAME, 5 mg L-NAME/10 ml tap water)-treated RGS2-deficient (RGS2−/−) and RGS2-sufficient (RGS2+/+) mice and assessed autonomic function. Without L-NAME, RGS2−/− mice showed during day and night a similar increase of MAP compared with controls. L-NAME treatment increased MAP in both strains. nNOS is involved in this L-NAME-dependent blood pressure increase, since 7-nitroindazole increased MAP by 8 and 9 mmHg (P < 0.05) in both strains. The L-NAME-induced MAP increase of 14–15 mmHg during night was similar in both strains. However, the L-NAME-induced MAP increase during the day was smaller in RGS2−/− than in RGS2+/+ (11 ± 1 vs. 17 ± 2 mmHg; P < 0.05). Urinary norepinephrine and epinephrine excretion was higher in RGS2−/− than in RGS2+/+ mice. The MAP decrease after prazosin was more pronounced in L-NAME-RGS2−/−. HR variability parameters [root mean square of successive differences (RMSSD), low-frequency (LF) power, and high-frequency (HF) power] and baroreflex sensitivity were increased in RGS2−/−. Atropine and atropine plus metoprolol markedly reduced RMSSD, LF, and HF. Our data suggest an interaction between RGS2 and the NO-cGMP pathway. The blunted L-NAME response in RGS2−/− during the day suggests impaired NO signaling. The MAP increases during the active phase in RGS2−/− mice may be related to central sympathetic activation and increased vascular adrenergic responsiveness. PMID:16269576

Maintenance of cytosolic calcium is crucial to extend l-arginine therapeutic benefits during continuous dosing.

PubMed

Mohan, Srinidi; Harding, Lisa

2016-10-01

The therapeutic benefits associated with short-term l-arginine supplementation are lost during continuous dosing. AMP-activated protein kinase (AMPK) functional modulation has been correlated with l-arginine therapeutic effectiveness, and with tolerance development during continuous supplementation. However, the metabolic link that is responsible for AMPK functional modulation during continuous l-arginine exposure is currently not known. To explore this, we incubated HUVECs for 7 days with 100 μmol/L l-arginine, in the presence or absence of other agents; and monitored their effects for eNOS function, and on tolerance sparing effects (viz, cellular glucose accumulation, and oxidative stress). HUVEC co-incubation with 100 μmol/L l-arginine and ≤1200 mg/mL calcium (Ca 2+ ) for 7 days avoided tolerance development, with an at least 1-fold increase in the eNOS and AMPK functional activity; and an 1-fold increase in overall cellular glucose uptake. The overall cellular cytosolic Ca 2+ was below 200 nmol/L, with no change in cellular glucose and superoxide/peroxynitrite (O 2 •- /ONOO - ) level from control. However, tolerance sparing effects of at least 70% decrease in eNOS and AMPK functional response, with an 1-fold reduction in glucose uptake, and at least 2-fold increase in O 2 •- /ONOO - were observed in cells exposed for 7 days to 100 μmol/L l-arginine at Ca 2+ co-incubation concentration of >1200 mg/mL. The >1200 mg/mL Ca2+ co-incubation condition, also improved the overall cellular Ca 2+ to >200 nmol/L. Similar tolerance response was observed in cells co-treated with 100 μmol/L l-arginine and ≤1200 mg/mL Ca 2+ in the presence of Ca 2+ influx inhibitor (20 μmol/L 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetra acetic acid), or eNOS activity inhibitor (30 μmol/L l-N G -nitroarginine methyl ester). No tolerance response was seen in cells incubated for 7 days with 100 μmol/L l-arginine and ≤1200 mg/mL Ca 2+ ; even in the presence of the inhibitor for cellular glucose induction (30 μmol/L 5-chloro-2-(n-(2,5-dichlorobenzenesulfonamide))-benzoxazole). The present study thus provides the first definitive evidence that shows the need to maintain cytosolic Ca 2+ within a threshold limit of less than 200 nmol/L to extend l-arginine therapeutic efficacy during continuous dosing, without any potential tolerance development. Copyright © 2016 Elsevier Inc. All rights reserved.

Fumagillin Prodrug Nanotherapy Suppresses Macrophage Inflammatory Response via Endothelial Nitric Oxide

PubMed Central

2015-01-01

Antiangiogenesis has been extensively explored for the treatment of a variety of cancers and certain inflammatory processes. Fumagillin, a mycotoxin produced by Aspergillus fumigatus that binds methionine aminopeptidase 2 (MetAP-2), is a potent antiangiogenic agent. Native fumagillin, however, is poorly soluble and extremely unstable. We have developed a lipase-labile fumagillin prodrug (Fum-PD) that eliminated the photoinstability of the compound. Using αvβ3-integrin-targeted perfluorocarbon nanocarriers to deliver Fum-PD specifically to angiogenic vessels, we effectively suppressed clinical disease in an experimental model of rheumatoid arthritis (RA). The exact mechanism by which Fum-PD-loaded targeted nanoparticles suppressed inflammation in experimental RA, however, remained unexplained. We herein present evidence that Fum-PD nanotherapy indirectly suppresses inflammation in experimental RA through the local production of endothelial nitric oxide (NO). Fum-PD-induced NO activates AMP-activated protein kinase (AMPK), which subsequently modulates macrophage inflammatory response. In vivo, NO-induced AMPK activation inhibits mammalian target of rapamycin (mTOR) activity and enhances autophagic flux, as evidenced by p62 depletion and increased autolysosome formation. Autophagy in turn mediates the degradation of IkappaB kinase (IKK), suppressing the NF-κB p65 signaling pathway and inflammatory cytokine release. Inhibition of NO production by NG-nitro-l-arginine methyl ester (l-NAME), a nitric oxide synthase inhibitor, reverses the suppression of NF-κB-mediated inflammatory response induced by Fum-PD nanotherapy. These unexpected results uncover an activity of Fum-PD nanotherapy that may be further explored in the treatment of angiogenesis-dependent diseases. PMID:24941020

Gastric relaxation induced by hyperglycemia is mediated by vagal afferent pathways in the rat

PubMed Central

Zhou, Shi-Yi; Lu, Yuan-Xu; Owyang, Chung

2011-01-01

Hyperglycemia has a profound effect on gastric motility. However, little is known about site and mechanism that sense alteration in blood glucose level. The identification of glucose-sensing neurons in the nodose ganglia led us to hypothesize that hyperglycemia acts through vagal afferent pathways to inhibit gastric motility. With the use of a glucose clamp rat model, we showed that glucose decreased intragastric pressure in a dose-dependent manner. In contrast to intravenous infusion of glucose, intracisternal injection of glucose at 250 and 500 mg dL−1 had little effect on intragastric pressure. Pretreatment with hexamethonium, as well as truncal vagotomy, abolished the gastric motor responses to hyperglycemia (250 mg dL−1), and perivagal and gastroduodenal applications of capsaicin significantly reduced the gastric responses to hyperglycemia. In contrast, hyperglycemia had no effect on the gastric contraction induced by electrical field stimulation or carbachol (10−5 M). To rule out involvement of serotonergic pathways, we showed that neither granisetron (5-HT3 antagonist, 0.5 g kg−1) nor pharmacological depletion of 5-HT using p-chlorophenylalanine (5-HT synthesis inhibitor) affected gastric relaxation induced by hyperglycemia. Lastly, NG-nitro-L-arginine methyl ester (l-NAME) and a VIP antagonist each partially reduced gastric relaxation induced by hyperglycemia, and in combination, completely abolished gastric responses. In conclusion, hyperglycemia inhibits gastric motility through a capsaicin-sensitive vagal afferent pathway originating from the gastroduodenal mucosa. Hyperglycemia stimulates vagal afferents, which, in turn, activate vagal efferent cholinergic pathways synapsing with intragastric nitric oxide- and VIP-containing neurons to mediate gastric relaxation. PMID:18356537

High salt intake shifts the mechanisms of flow-induced dilation in the middle cerebral arteries of Sprague-Dawley rats.

PubMed

Matic, Anita; Jukic, Ivana; Stupin, Ana; Baric, Lidija; Mihaljevic, Zrinka; Unfirer, Sanela; Tartaro Bujak, Ivana; Mihaljevic, Branka; Lombard, Julian H; Drenjancevic, Ines

2018-06-15

The goal of this study was to examine the effect of 1-week of high salt (HS) intake and the role of oxidative stress in changing the mechanisms of flow-induced dilation (FID) in isolated pressurized middle cerebral arteries (MCA) of male Sprague-Dawley rats (N=15-16/per group). Reduced FID in the HS group was restored by intake of the superoxide scavenger TEMPOL (HS+TEMPOL in vivo group). Nitric oxide synthases (NOS) inhibitor N ω -nitro-L-arginine methyl ester (L-NAME), COX inhibitor indomethacin (INDO) and selective inhibitor of microsomal CYP450 epoxidase activity N-(methylsulfonyl)-2-(2-propynyloxy)-benzenehexanamide (MS-PPOH) significantly reduced FID in the LS group, while FID in the HS group was mediated by NO only. COX-2 mRNA (but not protein) expression was decreased in the HS and HS+TEMPOL in vivo groups. HIF-1α and VEGF protein levels were increased in the HS group but decreased in the HS+TEMPOL in vivo group. Assessment by direct fluorescence of MCA under flow revealed significantly reduced vascular NO levels and increased superoxide/reactive oxygen species levels in the HS group. These results suggest that HS intake impairs FID and changes FID mechanisms to entirely NO-dependent, in contrast to the LS group where FID is NO, prostanoid and epoxyeicosatrienoic acids (EET's) dependent. Those changes were accompanied by increased lipid peroxidation products in the plasma of HS-fed rats, increased vascular superoxide/reactive oxygen species levels and decreased NO levels; together with increased expression of HIF-1α and VEGF.

In vitro effect of nicorandil on the carbachol-induced contraction of the lower esophageal sphincter of the rat.

PubMed

Shimbo, Tomonori; Adachi, Takeshi; Fujisawa, Susumu; Hongoh, Mai; Ohba, Takayoshi; Ono, Kyoichi

2016-08-01

The lower esophageal sphincter (LES) is a specialized region of the esophageal smooth muscle that allows the passage of a swallowed bolus into the stomach. Nitric oxide (NO) plays a major role in LES relaxation. Nicorandil possesses dual properties of a NO donor and an ATP-sensitive potassium channel (KATP channel) agonist, and is expected to reduce LES tone. This study investigated the mechanisms underlying the effects of nicorandil on the LES. Rat LES tissues were placed in an organ bath, and activities were recorded using an isometric force transducer. Carbachol-induced LES contraction was significantly inhibited by KATP channel agonists in a concentration-dependent manner; pinacidil > nicorandil ≈ diazoxide. Nicorandil-induced relaxation of the LES was prevented by pretreatment with glibenclamide, whereas N(G)-nitro-l-arginine methyl ester (l-NAME), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and iberiotoxin were ineffective at preventing nicorandil-induced LES relaxation. Furthermore, nicorandil did not affect high K(+)-induced LES contraction. Reverse-transcription polymerase chain reaction analysis and immunohistochemistry revealed expression of KCNJ8 (Kir6.1), KCNJ11 (Kir6.2), ABCC8 (SUR1) and ABCC9 (SUR2) subunits of the KATP channel in the rat lower esophagus. These findings indicate that nicorandil causes LES relaxation chiefly by activating the KATP channel, and that it may provide an additional pharmacological tool for the treatment of spastic esophageal motility disorders. Copyright © 2016 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

NECA and bradykinin at reperfusion reduce infarction in rabbit hearts by signaling through PI3K, ERK, and NO.

PubMed

Yang, Xi-Ming; Krieg, Thomas; Cui, Lin; Downey, James M; Cohen, Michael V

2004-03-01

The adenosine A1/A2 adenosine agonist 5'-(N-ethylcarboxamido) adenosine (NECA) and bradykinin both limit infarction when administered at reperfusion in rabbits. This study compares the signal transduction pathways responsible for their anti-infarct effect. Receptor agonists were administered to isolated rabbit hearts starting 25 min after the onset of a 30-min period of ischemia and continued into the 2-h reperfusion period. Infarct size was measured. Both NECA and bradykinin decreased infarction from 31.5 +/- 2.4% of the risk zone in untreated hearts to 11.8 +/- 2.0% and 15.4 +/- 2.4%, respectively (P<0.05). Protection from both agents was blocked by PD98059, wortmannin, and Nomega-nitro-L-arginine methyl ester (L-NAME), thus demonstrating dependence on activation of extracellular regulated kinase (ERK) and phosphatidylinositol 3-kinase (PI3K) and stimulation of nitric oxide synthase (NOS). Both wortmannin and PD98059 prevented phosphorylation of ERK 1/2 in NECA-treated hearts, whereas only wortmannin and not PD98059 blocked Akt phosphorylation. These data suggest Akt is upstream of ERK 1/2. In addition, 8-(3-chlorostyryl) caffeine blocked NECA's protection indicating that A2 adenosine receptors trigger NECA's anti-infarct effect. Of note, both bradykinin and acetylcholine (ACh) administered before ischemia to trigger preconditioning's cardioprotection use PI3K and NOS in their signaling pathway. Curiously, however, ACh, unlike bradykinin, was not protective when administered at reperfusion. Hence, both NECA and bradykinin administered at reperfusion protect through a common signaling pathway that includes PI3K, NO, and ERK.

Effects of coarse chalk dust particles (2.5-10 μm) on respiratory burst and oxidative stress in alveolar macrophages.

PubMed

Zhang, Yuexia; Yang, Zhenhua; Feng, Yan; Li, Ruijin; Zhang, Quanxi; Geng, Hong; Dong, Chuan

2015-08-01

The main aim of the present study was to examine in vitro responses of rat alveolar macrophages (AMs) exposed to coarse chalk dust particles (particulate matter in the size range 2.5-10 μm, PM(coarse)) by respiratory burst and oxidative stress. Chalk PM(coarse)-induced respiratory burst in AMs was measured by using a luminol-dependent chemiluminescence (CL) method. Also, the cell viability; lactate dehydrogenase (LDH) release; levels of cellular superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), malondialdehyde (MDA), and acid phosphatase (ACP); plasma membrane ATPase; and extracellular nitric oxide (NO) level were determined 4 h following the treatment with the different dosages of chalk PM(coarse). The results showed that chalk PM(coarse) initiated the respiratory burst of AMs as indicated by strong CL, which was inhibited by diphenyleneiodonium chloride and L-N-nitro-L-arginine methyl ester hydrochloride. It suggested that chalk PM(coarse) induced the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in AMs. This hypothesis was confirmed by the fact that chalk PM(coarse) resulted in a significant decrease of intracellular SOD, GSH, ACP, and ATPase levels and a notable increase of intracellular CAT, MDA content, and extracellular NO level, consequently leading to a decrease of the cell viability and a increase of LDH release. It was concluded that AMs exposed to chalk PM(coarse) can suffer from cytotoxicity which may be mediated by generation of excessive ROS/RNS. Graphical Abstract The possible mechanism of coarse chalk particles-induced adverse effects in AMs.

Effect of 5-hydroxytryptamine on duodenal mucosal bicarbonate secretion in mice.

PubMed

Tuo, Bi-Guang; Isenberg, Jon I

2003-09-01

5-hydroxytryptamine (5-HT) is an important neurotransmitter and intercellular messenger that modulates many gastrointestinal functions. Because little is known about the role of 5-HT in the regulation of duodenal bicarbonate secretion, we examined the role of 5-HT on duodenal bicarbonate secretion and define neural pathways involved in the actions of 5-HT. Duodenal mucosa from National Institutes of Health Swiss mice was stripped of seromuscular layers and mounted in Ussing chambers. The effect of 5-HT on duodenal bicarbonate secretion was determined by the pH stat technique. Acetylcholine (ACh) release from duodenal mucosa was assessed by preincubating the tissue with [(3)H] choline and measuring 5-HT-evoked release of tritium. 5-HT added to the serosal bath markedly stimulated duodenal bicarbonate secretion and short circuit current (Isc) in a dose-dependent manner (10(-7) mol/L to 10(-3) mol/L; P < 0.0001), whereas mucosally added 5-HT was without effect. 5-HT-stimulated bicarbonate secretion was independent of luminal Cl(-). Pretreatment with tetrodotoxin (TTX) (10(-6) mol/L) or atropine (10(-5) mol/L) markedly reduced 5-HT-stimulated duodenal bicarbonate secretion (by 60% and 65%, respectively; P < 0.001) and Isc (by 45% and 27%, respectively; P < 0.001 and P < 0.05). Pretreatment with N(omega)-nitro-l-arginine methyl ester (l-NAME) (10(-3) mol/L), propranolol (10(-5) mol/L), or phentolamine (10(-5) mol/L) did not significantly alter 5-HT-stimulated duodenal mucosal bicarbonate secretion or Isc. 5-HT concentration-dependently evoked ACh release from duodenal mucosal preparations (P < 0.0001). TTX markedly inhibited 5-HT-evoked ACh release (P < 0.001). 5-HT is a potent activator of duodenal mucosal bicarbonate secretion in mice. Duodenal bicarbonate secretion induced by 5-HT in vitro occurs principally via a cholinergic neural pathway.

Pharmacological characterization of mechanisms involved in the vasorelaxation produced by rosuvastatin in aortic rings from rats with a cafeteria-style diet

PubMed Central

López-Canales, Jorge Skiold; Lozano-Cuenca, Jair; López-Canales, Oscar Alberto; Aguilar-Carrasco, José Carlos; Aranda-Zepeda, Lidia; López-Sánchez, Pedro; Castillo-Henkel, Enrique Fernando; López-Mayorga, Ruth Mery; Valencia-Hernández, Ignacio

2015-01-01

The present study aimed to investigate the possible influence of several inhibitors and blockers on the vascular effect produced by the acute in vitro application of rosuvastatin to phenylephrine-precontracted aortic rings from rats with a semi-solid, cafeteria-style (CAF) diet. It also aimed to examine the effects of rosuvastatin on the expression of endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase, constitutive cyclooxygenase, and inducible cyclooxygenase in aortic rings from rats with a CAF diet. From comparisons of the effect on phenylephrine-precontracted aortic rings extracted from rats with two different diets (a standard and a CAF diet), it was found that 10−9–10−5-mol/L rosuvastatin produced lower concentration-dependent vasorelaxation on rings from the CAF diet group. The vasorelaxant effect was unaffected by the vehicle, but it was significantly attenuated by 10−5-mol/L NG-nitro-l-arginine methyl ester, 10−2-mol/L tetraethylammonium, 10−3-mol/L 4-aminopyridine, 10−7-mol/L apamin plus 10−7-mol/L charybdotoxin, 10−5-mol/L indomethacin, or 10−5-mol/L cycloheximide. Moreover, in aortic rings from rats with a CAF diet, rosuvastatin enhanced the expression of eNOS, inducible nitric oxide synthase, constitutive cyclooxygenase, and inducible cyclooxygenase. The acute in vitro application of rosuvastatin to phenylephrine-precontracted aortic rings from rats with a CAF diet had a vasorelaxant effect. Overall, the present results suggest that the stimulation of eNOS, the opening of Ca2+-activated and voltage-activated K+ channels, the stimulation of prostaglandin synthesis and enhanced protein levels of eNOS, inducible nitric oxide synthase, constitutive cyclooxygenase, and inducible cyclooxygenase are involved in this relaxant effect. PMID:25881486

Protective effect of prior physical conditioning on relaxing response of corpus cavernosum from rats made hypertensive by nitric oxide inhibition.

PubMed

Claudino, M A; Priviero, F B M; Camargo, E A; Teixeira, C E; De Nucci, G; Antunes, E; Zanesco, A

2007-01-01

The aim of this work was to evaluate the influence of run training on the responsiveness of corpus cavernosum (CC) from rats made hypertensive by treatment with nitric oxide (NO) synthesis inhibitor. Wistar rats were divided into sedentary control (C-SD), exercise training (C-TR), N(omega)-nitro-L-arginine methyl ester (L-NAME) sedentary (LN-SD) and L-NAME trained (LN-TR) groups. The run training program consisted in 8 weeks in a treadmill, 5 days/week, each session lasted 60 min. L-NAME treatment (2 and 10 mg/rat/day) started after 4 weeks of prior physical conditioning and lasted 4 weeks. Concentration-response curves were obtained for acetylcholine (ACh), sodium nitroprusside (SNP), sildenafil and BAY 41-2272. The effect of electrical field stimulation (EFS) on the relaxations responses of CC was evaluated. Run training prevented the arterial hypertension induced by L-NAME treatment (LN-SD: 135+/-2 and 141+/-2 mm Hg for both doses of L-NAME) compared to LN-SD groups (154+/-1 and 175+/-2 mm Hg, for 2 and 10 mg of L-NAME, respectively). Run training produced an increase in the maximal responses (E(max)) of CC for ACh (C-SD: 47+/-3; C-TR: 52+/-1; and LN-TR: 53+/-3%) and SNP (C-SD: 89+/-1; C-TR: 98+/-1; and LN-TR: 95+/-1%). Both potency and E(max) for ACh were reduced in a dose of 10 mg of L-NAME, and run training restored the reduction of E(max) for ACh. No changes were found for BAY 41-2271 and sildenafil. Relaxing responses to EFS was reduced by L-NAME treatment that was restored by prior physical conditioning. In conclusion, our study shows a beneficial effect of prior physical conditioning on the impaired CC relaxing responses in rats made hypertensive by chronic NO blockade.

Acute administration of single oral dose of grape seed polyphenols restores blood pressure in a rat model of metabolic syndrome: role of nitric oxide and prostacyclin.

PubMed

Pons, Zara; Margalef, Maria; Bravo, Francisca I; Arola-Arnal, Anna; Muguerza, Begoña

2016-03-01

The aims of this study were to evaluate the antihypertensive effectiveness of different doses of grape seed polyphenols in cafeteria diet-fed hypertensive rats (CHRs) and to establish the mechanism involved in the blood pressure (BP) lowering effect of these compounds in this experimental model of metabolic syndrome (MS). Male 8-week-old Wistar rats were fed cafeteria or standard (ST) diet for 10 weeks. After this, the antihypertensive effect of a single oral administration of a polyphenol grape seed extract (GSPE) was tested at different doses (250, 375 and 500 mg/kg) in CHRs. BP was recorded before and 2, 4, 6, 8, 24 and 48 h post-administration. The hypotensive effect of GSPE was also proved in ST diet-fed rats. Additionally, in other experiment, CHRs were orally administered 375 mg/kg GSPE. Four hours post-administration, the rats were intraperitoneally administrated 30 mg/kg NG-nitro-L-arginine methyl ester (L-NAME) or 5 mg/kg indomethacin [inhibitors of nitric oxide (NO) and prostacyclin synthesis, respectively]. BP was recorded initially and 6 h post-administration. GSPE produced a decrease in SBP and DBP, the most effective dose (375 mg/kg) showing an antihypertensive effect in CHRs similar to the drug captopril, and did not affect BP of ST diet-fed rats. The antihypertensive effect was completely abolished by L-NAME and partially inhibited by indomethacin. GSPE acts as an antihypertensive agent in a rat model of hypertension associated with MS. The change in endothelium-derived NO availability is one of the mechanisms involved in the antihypertensive effect of GSPE in CHRs. Additionally, endothelial prostacyclin contributes to the effect of GSPE on arterial BP.

Vasoconstrictor and vasodilator responses to tryptamine of rat-isolated perfused mesentery: comparison with tyramine and β-phenylethylamine

PubMed Central

Anwar, MA; Ford, WR; Broadley, KJ; Herbert, AA

2012-01-01

BACKGROUND AND PURPOSE Tryptamine increases blood pressure by vasoconstriction, but little is known about its actions on the mesentery, in particular the resistance arteries. Tryptamine interacts with trace amine-associated receptors (TAARs) and because of its structural similarity to 5-HT, it may also interact with 5-HT receptors. Our hypothesis is therefore that the rat mesenteric arterial bed will exhibit vasopressor and vasodepressor responses to tryptamine via both 5-HT and TAARs. EXPERIMENTAL APPROACH Tryptamine-evoked responses were assayed from pressure changes of the rat-isolated mesenteric vasculature perfused at constant flow rate in the absence and presence of adrenoceptor and 5-HT receptor antagonists. KEY RESULTS Tryptamine caused dose-dependent vasoconstriction of the mesenteric arterial bed as increases in perfusion pressure. These were unaffected by the α1-adrenoceptor antagonist, prazosin, but were attenuated by the non-selective α-adrenoceptor antagonist, phentolamine. The 5-HT2A receptor antagonists, ketanserin and ritanserin, abolished the tryptamine-induced pressure increases to reveal vasodilator responses in mesenteric beds preconstricted with phenylephrine. These tryptamine-induced vasodilator responses were unaffected by the 5-HT7 receptor antagonist, SB269970, but were eliminated by the NOS inhibitor, Nω-nitro-L-arginine methyl ester (L-NAME). Tyramine and β-phenylethylamine also caused vasodilatation in pre-constricted vasculature, which was also abolished by L-NAME. CONCLUSIONS AND IMPLICATIONS Tryptamine causes vasoconstriction of the mesenteric vasculature via 5-HT2A receptors, which when inhibited exposed vasorelaxant effects in pre-constricted tissues. The vasodilatation was independent of 5-HT2A and 5-HT7 receptors but like that for tyramine and β-phenylethylamine was due to NO release. Potency orders suggest TAAR involvement in the vasodilatation by these trace amines. PMID:21958009

Vasoconstrictor and vasodilator responses to tryptamine of rat-isolated perfused mesentery: comparison with tyramine and β-phenylethylamine.

PubMed

Anwar, M A; Ford, W R; Broadley, K J; Herbert, A A

2012-04-01

Tryptamine increases blood pressure by vasoconstriction, but little is known about its actions on the mesentery, in particular the resistance arteries. Tryptamine interacts with trace amine-associated receptors (TAARs) and because of its structural similarity to 5-HT, it may also interact with 5-HT receptors. Our hypothesis is therefore that the rat mesenteric arterial bed will exhibit vasopressor and vasodepressor responses to tryptamine via both 5-HT and TAARs. Tryptamine-evoked responses were assayed from pressure changes of the rat-isolated mesenteric vasculature perfused at constant flow rate in the absence and presence of adrenoceptor and 5-HT receptor antagonists. Tryptamine caused dose-dependent vasoconstriction of the mesenteric arterial bed as increases in perfusion pressure. These were unaffected by the α(1) -adrenoceptor antagonist, prazosin, but were attenuated by the non-selective α-adrenoceptor antagonist, phentolamine. The 5-HT(2A) receptor antagonists, ketanserin and ritanserin, abolished the tryptamine-induced pressure increases to reveal vasodilator responses in mesenteric beds preconstricted with phenylephrine. These tryptamine-induced vasodilator responses were unaffected by the 5-HT(7) receptor antagonist, SB269970, but were eliminated by the NOS inhibitor, N(ω) -nitro-L-arginine methyl ester (L-NAME). Tyramine and β-phenylethylamine also caused vasodilatation in pre-constricted vasculature, which was also abolished by L-NAME. Tryptamine causes vasoconstriction of the mesenteric vasculature via 5-HT(2A) receptors, which when inhibited exposed vasorelaxant effects in pre-constricted tissues. The vasodilatation was independent of 5-HT(2A) and 5-HT(7) receptors but like that for tyramine and β-phenylethylamine was due to NO release. Potency orders suggest TAAR involvement in the vasodilatation by these trace amines. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

Increased cavernosal relaxation by Phoneutria nigriventer toxin, PnTx2-6, via activation at NO/cGMP signaling.

PubMed

Nunes, K P; Wynne, B M; Cordeiro, M N; Borges, M H; Richardson, M; Leite, R; DeLima, M E; Webb, R C

2012-01-01

Erectile dysfunction (ED) mechanisms in diabetic patients are multifactorial and often lead to resistance to current therapy. Animal toxins have been used as pharmacological tools to study penile erection. Human accidents involving the venom of Phoneutria nigriventer spider are characterized by priapism. We hypothesize that PnTx2-6 potentiates cavernosal relaxation in diabetic mice by increasing cyclic guanosine monophosphate (cGMP). This effect is neuronal nitric oxide synthase (nNOS) dependent. Cavernosal strips were contracted with phenylephrine (10(-5) M) and relaxed by electrical field stimulation (20 V, 1-32 Hz) in the presence or absence of PnTx2-6 (10(-8) M). Cavernosal strips from nNOS- and endothelial nitric oxide synthase (eNOS)-knockout (KO) mice, besides nNOS inhibitor (10(-5) M), were used to evaluate the role of this enzyme in the potentiation effect evoked by PnTx2-6. Tissue cGMP levels were determined after stimulation with PnTx2-6 in presence or absence of N-nitro-L-arginine methyl ester (L-NAME) (10(-4) M) and ω-conotoxin GVIA (10(-6) M), an N-type calcium channel inhibitor. Results showed that PnTx2-6 enhanced cavernosal relaxation in diabetic mice (65%) and eNOS KO mice, but not in nNOS KO mice. The toxin effect in the cavernosal relaxation was abolished by nNOS inhibitor. cGMP levels are increased by PnTx2-6, however, L-NAME abolished this enhancement as well as ω-conotoxin GVIA. We conclude that PnTx2-6 facilitates penile relaxation in diabetic mice through a mechanism dependent on nNOS, probably via increasing nitric oxide/cGMP production.

Prostacyclin and milrinone by aerosolization improve pulmonary hemodynamics in newborn lambs with experimental pulmonary hypertension.

PubMed

Kumar, Vasanth H; Swartz, Daniel D; Rashid, Nasir; Lakshminrusimha, Satyan; Ma, Changxing; Ryan, Rita M; Morin, Frederick C

2010-09-01

Aerosolized prostacyclin (PGI2) produces selective pulmonary vasodilation in patients with pulmonary hypertension (PH). The response to PGI2 may be increased by phosphodiesterase type 3 inhibitors such as milrinone. We studied the dose response effects of aerosolized PGI2 and aerosolized milrinone both alone and in combination on pulmonary and systemic hemodynamics in newborn lambs with Nomega-nitro-L-arginine methyl ester (L-NAME)-induced PH. We hypothesized that coaerosolization of PGI2 with milrinone would additively decrease pulmonary vascular resistance (PVR), prolong the duration of action of PGI2, and selectively dilate the pulmonary vasculature. Near-term lambs were delivered by C-section and instrumented and PH was induced by L-NAME (bolus 25 mg/kg; infusion 10 mg.kg(-1).h(-1)) and indomethacin. In the first set of experiments, PGI2 was aerosolized at random doses of 2, 20, 100, 200, 500, and 1,000 ng.kg(-1).min(-1) followed by milrinone at doses of 0.1, 1, and 10 microg.kg(-1).min(-1) over 10 min. In the second set of experiments, milrinone at 1 microg.kg(-1).min(-1) was aerosolized in combination with PGI2 at doses of 20, 100, and 200 ng.kg(-1).min(-1) over 10 min. Pulmonary arterial pressures (PAP) and PVR decreased significantly with increasing doses of aerosolized PGI2 and milrinone. The combination of PGI2 and milrinone significantly reduced PAP and PVR more than either of the drugs aerosolized alone. Addition of milrinone significantly increased the duration of action of PGI2. When aerosolized independently, PGI2 and milrinone selectively dilated the pulmonary vasculature but the combination did not. Milrinone enhances the vasodilatory effects of PGI2 on the pulmonary vasculature but caution must be exercised regarding systemic hypotension.

Daily physical activity enhances reactivity to insulin in skeletal muscle arterioles of hyperphagic Otsuka Long-Evans Tokushima Fatty rats.

PubMed

Mikus, Catherine R; Rector, R Scott; Arce-Esquivel, Arturo A; Libla, Jessica L; Booth, Frank W; Ibdah, Jamal A; Laughlin, M Harold; Thyfault, John P

2010-10-01

Insulin-mediated glucose disposal is dependent on the vasodilator effects of insulin. In type 2 diabetes, insulin-stimulated vasodilation is impaired as a result of an imbalance in NO and ET-1 production. We tested the hypothesis that chronic voluntary wheel running (RUN) prevents impairments in insulin-stimulated vasodilation associated with obesity and type 2 diabetes independent of the effects of RUN on adiposity by randomizing Otsuka Long Evans Tokushima Fatty (OLETF) rats, a model of hyperphagia-induced obesity and type 2 diabetes, to 1) RUN, 2) caloric restriction (CR; diet adjusted to match body weights of RUN group), or 3) sedentary control (SED) groups (n = 8/group) at 4 wk. At 40 wk, NO- and ET-1-mediated vasoreactivity to insulin (1-1,000 μIU/ml) was assessed in the presence of a nonselective ET-1 receptor blocker (tezosentan) or a NO synthase (NOS) inhibitor [N(G)-nitro-L-arginine methyl ester (L-NAME)], respectively, in second-order arterioles isolated from the white portion of the gastrocnemius muscle. Body weight, fasting plasma glucose, and hemoglobin A1c were lower in RUN and CR than SED (P < 0.05); however, the glucose area under the curve (AUC) following the intraperitoneal glucose tolerance test was lower only in the RUN group (P < 0.05). Vasodilator responses to all doses of insulin were greater in RUN than SED or CR in the presence of a tezosentan (P < 0.05), but group differences in vasoreactivity to insulin with coadministration of L-NAME were not observed. We conclude daily wheel running prevents obesity and type 2 diabetes-associated declines in insulin-stimulated vasodilation in skeletal muscle arterioles through mechanisms that appear to be NO mediated and independent of attenuating excess adiposity in hyperphagic rats.

Role for NK(1) and NK(2) receptors in the motor activity in mouse colon.

PubMed

Mulè, Flavia; Amato, Antonella; Serio, Rosa

2007-09-10

The present study examined the effects induced by endogenous and exogenous activation of NK(1) and NK(2) receptors on the mechanical activity of mouse proximal colon. Experiments were performed in vitro recording the changes in intraluminal pressure from isolated colonic segments. Electrical field stimulation in the presence of atropine and guanethidine produced a small relaxation, followed by nonadrenergic noncholinergic (NANC) contraction. SR140333, NK(1) receptor antagonist, or SR48968, NK(2) receptor antagonist, significantly reduced the contraction, although SR48968 appeared more efficacious. The co-administration of SR140333 and SR48968 virtually abolished the NANC contraction. [Sar(9), Met(O(2))(11)]-substance P, selective NK(1) receptor agonist, induced a concentration-dependent biphasic effect, contraction followed by reduction of the mechanical spontaneous activity. Both effects were antagonized by SR140333, but not by SR48968. [beta-Ala(8)]-neurokinin A (4-10), selective NK(2) receptor agonist, evoked concentration-dependent contraction, which was antagonized by SR48968, but not by SR140333. The contraction induced by [Sar(9), Met(O(2))(11)]-substance P, but not by [beta-Ala(8)]-neurokinin A (4-10), was reduced by tetrodotoxin or atropine, and increased by N(omega)-nitro-L-arginine methyl ester (L-NAME), inhibitor of nitric oxide synthase. The inhibitory effects induced by [Sar(9), Met(O(2))(11)]-substance P were abolished by tetrodotoxin or L-NAME. The results of the present study suggest that in mouse colon both NK(1) and NK(2) receptors are junctionally activated by endogenous tachykinins to cause an additive response. NK(1) receptors appear to be located on cholinergic and on nitrergic neurons as well as on smooth muscle cells, whereas NK(2) receptors seem to be present exclusively on smooth muscle cells.

The mechanism of bradykinin-induced endothelium-dependent contraction and relaxation in the porcine interlobar renal artery

PubMed Central

Ihara, Eikichi; Hirano, Katsuya; Derkach, Dmitry N; Nishimura, Junji; Nawata, Hajime; Kanaide, Hideo

2000-01-01

The mechanism of endothelium-dependent regulation of vascular tone of bradykinin was investigated by simultaneously monitoring the changes in the cytosolic Ca2+ concentration and the force of smooth muscle in fura-2-loaded strips of the porcine renal artery with endothelium. During phenylephrine-induced sustained contraction, bradykinin (>3×10−9 M) caused endothelium-dependent triphasic changes in the force of the strips, composed of an initial relaxation, a subsequent transient contraction and a late sustained relaxation. At low concentrations (10−10–10−9 M), bradykinin caused an endothelium-dependent biphasic relaxation with no contraction. A thromboxane A2 (TXA2)/prostaglandin H2 (PGH2) receptor antagonist (10−5 M ONO-3708) completely inhibited, while a TXA2 synthase inhibitor (10−5 M OKY-046) only partially inhibited, the transient contraction induced by bradykinin. Under conditions where the bradykinin-induced contraction was inhibited by ONO-3708 during the phenylephrine-induced contraction, bradykinin induced only a transient relaxation in the presence of NΩ-nitro-L-arginine methyl ester (L-NAME). This transient relaxation was inhibited when the precontraction was initiated by phenylephrine plus 40 mM extracellular K+. The removal of L-NAME from this condition caused a partial reappearance of the initial relaxation and a complete reappearance of the sustained relaxation. In conclusion, bradykinin caused the endothelium-dependent triphasic regulation of vascular tone in the porcine renal artery. The concentrations of bradykinin required to induce a contraction was higher than that required to induce relaxation. Both TXA2 and PGH2 were involved in the bradykinin-induced contraction. The initial relaxation was mediated by nitric oxide and hyperpolarizing factors while the sustained relaxation depended on nitric oxide. PMID:10696094

Recombinant heat shock protein 27 (HSP27/HSPB1) protects against cadmium-induced oxidative stress and toxicity in human cervical cancer cells.

PubMed

Alvarez-Olmedo, Daiana G; Biaggio, Veronica S; Koumbadinga, Geremy A; Gómez, Nidia N; Shi, Chunhua; Ciocca, Daniel R; Batulan, Zarah; Fanelli, Mariel A; O'Brien, Edward R

2017-05-01

Cadmium (Cd) is a carcinogen with several well-described toxicological effects in humans, but its molecular mechanisms are still not fully understood. Overexpression of heat shock protein 27 (HSP27/HSPB1)-a multifunctional protein chaperone-has been shown to protect cells from oxidative damage and apoptosis triggered by Cd exposure. The aims of this work were to investigate the potential use of extracellular recombinant HSP27 to prevent/counteract Cd-induced cellular toxicity and to evaluate if peroxynitrite was involved in the development of Cd-induced toxicity. Here, we report that the harmful effects of Cd correlated with changes in oxidative stress markers: upregulation of reactive oxygen species, reduction in nitric oxide (NO) bioavailability, increment in lipid peroxidation, peroxynitrite (PN), and protein nitration; intracellular HSP27 was reduced. Treatments with Cd (100 μM) for 24 h or with the peroxynitrite donor, SIN-1, decreased HSP27 levels (~50%), suggesting that PN formation is responsible for the reduction of HSP27. Pre-treatments of the cells either with Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME) (a pharmacological inhibitor of NO synthase) or with recombinant HSP27 (rHSP27) attenuated the disruption of the cellular metabolism induced by Cd, increasing in a 55 and 52%, respectively, the cell viability measured by CCK-8. Cd induced necrotic cell death pathways, although apoptosis was also activated; pre-treatment with L-NAME or rHSP27 mitigated cell death. Our findings show for the first time a direct relationship between Cd-induced toxicity and PN production and a role for rHSP27 as a potential therapeutic agent that may counteract Cd toxicity.

Relationship between changes in the cochlear blood flow and disorder of hearing function induced by blast injury in guinea pigs.

PubMed

Chen, Wei; Wang, Jianmin; Chen, Jing; Chen, Jichuan; Chen, Zhiqiang

2013-01-01

The auditory system is the most susceptible to damages from blast waves. Blast injuries always lead to varying degrees of hearing impairment. Although a disorder of the cochlear blood flow (CoBF) has been considered to be related to many pathological processes of the auditory system and to contribute to various types of hearing loss, changes in the CoBF induced by blast waves and the relationship between such changes and hearing impairment are undefined. To observe the changes in the cochlear microcirculation after exposure to an explosion blast, investigate the relationship between changes in the CoBF and hearing impairment and subsequently explore the mechanism responsible for the changes in the CoBF, we detected the perfusion of the cochlear microcirculation and hearing threshold shift after exposure to an explosion blast. Then, an N-nitro-L-arginine-methyl ester (L-NAME, NO synthase inhibitor) solution and artificial perilymph were applied to the round window (RW) of the cochlea before the blast exposure, followed by an evaluation of the CoBF and hearing function. The results indicated that the changes in the CoBF were correlated to the strength of the blast wave. The cochlear blood flow significantly increased when the peak value of the blast overpressure was greater than approximately 45 kPa, and there was no significant change in the cochlear blood flow when the peak value of the blast overpressure was less than approximately 35 kPa. Following local administration of the NO synthase inhibitor L-NAME, the increase in the CoBF induced by the blast was inhibited, and this reduction was significantly associated with the hearing threshold.

Nicorandil improves post-fatigue tension in slow skeletal muscle fibers by modulating glutathione redox state.

PubMed

Sánchez-Duarte, E; Trujillo, X; Cortés-Rojo, C; Saavedra-Molina, A; Camargo, G; Hernández, L; Huerta, M; Montoya-Pérez, R

2017-04-01

Fatigue is a phenomenon in which force reduction has been linked to impairment of several biochemical processes. In skeletal muscle, the ATP-sensitive potassium channels (K ATP ) are actively involved in myoprotection against metabolic stress. They are present in sarcolemma and mitochondria (mitoK ATP channels). K + channel openers like nicorandil has been recognized for their ability to protect skeletal muscle from ischemia-reperfusion injury, however, the effects of nicorandil on fatigue in slow skeletal muscle fibers has not been explored, being the aim of this study. Nicorandil (10 μM), improved the muscle function reversing fatigue as increased post-fatigue tension in the peak and total tension significantly with respect to the fatigued condition. However, this beneficial effect was prevented by the mitoK ATP channel blocker 5-hydroxydecanoate (5-HD, 500 μM) and by the free radical scavenger N-2-mercaptopropionyl glycine (MPG, 1 mM), but not by the nitric oxide (NO) synthase inhibitor Nω-nitro-L-arginine methyl ester (L-NAME, 100 μM). Nicorandil also decreased lipid peroxidation and maintained both reduced glutathione (GSH) levels and an elevated GSH/GSSG ratio, whereas total glutathione (TGSH) remained unaltered during post-fatigue tension. In addition, NO production, measured through nitrite concentrations was significantly increased with nicorandil during post-fatigue tension; this increase remained unaltered in the presence of nicorandil plus L-NAME, nonetheless, this effect was reversed with nicorandil plus MPG. Hence, these results suggest that nicorandil improves the muscle function reversing fatigue in slow skeletal muscle fibers of chicken through its effects not only as a mitoK ATP channel opener but also as NO donor and as an antioxidant.

Mechanisms of Nattokinase in protection of cerebral ischemia.

PubMed

Ji, Hongrui; Yu, Liang; Liu, Keyu; Yu, Zhigang; Zhang, Qian; Zou, Fengjuan; Liu, Bo

2014-12-15

In vivo, the level of cyclic Adenosine Monophosphate (cAMP) and the pathway of the Janus Kinase1/Signal Transducers and Activators of Transcription1 (JAK1/STAT1) were studied. In vitro, the Ca(2+) mobilization in human platelet stimulated by thrombin was observed. In addition, vasomotion of vascular smooth muscle was measured by adding KCl or norepinephrine(NE) under the Ca(2+) contained bath solutions. The effect induced by NE in the presence of N-nitro-L-arginine methyl ester (L-NAME) or indometacin (Indo) was also detected. At last, the levels of tissue plasminogen activator (t-PA) and Plasminogen activator inhibitor-1 (PAI-1) in cultured supernatans in Human umbilical vein endothelial cells (Huvecs) were measured by means of ELISA kit. Results showed that Nattokinase (NK) significantly increased the cAMP level, activated the signal passage of JAK1/STAT1 in injured part and inhibited remarkably the rise of platelet intracellular Ca(2+) ([Ca(2+)]i) in human platelet. Furthermore, NK relaxed rat thoracic aortic artery in the dose-dependent manner and in the endothelium dependent manner and its effect could be attenuated by L-NAME. Also, the secretion of t-PA and PAI-1 were reduced stimulated by Adr on Huvecs. These data indicated that the neuroprotective effect of NK was associated with its antiplatelet activity by elevating cAMP level and attenuating the calcium release from calcium stores; with its anti-apoptotic effect through the activation of JAK1/STAT1 pathway; with its relaxing vascular smooth muscle by promoting synthesis and release of NO, reducing ROC calcium ion influx and with its protection on endothelial cells through increasing fibrinolytic activity and facilitating spontaneous thrombolysis. Copyright © 2014 Elsevier B.V. All rights reserved.

Magnesium sulfate versus esomeprazole impact on the neonates of preeclamptic rats.

PubMed

Shafik, Amani N; Khattab, Mahmoud A; Osman, Ahmed H

2018-06-01

Preeclampsia represents a major complication of pregnancy, associated with greater maternal and fetal complications. We compared the effects of esomeprazole (a proton pump inhibitor) and magnesium sulfate (MgSO4) on the deleterious effects observed on the mother and neonates in experimentally induced preeclampsia in rats. Preeclampsia was induced in pregnant rats with NG-nitro-l-arginine methyl ester (L-NAME) starting from day 10-till end of pregnancy. Pregnant rats were divided into four groups: control pregnant; untreated preeclampsia; preeclamptic rats treated with MgSO4 and preeclamptic treated with esomeprazole. Treatment was started on day 14 and continued until end of pregnancy. Systolic blood pressure, gestation duration, the total number of pups/fetal resorption, pups birth weight, and histopathology examination of the pup's organs were recorded. In comparison with the L-NAME group, the MgSO4 and esomeprazole treatment reduced the values of systolic blood pressure; MgSO4 normalized gestational duration while esomeprazole prolonged it (post-term pregnancy); both restored number of delivered pups; with no statistical differences between the numbers of died pups between the four groups studied while with esomeprazole, out of 10 pregnant females, 2 of them had complete intrauterine fetal resorption; esomeprazole normalized birth weight and histological structure of fetal liver, kidney, and brain. On the other side, MgSO4 treatment gave rise to lower than normal birth weight and minimal tissue damage. Esomeprazole and MgSO4 improved systolic blood pressure, prevented preterm labor and restored numbers of pups delivered and fetal weight. Esomeprazole prolonged gestational period post-term with subsequent improving reproductive outcome. Copyright © 2018 Elsevier B.V. All rights reserved.

Antinociception after both peripheral and intrathecal injection of oxotremorine is modulated by spinal nitric oxide.

PubMed

Machelska, H; Pavone, F; Capone, F; Przewłocka, B

1999-03-01

The present study investigated the role of spinal nitric oxide (NO) in the antinociception induced by intraperitoneal (i.p.) and intrathecal (i.th.) injection of oxotremorine. The experiments were carried out on male Wistar rats, which had cannulas chronically implanted in the lumbar enlargement of the spinal cord. Antinociceptive effects were evaluated using a tail-flick and a paw pressure test. To raise the spinal NO level, the rats received the NO donor, 3-morpholino-sydnonimine (SIN-1, 10 and 100 microg/5 microl); to lower the NO level, the inhibitor of NO synthase, N-nitro-L-arginine methyl ester (L-NAME, 50 and 400 microg/5 microl), was administered. Both those substances were injected i.th. Systemic injections of oxotremorine (0.02 and 0.1 mg/kg) produced a significant increase in the thermal nociceptive threshold, while the mechanical threshold was affected only by the higher dose (0.1 mg/kg) of the muscarinic agonist. I.th. injections of oxotremorine (0.1 ng, 1 ng, 1 microg/5 microl) produced significant antinociception in both those tests. I.th. administration of SIN-1 in doses which themselves did not affect the nociceptive threshold antagonized both the peripheral and central oxotremorine antinociception. I.th. administration of L-NAME (50 and 400 microg/5 microl) did not change the nociceptive threshold, but dose-dependently potentiated the effects of oxotremorine injected i.p. in both tests; however, the effect of i.th. administration of oxotremorine was potentiated only in the tail-flick test. Our results demonstrate that irrespective of the way of its injection, the antinociceptive effect of oxotremorine is modulated by activity of the spinal NO. Moreover, our results further support the hypothesis that NO present in the spinal cord exerts pronociceptive effects.

Gastroprotective activity of ferruginol in mice and rats: effects on gastric secretion, endogenous prostaglandins and non-protein sulfhydryls.

PubMed

Areche, Carlos; Theoduloz, Cristina; Yáñez, Tania; Souza-Brito, Alba R M; Barbastefano, Víctor; de Paula, Débora; Ferreira, Anderson L; Schmeda-Hirschmann, Guillermo; Rodríguez, Jaime A

2008-02-01

The gastroprotective mechanism of the natural diterpene ferruginol was assessed in mice and rats. The involvement of gastric prostaglandins (PGE(2)), reduced glutathione, nitric oxide or capsaicin receptors was evaluated in mice either treated or untreated with indometacin, N-ethylmaleimide (NEM), N-nitro-L-arginine methyl ester (L-NAME) or ruthenium red, respectively, and then orally treated with ferruginol or vehicle. Gastric lesions were induced by oral administration of ethanol. The effects of ferruginol on the parameters of gastric secretion were assessed in pylorus-ligated rats. Gastric PGE(2) content was determined in rats treated with ferruginol and/or indometacin. The reduction of gastric glutathione (GSH) content was determined in rats treated with ethanol after oral administration of ferruginol, lansoprazole or vehicle. Finally, the acute oral toxicity was assessed in mice. Indometacin reversed the gastroprotective effect of ferruginol (25 mg kg(-1)) but not NEM, ruthenium red or L-NAME. The diterpene (25 mg kg(-1)) increased the gastric juice volume and its pH value, and reduced the titrable acidity but was devoid of effect on the gastric mucus content. Ferruginol (25, 50 mg kg(-1)) increased gastric PGE(2) content in a dose-dependent manner and prevented the reduction in GSH observed due to ethanol-induced gastric lesions in rats. Single oral doses up to 3 g kg(-1) ferruginol did not elicit mortality or acute toxic effects in mice. Our results showed that ferruginol acted as a gastroprotective agent stimulating the gastric PGE(2) synthesis, reducing the gastric acid output and improving the antioxidant capacity of the gastric mucosa by maintaining the GSH levels.

Different natriuretic responses in obese and lean rats in response to nitric oxide reduction.

PubMed

Ambrozewicz, Marta A; Khraibi, Ali A; Simsek-Duran, Fatma; DeBose, Sophia C; Baydoun, Hind A; Dobrian, Anca D

2011-08-01

Nitric oxide (NO) is an important regulator of renal sodium transport and participates in the control of natriuresis and diuresis. In obesity, the nitric oxide bioavailability was reportedly reduced, which may contribute to the maintenance of hypertension. The aim of this study was to determine the effect of NO depletion on renal sodium handling in a model of diet-induced obesity hypertension. Obese hypertensive (obesity-prone (OP)) and lean normotensive (obesity-resistant (OR)) Sprague-Dawley rats were treated with 1.2 mg/kg/day N(G)-nitro-L-arginine-methyl ester (L-NAME) for 4 weeks to inhibit NO synthesis. Acute pressure natriuresis and diuresis were measured in response to an increase in perfusion pressure. NHE3 and Na(+), K(+)-ATPase protein expression were measured by Western blot and NHE3 activity was determined as the rate of pH change in brush border membrane vesicles. NHE3 membrane localization was determined by confocal microscopy. L-NAME did not significantly attenuate the natriuretic and diuretic responses to increases in renal perfusion pressure (RPP) in OP rats while inducing a significant reduction in OR rats. Following chronic NO inhibition, NHE3 protein expression and activity and Na(+), K(+)-ATPase protein expression were significantly increased in the OR but not in the OP group. Immunofluorescence studies indicated that the increase in NHE3 activity could be, at least in part, due to NHE3 membrane trafficking. Obese hypertensive rats have a weaker natriuretic response in response to NO inhibition compared to lean rats and the mechanism involves different regulation of the apical sodium exchanger NHE3 expression, activity, and trafficking.

Fluid replacement modulates oxidative stress- but not nitric oxide-mediated cutaneous vasodilation and sweating during prolonged exercise in the heat.

PubMed

McNeely, Brendan D; Meade, Robert D; Fujii, Naoto; Seely, Andrew J E; Sigal, Ronald J; Kenny, Glen P

2017-12-01

The roles of nitric oxide synthase (NOS), reactive oxygen species (ROS), and angiotensin II type 1 receptor (AT 1 R) activation in regulating cutaneous vasodilation and sweating during prolonged (≥60 min) exercise are currently unclear. Moreover, it remains to be determined whether fluid replacement (FR) modulates the above thermoeffector responses. To investigate, 11 young men completed 90 min of continuous moderate intensity (46% V̇o 2peak ) cycling performed at a fixed rate of metabolic heat production of 600 W (No FR condition). On a separate day, participants completed a second session of the same protocol while receiving FR to offset sweat losses (FR condition). Cutaneous vascular conductance (CVC) and local sweat rate (LSR) were measured at four intradermal microdialysis forearm sites perfused with: 1 ) lactated Ringer (Control); 2 ) 10 mM N G -nitro-l-arginine methyl ester (l-NAME, NOS inhibition); 3 ) 10 mM ascorbate (nonselective antioxidant); or 4 ) 4.34 nM losartan (AT 1 R inhibition). Relative to Control (71% CVC max at both time points), CVC with ascorbate (80% and 83% CVC max ) was elevated at 60 and 90 min of exercise during FR (both P < 0.02) but not at any time during No FR (all P > 0.31). In both conditions, CVC was reduced at end exercise with l-NAME (60% CVC max ; both P < 0.02) but was not different relative to Control at the losartan site (76% CVC max ; both P > 0.19). LSR did not differ between sites in either condition (all P > 0.10). We conclude that NOS regulates cutaneous vasodilation, but not sweating, irrespective of FR, and that ROS influence cutaneous vasodilation during prolonged exercise with FR. Copyright © 2017 the American Physiological Society.

Nitric oxide-dependent modulation of sympathetic neural control of oxygenation in exercising human skeletal muscle

PubMed Central

Chavoshan, Bahman; Sander, Mikael; Sybert, Troy E; Hansen, Jim; Victor, Ronald G; Thomas, Gail D

2002-01-01

Nitric oxide (NO) attenuates α-adrenergic vasoconstriction in contracting rodent skeletal muscle, but it is unclear if NO plays a similar role in human muscle. We therefore hypothesized that in humans, NO produced in exercising skeletal muscle blunts the vasoconstrictor response to sympathetic activation. We assessed vasoconstrictor responses in the microcirculation of human forearm muscle using near-infrared spectroscopy to measure decreases in muscle oxygenation during reflex sympathetic activation evoked by lower body negative pressure (LBNP). Experiments were performed before and after NO synthase inhibition produced by systemic infusion of NG-nitro-l-arginine methyl ester (l-NAME). Before l-NAME, LBNP at −20 mmHg decreased muscle oxygenation by 20 ± 2 % in resting forearm and by 2 ± 3 % in exercising forearm (n = 20), demonstrating metabolic modulation of sympathetic vasoconstriction. As expected, l-NAME increased mean arterial pressure by 17 ± 3 mmHg, leading to baroreflex-mediated supression of baseline muscle sympathetic nerve activity (SNA). The increment in muscle SNA in response to LBNP at −20 mmHg also was attenuated after l-NAME (before, +14 ± 2; after, +8 ± 1 bursts min−1; n = 6), but this effect of l-NAME was counteracted by increasing LBNP to −40 mmHg (+19 ± 2 bursts min−1). After l-NAME, LBNP at −20 mmHg decreased muscle oxygenation similarly in resting (−11 ± 3 %) and exercising (−10 ± 2 %) forearm (n = 12). Likewise, LBNP at −40 mmHg decreased muscle oxygenation both in resting (−19 ± 4 %) and exercising (−21 ± 5 %) forearm (n = 8). These data advance the hypothesis that NO plays an important role in modulating sympathetic vasoconstriction in the microcirculation of exercising muscle, because such modulation is abrogated by NO synthase inhibition with l-NAME. PMID:11927694

Large BP-dependent and -independent differences in susceptibility to nephropathy after nitric oxide inhibition in Sprague-Dawley rats from two major suppliers

PubMed Central

Polichnowski, Aaron; Licea-Vargas, Hector; Picken, Maria; Long, Jianrui; Williamson, Geoffrey; Bidani, Anil

2012-01-01

The Nω-nitro-l-arginine methyl ester (l-NAME) model is widely employed to investigate the role of nitric oxide (NO) in renal injury. The present studies show that Sprague-Dawley rats from Harlan (H) and Charles River (CR) exhibit strikingly large differences in susceptibility to l-NAME nephropathy. After 4 wk of l-NAME (∼50 mg·kg−1·day−1 in drinking water), H rats (n = 13) exhibited the expected hypertension [average radiotelemetric systolic blood pressure (BP), 180 ± 3 mmHg], proteinuria (136 ± 17 mg/24 h), and glomerular injury (GI) (12 ± 2%). By contrast, CR rats developed less hypertension (142 ± 4), but surprisingly no proteinuria or GI, indicating a lack of glomerular hypertension. Additional studies showed that conscious H, but not CR, rats exhibit dose-dependent renal vasoconstriction after l-NAME. To further investigate these susceptibility differences, l-NAME was given 2 wk after 3/4 normotensive nephrectomy (NX) and comparably impaired renal autoregulation in CR-NX and H-NX rats. CR-NX rats, nevertheless, still failed to develop proteinuria and GI despite moderate hypertension (144 ± 2 mmHg, n = 29). By contrast, despite an 80–90% l-NAME dose reduction and lesser BP increases (169 ± 4 mmHg), H-NX rats (n = 20) developed greater GI (26 ± 3%) compared with intact H rats. Linear regression analysis showed significant (P < 0.01) differences in the slope of the relationship between BP and GI between H-NX (slope 0.56 ± 0.14; r = 0.69; P < 0.008) and CR-NX (slope 0.09 ± 0.06; r = 0.29; P = 0.12) rats. These data indicate that blunted BP responses to l-NAME in the CR rats are associated with BP-independent resistance to nephropathy, possibly mediated by a resistance to the renal (efferent arteriolar) vasoconstrictive effects of NO inhibition. PMID:21937607

Role of nitric oxide in long-term potentiation of the rat medial vestibular nuclei.

PubMed

Grassi, S; Pettorossi, V E

2000-01-01

In rat brainstem slices, we investigated the role of nitric oxide in long-term potentiation induced in the ventral portion of the medial vestibular nuclei by high-frequency stimulation of the primary vestibular afferents. The nitric oxide scavenger [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide ] and the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester were administered before and after induction of potentiation. Both drugs completely prevented long-term potentiation, whereas they did not impede the potentiation build-up, or affect the already established potentiation. These results demonstrate that the induction, but not the maintenance of vestibular long-term potentiation, depends on the synthesis and release into the extracellular medium of nitric oxide. In addition, we analysed the effect of the nitric oxide donor sodium nitroprusside on vestibular responses. Sodium nitroprusside induced long-term potentiation, as evidenced through the field potential enhancement and unit peak latency decrease. This potentiation was impeded by D, L-2-amino-5-phosphonopentanoic acid, and was reduced under blockade of synaptosomal platelet-activating factor receptors by ginkgolide B and group I metabotropic glutamate receptors by (R,S)-1-aminoindan-1, 5-dicarboxylic acid. When reduced, potentiation fully developed following the washout of antagonist, demonstrating an involvement of platelet-activating factor and group I metabotropic glutamate receptors in its full development. Potentiation induced by sodium nitroprusside was also associated with a decrease in the paired-pulse facilitation ratio, which persisted under ginkgolide B, indicating that nitric oxide increases glutamate release independently of platelet-activating factor-mediated presynaptic events. We suggest that nitric oxide, released after the activation of N-methyl-D-aspartate receptors, acts as a retrograde messenger leading to an enhancement of glutamate release to a sufficient level for triggering potentiation. Once the synaptic efficacy has changed, it becomes a long-lasting phenomenon only through a subsequent action of platelet-activating factor.

Cigarette smoke-inhibition of neurogenic bronchoconstriction in guinea-pigs in vivo: involvement of exogenous and endogenous nitric oxide

PubMed Central

Emms, Joanne C; Rogers, Duncan F

1997-01-01

We investigated the effect of acute inhalation of cigarette smoke on subsequent non-adrenergic, non-cholinergic (NANC) neural bronchoconstriction in anaesthetized guinea-pigs in vivo by use of pulmonary insufflation pressure (PIP) as an index of airway tone. The contribution of endogenous nitric oxide (NO) was investigated with the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME). The contribution of plasma exudation to the response was investigated with Evans blue dye as a plasma marker. Inhalation of 50 tidal volumes of cigarette smoke or air had no significant effect on baseline PIP. In the presence of propranolol and atropine (1 mg kg−1 each), electrical stimulation of the vagus nerves in animals given air 30 min previously induced a frequency-dependent increase in PIP above sham stimulated controls (16 fold increase at 2.5 Hz, 24 fold increase at 10 Hz). In contrast, in smoke-exposed animals, the increase in subsequent vagally-induced PIP was markedly less than in the air controls (90% less at 2.5 Hz, 76% less at 10 Hz). L-NAME (10 mg kg−1), given 10 min before air or smoke, potentiated subsequent vagally-induced (2.5 Hz) NANC bronchoconstriction by 338% in smoke-exposed animals, but had no significant effect in air-exposed animals. The inactive enantiomer D-NAME (10 mg kg−1) had no effect, and the potentiation by L-NAME was partially reversed by the NO-precursor L-arginine (100 mg kg−1). Vagal stimulation did not affect the magnitude of vagally-induced bronchoconstriction 30 min later. Cigarette smoke exposure reduced the magnitude of subsequent bronchoconstriction induced by neurokinin A (NKA) by 37% compared with the effect of NKA in air-exposed animals. L-NAME had no significant effect on the smoke-induced inhibition of NKA-induced bronchoconstriction. Vagally-induced plasma exudation in the main bronchi was greater in smoke-exposed animals compared with air-exposed animals (120% greater at 2.5 Hz, 82% greater at 10 Hz). We conclude that cigarette smoke-induced inhibition of subsequent NANC neurogenic bronchoconstriction is not associated with inhibition of airway plasma exudation and is mediated in part via exogenous smoke-derived NO, or another bronchoprotective molecule, and by endogenous NO. PMID:9375977

Impairment of endothelium-dependent relaxation of rat aortas by homocysteine thiolactone and attenuation by captopril.

PubMed

Liu, Yu-Hui; You, Yu; Song, Tao; Wu, Shu-Jing; Liu, Li-Ying

2007-08-01

To explore the effects of angiotensin-converting enzyme (ACE) inhibitors on endothelial dysfunction induced by homocysteine thiolactone (HTL). Both endothelium-dependent relaxation and nondependent relaxation of thoracic aortic rings in rats induced by acetylcholine (Ach) or sodium nitroprusside (SNP) and biochemical parameters including malondialdehyde (MDA) and nitric oxide (NO) were measured in rat isolated aorta. Exposure of aortic rings to HTL (3 to 30 mM) for 90 minutes made a significant inhibition of endothelium-dependent relaxation induced by Ach, decreased contents of NO, and increased MDA concentration in aortic tissue. After incubation of aortic rings with captopril (0.003 to 0.03 mM) attenuated the inhibition of endothelium-dependent relaxation (EDR) and significantly resisted the decrease of NO content and elevation of MDA concentration caused by HTL (30 mmol/L) in aortic tissues, a similarly protective effect was observed when the aortic rings were incubated with both N-acetylcysteine (0.05 mM). Treatment with enalaprilat (0.003 to 0.01 mM) made no significant difference with the HTL (30 mM) group regarding EDR, but enalaprilat (0.03 mM) and losartan (0.03 mM) could partly restore the EDR in response to HTL (30 mM). Captopril was more effective than enalaprilat and losartan in attenuation of the inhibition of on acetylcholine-stimulated aortic relaxation by HTL in the same concentration. Moreover, superoxide dismutase (SOD, 200 U/mL), which is a scavenger of superoxide anions, apocynin (0.03 mM), which is an inhibitor of NADPH oxidase, and l-Arginine (3 mmol/L), a precursor of nitric oxide (NO), could reduce HTL (30 mM)-induced inhibition of EDR. After pretreatment with not only the NO synthase inhibitor Nomega-nitro-l-arginine methyl ester (L-NAME, 0.01 mM) but also the free sulfhydryl group blocking agent p-hydroxymercurybenzoate (PHMB, 0.05 mM) could abolish the protection of captopril and N-acetylcysteine, respectively. These results suggest that mechanisms of endothelial dysfunction induced by HTL may include the decrease of NO and the generation of oxygen free radicals and that captopril can restore the inhibition of EDR induced by HTL in isolated rat aorta, which may be related to scavenging oxygen free radicals and may be sulfhydryl-dependent.

Effects of NO-modulating agents on the development of acute painful reaction in rats.

PubMed

Dyuizen, I V; Lamash, N E

2008-08-01

Painful reaction of rats to intraperitoneal injections of L-arginine, Nw-nitro-L-arginine, and agmatine was studied on the model of formalin-induced inflammation. All drugs exhibited a dubious effect on the patterns of nociceptive behavior depending on the phase of painful reaction. The dynamics of nitrate/nitrite content in animal blood and serum indicated the presence of NO-dependent and NO-independent components in the mechanisms of pharmacological effects of these drugs.

Anxiolytic effects of phosphodiesterase-2 inhibitors associated with increased cGMP signaling.

PubMed

Masood, Anbrin; Huang, Ying; Hajjhussein, Hassan; Xiao, Lan; Li, Hao; Wang, Wei; Hamza, Adel; Zhan, Chang-Guo; O'Donnell, James M

2009-11-01

Phosphodiesterase (PDE)-2 is a component of the nitric-oxide synthase (NOS)/guanylyl cyclase signaling pathway in the brain. Given recent evidence that pharmacologically induced changes in NO-cGMP signaling can affect anxiety-related behaviors, the effects of the PDE2 inhibitors (2-(3,4-dimethoxybenzyl)-7-det-5-methylimidazo-[5,1-f][1,2,4]triazin-4(3H)-one) (Bay 60-7550) and 3-(8-methoxy-1-methyl-2-oxo-7-phenyl-2,3-dihydro-1H-benzo[e][1,4]diazepin-5-yl)benzamide (ND7001), as well as modulators of NO, were assessed on cGMP signaling in neurons and on the behavior of mice in the elevated plus-maze, hole-board, and open-field tests, well established procedures for the evaluation of anxiolytics. Bay 60-7550 (1 microM) and ND7001 (10 microM) increased basal and N-methyl-d-aspartate- or detanonoate-stimulated cGMP in primary cultures of rat cerebral cortical neurons; Bay 60-7550, but not ND7001, also increased cAMP. Increased cGMP signaling, either by administration of the PDE2 inhibitors Bay 60-7550 (0.5, 1, and 3 mg/kg) or ND7001 (1 mg/kg), or the NO donor detanonoate (0.5 mg/kg), antagonized the anxiogenic effects of restraint stress on behavior in the three tests. These drugs also produced anxiolytic effects on behavior in nonstressed mice in the elevated plus-maze and hole-board tests; these effects were antagonized by the guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (20 mg/kg). By contrast, the NOS inhibitor N(omega)-nitro-l-arginine methyl ester (50 mg/kg), which reduces cGMP signaling, produced anxiogenic effects similar to restraint stress. Overall, the present behavioral and neurochemical data suggest that PDE2 may be a novel pharmacological target for the development of drugs for the treatment of anxiety disorders.

Agmatine enhances the anticonvulsant effect of lithium chloride on pentylenetetrazole-induced seizures in mice: Involvement of L-arginine/nitric oxide pathway.

PubMed

Bahremand, Arash; Ziai, Pouya; Khodadad, Tina Kabiri; Payandemehr, Borna; Rahimian, Reza; Ghasemi, Abbas; Ghasemi, Mehdi; Hedayat, Tina; Dehpour, Ahmad Reza

2010-07-01

After nearly 60years, lithium is still the mainstay in the treatment of mood disorders. In addition to its antimanic and antidepressant effects, lithium also has anticonvulsant properties. Similar to lithium, agmatine plays a protective role in the central nervous system against seizures and has been reported to enhance the effect of different antiepileptic agents. Moreover, both agmatine and lithium have modulatory effects on the L-arginine/nitric oxide pathway. This study was designed to investigate: (1) whether agmatine and lithium exert a synergistic effect against clonic seizures induced by pentylenetetrazole and (2) whether or not this synergistic effect is mediated through inhibition of the L-arginine/nitric oxide pathway. In our study, acute administration of a single potent dose of lithium chloride (30mg/kg ip) increased seizure threshold, whereas pretreatment with a low and independently noneffective dose of agmatine (3mg/kg) potentiated a subeffective dose of lithium (10mg/kg). N(G)-L-arginine methyl ester (L-NAME, nonspecific nitric oxide synthase inhibitor) at 1 and 5mg/kg and 7-nitroindazole (7-NI, preferential neuronal nitric oxide synthase inhibitor) at 15 and 30mg/kg augmented the anticonvulsant effect of the noneffective combination of lithium (10mg/kg ip) and agmatine (1mg/kg), whereas several doses (20 and 40mg/kg) of aminoguanidine (inducible nitric oxide synthase inhibitor) failed to alter the seizure threshold of the same combination. Furthermore, pretreatment with independently noneffective doses (30 and 60mg/kg) of L-arginine (substrate for nitric oxide synthase) inhibited the potentiating effect of agmatine (3mg/kg) on lithium (10mg/kg). Our findings demonstrate that agmatine and lithium chloride have synergistic anticonvulsant properties that may be mediated through the L-arginine/nitric oxide pathway. In addition, the role of constitutive nitric oxide synthase versus inducible nitric oxide synthase is prominent in this phenomenon. Copyright 2010 Elsevier Inc. All rights reserved.

Effects of Nitric Oxide Synthase Inhibition on Fiber-Type Composition, Mitochondrial Biogenesis, and SIRT1 Expression in Rat Skeletal Muscle

PubMed Central

Suwa, Masataka; Nakano, Hiroshi; Radak, Zsolt; Kumagai, Shuzo

2015-01-01

It was hypothesized that nitric oxide synthases (NOS) regulated SIRT1 expression and lead to a corresponding changes of contractile and metabolic properties in skeletal muscle. The purpose of the present study was to investigate the influence of long-term inhibition of nitric oxide synthases (NOS) on the fiber-type composition, metabolic regulators such as and silent information regulator of transcription 1 (SIRT1) and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), and components of mitochondrial biogenesis in the soleus and plantaris muscles of rats. Rats were assigned to two groups: control and NOS inhibitor (Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME), ingested for 8 weeks in drinking water)-treated groups. The percentage of Type I fibers in the L-NAME group was significantly lower than that in the control group, and the percentage of Type IIA fibers was concomitantly higher in soleus muscle. In plantaris muscle, muscle fiber composition was not altered by L-NAME treatment. L-NAME treatment decreased the cytochrome C protein expression and activity of mitochondrial oxidative enzymes in the plantaris muscle but not in soleus muscle. NOS inhibition reduced the SIRT1 protein expression level in both the soleus and plantaris muscles, whereas it did not affect the PGC-1α protein expression. L-NAME treatment also reduced the glucose transporter 4 protein expression in both muscles. These results suggest that NOS plays a role in maintaining SIRT1 protein expression, muscle fiber composition and components of mitochondrial biogenesis in skeletal muscle. Key points NOS inhibition by L-NAME treatment decreased the SIRT1 protein expression in skeletal muscle. NOS inhibition induced the Type I to Type IIA fiber type transformation in soleus muscle. NOS inhibition reduced the components of mitochondrial biogenesis and glucose metabolism in skeletal muscle. PMID:26336341

Fatty Acid Oxidation Changes and the Correlation with Oxidative Stress in Different Preeclampsia-Like Mouse Models

PubMed Central

Ding, Xiaoyan; Yang, Zi; Han, Yiwei; Yu, Huan

2014-01-01

Background Long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) expression is decreased in placenta of some cases of preeclampsia (PE) which may result in free fatty acid (FFA) increased. High FFA level will induce oxidative stress, so abnormal long-chain fatty acid-oxidation may participate in the pathogenesis of PE through oxidative stress pathway. Methods PE-like groups were ApoC3 transgenic mice with abnormal fatty acid metabolism, classical PE-like models with injection of Nw-nitro-L-arginine-methyl ester (L-NA) or lipopolysaccharide (LPS) and the antiphospholipid syndrome (APS) mouse model with β2GPI injection (ApoC3+NS, ApoC3+L-NA, L-NA, LPS and β2GPI groups). The control group was wild-type mice with normal saline injection. Except for β2GPI mice, the other mice were subdivided into pre-implantation (Pre) and mid-pregnancy (Mid) subgroups by injection time. Results All PE-like groups showed hypertension and proteinuria except ApoC3+NS mice only showed hypertension. Serum FFA levels increased significantly except in LPS group compared to controls (P<0.05). LCHAD mRNA and protein expression in the liver and placenta was significantly higher for ApoC3+NS, ApoC3+L-NA and β2GPI mice and lower for L-NA mice than controls (P<0.05) but did not differ between LPS mice and controls. P47phox mRNA and protein expression in the liver significantly increased in all PE-like groups except LPS group, while P47phox expression in the placenta only significantly increased in L-NA and β2GPI groups. Conclusions Abnormal long-chain fatty acid-oxidation may play a different role in different PE-like models and in some cases participate in the pathogenesis of PE through oxidative stress pathway. PMID:25302499

Hypersensitivity of prediabetic JCR:LA-cp rats to fine airborne combustion particle-induced direct and noradrenergic-mediated vascular contraction.

PubMed

Proctor, Spencer D; Dreher, Kevin L; Kelly, Sandra E; Russell, James C

2006-04-01

Particulate matter with mean aerodynamic diameter < or =2.5 microm (PM(2.5)), from diesel exhaust, coal or residual oil burning, and from industrial plants, is a significant component of airborne pollution. Type 2 diabetes is associated with enhanced risk of adverse cardiovascular events following exposure to PM(2.5). Particle properties, sources, and pathophysiological mechanisms responsible are unknown. We studied effects of residual oil fly ash (ROFA) from a large U.S. powerplant on vascular function in a prediabetic, hyperinsulinemic model, the JCR:LA-cp rat. Residual oil fly ash leachate (ROFA-L) was studied using aortic rings from young-adult, obese, insulin-resistant rats and lean normal rats in vitro. Contractile response to phenylephrine and relaxant response to acetylcholine were determined in the presence and absence of L-NAME (N(G)-nitro-L-arginine methyl ester). In a separate series of studies, the direct contractile effects of ROFA-L on repeated exposure were determined. ROFA-L (12.5 microg ml(-1)) increased phenylephrine-mediated contraction in obese (p < 0.05), but not in lean rat aortae, with the effect being exacerbated by L-NAME, and it reduced acetylcholine-mediated relaxation of both obese and lean aortae (p < 0.0001). Initial exposure of aortae to ROFA-L caused a small contractile response (<0.05 g), which was markedly greater on second exposure in the obese (approximately 0.6 g, p < 0.0001) aortae but marginal in lean (approximately 0.1 g) aortae. Our data demonstrate that bioavailable constituents of oil combustion particles enhance noradrenergic-mediated vascular contraction, impair endothelium-mediated relaxation, and induce direct vasocontraction in prediabetic rats. These observations provide the first direct evidence of the causal properties of PM(2.5) and identify the pathophysiological role of the early prediabetic state in susceptibility to environmentally induced cardiovascular disease. These are important implications for public health and public policy.

Cyclooxygenase inhibition does not alter methacholine-induced sweating

PubMed Central

Fujii, Naoto; McGinn, Ryan; Paull, Gabrielle; Stapleton, Jill M.; Meade, Robert D.

2014-01-01

Cholinergic agents (e.g., methacholine) induce cutaneous vasodilation and sweating. Reports indicate that either nitric oxide (NO), cyclooxygenase (COX), or both can contribute to cholinergic cutaneous vasodilation. Also, NO is reportedly involved in cholinergic sweating; however, whether COX contributes to cholinergic sweating is unclear. Forearm sweat rate (ventilated capsule) and cutaneous vascular conductance (CVC, laser-Doppler perfusion units/mean arterial pressure) were evaluated in 10 healthy young (24 ± 4 yr) adults (7 men, 3 women) at four skin sites that were continuously perfused via intradermal microdialysis with 1) lactated Ringer (control), 2) 10 mM ketorolac (a nonselective COX inhibitor), 3) 10 mM NG-nitro-l-arginine methyl ester (l-NAME, a nonselective NO synthase inhibitor), or 4) a combination of 10 mM ketorolac + 10 mM l-NAME. At the four skin sites, methacholine was simultaneously infused in a dose-dependent manner (1, 10, 100, 1,000, 2,000 mM). Relative to the control site, forearm CVC was not influenced by ketorolac throughout the protocol (all P > 0.05), whereas l-NAME and ketorolac + l-NAME reduced forearm CVC at and above 10 mM methacholine (all P < 0.05). Conversely, there was no main effect of treatment site (P = 0.488) and no interaction of methacholine dose and treatment site (P = 0.711) on forearm sweating. Thus forearm sweating (in mg·min−1·cm−2) from baseline up to the maximal dose of methacholine was not different between the four sites (at 2,000 mM, control 0.50 ± 0.23, ketorolac 0.44 ± 0.23, l-NAME 0.51 ± 0.22, and ketorolac + l-NAME 0.51 ± 0.23). We show that both NO synthase and COX inhibition do not influence cholinergic sweating induced by 1–2,000 mM methacholine. PMID:25213633

Effects of chronic nitric oxide synthase inhibition on V'O2max and exercise capacity in mice.

PubMed

Wojewoda, M; Przyborowski, K; Sitek, B; Zakrzewska, A; Mateuszuk, L; Zoladz, J A; Chlopicki, S

2017-03-01

Acute inhibition of NOS by L-NAME (N ω -nitro-L-arginine methyl ester) is known to decrease maximal oxygen consumption (V'O 2max ) and impair maximal exercise capacity, whereas the effects of chronic L-NAME treatment on V'O 2max and exercise performance have not been studied so far. In this study, we analysed the effect of L-NAME treatment, (LN2 and LN12, respectively) on V'O 2max and exercise capacity (in maximal incremental running and prolonged sub-maximal incremental running tests), systemic NO bioavailability (plasma nitrite (NO 2 - ) and nitrate (NO 3 - )) and prostacyclin (PGI 2 ) production in C57BL6/J mice. Mice treated with L-NAME for 2 weeks (LN2) displayed higher V'O 2max and better running capacity than age-matched control mice. In LN2 mice, NO bioavailability was preserved, as evidenced by maintained NO 2 - plasma concentration. PGI 2 production was activated (increased 6-keto-PGF 1α plasma concentration) and the number of circulating erythrocytes (RBC) and haemoglobin concentration were increased. In mice treated with L-NAME for 12 weeks (LN12), NO bioavailability was decreased (lower NO 2 - plasma concentration), and 6-keto-PGF 1α plasma concentration and RBC number were not elevated compared to age-matched control mice. However, LN12 mice still performed better during the maximal incremental running test despite having lower V'O 2max . Interestingly, the LN12 mice showed poorer running capacity during the prolonged sub-maximal incremental running test. To conclude, short-term (2 weeks) but not long-term (12 weeks) treatment with L-NAME activated robust compensatory mechanisms involving preservation of NO2- plasma concentration, overproduction of PGI 2 and increased number of RBCs, which might explain the fully preserved exercise capacity despite the inhibition of NOS.

Grape seed proanthocyanidin extract attenuates oxidant injury in cardiomyocytes.

PubMed

Shao, Zuo-Hui; Becker, Lance B; Vanden Hoek, Terry L; Schumacker, Paul T; Li, Chang-Qing; Zhao, Danhong; Wojcik, Kim; Anderson, Travis; Qin, Yimin; Dey, Lucy; Yuan, Chun-Su

2003-06-01

This study sought to test whether grape seed proanthocyanidin extract (GSPE) attenuates exogenous and endogenous oxidant stress induced in chick cardiomyocytes and whether this cytoprotection is mediated by PKC activation, mito K(ATP) channel opening, NO production, oxidant scavenging, or iron chelating effects. Cells were exposed to hydrogen peroxide (H(2)O(2)) (exogenous oxidant stress, 0.5mM) or antimycin A (endogenous oxidant stress, 100 micro M) for 2h following pretreatment with GSPE at various concentrations for 2h. Cells were also pretreated with GSPE or with inhibitors of PKC (chelerytherine), mito K(ATP) channel (5-hydroxydecanoate), nitric oxide synthase (nitro-L-arginine methyl ester) for 2h. Oxidant stress was measured by 2',7'-dichlorofluorescin diacetate and cell viability was assessed using propidium iodide. Free radical scavenging and iron chelating ability was tested in vitro. GSPE dose-dependently attenuated oxidant formation and significantly improved cell survival and contractile function. However, inhibitors of PKC, mito K(ATP) channel or NO synthase failed to abolish the protective action of GSPE during H(2)O(2) or antimycin A exposure. In vitro studies suggested that GSPE scavenges H(2)O(2), hydroxyl radical and superoxide, and may chelate iron. These results indicate that GSPE confers cardioprotection against exogenous H(2)O(2)- or antimycin A-induced oxidant injury. Its effect does not require PKC, mito K(ATP) channel, or NO synthase, presumably because it acts by reactive oxygen species scavenging and iron chelating directly.

Mesenchymal stem cell-conditioned medium triggers neuroinflammation and reactive species generation in organotypic cultures of rat hippocampus.

PubMed

Horn, Ana Paula; Bernardi, Andressa; Luiz Frozza, Rudimar; Grudzinski, Patrícia Bencke; Hoppe, Juliana Bender; de Souza, Luiz Fernando; Chagastelles, Pedro; de Souza Wyse, Angela Terezinha; Bernard, Elena Aida; Battastini, Ana Maria Oliveira; Campos, Maria Martha; Lenz, Guido; Nardi, Nance Beyer; Salbego, Christianne

2011-07-01

Cell therapy using bone marrow-derived mesenchymal stem cells (MSCs) seems to be a new alternative for the treatment of neurodegenerative diseases. Despite several promising results with their use, possible side effects are still unknown. In a previous work, we have shown that MSC-conditioned medium is toxic to hippocampal slice cultures and aggravates cell death induced by oxygen and glucose deprivation. In this work, we investigated whether the inflammatory response and/or reactive species formation could be involved in that toxicity. Rat organotypic hippocampal cultures were exposed for 24 h to conditioned medium from MSCs isolated from rat bone marrow. A marked glial activation was observed after exposure of cultures to MSC-conditioned medium, as evidenced by glial fibrillary acid protein (GFAP) and isolectin B(4) increase. Tumor necrosis factor-α and interleukin-6 levels were increased in the culture medium, and 2,7-dihydrodichlorofluorescein diacetate oxidation (indicating reactive species generation) and inducible nitric oxide synthase (iNOS) immunocontent were also higher after exposure of cultures to MSC-conditioned medium. Antioxidants (ascorbic acid and TROLOX(®)), N(ω)-nitro-l-arginine methyl ester hydrochloride, and anti-inflammatory drugs (indomethacin and dexamethasone) reduced cell death in hippocampal organotypic cultures after their exposure to MSC-conditioned medium. The results obtained here suggest that MSC-secreted factors trigger reactive species generation and neuroinflammation in organotypic cultures of hippocampus, introducing a note of caution in the use of these cells for neurological application.

Identification of the Muscarinic Acetylcholine Receptor Subtype Mediating Cholinergic Vasodilation in Murine Retinal Arterioles

PubMed Central

Sniatecki, Jan J.; Goloborodko, Evgeny; Steege, Andreas; Zavaritskaya, Olga; Vetter, Jan M.; Grus, Franz H.; Patzak, Andreas; Wess, Jürgen; Pfeiffer, Norbert

2011-01-01

Purpose. To identify the muscarinic acetylcholine receptor subtype that mediates cholinergic vasodilation in murine retinal arterioles. Methods. Muscarinic receptor gene expression was determined in murine retinal arterioles using real-time PCR. To assess the functional relevance of muscarinic receptors for mediating vascular responses, retinal vascular preparations from muscarinic receptor–deficient mice were studied in vitro. Changes in luminal arteriole diameter in response to muscarinic and nonmuscarinic vasoactive substances were measured by video microscopy. Results. Only mRNA for the M3 receptor was detected in retinal arterioles. Thus, M3 receptor–deficient mice (M3R−/−) and respective wild-type controls were used for functional studies. Acetylcholine concentration-dependently dilated retinal arterioles from wild-type mice. In contrast, vasodilation to acetylcholine was almost completely abolished in retinal arterioles from M3R−/− mice, whereas responses to the nitric oxide (NO) donor nitroprusside were retained. Carbachol, an acetylcholinesterase-resistant analog of acetylcholine, also evoked dilation in retinal arterioles from wild-type, but not from M3R−/−, mice. Vasodilation responses from wild-type mice to acetylcholine were negligible after incubation with the non–subtype-selective muscarinic receptor blocker atropine or the NO synthase inhibitor Nω-nitro-l-arginine methyl ester, and were even reversed to contraction after endothelial damage with 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate. Conclusions. These findings provide evidence that endothelial M3 receptors mediate cholinergic vasodilation in murine retinal arterioles via activation of NO synthase. PMID:21873683

Bidirectional regulation of human colonic smooth muscle contractility by tachykinin NK(2) receptors.

PubMed

Nakamura, Akihiro; Tanaka, Takahiro; Imanishi, Akio; Kawamoto, Makiko; Toyoda, Masao; Mizojiri, Gaku; Tsukimi, Yasuhiro

2011-01-01

In this study, we attempted to clarify the mechanism of tachykinin-induced motor response in isolated smooth muscle preparations of the human colon. Fresh specimens of normal colon were obtained from patients suffering from colonic cancer. Using mucosa-free smooth muscle strips, smooth muscle tension with circular direction was monitored isometrically. Substance P (SP), neurokinin A (NKA), and neurokinin B (NKB) produced marked contraction. All of these contractions were inhibited by saredutant, a selective NK(2)-R antagonist, but not by CP122721, a selective NK(1)-R antagonist or talnetant, a selective NK(3)-R antagonist. βAla(8)-NKA(4-10) induced concentration-dependent contraction similar to NKA, but Sar(9)-Met(11)-SP and Met-Phe(7)-NKB did not cause marked contraction. Colonic contraction induced by βAla(8)-NKA(4-10) was completely blocked by saredutant, but not by atropine. Tetrodotoxin or N(G)-nitro-L-arginine methyl ester pretreatment significantly enhanced βAla(8)-NKA(4-10)-induced contraction. Immunohistochemical analysis showed that the NK(2)-R was expressed on the smooth muscle layers and myenteric plexus where it was also co-expressed with neuronal nitric oxide synthase in the myenteric plexus. These results suggest that the NK(2)-R is a major contributor to tachykinin-induced smooth muscle contraction in human colon and that the NK(2)-R-mediated response consists of an excitatory component via direct action on the smooth muscle and an inhibitory component possibly via nitric oxide neurons.

Effect of N-acetylcysteine on vascular endothelium function in aorta from oophorectomized rats.

PubMed

Delgado, J L; Landeras, J; Carbonell, L F; Parilla, J J; Abad, L; Quesada, T; Fiol, G; Hernández, I

1999-01-01

1. Experiments were performed to examine and to compare vascular endothelial function in aortic rings from oophorectomized and from ovary-intact rats and to test the effect of thiol compound as N-acetylcysteine on endothelial function. 2. In precontracted aortic rings from oophorectomized and intact rats, vascular endothelial function was evaluated by measuring changes in isometric force in response to cumulative doses of superoxide dismutase, acetylcholine and sodium nitroprusside. 3. In studies designed to assess the tone-related release of nitric oxide from aortic rings moderately precontracted with phenylephrine, superoxide dismutase produced a lower concentration-related relaxant response in aortic rings from oophorectomized rats than from ovary intact rats. 4. Acetylcholine caused a concentration- and endothelium-dependent relaxation of less magnitude in aortic rings from oophorectomized animals compared with those from ovary-intact rats. Addition of N-omega-nitro-L-arginine methyl ester eliminated the relaxation induced by both superoxide dismutase and acetylcholine. 5. No differences between groups were noticed in the concentration-relaxation curve induced by sodium nitroprusside. 6. Preincubation with N-acetylcysteine normalized the depressed vasorelaxant response to acetylcholine in the aortic rings from oophorectomized rats, whereas the concentration-response curve for acetylcholine in aortic rings from ovary-intact rats did not alter. 7. These results suggest that the absence of ovary estrogens is associated with a vascular endothelium dysfunction that can be reverted by addition of N-acetylcysteine, a thiol-containing compound with a free radical scavenger effect.

Mechanism of thrombin-induced vasodilation in human coronary arterioles.

PubMed

Bosnjak, John J; Terata, Ken; Miura, Hiroto; Sato, Atsushi; Nicolosi, Alfred C; McDonald, Monica; Manthei, Sara A; Saito, Takashi; Hatoum, Ossama A; Gutterman, David D

2003-04-01

Thrombin (Thromb), activated as part of the clotting cascade, dilates conduit arteries through an endothelial pertussis toxin (PTX)-sensitive G-protein receptor and releases nitric oxide (NO). Thromb also acts on downstream microvessels. Therefore, we examined whether Thromb dilates human coronary arterioles (HCA). HCA from right atrial appendages were constricted by 30-50% with endothelin-1. Dilation to Thromb (10(-4)-1 U/ml) was assessed before and after inhibitors with videomicroscopy. There was no tachyphylaxis to Thromb dilation (maximum dilation = 87.0%, ED(50) = 1.49 x 10(-2)). Dilation to Thromb was abolished with either hirudin or denudation but was not affected by PTX. Neither N(omega)-nitro-l-arginine methyl ester (n = 7), indomethacin (n = 9), (1)H-[1,2,4] oxadiazolo-[4,3-a]quinoxalin-1-one (n = 6), tetraethylammonium chloride (n = 5), nor iberiotoxin (n = 4) reduced dilation to Thromb. However, KCl (maximum dilation = 89 +/- 5 vs. 20 +/- 10%; P < 0.05; n = 7), tetrabutylammonium chloride (maximum dilation = 79 +/- 7 vs. 21 +/- 4%; P < 0.05; n = 5), and charybdotoxin (maximum dilation = 89 +/- 4 vs. 10 +/- 2%; P < 0.05; n = 4) attenuated dilation to Thromb. In contrast to animal models, Thromb-induced dilation in human arterioles is independent of G(i)-protein activation and NO release. However, Thromb dilation is endothelium dependent, is maintained on consecutive applications, and involves activation of K(+) channels. We speculate that an endothelium-derived hyperpolarizing factor contributes to Thromb-induced dilation in HCA.

Angiotensin-(1-7) augments endothelium-dependent relaxations of porcine coronary arteries to bradykinin by inhibiting angiotensin-converting enzyme 1.

PubMed

Raffai, Gábor; Khang, Gilson; Vanhoutte, Paul M

2014-05-01

Angiotensin-converting enzyme 2 (ACE2) converts angiotensin II to angiotensin-(1-7) that activates Mas receptors, inhibits ACE1, and modulates bradykinin receptor sensitivity. This in vitro study compared the direct and indirect effects of angiotensin-(1-7), the ACE1 inhibitor captopril, and diminazene aceturate (DIZE) an alleged ACE2 activator in rings of porcine coronary arteries, by measuring changes of isometric tension. Angiotensin-(1-7), captopril, and DIZE did not cause significant changes in tension before or after desensitization of bradykinin receptors in preparations contracted with U46619. Bradykinin caused concentration-dependent and endothelium-dependent relaxations that were not affected by DIZE but were potentiated to a similar extent by angiotensin-(1-7) and captopril, given alone or in combination. Bradykinin responses potentiated by angiotensin-(1-7) and captopril were not affected by the BK1 antagonist SSR240612 and remained augmented in the presence of either N-nitro-L-arginine methyl ester hydrochloride plus indomethacin or TRAM-34 plus UCL-1684. ACE2 was identified in the coronary endothelium by immunofluorescence, but its basal activity was not influenced by DIZE. These results suggest that in coronary arteries, angiotensin-(1-7) and captopril both improves NO bioavailability and enhances endothelium-dependent hyperpolarization to bradykinin solely by ACE1 inhibition. Endothelial ACE2 activity cannot be increased by DIZE to produce local adequate amounts of angiotensin-(1-7) to influence vascular tone.

A potential mechanism for the impairment of nitric oxide formation caused by prolonged oral exposure to arsenate in rabbits.

PubMed

Pi, Jingbo; Horiguchi, Satomi; Sun, Yang; Nikaido, Masatoshi; Shimojo, Nobuhiro; Hayashi, Toshio; Yamauchi, Hiroshi; Itoh, Ken; Yamamoto, Masayuki; Sun, Guifan; Waalkes, Michael P; Kumagai, Yoshito

2003-07-01

We have recently found evidence for impairment of nitric oxide (NO) formation and induction of oxidative stress in residents of an endemic area of chronic arsenic poisoning in Inner Mongolia, China. To investigate the underlying mechanisms responsible for these phenomena, a subchronic animal experiment was conducted using male New Zealand White rabbits. After 18 weeks of continuous exposure of rabbits to 5 mg/l of arsenate in drinking water, a significant decrease in systemic NO production occurred, as shown by significantly reduced plasma NO metabolites levels (76% of control) and a tendency towards decreased serum cGMP levels (81.4% of control). On the other hand, increased oxidative stress, as shown by significantly increased urinary hydrogen peroxide (H(2)O(2)) (120% of control), was observed in arsenate-exposed rabbits. In additional experiments measuring aortic tension, the addition of either the calcium ionophore A23187 or acethylcholine (ACh) induced a transient vasoconstriction of aortic rings prepared from arsenate-exposed rabbits, but not in those prepared from control animals. This calcium-dependent contractility action observed in aorta rings from arsenate-exposed rabbits was markedly attenuated by the superoxide (O2(.-)) scavenging enzyme Cu, Zn-SOD, as well as diphenyleneiodonium (DPI) or N(G)-nitro-L-arginine methyl ester (L-NAME), which are inhibitors for nitric oxide synthase (NOS). However, the cyclooxygenase inhibitor indomethacin or the xanthine oxidase blocker allopurinol had no effect on this vasoconstriction. These results suggest that arsenate-mediated reduction of systemic NO may be associated with the enzymatic uncoupling reaction of NOS with a subsequent enhancement of reactive oxygen species such as O2(.-), an endothelium-derived vasoconstricting factor. Furthermore, hepatic levels of (6R)-5,6,7,8-tetrahydro-L-biopterin (BH(4)), a cofactor for NOS, were markedly reduced in arsenate-exposed rabbits to 62% of control, while no significant change occurred in cardiac L-arginine levels. These results suggest that prolonged exposure of rabbits to oral arsenate may impair the bioavailability of BH(4) in endothelial cells and, as a consequence, disrupt the balance between NO and O2(.-) produced from endothelial NOS, such that enhanced free radicals are produced at the expense of NO.

Inactivation of Nitric Oxide Synthesis Exacerbates the Development of Alzheimer Disease Pathology in APPPS1 Mice (Amyloid Precursor Protein/Presenilin-1).

PubMed

Cifuentes, Diana; Poittevin, Marine; Bonnin, Philippe; Ngkelo, Anta; Kubis, Nathalie; Merkulova-Rainon, Tatyana; Lévy, Bernard I

2017-07-31

The epidemiological link between hypertension and Alzheimer disease is established. We previously reported that hypertension aggravates the Alzheimer-like pathology in APPPS1 mice (amyloid precursor protein/presenilin-1, mouse model of Alzheimer disease) with angiotensin II-induced hypertension, in relation with hypertension and nitric oxide deficiency. To provide further insights into the role of nitric oxide in the hypertension-Alzheimer disease cross-talk, we studied the effects of nitric oxide blockade in APPPS1 mice using N (ω)-nitro-l-arginine methyl ester (l-NAME) alone or in combination with hydralazine, to normalize blood pressure. Compared with normotensive APPPS1 mice, those with l-NAME-induced hypertension had greater amyloid burden ( P <0.05), increased cortical amyloid angiopathy ( P <0.01), decreased regional microvascular density ( P <0.05), and deficient long-term spatial reference memory ( P <0.001). Blood pressure normalization with hydralazine did not protect APPPS1 mice from l-NAME-induced deterioration except for cortical amyloid angiopathy, linked to hypertension-induced arterial wall remodeling. By testing the cerebrovascular response to hypercapnic breathing, we evidenced early functional impairment of cerebral vasomotor activity in APPPS1 mice. Whereas in control wild-type normotensive mice, carbon dioxide breathing resulted in 15±1.3% increase in the mean blood flow velocity ( P <0.001), paradoxical mild decrease (1.5±0.4%) was recorded in normotensive APPPS1 mice ( P <0.001). Carbon dioxide-induced decrease in mean blood flow velocity was not significantly modified in l-NAME-treated hypertensive APPPS1 mice (2.5±1.2%) and partly reversed to mild vasodilation by hydralazine (3.2±1.5%, P <0.01). These results suggest that impaired nitric oxide bioavailability exacerbates the pathophysiology of Alzheimer disease, essentially impacting amyloid load and cognitive impairment, independently of l-NAME-induced hypertension. Only cerebral amyloid angiopathy seems to be dependent on hypertension. © 2017 American Heart Association, Inc.

Impaired nitric oxide modulation of myocardial oxygen consumption in genetically cardiomyopathic hamsters.

PubMed

Loke, K E; Messina, E J; Mital, S; Hintze, T H

2000-12-01

We investigated the role of kinin and nitric oxide (NO) in the modulation of cardiac O(2)consumption in Syrian hamsters with overt heart failure (HF) and age-matched normal hamsters. Using echocardiography, the hamsters with heart failure had reduced ejection fraction [31(+/-8) v 76(+/-5)%] and LV dilation [4.9(+/-0. 2) v 5.7(+/-0.3) mm, both P<0.05 from normal]. O(2)consumption in the left ventricular free wall was measured using a Clark-type O(2)electrode in an air-tight chamber, containing Krebs solution buffered with Hepes (37 degrees C, pH 7.4). Concentration response curves to bradykinin (BK), ramiprilat (RAM), amlodipine (AMLO) and the NO donor, S -nitroso- N -acetyl-penicillamine (SNAP) were performed. Basal myocardial O(2)consumption was lower in the HF group compared to normal [316(+/-21) v 404(+/-36) nmol O(2)/min/g, respectively, P<0.05]. In the hearts from normal hamsters BK (10(-4)mol/l), RAM (10(-4)mol/l), and AMLO (10(-5)mol/l) all significantly reduced myocardial O(2)consumption by 42(+/-6)%, 29(+/-7)% and 27(+/-5)% respectively. This reduction was attenuated in the presence of N -nitro- l -arginine methyl ester (l -NAME) [BK: 3.3(+/-1.5)%, RAM: 3.3(+/-1.2)%, AMLO: 2.3(+/-1.2)%, P<0.05]. Interestingly in the hearts from HF group, BK, RAM and AMLO caused a significantly smaller reduction in myocardial O(2)consumption [10(+/-2)%, 2.5(+/-1.3)%, 6.3(+/-2.3)%, P<0.05]. In contrast, the NO donor SNAP reduced myocardial O(2)consumption in both groups and all those responses were not affected by l -NAME. These data indicate that endogenous NO production through the kinin-dependent mechanism is impaired at end-stage heart failure. The loss of kinin and NO control of mitochondrial respiration may contribute to the pathogenesis of heart failure. Copyright 2000 Academic Press.

Acetylcholine released from cholinergic nerves contributes to cutaneous vasodilation during heat stress

NASA Technical Reports Server (NTRS)

Shibasaki, Manabu; Wilson, Thad E.; Cui, Jian; Crandall, Craig G.

2002-01-01

Nitric oxide (NO) contributes to active cutaneous vasodilation during a heat stress in humans. Given that acetylcholine is released from cholinergic nerves during whole body heating, coupled with evidence that acetylcholine causes vasodilation via NO mechanisms, it is possible that release of acetylcholine in the dermal space contributes to cutaneous vasodilation during a heat stress. To test this hypothesis, in seven subjects skin blood flow (SkBF) and sweat rate were simultaneously monitored over three microdialysis membranes placed in the dermal space of dorsal forearm skin. One membrane was perfused with the acetylcholinesterase inhibitor neostigmine (10 microM), the second membrane was perfused with the NO synthase inhibitor N(G)-nitro-l-arginine methyl ester (l-NAME; 10 mM) dissolved in the aforementioned neostigmine solution (l-NAME(Neo)), and the third membrane was perfused with Ringer solution as a control site. Each subject was exposed to approximately 20 min of whole body heating via a water-perfused suit, which increased mean body temperature from 36.4 +/- 0.1 to 37.5 +/- 0.1 degrees C (P < 0.05). After the heat stress, SkBF at each site was normalized to its maximum value, identified by administration of 28 mM sodium nitroprusside. Mean body temperature threshold for cutaneous vasodilation was significantly lower at the neostigmine-treated site relative to the other sites (neostigmine: 36.6 +/- 0.1 degrees C, l-NAME(Neo): 37.1 +/- 0.1 degrees C, control: 36.9 +/- 0.1 degrees C), whereas no significant threshold difference was observed between the l-NAME(Neo)-treated and control sites. At the end of the heat stress, SkBF was not different between the neostigmine-treated and control sites, whereas SkBF at the l-NAME(Neo)-treated site was significantly lower than the other sites. These results suggest that acetylcholine released from cholinergic nerves is capable of modulating cutaneous vasodilation via NO synthase mechanisms early in the heat stress but not after substantial cutaneous vasodilation.

[Effect of astaxanthin on preeclampsia rat model].

PubMed

Xuan Rong-rong; Gao Xin; Wu, Wei; Chen, Hai-min

2014-10-01

The effect of astaxanthin on N(Ω)-nitro-L-arginine methyl ester (L-NAME) induced preeclampsia disease rats was investigated. Thirty pregnant Sprague-Dawley rats were randomly divided into three groups (n = 10): blank group, L-NAME group and astaxanthin group. From day 5 to 20, astaxanthin group rats were treated with astaxanthin (25 mg x kg(-1) x d(-1) x bw(-1)) from pregnancy (day 5). To establish the preeclamptic rat model, L-NAME group and astaxanthin group rats were injected with L-NAME (125 mg x kg(-1) x d(-1) x bw(-1)) from days 10-20 of pregnancy. The blood pressure and urine protein were recorded. Serum of each group was collected and malondialdehyde (MDA), superoxide dismutase (SOD) and nitric oxide synthase (NOS) activities were analyzed. Pathological changes were observed with HE stain. The expression of NF-κB (nuclear factor kappa B), ROCK II (Rho-associated protein kinase II), HO-1 (heme oxygenase-1) and Caspase 3 were analyzed with immunohistochemistry. L-NAME induced typical preeclampsia symptoms, such as the increased blood pressure, urinary protein, the content of MDA, etc. Astaxanthin significantly reduced the blood pressure (P < 0.01), the content of MDA (P < 0.05), and increased the activity of SOD (P < 0.05) of preeclampsia rats. The urinary protein, NO, and NOS were also decreased. HE stain revealed that after treated with astaxanthin, the thickness of basilal membrane was improved and the content of trophoblast cells and spiral arteries was reduced. Immunohistochemistry results revealed that the expressions of NF-κB, ROCK II and Caspase 3 in placenta tissue were effectively decreased, and HO-1 was increased. Results indicated that astaxanthin can improve the preeclampsia symptoms by effectively reducing the oxidative stress and inflammatory damages of preeclampsia. It revealed that astaxanthin may be benefit for prevention and treatment of preeclampsia disease.

Nitric oxide, prostaglandins and angiotensin II in the regulation of renal medullary blood flow during volume expansion.

PubMed

Moreno, Carol; Llinás, María T; Rodriguez, Francisca; Moreno, Juan M; Salazar, F Javier

2016-03-01

Regulation of medullary blood flow (MBF) is essential in maintaining renal function and blood pressure. However, it is unknown whether outer MBF (OMBF) and papillary blood flow (PBF) are regulated independently when extracellular volume (ECV) is enhanced. The aim of this study was to determine whether OMBF and PBF are differently regulated and whether there is an interaction between nitric oxide (NO), prostaglandins (PGs) and angiotensin II (Ang II) in regulating OMBF and PBF when ECV is enhanced. To achieve these goals, OMBF and PBF were measured by laser-Doppler in volume-expanded rats treated with a cyclooxygenase inhibitor (meclofenamate, 3 mg/kg) and/or a NO synthesis inhibitor (L-nitro-arginine methyl ester (L-NAME), 3 μg/kg/min) and/or Ang II (10 ng/kg/min). OMBF was unchanged by NO or PGs synthesis inhibition but decreased by 36 % (P < 0.05) when L-NAME and meclofenamate were infused simultaneously. PBF was similarly reduced by L-NAME (12 %), meclofenamate (17 %) or L-NAME + meclofenamate (19 %). Ang II did not modify OMBF, but it led to a similar decrease (P < 0.05) in OMBF when it was administered to rats with reduced NO (32 %), PGs (36 %) or NO and PGs (37 %) synthesis. In contrast, the fall in PBF induced by Ang II (12 %) was enhanced (P < 0.05) by the simultaneous PGs (30 %) or PGs and NO (31 %) synthesis inhibition but not in L-NAME-treated rats (20 %). This study presents novel findings suggesting that blood flows to the outer medulla and renal papilla are differently regulated and showing that there is a complex interaction between NO, PGs and Ang II in regulating OMBF and PBF when ECV is enhanced.

Increased Angiotensin II Sensitivity Contributes to Microvascular Dysfunction in Women Who Have Had Preeclampsia.

PubMed

Stanhewicz, Anna E; Jandu, Sandeep; Santhanam, Lakshmi; Alexander, Lacy M

2017-08-01

Women who have had preeclampsia have increased cardiovascular disease risk; however, the mechanism(s) responsible for this association remain unclear. Microvascular damage sustained during a preeclamptic pregnancy may persist postpartum. The putative mechanisms mediating this dysfunction include a reduction in NO-dependent dilation and an increased sensitivity to angiotensin II. In this study, we evaluated endothelium-dependent dilation, angiotensin II sensitivity, and the therapeutic effect of angiotensin II receptor blockade (losartan) on endothelium-dependent dilation in vivo in the microvasculature of women with a history of preeclampsia (n=12) and control women who had a healthy pregnancy (n=12). We hypothesized that preeclampsia would have (1) reduced endothelium-dependent dilation, (2) reduced NO-mediated dilation, and (3) increased sensitivity to angiotensin II. We further hypothesized that localized losartan would increase endothelium-dependent vasodilation in preeclampsia. We assessed microvascular endothelium-dependent vasodilator function by measurement of cutaneous vascular conductance responses to graded infusion of acetylcholine (acetylcholine; 10 -7 -102 mmol/L) and a standardized local heating protocol in control sites and sites treated with 15 mmol/L L-NAME ( N G -nitro-l-arginine methyl ester; NO-synthase inhibitor) or 43 µmol/L losartan. Further, we assessed microvascular vasoconstrictor sensitivity to angiotensin II (10 -20 -10 -4 mol/L). Preeclampsia had significantly reduced endothelium-dependent dilation (-0.3±0.5 versus -1.0±0.4 log EC50 ; P <0.001) and NO-dependent dilation (16±3% versus 39±6%; P =0.006). Preeclampsia also had augmented vasoconstrictor sensitivity to angiotensin II (-10.2±1.3 versus -8.3±0.5; P =0.006). Angiotensin II type I receptor inhibition augmented endothelium-dependent vasodilation and NO-dependent dilation in preeclampsia but had no effect in healthy pregnancy. These data suggest that women who have had preeclampsia have persistent microvascular dysfunction postpartum, mediated, in part, by increased sensitivity to angiotensin II. © 2017 American Heart Association, Inc.

Inhibitory effects of patchouli alcohol on stress-induced diarrhea-predominant irritable bowel syndrome

PubMed Central

Zhou, Tian-Ran; Huang, Jing-Jing; Huang, Zi-Tong; Cao, Hong-Ying; Tan, Bo

2018-01-01

AIM To elucidate the mechanism of patchouli alcohol (PA) in treatment of rat models of diarrhea-predominant irritable bowel syndrome (IBS-D). METHODS We studied the effects of PA on colonic spontaneous motility using its cumulative log concentration (3 × 10−7 mol/L to 1 × 10−4 mol/L). We then determined the responses of the proximal and distal colon segments of rats to the following stimuli: (1) carbachol (1 × 10−9 mol/L to 1 × 10−5 mol/L); (2) neurotransmitter antagonists including Nω-nitro-L-arginine methyl ester hydrochloride (10 μmol/L) and (1R*, 2S*)-4-[2-Iodo-6-(methylamino)-9H-purin-9-yl]-2-(phosphonooxy)bicyclo[3.1.0]hexane-1-methanol dihydrogen phosphate ester tetraammonium salt (1 μmol/L); (3) agonist α,β-methyleneadenosine 5′-triphosphate trisodium salt (100 μmol/L); and (4) single KCl doses (120 mmol/L). The effects of blockers against antagonist responses were also assessed by pretreatment with PA (100 μmol/L) for 1 min. Electrical-field stimulation (40 V, 2-30 Hz, 0.5 ms pulse duration, and 10 s) was performed to observe nonadrenergic, noncholinergic neurotransmitter release in IBS-D rat colon. The ATP level of Kreb’s solution was also determined. RESULTS PA exerted a concentration-dependent inhibitory effect on the spontaneous contraction of the colonic longitudinal smooth muscle, and the half maximal effective concentration (EC50) was 41.9 μmol/L. In comparison with the KCl-treated IBS-D group, the contractile response (mg contractions) in the PA + KCl-treated IBS-D group (11.87 ± 3.34) was significantly decreased in the peak tension (P < 0.01). Compared with CCh-treated IBS-D rat colon, the cholinergic contractile response of IBS-D rat colonic smooth muscle (EC50 = 0.94 μmol/L) was significantly decreased by PA (EC50 = 37.43 μmol/L) (P < 0.05). Lack of nitrergic neurotransmitter release in stress-induced IBS-D rats showed contraction effects on colonic smooth muscle. Pretreatment with PA resulted in inhibitory effect on L-NAME-induced (10 μmol/L) contraction (P < 0.05). ATP might not be the main neurotransmitter involved in inhibitory effects of PA in the colonic relaxation of stress-induced IBS-D rats. CONCLUSION PA application may serve as a new therapeutic approach for IBS-D. PMID:29456408

L-arginine prevents xanthoma development and inhibits atherosclerosis in LDL receptor knockout mice.

PubMed

Aji, W; Ravalli, S; Szabolcs, M; Jiang, X C; Sciacca, R R; Michler, R E; Cannon, P J

1997-01-21

The potential antiatherosclerotic actions of NO were investigated in four groups of mice (n = 10 per group) lacking functional LDL receptor genes, an animal model of familial hypercholesterolemia. Group 1 was fed a regular chow diet. Groups 2 through 4 were fed a 1.25% high-cholesterol diet. In addition, group 3 received supplemental L-arginine and group 4 received L-arginine and N omega-nitro-L-arginine (L-NA), an inhibitor of NO synthase (NOS). Animals were killed at 6 months; aortas were stained with oil red O for planimetry and with antibodies against constitutive and inducible NOSs. Plasma cholesterol was markedly increased in the animals receiving the high-cholesterol diet. Xanthomas appeared in all mice fed the high-cholesterol diet alone but not in those receiving L-arginine. Aortic atherosclerosis was present in all mice on the high-cholesterol diet. The mean atherosclerotic lesion area was reduced significantly (P < .01) in the cholesterol-fed mice given L-arginine compared with those receiving the high-cholesterol diet alone. The mean atherosclerotic lesion area was significantly larger (P < .01) in cholesterol-fed mice receiving L-arginine + L-NA than in those on the high-cholesterol diet alone. Within the atherosclerotic plaques, endothelial cells immunoreacted for endothelial cell NOS; macrophages, foam cells, and smooth muscle cells immunostained strongly for inducible NOS and nitrotyrosine residues. The data indicate that L-arginine prevents xanthoma formation and reduces atherosclerosis in LDL receptor knockout mice fed a high-cholesterol diet. The abrogation of the beneficial effects of L-arginine by L-NA suggests that the antiatherosclerotic actions of L-arginine are mediated by NOS. The data suggest that L-arginine may be beneficial in familial hypercholesterolemia.

Agmatine Induced NO Dependent Rat Mesenteric Artery Relaxation and its Impairment in Salt-Sensitive Hypertension

PubMed Central

Gadkari, Tushar V.; Cortes, Natalie; Madrasi, Kumpal; Tsoukias, Nikolaos M.; Joshi, Mahesh S.

2013-01-01

L-arginine and its decarboxylated product, agmatine are important mediators of NO production and vascular relaxation. However, the underlying mechanisms of their action are not understood. We have investigated the role of arginine and agmatine in resistance vessel relaxation of Sprague-Dawley (SD) and Dahl salt-sensitive hypertensive rats. Second or 3rd-order mesenteric arterioles were cannulated in an organ chamber, pressurized and equilibrated before perfusing intraluminally with agonists. The vessel diameters were measured after mounting on the stage of a microscope fitted with a video camera. The gene expression in Dahl rat vessel homogenates was ascertained by real-time PCR. L-arginine initiated relaxations (EC50, 5.8 ± 0.7 mM; n = 9) were inhibited by arginine decarboxylase (ADC) inhibitor, difluoromethylarginine (DFMA) (EC50, 18.3 ± 1.3 mM; n = 5) suggesting that arginine-induced vessel relaxation was mediated by agmatine formation. Agmatine relaxed the SD rat vessels at significantly lower concentrations (EC50, 138.7 ± 12.1 μM; n = 22), which was compromised by L-NAME (L-NG-Nitroarginine methyl ester, an eNOS inhibitor), RX821002 (α-2 AR antagonist) and pertussis toxin (G-protein inhibitor). The agmatine-mediated vessel relaxation from high salt Dahl rats was abolished as compared to that from normal salt rats (EC50, 143.9 ± 23.4 μM; n = 5). The α-2A AR, α-2B AR and eNOS mRNA expression was downregulated in mesenteric arterioles of high-salt treated Dahl hypertensive rats. These findings demonstrate that agmatine facilitated the relaxation via activation of α-2 adrenergic G-protein coupled receptor and NO synthesis, and this pathway is compromised in salt-sensitive hypertension. PMID:23994446

Agmatine induced NO dependent rat mesenteric artery relaxation and its impairment in salt-sensitive hypertension.

PubMed

Gadkari, Tushar V; Cortes, Natalie; Madrasi, Kumpal; Tsoukias, Nikolaos M; Joshi, Mahesh S

2013-11-30

l-Arginine and its decarboxylated product, agmatine are important mediators of NO production and vascular relaxation. However, the underlying mechanisms of their action are not understood. We have investigated the role of arginine and agmatine in resistance vessel relaxation of Sprague-Dawley (SD) and Dahl salt-sensitive hypertensive rats. Second or 3rd-order mesenteric arterioles were cannulated in an organ chamber, pressurized and equilibrated before perfusing intraluminally with agonists. The vessel diameters were measured after mounting on the stage of a microscope fitted with a video camera. The gene expression in Dahl rat vessel homogenates was ascertained by real-time PCR. l-Arginine initiated relaxations (EC50, 5.8±0.7mM; n=9) were inhibited by arginine decarboxylase (ADC) inhibitor, difluoromethylarginine (DFMA) (EC50, 18.3±1.3mM; n=5) suggesting that arginine-induced vessel relaxation was mediated by agmatine formation. Agmatine relaxed the SD rat vessels at significantly lower concentrations (EC50, 138.7±12.1μM; n=22), which was compromised by l-NAME (l-N(G)-nitroarginine methyl ester, an eNOS inhibitor), RX821002 (α-2 AR antagonist) and pertussis toxin (G-protein inhibitor). The agmatine-mediated vessel relaxation from high salt Dahl rats was abolished as compared to that from normal salt rats (EC50, 143.9±23.4μM; n=5). The α-2A AR, α-2B AR and eNOS mRNA expression was downregulated in mesenteric arterioles of high-salt treated Dahl hypertensive rats. These findings demonstrate that agmatine facilitated the relaxation via activation of α-2 adrenergic G-protein coupled receptor and NO synthesis, and this pathway is compromised in salt-sensitive hypertension. Copyright © 2013 Elsevier Inc. All rights reserved.

Metabolic Diversity for Degradation, Detection, and Synthesis of Nitro Compounds and Toxins

DTIC Science & Technology

2012-07-08

Figure 24. p-Hydroxycinnamic acid methyl ester (HCAME) accumulated transiently in cultures provided with CPhos as the sole carbon, nitrogen...and salicylate 1,2-dioxygenase from Pseudaminobacter salicylatoxidans (22% amino acid identity). The enzymes share a conserved histidine pair serving...to anchor Fe2+ and a conserved domain. 5NSA dioxygenase is active against salicylate , 5-chlorosalicylate, and 5-bromosalicylate; and inhibited by

Insulin Restores Gestational Diabetes Mellitus–Reduced Adenosine Transport Involving Differential Expression of Insulin Receptor Isoforms in Human Umbilical Vein Endothelium

PubMed Central

Westermeier, Francisco; Salomón, Carlos; González, Marcelo; Puebla, Carlos; Guzmán-Gutiérrez, Enrique; Cifuentes, Fredi; Leiva, Andrea; Casanello, Paola; Sobrevia, Luis

2011-01-01

OBJECTIVE To determine whether insulin reverses gestational diabetes mellitus (GDM)–reduced expression and activity of human equilibrative nucleoside transporters 1 (hENT1) in human umbilical vein endothelium cells (HUVECs). RESEARCH DESIGN AND METHODS Primary cultured HUVECs from full-term normal (n = 44) and diet-treated GDM (n = 44) pregnancies were used. Insulin effect was assayed on hENT1 expression (protein, mRNA, SLC29A1 promoter activity) and activity (initial rates of adenosine transport) as well as endothelial nitric oxide (NO) synthase activity (serine1177 phosphorylation, l-citrulline formation). Adenosine concentration in culture medium and umbilical vein blood (high-performance liquid chromatography) as well as insulin receptor A and B expression (quantitative PCR) were determined. Reactivity of umbilical vein rings to adenosine and insulin was assayed by wire myography. Experiments were in the absence or presence of l-NG-nitro-l-arginine methyl ester (l-NAME; NO synthase inhibitor) or ZM-241385 (an A2A-adenosine receptor antagonist). RESULTS Umbilical vein blood adenosine concentration was higher, and the adenosine- and insulin-induced NO/endothelium-dependent umbilical vein relaxation was lower in GDM. Cells from GDM exhibited increased insulin receptor A isoform expression in addition to the reported NO–dependent inhibition of hENT1-adenosine transport and SLC29A1 reporter repression, and increased extracellular concentration of adenosine and NO synthase activity. Insulin reversed all these parameters to values in normal pregnancies, an effect blocked by ZM-241385 and l-NAME. CONCLUSIONS GDM and normal pregnancy HUVEC phenotypes are differentially responsive to insulin, a phenomenon where insulin acts as protecting factor for endothelial dysfunction characteristic of this syndrome. Abnormal adenosine plasma levels, and potentially A2A-adenosine receptors and insulin receptor A, will play crucial roles in this phenomenon in GDM. PMID:21515851

Electron paramagnetic resonance investigation on modulatory effect of 17beta-estradiol on membrane fluidity of erythrocytes in postmenopausal women.

PubMed

Tsuda, K; Kinoshita, Y; Kimura, K; Nishio, I; Masuyama, Y

2001-08-01

Many studies have shown that estrogen may exert cardioprotective effects and reduce the risk of hypertension and coronary events. On the other hand, it has been proposed that cell membrane abnormalities play a role in the pathophysiology of hypertension, although it is not clear whether estrogen would influence membrane function in essential hypertension. The present study was performed to investigate the effects of 17beta-estradiol (E(2)) on membrane fluidity of erythrocytes in normotensive and hypertensive postmenopausal women. We determined the membrane fluidity of erythrocytes by means of an electron paramagnetic resonance and spin-labeling method. In an in vitro study, E(2) significantly decreased the order parameter for 5-nitroxide stearate and the peak height ratio for 16-nitroxide stearate obtained from electron paramagnetic resonance spectra of erythrocyte membranes in normotensive postmenopausal women. The finding indicates that E(2) might increase the membrane fluidity of erythrocytes. The effect of E(2) was significantly potentiated by the NO donor, S-nitroso-N-acetylpenicillamine, and a cGMP analogue, 8-bromo-cGMP. In contrast, the change in the membrane fluidity evoked by E(2) was attenuated in the presence of the NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester, and asymmetric dimethyl-L-arginine. In hypertensive postmenopausal women, the membrane fluidity of erythrocytes was significantly lower than that in normotensive postmenopausal women. The effect of E(2) on membrane fluidity was significantly more pronounced in the erythrocytes of hypertensive postmenopausal women than in the erythrocytes of normotensive postmenopausal women. The results of the present study showed that E(2) significantly increased the membrane fluidity and improved the microviscosity of erythrocyte membranes, partially mediated by an NO- and cGMP-dependent pathway. Furthermore, the greater action of E(2) in hypertension might be consistent with the hypothesis that E(2) could have a beneficial effect in regulating rheological behavior of erythrocytes and could have a crucial role in the improvement of the microcirculation in hypertension.

Dimethylarginine dimethylaminohydrolase 1 is involved in spinal nociceptive plasticity.

PubMed

DʼMello, Richard; Sand, Claire A; Pezet, Sophie; Leiper, James M; Gaurilcikaite, Egle; McMahon, Stephen B; Dickenson, Anthony H; Nandi, Manasi

2015-10-01

Activation of neuronal nitric oxide synthase, and consequent production of nitric oxide (NO), contributes to spinal hyperexcitability and enhanced pain sensation. All NOS isoforms are inhibited endogenously by asymmetric dimethylarginine, which itself is metabolised by dimethylarginine dimethylaminohydrolase (DDAH). Inhibition of DDAH can indirectly attenuate NO production by elevating asymmetric dimethylarginine concentrations. Here, we show that the DDAH-1 isoform is constitutively active in the nervous system, specifically in the spinal dorsal horn. DDAH-1 was found to be expressed in sensory neurons within both the dorsal root ganglia and spinal dorsal horn; L-291 (NG-[2-Methoxyethyl]-L-arginine methyl ester), a DDAH-1 inhibitor, reduced NO synthesis in cultured dorsal root ganglia neurons. Spinal application of L-291 decreased N-methyl-D-aspartate-dependent postdischarge and windup of dorsal horn sensory neurons--2 measures of spinal hyperexcitability. Finally, spinal application of L-291 reduced both neuronal and behavioral measures of formalin-induced central sensitization. Thus, DDAH-1 may be a potential therapeutic target in neuronal disorders, such as chronic pain, where elevated NO is a contributing factor.

Mechanisms of Improved Aortic Stiffness by Arotinolol in Spontaneously Hypertensive Rats

PubMed Central

Zhou, Wugang; Hong, Mona; Zhang, Ke; Chen, Dongrui; Han, Weiqing; Shen, Weili; Zhu, Dingliang; Gao, Pingjin

2014-01-01

Objectives This study investigates the effects on aortic stiffness and vasodilation by arotinolol and the underlying mechanisms in spontaneously hypertensive rats (SHR). Methods The vasodilations of rat aortas, renal and mesenteric arteries were evaluated by isometric force recording. Nitric oxide (NO) was measured in human aortic endothelial cells (HAECs) by fluorescent probes. Sixteen-week old SHRs were treated with metoprolol (200 mg·kg-1·d-1), arotinolol (30 mg·kg-1·d-1) for 8 weeks. Central arterial pressure (CAP) and pulse wave velocity (PWV) were evaluated via catheter pressure transducers. Collagen was assessed by immunohistochemistry and biochemistry assay, while endothelial nitric oxide synthase (eNOS) and eNOS phosphorylation (p-eNOS) of HAECs or aortas were analyzed by western blotting. Results Arotinolol relaxed vascular rings and the relaxations were attenuated by Nω-nitro-L-arginine methyl ester (L-NAME, NO synthase inhibitor) and the absence of endothelium. Furthermore, arotinolol-induced relaxations were attenuated by 4-aminopyridine (4-AP, Kv channels blocker). Arotinolol produced more nitric oxide compared to metoprolol and increased the expression of p-eNOS in HAECs. These results indicated that arotinolol-induced vasodilation involves endothelium-derived NO and Kv channels. The treatement with arotinolol in 8 weeks, but not metoprolol, markedly decreased CAP and PWV. Biochemistry assay and immunohistochemistry showed that aortic collagen depositions in the arotinolol groups were reduced compared with SHRs with metoprolol. Moreover, eNOS phosphorylation was significantly increased in aortinolol-treated SHR compared with SHRs with metoprolol. Conclusions Arotinolol improves arterial stiffness in SHR, which involved in increasing NO and decreasing collagen contents in large arteries. PMID:24533142

Vagally mediated effects of brain stem dopamine on gastric tone and phasic contractions of the rat.

PubMed

Anselmi, L; Toti, L; Bove, C; Travagli, R A

2017-11-01

Dopamine (DA)-containing fibers and neurons are embedded within the brain stem dorsal vagal complex (DVC); we have shown previously that DA modulates the membrane properties of neurons of the dorsal motor nucleus of the vagus (DMV) via DA1 and DA2 receptors. The vagally dependent modulation of gastric tone and phasic contractions, i.e., motility, by DA, however, has not been characterized. With the use of microinjections of DA in the DVC while recording gastric tone and motility, the aims of the present study were 1 ) assess the gastric effects of brain stem DA application, 2 ) identify the DA receptor subtype, and, 3 ) identify the postganglionic pathway(s) activated. Dopamine microinjection in the DVC decreased gastric tone and motility in both corpus and antrum in 29 of 34 rats, and the effects were abolished by ipsilateral vagotomy and fourth ventricular treatment with the selective DA2 receptor antagonist L741,626 but not by application of the selective DA1 receptor antagonist SCH 23390. Systemic administration of the cholinergic antagonist atropine attenuated the inhibition of corpus and antrum tone in response to DA microinjection in the DVC. Conversely, systemic administration of the nitric oxide synthase inhibitor nitro-l-arginine methyl ester did not alter the DA-induced decrease in gastric tone and motility. Our data provide evidence of a dopaminergic modulation of a brain stem vagal neurocircuit that controls gastric tone and motility. NEW & NOTEWORTHY Dopamine administration in the brain stem decreases gastric tone and phasic contractions. The gastric effects of dopamine are mediated via dopamine 2 receptors on neurons of the dorsal motor nucleus of the vagus. The inhibitory effects of dopamine are mediated via inhibition of the postganglionic cholinergic pathway. Copyright © 2017 the American Physiological Society.

Basal activity of voltage-gated Ca(2+) channels controls the IP3-mediated contraction by α(1)-adrenoceptor stimulation of mouse aorta segments.

PubMed

Leloup, Arthur J; Van Hove, Cor E; De Meyer, Guido R Y; Schrijvers, Dorien M; Fransen, Paul

2015-08-05

α1-Adrenoceptor stimulation of mouse aorta causes intracellular Ca(2+) release from sarcoplasmic reticulum Ca(2+) stores via stimulation of inositoltriphosphate (IP3) receptors. It is hypothesized that this Ca(2+) release from the contractile and IP3-sensitive Ca(2+) store is under the continuous dynamic control of time-independent basal Ca(2+) influx via L-type voltage-gated Ca(2+) channels (LCC) residing in their window voltage range. Mouse aortic segments were α1-adrenoceptor stimulated with phenylephrine in the absence of external Ca(2+) (0Ca) to measure phasic isometric contractions. They gradually decreased with time in 0Ca, were inhibited with 2-aminoethoxydiphenyl borate, and declined with previous membrane potential hyperpolarization (levcromakalim) or with previous inhibition of LCC (diltiazem). Former basal stimulation of LCC with depolarization (15 mM K(+)) or with BAY K8644 increased the subsequent phasic contractions by phenylephrine in 0Ca. Although exogenous NO (diethylamine NONOate) reduced the phasic contractions by phenylephrine, stimulation of endothelial cells with acetylcholine in 0Ca failed to attenuate these phasic contractions. Finally, inhibition of the basal release of NO with N(Ω)-nitro-L-arginine methyl ester also attenuated the phasic contractions by phenylephrine. Results indicated that α1-adrenoceptor stimulation with phenylephrine causes phasic contractions, which are controlled by basal LCC and endothelial NO synthase activity. Endothelial NO release by acetylcholine was absent in 0Ca. Given the growing interest in the active regulation of arterial compliance, the dependence of contractile SR Ca(2+) store-refilling in basal conditions on the activity of LCC and basal eNOS may contribute to a more thorough understanding of physiological mechanisms leading to arterial stiffness. Copyright © 2015. Published by Elsevier B.V.

Tetrahydrobiopterin improves hippocampal nitric oxide-linked long-term memory.

PubMed

Latini, Alexandra; de Bortoli da Silva, Lucila; da Luz Scheffer, Débora; Pires, Ananda Christina Staats; de Matos, Filipe José; Nesi, Renata T; Ghisoni, Karina; de Paula Martins, Roberta; de Oliveira, Paulo Alexandre; Prediger, Rui D; Ghersi, Marisa; Gabach, Laura; Pérez, Mariela Fernanda; Rubiales-Barioglio, Susana; Raisman-Vozari, Rita; Mongeau, Raymond; Lanfumey, Laurence; Aguiar, Aderbal Silva

2018-06-11

Tetrahydrobiopterin (BH4) is synthesized by the combined action of three metabolic pathways, namely de novo synthesis, recycling, and salvage pathways. The best-known function of BH4 is its mandatory action as a natural cofactor of the aromatic amino acid hydroxylases and nitric oxide synthases. Thus, BH4 is essential for the synthesis of nitric oxide, a retrograde neurotransmitter involved in learning and memory. We investigated the effect of BH4 (4-4000 pmol) intracerebroventricular administration on aversive memory, and on BH4 metabolism in the hippocampus of rodents. Memory-related behaviors were assessed in Swiss and C57BL/6 J mice, and in Wistar rats. It was consistently observed across all rodent species that BH4 facilitates aversive memory acquisition and consolidation by increasing the latency to step-down in the inhibitory avoidance task. This effect was associated with a reduced threshold to generate hippocampal long-term potentiation process. In addition, two inhibitors of memory formation (N(ω)-nitro-L-arginine methyl ester - L-Name - and dizocilpine - MK-801 -) blocked the enhanced effect of BH4 on memory, while the amnesic effect was not rescue by the co-administration of BH4 or a cGMP analog (8-Br-cGMP). The data strongly suggest that BH4 enhances aversive memory by activating the glutamatergic neurotransmission and the retrograde activity of NO. It was also demonstrated that BH2 can be converted into BH4 by activating the BH4 salvage pathway under physiological conditions in the hippocampus. This is the first evidence showing that BH4 enhances aversive memory and that the BH4 salvage pathway is active in the hippocampus. Copyright © 2018 Elsevier Inc. All rights reserved.

Comparative effects of avocado oil and losartan on blood pressure, renal vascular function, and mitochondrial oxidative stress in hypertensive rats.

PubMed

Márquez-Ramírez, Cristian Adrián; Hernández de la Paz, José Lucio; Ortiz-Avila, Omar; Raya-Farias, Andrés; González-Hernández, Juan Carlos; Rodríguez-Orozco, Alain Raimundo; Salgado-Garciglia, Rafael; Saavedra-Molina, Alfredo; Godínez-Hernández, Daniel; Cortés-Rojo, Christian

2018-03-20

Angiotensin II (Ang-II) antagonism alleviates hypertensive kidney damage by improving mitochondrial function and decreasing oxidative stress. This condition also is associated with altered renal vascular tone due to enhanced constriction by Ang-II. Thus, approaches ameliorating these events are desirable to alleviate kidney damage. Avocado oil, a source of antioxidants and oleic acid, is known to improve mitochondrial function, while oleic acid has antihypertensive effects. Therefore, the aim of this study was to test whether avocado oil counteracts, to a similar degree as the Ang-II blocker losartan, the deleterious effects of hypertension on blood pressure, renal vascular performance, kidney mitochondrial function, and oxidative stress. Hypertensive rats induced with Nω-nitro-l-arginine methyl ester (L-NAME) were supplemented during 45 d with avocado oil or losartan. Vascular responses were analyzed in perfused kidney. Membrane potential, reactive oxygen species levels, and glutathione were analyzed in isolated kidney mitochondria. In hypertensive rats, avocado oil decreased 21.2% and 15.5% diastolic and systolic blood pressures, respectively, and alleviated impaired renal vasodilation. Hypertension decreased membrane potential by 83.7% and augmented reactive oxygen species levels by 51% in mitochondria fueled with a complex I substrate, whereas it augmented the levels of oxidized glutathione in 48%. These alterations were normalized by avocado oil at a comparable degree to losartan. Because avocado oil mimicked the effects of losartan, we propose that the effects of avocado oil might be mediated by decreasing the actions of Ang-II on mitochondria. These results suggest that avocado oil intake might be a nutritional approach to attenuate the deleterious effects of hypertension on kidney. Copyright © 2018 Elsevier Inc. All rights reserved.

Nitric oxide-mediated modulation of the murine locomotor network

PubMed Central

Foster, Joshua D.; Dunford, Catherine; Sillar, Keith T.

2013-01-01

Spinal motor control networks are regulated by neuromodulatory systems to allow adaptability of movements. The present study aimed to elucidate the role of nitric oxide (NO) in the modulation of mammalian spinal locomotor networks. This was investigated with isolated spinal cord preparations from neonatal mice in which rhythmic locomotor-related activity was induced pharmacologically. Bath application of the NO donor diethylamine NONOate (DEA/NO) decreased the frequency and modulated the amplitude of locomotor-related activity recorded from ventral roots. Removal of endogenous NO with coapplication of a NO scavenger (PTIO) and a nitric oxide synthase (NOS) blocker [nitro-l-arginine methyl ester (l-NAME)] increased the frequency and decreased the amplitude of locomotor-related activity. This demonstrates that endogenously derived NO can modulate both the timing and intensity of locomotor-related activity. The effects of DEA/NO were mimicked by the cGMP analog 8-bromo-cGMP. In addition, the soluble guanylyl cyclase (sGC) inhibitor ODQ blocked the effects of DEA/NO on burst amplitude and frequency, although the frequency effect was only blocked at low concentrations of DEA/NO. This suggests that NO-mediated modulation involves cGMP-dependent pathways. Sources of NO were studied within the lumbar spinal cord during postnatal development (postnatal days 1–12) with NADPH-diaphorase staining. NOS-positive cells in the ventral horn exhibited a rostrocaudal gradient, with more cells in rostral segments. The number of NOS-positive cells was also found to increase during postnatal development. In summary, we have shown that NO, derived from sources within the mammalian spinal cord, modulates the output of spinal motor networks and is therefore likely to contribute to the fine-tuning of locomotor behavior. PMID:24259545

Nitric oxide alterations in cardiovascular system of rats with Parkinsonism induced by 6-OHDA and submitted to previous exercise.

PubMed

de Jager, Lorena; Amorim, Eric Diego Turossi; Lucchetti, Bruno Fernando Cruz; Lopes, Fernanda Novi Cortegoso; Crestani, Carlos Cesar; Pinge-Filho, Phileno; Martins-Pinge, Marli Cardoso

2018-07-01

Studies showed that physical exercise decreases the risk of developing Parkinson's disease (PD) as slowing its progression. Nitric oxide (NO) increases in the substantia nigra pars compacta (SNpc) of individuals with PD. However, no study has evaluated the effects of exercise on peripheral NO levels and its modulatory effects on cardiovascular dysfunctions of subjects with PD. Trained (T) or sedentary (S) animals underwent stereotactic surgery for bilateral 6-hydroxydopamine (6-OHDA) or vehicle microinfusion (Sham group). After 6 days, the animals were catheterized for baseline parameters, followed by inhibition of NOS by Nw-nitro-arginine-methyl ester (L-NAME, 10 mg/kg - i.v.). Nitrite concentration was performed in the aorta, heart, kidney, adrenal and plasma. After exercise, the animals presented resting bradycardia (6-OHDA T and Sham T). NO was increased in the aorta of 6-OHDA S, and decreased in 6-OHDA T animals. In the heart, NO was increased in Sham T compared to sedentary and decreased in 6-OHDA T relative to 6-OHDA S and Sham T animals. At the kidney, NO decrease in 6-OHDA S and Sham T when compared to Sham S and, in adrenal gland, there was a decrease in 6-OHDA T in relation to 6-OHDA S. L-NAME promoted lower increases in MAP in 6-OHDA groups. The decreases of HR were enhanced due to physical training. 6-OHDA S group presented decreased systolic arterial pressure variability, not altered by exercise. Our data showed alterations in peripheral NO in the association of exercise with Parkinsonism in the cardiovascular function. Copyright © 2018 Elsevier Inc. All rights reserved.

Involvement of proteinase activated receptor-2 in the vascular response to sphingosine 1-phosphate.

PubMed

Roviezzo, Fiorentina; De Angelis, Antonella; De Gruttola, Luana; Bertolino, Antonio; Sullo, Nikol; Brancaleone, Vincenzo; Bucci, Mariarosaria; De Palma, Raffaele; Urbanek, Konrad; D'Agostino, Bruno; Ianaro, Angela; Sorrentino, Raffaella; Cirino, Giuseppe

2014-04-01

S1P (sphingosine 1-phosphate) represents one of the key latest additions to the list of vasoactive substances that modulate vascular tone. PAR-2 (proteinase activated receptor-2) has been shown to be involved in cardiovascular function. In the present study, we investigated the involvement of PAR-2 in S1P-induced effect on vascular tone. The present study has been performed by using isolated mouse aortas. Both S1P and PAR-2 agonists induced endothelium-dependent vasorelaxation. L-NAME (N(G)-nitro-L-arginine methyl ester) and wortmannin abrogated the S1P-induced vasorelaxatioin, while significantly inhibiting the PAR-2-mediated effect. Either ENMD1068, a PAR-2 antagonist, or gabexate, a serine protease inhibitor, significantly inhibited S1P-induced vasorelaxation. Aortic tissues harvested from mice overexpressing PAR-2 displayed a significant increase in vascular response to S1P as opposed to PAR-2-null mice. Immunoprecipitation and immunofluorescence studies demonstrated that S1P(1) interacted with PAR-2 and co-localized with PAR-2 on the vascular endothelial surface. Furthermore, S1P administration to vascular tissues triggered PAR-2 mobilization from the plasma membrane to the perinuclear area; S1P-induced translocation of PAR-2 was abrogated when aortic rings were pre-treated with ENMD1068 or when caveolae dysfunction occurred. Similarly, experiments performed in cultured endothelial cells (human umbilical vein endothelial cells) showed a co-localization of S1P(1) and PAR2, as well as the ability of S1P to induce PAR-2 trafficking. Our results suggest that S1P induces endothelium-dependent vasorelaxation mainly through S1P(1) and involves PAR-2 transactivation.

Possible mechanisms of action of Caesalpinia pyramidalis against ethanol-induced gastric damage.

PubMed

Diniz, Polyana B F; Ribeiro, Ana Roseli S; Estevam, Charles S; Bani, Cristiane C; Thomazzi, Sara M

2015-06-20

Caesalpinia pyramidalis Tul. (Fabaceae), known as "catingueira", is an endemic tree of the Northeast region of Brazil. This plant, mainly inner bark and flowers, has been used in traditional medicine to treat gastritis, heartburn, indigestion, stomachache, dysenteries, and diarrheas. The ethanol extract of C. pyramidalis inner bark was used in rats via oral route, at the doses of 30, 100, and 300 mg/kg, in the ethanol-induced ulcer model and some of the mechanisms underlying to the gastroprotective effect of this plant investigated. The ethanol extract of C. pyramidalis inner bark (100 mg/kg) produced reduction (P < 0.001) on the total lesion area in the ethanol-induced gastric damage. The gastroprotective response caused by the ethanol extract (100 mg/kg) was significantly attenuated (P < 0.05) by intraperitoneal treatment of rats with DL-Propargylglycine (PAG, a cystathionine-γ-lyase inhibitor; 25 mg/kg), but not by Nw-nitro-L-arginine methyl ester hydrochloride (L-NAME, an inhibitor of nitric oxide synthase; 70 mg/kg), and confirmed by microscopic evidence. The ethanol extract significantly decreased the number of mucosal mast cells compared to vehicle-treated group. The inflammatory cells of the ethanol extract (100 mg/kg)-treated ulcerated rats exhibited an upregulation of interleukin (IL)-4 protein expression and downregulation of inducible nitric oxide synthase (iNOS) expression, observed by immunohistochemistry and flow cytometer. The present results suggest that the ethanol extract of C. pyramidalis produced dose-related gastroprotective response on ethanol-induce ulcer in rats through mechanisms that involved an interaction with endogenous hydrogen sulfide and reduction of inflammatory process with imbalance between pro-inflammatory and anti-inflammatory mediators, supporting the popular usage of this plant. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Nitric Oxide Synthase-Mediated Phytoalexin Accumulation in Soybean Cotyledons in Response to the Diaporthe phaseolorum f. sp. meridionalis Elicitor1

PubMed Central

Modolo, Luzia Valentina; Cunha, Fernando Queiroz; Braga, Márcia Regina; Salgado, Ione

2002-01-01

Phytoalexin biosynthesis is part of the defense mechanism of soybean (Glycine max) plants against attack by the fungus Diaporthe phaseolorum f. sp. meridionalis (Dpm), the causal agent of stem canker disease. The treatment of soybean cotyledons with Dpm elicitor or with sodium nitroprusside (SNP), a nitric oxide (NO) donor, resulted in a high accumulation of phytoalexins. This response did not occur when SNP was replaced by ferricyanide, a structural analog of SNP devoid of the NO moiety. Phytoalexin accumulation induced by the fungal elicitor, but not by SNP, was prevented when cotyledons were pretreated with NO synthase (NOS) inhibitors. The Dpm elicitor also induced NOS activity in soybean tissues proximal to the site of inoculation. The induced NOS activity was Ca2+- and NADPH-dependent and was sensitive to the NOS inhibitors NG-nitro-l-arginine methyl ester, aminoguanidine, and l-N6-(iminoethyl) lysine. NOS activity was not observed in SNP-elicited tissues. An antibody to brain NOS labeled a 166-kD protein in elicited and nonelicited cotyledons. Isoflavones (daidzein and genistein), pterocarpans (glyceollins), and flavones (apigenin and luteolin) were identified after exposure to the elicitor or SNP, although the accumulation of glyceollins and apigenin was limited in SNP-elicited compared with fungal-elicited cotyledons. NOS activity preceded the accumulation of these flavonoids in tissues treated with the Dpm elicitor. The accumulation of these metabolites was faster in SNP-elicited than in fungal-elicited cotyledons. We conclude that the response of soybean cotyledons to Dpm elicitor involves NO formation via a constitutive NOS-like enzyme that triggers the biosynthesis of antimicrobial flavonoids. PMID:12427995

Hemodynamic actions of systemically injected pituitary adenylate cyclase activating polypeptide-27 in the rat

NASA Technical Reports Server (NTRS)

Whalen, E. J.; Johnson, A. K.; Lewis, S. J.

1999-01-01

The aims of this study were (1) to characterize the hemodynamic mechanisms underlying the hypotensive effects of pituitary adenylate cyclase activating polypeptide-27 (PACAP-27 0.1-2.0 nmol/kg, i.v.) in pentobarbital-anesthetized rats, and (2) to determine the roles of the autonomic nervous system, adrenal catecholamines and endothelium-derived nitric oxide (NO) in the expression of PACAP-27-mediated effects on hemodynamic function. PACAP-27 produced dose-dependent decreases in mean arterial blood pressure and hindquarter and mesenteric vascular resistances in saline-treated rats. PACAP-27 also produced pronounced falls in mean arterial blood pressure in rats treated with the ganglion blocker, chlorisondamine (5 mg/kg, i.v.). The hypotensive and vasodilator actions of PACAP-27 were not attenuated by the beta-adrenoceptor antagonist, propranolol (1 mg/kg, i.v.), or the NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME 50 micromol/kg, i.v.). PACAP-27 produced dose-dependent increases in heart rate whereas the hypotensive response produced by the nitrovasodilator, sodium nitroprusside (10 microg/kg, i.v.), was associated with a minimal tachycardia. The PACAP-27-induced tachycardia was unaffected by chlorisondamine, but was virtually abolished by propranolol. These results suggest that the vasodilator effects of PACAP-27 are due to actions in the microcirculation rather than to the release of adrenal catecholamines and that this vasodilation may not involve the release of endothelium-derived NO. These results also suggest that PACAP-27 produces tachycardia by directly releasing norepinephrine from cardiac sympathetic nerve terminals rather than by direct or baroreceptor reflex-mediated increases in sympathetic nerve activity.

In a non-human primate model, aging disrupts the neural control of intestinal smooth muscle contractility in a region-specific manner.

PubMed

Tran, L; Greenwood-Van Meerveld, B

2014-03-01

Incidences of gastrointestinal (GI) motility disorders increase with age. However, there is a paucity of knowledge about the aging mechanisms leading to GI dysmotility. Motility in the GI tract is a function of smooth muscle contractility, which is modulated in part by the enteric nervous system (ENS). Evidence suggests that aging impairs the ENS, thus we tested the hypothesis that senescence in the GI tract precipitates abnormalities in smooth muscle and neurally mediated contractility in a region-specific manner. Jejunal and colonic circular muscle strips were isolated from young (4-10 years) and old (18+ years) baboons. Myogenic responses were investigated using potassium chloride (KCl) and carbachol (CCh). Neurally mediated contractile responses were evoked by electrical field stimulation (EFS) and were recorded in the absence and presence of atropine (1 μM) or NG-Nitro-l-arginine methyl ester (l-NAME; 100 μM). The myogenic responses to KCl in the jejunum and colon were unaffected by age. In the colon, but not the jejunum, CCh-induced contractile responses were reduced in aged animals. Compared to young baboons, there was enhanced EFS-induced contractility of old baboon jejunal smooth muscle in contrast to the reduced contractility in the colon. The effect of atropine on the EFS response was lower in aged colonic tissue, suggesting reduced participation of acetylcholine. In aged jejunal tissue, higher contractile responses to EFS were found to be due to reduced nitregic inhibition. These findings provide key evidence for the importance of intestinal smooth muscle and ENS senescence in age-associated GI motility disorders. © 2014 The Authors. Neurogastroenterology & Motility published by John Wiley & Sons Ltd.

Chronic resveratrol enhances endothelium-dependent relaxation but does not alter eNOS levels in aorta of spontaneously hypertensive rats.

PubMed

Rush, James W E; Quadrilatero, Joe; Levy, Andrew S; Ford, Rebecca J

2007-06-01

Spontaneously hypertensive rats (SHRs) were administered the red wine polyphenol resveratrol in drinking water at 0, 0.448, or 4.48 mg/l (control, low, or high, respectively) for 28 days. The low dosage was chosen to mimic moderate red wine consumption. After the treatment period, thoracic aorta rings were excised for in vitro assessment of vasomotor function. Chronic resveratrol significantly improved endothelium-dependent relaxation to acetylcholine (Ach), increasing maximal values to 80.8% +/- 5.2% and 80.8% +/- 5.0% in low and high groups, respectively, compared with 60.7% +/- 1.4% in controls (P<0.01). This treatment effect was eliminated in the presence of the endothelial nitric oxide synthase (eNOS) blocker N(omega)-nitro-L-arginine methyl ester. Resveratrol did not affect relaxation to sodium nitroprusside or systolic blood pressure in SHRs. In contrast to the SHR results, chronic resveratrol in Sprague Dawley rats did not affect vasomotor function in aorta rings in response to Ach. Hydrogen peroxide was reduced in the SHR thoracic aorta by a high dosage of resveratrol (P<0.05), but it was not significantly altered in other tissues tested. Thoracic aorta immunoblots revealed no significant treatment effects in SHRs on eNOS, superoxide dismutases 1 and 2, gp91phox, or Hsp90. Thus, these data provide novel evidence of improved endothelium-dependent vasorelaxation in hypertensive, but not normotensive, animals as a result of chronic resveratrol consumption mimicking dosages resulting from moderate red wine consumption. This response was not dependent on increases in eNOS expression but was dependent on improved NO bioavailability.

Lower-limb veins are thicker and vascular reactivity is decreased in a rat PCOS model: concomitant vitamin D3 treatment partially prevents these changes.

PubMed

Várbíró, Szabolcs; Sára, Levente; Antal, Péter; Monori-Kiss, Anna; Tőkés, Anna-Mária; Monos, Emil; Benkő, Rita; Csibi, Noémi; Szekeres, Maria; Tarszabo, Robert; Novak, Agnes; Paragi, Péter; Nádasy, György L

2014-09-15

Polycystic ovary syndrome (PCOS) causes vascular damage to arteries; however, there are no data for its effect on veins. Our aim was to clarify the effects of dihydrotestosterone (DHT)-induced PCOS both on venous biomechanics and on pharmacological reactivity in a rat model and to test the possible modulatory role of vitamin D3 (vitD). PCOS was induced in female Wistar rats by DHT treatment (83 μg/day, subcutaneous pellet). After 10 wk, the venous biomechanics, norepinephrine (NE)-induced contractility, and acetylcholine-induced relaxation were tested in saphenous veins from control animals and from animals treated with DHT or DHT with vitD using pressure angiography. Additionally, the expression levels of endothelial nitric oxide synthase (eNOS) and cyclooxygenase (COX-2) were measured using immunohistochemistry. Increased diameter, wall thickness, and distensibility as well as decreased vasoconstriction were detected after the DHT treatment. Concomitant vitD treatment lowered the mechanical load on the veins, reduced distensibility, and resulted in vessels that were more relaxed. Although there was no difference in the endothelial dilation tested using acetylcholine (ACh), the blocking effect of N(G)-nitro-l-arginine methyl ester (l-NAME) was lower and was accompanied by lower COX-2 expression in the endothelium after the DHT treatment. Supplementation with vitD prevented these alterations. eNOS expression did not differ among the three groups. We conclude that the hyperandrogenic state resulted in thicker vein walls. These veins showed early remodeling and altered vasorelaxant mechanisms similar to those of varicose veins. Alterations caused by the chronic DHT treatment were prevented partially by concomitant vitD administration. Copyright © 2014 the American Physiological Society.

Astaxanthin blocks preeclampsia progression by suppressing oxidative stress and inflammation.

PubMed

Xuan, Rong-Rong; Niu, Ting-Ting; Chen, Hai-Min

2016-09-01

To investigate the antioxidative effect of astaxanthin on Nω-nitro-L-arginine methyl ester (L-NAME)-induced preeclamptic rats. Cell survival, the level of reactive oxygen species (ROS) and the changes in mitochondrial membrane potential (MMP) were examined in astaxanthin and H2O2-treated human umbilical vein endothelial cells (HUVECs). The preeclamptic Sprague-Dawley (SD) rat model was established by injection of L‑NAME and treatment with astaxanthin. The activities of malondialdehyde (MDA), superoxide dismutase (SOD) and nitric oxide synthase (NOS) in serum were analyzed. Pathological changes were examined by hematoxylin and eosin (H&E) staining. The expression of nuclear factor (NF)‑κB, Rho‑associated protein kinase II (ROCK II), heme oxygenase‑1 (HO‑1) and caspase 3 in preeclamptic placentas were examined by immunohistochemistry. Astaxanthin significantly reduced H2O2‑induced HUVEC cell death, decreased ROS and increased MMP. Astaxanthin significantly reduced blood pressure and the content of MDA, but significantly increased the activity of SOD in preeclamptic rats. The urinary protein and the level of NO and NOS were also decreased. H&E staining revealed that the thickness of the basilar membrane was increased, while the content of trophoblast cells and spiral arteries were reduced following astaxanthin treatment. Immunohistochemistry results showed that the expression of NF‑κB, ROCK II and caspase 3 in preeclamptic placentas was significantly decreased after astaxanthin treatment, while HO‑1 expression was increased. In conclusion, astaxanthin inhibited H2O2‑induced oxidative stress in HUVECs. Astaxanthin treatment significantly improved L‑NAME‑induced preeclamptic symptoms and reduced the oxidative stress and inflammatory damages in preeclamptic placentas. Astaxanthin treatment may effectively prevent and treat preeclampsia.

Altered skin flowmotion in hypertensive humans

PubMed Central

Bruning, R.S.; Kenney, W.L.; Alexander, L.M.

2017-01-01

Essential hypertensive humans exhibit attenuated cutaneous nitric oxide (NO)-dependent vasodilation. Using spectral analysis (fast Fourier transformation) we aimed to characterize the skin flowmotion contained in the laser-Doppler flowmetry recordings during local heating-induced vasodilation before and after concurrent pharmacological inhibition of nitric oxide synthase (NOS) in hypertensive and age-matched normotensive men and women. We hypothesized that hypertensive subjects would have lower total power spectral densities (PSD), specifically in the frequency intervals associated with intrinsic endothelial and neurogenic control of the microvasculature. Furthermore, we hypothesized that NOS inhibition would attenuate the endothelial frequency interval. Laser-Doppler flowmetry recordings during local heating experiments from 18 hypertensive (MAP: 108±2mmHg) and 18 normotensive (MAP: 88±2mmHg) men and women were analyzed. Within site NO-dependent vasodilation was assessed by perfusion of a non-specific NOS inhibitor (NG-nitro-L-arginine methyl ester; L-NAME) through intradermal microdialysis during the heating-induced plateau in skin blood flow. Local heating-induced vasodilation increased total PSD for all frequency intervals (all p<0.001). Hypertensives had a lower total PSD (p=0.03) and absolute neurogenic frequency intervals (p<0.01) compared to the normotensives. When normalized as a percentage of total PSD, hypertensives had reduced neurogenic (p<0.001) and augmented myogenic contributions (p=0.04) to the total spectrum. NOS inhibition decreased total PSD (p<0.001) for both groups, but hypertensives exhibited lower absolute endothelial (p<0.01), neurogenic (p<0.05), and total PSD (p<0.001) frequency intervals compared to normotensives. These data suggest that essential hypertension results in altered neurogenic and NOS-dependent control of skin flowmotion and support the use of spectral analysis as a non-invasive technique to study vasoreactivity. PMID:24418051

The inhibition of nicotine-evoked relaxation of the guinea-pig isolated basilar artery by some analgesic drugs and progesterone

PubMed Central

Rhodes, Keith F; Buckingham, Julia C; Kennard, Christopher

1999-01-01

The purpose of this study was to investigate the mechanism of nicotine-evoked relaxation of the guinea-pig isolated basilar artery and to study the effects of drugs associated with the aetiology or treatment of migraine on the nicotine response. The guinea-pig isolated basilar artery, pre-contracted with prostaglandin F2α (PGF2α), in the presence of atropine (3 μM) and guanethidine (3 μM), relaxed on addition of nicotine (0.1 mM) in approximately 50% of preparations. The responses to nicotine were of short duration and blocked in preparations pre-treated for 10 min with capsaicin (1 μM) and are therefore probably a consequence of the stimulation of trigeminal C fibre terminals. Responses to nicotine were reduced in the presence of 5-carboxamidotryptamine, 5-hydroxytryptamine and sumatriptan in that order of potency. This is consistent with a 5-HT1 receptor mechanism. These agonists evoked small additional contractions in vessels pre-contracted with PGF2α. Indomethacin (0.3–10 μM), aspirin (10–30 μM), and nitro-L-arginine methyl ester (L-NAME, 0.1 mM) reduced nicotine-evoked relaxation of the basilar artery, suggesting the involvement of both nitric oxide and cyclo-oxygenase products in this response. Progesterone (1 μM) markedly reduced the response to nicotine, a possible reflection of the ion channel blocking activity of high concentrations of this compound. The guinea-pig basilar artery is a preparation in which the effects of drugs on responses to stimulation of trigeminal nerve terminals can be studied in vitro and may thus be of interest in assessing the actions of drugs used in treatment of headache. PMID:10193781

The effect of defibrotide on thromboembolism in the pulmonary vasculature of mice and rabbits and in the cerebral vasculature of rabbits.

PubMed Central

Paul, W.; Gresele, P.; Momi, S.; Bianchi, G.; Page, C. P.

1993-01-01

1. Administration of bovine thrombin (100 u kg-1) into the carotid artery of rabbits induces a sustained accumulation of 111 Indium-labelled platelets within the cranial vasculature over the subsequent 3 h. 2. Intracarotid (i.c.) administration of defibrotide (64 mg kg-1 bolus plus 64 mg kg-1 h-1 for 1 h) prior to i.c. thrombin (100 u kg-1) significantly reduces the ability of thrombin to induce cranial thromboembolism in rabbits. 3. Intravenous (i.v.) administration of thrombin (20 u kg-1) in rabbits induces a reversible accumulation of radiolabelled platelets into the thoracic circulation which is significantly reduced by i.v. administration of defibrotide (64 mg kg-1 bolus plus 64 mg kg-1 h-1 for 1 h) prior to i.v. thrombin. In contrast, platelet accumulation in response to adenosine diphosphate (ADP; 20 micrograms kg-1, i.v.) or platelet activating factor (PAF; 50 ng kg-1, i.v.) is not significantly affected by this treatment. 4. Intravenous administration of the nitric oxide (NO)-synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME; 10 mg kg-1) potentiates platelet accumulation induced by low dose thrombin (10 u kg-1, i.v.) within the pulmonary vasculature of rabbits. The potentiated response is significantly abrogated following pretreatment with defibrotide (64 mg kg-1 bolus plus 64 mg kg-1 h-1 for 1 h, i.v.). 5. Intravenous injection of human thrombin (1250 u kg-1) to mice induces death within the majority of animals which is significantly reduced by pretreatment with defibrotide (150-175 mg kg-1, i.v.).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8306102

The pharmacological modulation of thrombin-induced cerebral thromboembolism in the rabbit.

PubMed Central

May, G. R.; Paul, W.; Crook, P.; Butler, K. D.; Page, C. P.

1992-01-01

1. Intracarotid (i.c.) administration of thrombin induced a marked accumulation of 111indium-labelled platelets and 125I-labelled fibrinogen within the cranial vasculature of anaesthetized rabbits. 2. Thrombin (100 iu kg-1, i.c.) - induced platelet accumulation was completely abolished by pretreatment with desulphatohirudin (CGP 39393; 1 mg kg-1 i.c., 1 min prior to thrombin). Administration of CGP 39393 1 or 20 min after thrombin produced a significant reduction in platelet accumulation. 3. Intravenous (i.v.) administration of the platelet activating factor (PAF) receptor antagonist BN 52021 (10 mg kg-1) 5 min prior to thrombin (100 iu kg-1, i.c.) had no effect on platelet accumulation. 4. An inhibitor of NO biosynthesis, L-NG-nitro arginine methyl ester (L-NAME; 100 mg kg-1, i.c.), had no significant effect on the cranial platelet accumulation response to thrombin (10 iu kg-1, i.c.) when administered 5 min prior to thrombin. 5. Defibrotide (32 or 64 mg kg-1 bolus i.c. followed by 32 or 64 mg kg-1 h-1, i.c., infusion for 45 min) treatment begun 20 min after thrombin (100 iu kg-1, i.c.) did not significantly modify the cranial platelet accumulation response. 6. Cranial platelet accumulation induced by thrombin (100 iu kg-1, i.c.) was significantly reversed by the fibrinolytic drugs urokinase (20 iu kg-1, i.c., infusion for 45 min), anisoylated plasminogen streptokinase activator complex (APSAC) (200 micrograms kg-1, i.v. bolus) or recombinant tissue plasminogen activator (rt-PA; 100 micrograms kg-1, i.c. bolus followed by 20 micrograms kg-1 min-1, i.c., infusion for 45 min) administered 20 min after thrombin.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1504722

Effects of Chromium Picolinate on Vascular Reactivity and Cardiac Ischemia Reperfusion Injury in Spontaneously Hypertensive Rats

PubMed Central

Abebe, Worku; Liu, Jun Yao; Wimborne, Hereward; Mozaffari, Mahmood S.

2013-01-01

Chromium picolinate [Cr(pic)3] is a nutritional supplement widely promoted to exert beneficial metabolic effects in patients with type 2 diabetes/impaired glucose tolerance. Frequent comorbidities in these individuals include systemic hypertension, abnormal vascular function and ischemic heart disease but information on effects of the supplement on these aspects is sparse. Utilizing male spontaneously hypertensive rats (SHR), we examined potential impact of Cr(pic)3 on blood pressure, vascular reactivity and myocardial ischemia reperfusion injury (IRI). Dietary Cr(pic)3 supplementation (as 10 mg chromium/kg diet for 6 weeks) did not affect blood pressure of the SHR. Also, neither norepinephrine (NE) and potassium chloride (KCl)-induced contractility nor sodium nitroprusside (SNP)-induced relaxation of aortic smooth muscle from the SHR was altered by Cr(pic)3 treatment. However, Cr(pic)3 augmented endothelium-dependent relaxation of aortas, produced by acetylcholine (ACh), and this effect was abolished by N-nitro-L-arginine methyl ester (L-NAME) suggesting induction of nitric oxide (NO) production/release. Treatment with Cr(pic)3 did not affect baseline coronary flow rate and rate-pressure-product (RPP) or infarct size following regional IRI. Nonetheless, Cr(pic)3 treatment was associated with improved coronary flow and recovery of myocardial contractility and relaxation following ischemia reperfusion insult. In conclusion, dietary Cr(pic)3 treatment of SHR neither alters blood pressure nor vascular smooth muscle reactivity, but causes enhancement of endothelium-dependent vasorelaxation associated with NO production/release. Additionally, while the treatment does not affect infarct size, it improves functional recovery of the viable portion of the myocardium following IRI. PMID:20885007

Effects of chromium picolinate on vascular reactivity and cardiac ischemia-reperfusion injury in spontaneously hypertensive rats.

PubMed

Abebe, Worku; Liu, Jun Yao; Wimborne, Hereward; Mozaffari, Mahmood S

2010-01-01

Chromium picolinate [Cr(pic)(3)] is a nutritional supplement widely promoted to exert beneficial metabolic effects in patients with type 2 diabetes/impaired glucose tolerance. Frequent comorbidities in these individuals include systemic hypertension, abnormal vascular function and ischemic heart disease, but information on the effects of the supplement on these aspects is sparse. Utilizing male spontaneously hypertensive rats (SHR), we examined the potential impact of Cr(pic)(3) on blood pressure, vascular reactivity and myocardial ischemia-reperfusion injury (IRI). Dietary Cr(pic)(3) supplementation (as 10 mg chromium/kg diet for six weeks) did not affect blood pressure of the SHR. Also, neither norepinephrine (NE) and potassium chloride (KCl)-induced contractility nor sodium nitroprusside (SNP)-induced relaxation of aortic smooth muscle from the SHR was altered by Cr(pic)(3) treatment. However, Cr(pic)(3) augmented endothelium-dependent relaxation of aortas, produced by acetylcholine (ACh), and this effect was abolished by N-nitro-L-arginine methyl ester (L-NAME), suggesting induction of nitric oxide (NO) production/release. Treatment with Cr(pic)(3) did not affect baseline coronary flow rate and rate-pressure-product (RPP) or infarct size following regional IRI. Nonetheless, Cr(pic)(3) treatment was associated with improved coronary flow and recovery of myocardial contractility and relaxation following ischemia-reperfusion insult. In conclusion, dietary Cr(pic)(3) treatment of SHR alters neither blood pressure nor vascular smooth muscle reactivity but causes enhancement of endothelium-dependent vasorelaxation associated with NO production/release. Additionally, while the treatment does not affect infarct size, it improves functional recovery of the viable portion of the myocardium following IRI.

Biphasic effect of Psidium guajava Linn. (Myrtaceae) leaf aqueous extract on rat isolated vascular smooth muscles.

PubMed

Chiwororo, Witness D H; Ojewole, John A O

2008-12-01

In this study, we examined the effects of Psidium guajava Linn. leaf aqueous extract (PGE) on isolated, spontaneously-contracting portal veins, as well as on endothelium-intact and endothelium-denuded descending thoracic aortic ring preparations of healthy, normotensive rats. Graded concentrations of PGE (0.25-4.0 mg/ml) caused concentration-dependent, initial brief but significant (P<0.05) rises of the basal tones and amplitudes of pendular, rhythmic contractions, followed by secondary pronounced, longer-lasting and significant (P<0.05-0.001) inhibitions of contractile amplitudes of the isolated portal veins. Relatively low concentrations of PGE (<1.0 mg/ml) always contracted freshly-mounted, naïve, endothelium-intact aortic ring preparations. However, relatively high concentrations of PGE (1.0-4.0 mg/ml) always produced initial brief contractions/augmentations of noradrenaline (NA, 10(-7)M)-induced contractions of endothelium-intact and endothelium-denuded aortic ring preparations, followed by secondary, pronounced relaxations of the aortic ring muscles. Moreover, relatively high concentrations of PGE (1.0-4.0 mg/kg) always relaxed NA-induced contractions of the aortic ring preparations in a concentration-related manner. The arterial-relaxing effects of PGE were more pronounced in endothelium-intact aortic rings than in endothelium-denuded aortic ring preparations. The relaxant effects of PGE on endothelium-intact aortic rings were only partially inhibited by N(G)-nitro-L-arginine methyl ester (L-NAME, 100 microM), a nitric oxide synthase inhibitor, suggesting that the vasorelaxant effect of PGE on aortic rings is probably mediated via both endothelium-derived relaxing factor (EDRF)-dependent and EDRF-independent mechanisms. Taken together, the findings of this study indicate that PGE possesses a biphasic effect on rat isolated vascular smooth muscles.

Nitric oxide is not permissive for cutaneous active vasodilatation in humans.

PubMed

Wilkins, Brad W; Holowatz, Lacy A; Wong, Brett J; Minson, Christopher T

2003-05-01

The precise role of nitric oxide (NO) in cutaneous active vasodilatation in humans is unknown. We tested the hypothesis that NO is necessary to permit the action of an unknown vasodilator. Specifically, we investigated whether a low-dose infusion of exogenous NO, in the form of sodium nitroprusside (SNP), would fully restore vasodilatation in an area of skin in which endogenous NO was inhibited during hyperthermia. This finding would suggest a 'permissive' role for NO in active vasodilatation. Eight subjects were instrumented with three microdialysis fibres in forearm skin. Sites were randomly assigned to (1) Site A: control site; (2) Site B: NO synthase (NOS) inhibition during established hyperthermia; or (3) Site C: NOS inhibition throughout the protocol. Red blood cell flux was measured using laser-Doppler flowmetry (LDF) and cutaneous vascular conductance (CVC; LDF/mean arterial pressure) was normalized to maximal vasodilatation at each site. In Site B, NG-nitro-L-arginine methyl ester (L-NAME) infusion during hyperthermia reduced CVC by approximately 32 % (65 +/- 4 % CVCmax vs. 45 +/- 4 % CVCmax; P < 0.05). Vasodilatation was not restored to pre-NOS inhibition values in this site following low-dose SNP infusion (55 +/- 4 % CVCmax vs. 65 +/- 4 % CVCmax; P < 0.05). CVC remained significantly lower than the control site with low-dose SNP infusion in Site C (P < 0.05). The rise in CVC with low-dose SNP (deltaCVC) was significantly greater in Site B and Site C during hyperthermia compared to normothermia (P < 0.05). No difference in deltaCVC was observed between hyperthermia and normothermia in the control site (Site A). Thus, NO does not act permissively in cutaneous active vasodilatation in humans but may directly mediate vasodilatation and enhance the effect of an unknown active vasodilator.

Relaxant Effects of the Selective Estrogen Receptor Modulator, Bazedoxifene, and Estrogen Receptor Agonists in Isolated Rabbit Basilar Artery.

PubMed

Castelló-Ruiz, María; Salom, Juan B; Fernández-Musoles, Ricardo; Burguete, María C; López-Morales, Mikahela A; Arduini, Alessandro; Jover-Mengual, Teresa; Hervás, David; Torregrosa, Germán; Alborch, Enrique

2016-10-01

We have previously shown that the selective estrogen receptor modulator, bazedoxifene, improves the consequences of ischemic stroke. Now we aimed to characterize the effects and mechanisms of action of bazedoxifene in cerebral arteries. Male rabbit isolated basilar arteries were used for isometric tension recording and quantitative polymerase chain reaction. Bazedoxifene relaxed cerebral arteries, as 17-β-estradiol, 4,4',4″-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol [estrogen receptor (ER) α agonist], and G1 [G protein-coupled ER (GPER) agonist] did it (4,4',4″-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol > bazedoxifene = G1 > 17-β-estradiol). 2,3-Bis(4-hydroxyphenyl)-propionitrile (ERβ agonist) had no effect. Expression profile of genes encoding for ERα (ESR1), ERβ (ESR2), and GPER was GPER > ESR1 > ESR2. As to the endothelial mechanisms, endothelium removal, N-nitro-L-arginine methyl ester, and indomethacin, did not modify the relaxant responses to bazedoxifene. As to the K channels, both a high-K medium and the Kv blocker, 4-aminopyridine, inhibited the bazedoxifene-induced relaxations, whereas tetraethylammonium (nonselective K channel blocker), glibenclamide (selective KATP blocker) or iberiotoxin (selective KCa blocker) were without effect. Bazedoxifene also inhibited both Ca- and Bay K8644-elicited contractions. Therefore, bazedoxifene induces endothelium-independent relaxations of cerebral arteries through (1) activation of GPER and ERα receptors; (2) increase of K conductance through Kv channels; and (3) inhibition of Ca entry through L-type Ca channels. Such a profile is compatible with the beneficial effects of estrogenic compounds (eg, SERMs) on vascular function and, specifically, that concerning the brain. Therefore, bazedoxifene could be useful in the treatment of cerebral disorders in which the cerebrovascular function is compromised (eg, stroke).

A2-purinoceptor-mediated relaxation in the guinea-pig coronary vasculature: a role for nitric oxide.

PubMed Central

Vials, A.; Burnstock, G.

1993-01-01

1. The Langendorff heart preparation was used to investigate the mechanism of action of the endothelium-dependent vasodilatation evoked by adenosine and its analogues in the guinea-pig coronary vasculature. 2. The relative order of potency of adenosine and its analogues in causing a reduction in perfusion pressure was D-5'-(N-ethylcarboxamide)adenosine (NECA) = 2-[p-(2-carboxyethyl)phenylethylamino]-5'-N- ethylcarboxamidoadenosine (CGS 21680)> R-N6-(2-phenylisopropyl)adenosine (R-PIA) = adenosine = 2-chloroadenosine (2-CA) > S-N6-(2-phenylisopropyl)adenosine (S-PIA) = N6-cyclopentyl-adenosine (CPA); thus suggesting the presence of A2-purinoceptors in this preparation. 3. 8-(p-Sulphophenyl)theophylline (8-PSPT; 3 x 10(-5) M) significantly reduced both the maximum amplitude and area of the vasodilatation produced in response to adenosine (5 x 10(-10) -5 x 10(-8) mol) without having any effect on the response to the P2-purinoceptor agonist, 2-methylthioATP. The relaxation induced by adenosine (5 x 10(-12) -5 x 10(-8) mol) was unaffected by the selective A1-purinoceptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX; 10(-8) M). This antagonist profile suggests that only A2-purinoceptors are present in the guinea-pig coronary vasculature. 4. The areas of the vasodilator response to adenosine (5 x 10(-10) -5 x 10(-7 mol), NECA (5 x 10(-12) -5 x 10(-7) mol) and CGS 21680 (5 x 10(-12) -5 x 10(-10) mol) were significantly reduced by NG-nitro-L-arginine methyl ester (L-NAME; 3 x 10(-5) M).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8358543

Attenuation of stress-induced gastric lesions by lansoprazole, PD-136450 and ranitidine in rats.

PubMed

Chandranath, S I; Bastaki, S M A; D'Souza, A; Adem, A; Singh, J

2011-03-01

Combining restraint with cold temperature (4°C) consistently induces gastric ulceration in rats after 3.5 h. The cold restraint-stress (CRS) method provides a suitable model for acute ulcer investigations. This study compares the antiulcer activities of lansoprazole (a proton pump inhibitor), PD-136450 (CCK(2)/gastrin receptor antagonist) and ranitidine (histamine H(2) receptor antagonist) on CRS-induced gastric ulcers in rats. The results have shown that lansoprazole, which is a potent anti-secretory agent, provides complete protection in this model of ulcer formation. The use of indomethacin pretreatment to inhibit the prostaglandin (PG) synthesis and N(G)-nitro L-arginine methyl ester (L-NAME) pretreatment to inhibit nitric oxide synthase did not alter the lansoprazole-induced inhibition of ulcer index obtained in the untreated Wistar rats indicating that these two systems were not involved in the activation of lansoprazole. PD-136450, an effective anti-secretory agent against gastrin- but not dimaprit-induced stimulation, evoked a dose-dependent inhibition of CRS-induced gastric ulcers. The results show that both PG and nitric oxide pathways can influence the inhibitory effect of PD-136450 against CRS-induced gastric ulcer. The antiulcer activities of both lansoprazole and PD-136450 were compared to that of ranitidine. The results showed that ranitidine was more potent than lansoprazole and PD-136450 in inhibiting CRS-induced gastric ulcers and its effect was shown to be influenced by PG as well as nitric oxide synthase. The results of this study have demonstrated that although lansoprazole, PD-136450 and ranitidine were protective against CRS-induced gastric ulcers, the antiulcer activities of PD-136450 and ranitidine involved both PG and nitric oxide pathways, while lansoprazole acted independently of these two systems during CRS.

GPER agonist dilates mesenteric arteries via PI3K-Akt-eNOS and potassium channels in both sexes.

PubMed

Peixoto, Pollyana; Aires, Rosária Dias; Lemos, Virgínia Soares; Bissoli, Nazaré Souza; Santos, Roger Lyrio Dos

2017-08-15

The action of oestrogen has traditionally been attributed to the activation of nuclear receptors (ERα and ERβ). A third receptor, the G protein-coupled oestrogen receptor (GPER), has been described as mediator of the rapid action of oestrogen. Based on the possible protective role of oestrogen in the cardiovascular system, the present study was designed to determine whether selective GPER activation induces relaxation of mesenteric resistance arteries in both sexes and which signalling pathways are involved. Third-order mesenteric arteries were isolated, and concentration-response curves were plotted following the cumulative addition of the selective GPER agonist G-1 (1nM-10μM) following induction of contraction with phenylephrine (3μM). The vasodilatory effects of G-1 were assessed before and after removal of the endothelium or incubation for 30min with nitric oxide synthase (N ω -nitro-L-arginine methyl ester - L-NAME, 300μM) and cyclooxygenase (indomethacin - INDO, 10μM) inhibitors alone or combined, PI3K-Akt pathway inhibitor (LY-294,002, 2.5μM) or a potassium channel blocker (tetraethylammonium - TEA, 5mM). GPER immunolocalisation was also performed on the investigated arteries. The tested GPER agonist induced concentration-dependent relaxation of the mesenteric resistance arteries without differences related to sex that were partially endothelium dependent, mainly mediated by the PI3K-Akt-eNOS pathway and attenuated by nonspecific potassium channel blockade. In addition, the endothelial GPER immunolocalisation was stronger among females. This evidence provides a new perspective for understanding the mechanisms involved in the vascular responses triggered by oestrogen via GPER in both sexes. Copyright © 2017 Elsevier Inc. All rights reserved.

Effects of nesfatin-1 on atrial contractility and thoracic aorta reactivity in male rats.

PubMed

Barutcigil, Ayşe; Tasatargil, Arda

2017-10-13

This study aimed to examine the effects of nesfatin-1 on thoracic aorta vasoreactivity and to investigate the inotropic and chronotropic effects of nesfatin-1 on the spontaneous contractions of the isolated rat atria. Isolated right atria and thoracic aorta were used in organ baths. The reactivity of the thoracic aorta was evaluated by potassium chloride (KCl), phenylephrine (Phe), acetylcholine (ACh), and sodium nitroprusside (SNP). The effects of nesfatin-1 on the spontaneous contractions of the rat atria were also examined. Nesfatin-1 (0.1-100 ng/ml) produced a concentration-dependent relaxation response in rat thoracic aorta. The relaxant responses to nesfatin-1 were inhibited by the removal of endothelium, NO synthase blocker N-nitro-L-arginine methyl ester (L-NAME, 10 -4  M), and soluble guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 10 -5  M). Nesfatin-1 (10 ng/ml, 30 min) increased the relaxation responses to either ACh or SNP, and the contractile response to both Phe and KCl did not significantly change in the arteries that were incubated with nesfatin-1 compared with the controls. The thoracic aorta contractions induced by the stepwise addition of Ca 2+ to a high KCl solution with no Ca 2+ were not significantly changed by nesfatin-1. Under calcium-free conditions, the contractions of the thoracic aorta rings incubated with nesfatin-1 in response to Phe were not significantly lower than those of the rings from the control rats. Nesfatin-1 showed positive inotropic and chronotropic effects on rat atria. Nesfatin-1 significantly changed the vascular responsiveness in rat thoracic aorta and produced positive inotropic and chronotropic effects on rat atria.

Acute restraint stress induces endothelial dysfunction: role of vasoconstrictor prostanoids and oxidative stress.

PubMed

Carda, Ana P P; Marchi, Katia C; Rizzi, Elen; Mecawi, André S; Antunes-Rodrigues, José; Padovan, Claudia M; Tirapelli, Carlos R

2015-01-01

We hypothesized that acute stress would induce endothelial dysfunction. Male Wistar rats were restrained for 2 h within wire mesh. Functional and biochemical analyses were conducted 24 h after the 2-h period of restraint. Stressed rats showed decreased exploration on the open arms of an elevated-plus maze (EPM) and increased plasma corticosterone concentration. Acute restraint stress did not alter systolic blood pressure, whereas it increased the in vitro contractile response to phenylephrine and serotonin in endothelium-intact rat aortas. NG-nitro-l-arginine methyl ester (l-NAME; nitric oxide synthase, NOS, inhibitor) did not alter the contraction induced by phenylephrine in aortic rings from stressed rats. Tiron, indomethacin and SQ29548 reversed the increase in the contractile response to phenylephrine induced by restraint stress. Increased systemic and vascular oxidative stress was evident in stressed rats. Restraint stress decreased plasma and vascular nitrate/nitrite (NOx) concentration and increased aortic expression of inducible (i) NOS, but not endothelial (e) NOS. Reduced expression of cyclooxygenase (COX)-1, but not COX-2, was observed in aortas from stressed rats. Restraint stress increased thromboxane (TX)B(2) (stable TXA(2) metabolite) concentration but did not affect prostaglandin (PG)F2α concentration in the aorta. Restraint reduced superoxide dismutase (SOD) activity, whereas concentrations of hydrogen peroxide (H(2)O(2)) and reduced glutathione (GSH) were not affected. The major new finding of our study is that restraint stress increases vascular contraction by an endothelium-dependent mechanism that involves increased oxidative stress and the generation of COX-derived vasoconstrictor prostanoids. Such stress-induced endothelial dysfunction could predispose to the development of cardiovascular diseases.

Analysis of cardiovascular responses to the H2S donors Na2S and NaHS in the rat

PubMed Central

Yoo, Daniel; Jupiter, Ryan C.; Pankey, Edward A.; Reddy, Vishwaradh G.; Edward, Justin A.; Swan, Kevin W.; Peak, Taylor C.; Mostany, Ricardo

2015-01-01

Hydrogen sulfide (H2S) is an endogenous gaseous molecule formed from L-cysteine in vascular tissue. In the present study, cardiovascular responses to the H2S donors Na2S and NaHS were investigated in the anesthetized rat. The intravenous injections of Na2S and NaHS 0.03–0.5 mg/kg produced dose-related decreases in systemic arterial pressure and heart rate, and at higher doses decreases in cardiac output, pulmonary arterial pressure, and systemic vascular resistance. H2S infusion studies show that decreases in systemic arterial pressure, heart rate, cardiac output, and systemic vascular resistance are well-maintained, and responses to Na2S are reversible. Decreases in heart rate were not blocked by atropine, suggesting that the bradycardia was independent of parasympathetic activation and was mediated by an effect on the sinus node. The decreases in systemic arterial pressure were not attenuated by hexamethonium, glybenclamide, Nw-nitro-l-arginine methyl ester hydrochloride, sodium meclofenamate, ODQ, miconazole, 5-hydroxydecanoate, or tetraethylammonium, suggesting that ATP-sensitive potassium channels, nitric oxide, arachidonic acid metabolites, cyclic GMP, p450 epoxygenase metabolites, or large conductance calcium-activated potassium channels are not involved in mediating hypotensive responses to the H2S donors in the rat and that responses are not centrally mediated. The present data indicate that decreases in systemic arterial pressure in response to the H2S donors can be mediated by decreases in vascular resistance and cardiac output and that the donors have an effect on the sinus node independent of the parasympathetic system. The present data indicate that the mechanism of the peripherally mediated hypotensive response to the H2S donors is uncertain in the intact rat. PMID:26071540

Protective effects of long-term administration of Ziziphus jujuba fruit extract on cardiovascular responses in L-NAME hypertensive rats.

PubMed

Mohebbati, Reza; Bavarsad, Kosar; Rahimi, Maryam; Rakhshandeh, Hasan; Khajavi Rad, Abolfazl; Shafei, Mohammad Naser

2018-01-01

Ziziphus jujuba stimulates the release of nitric oxide (NO). Because NO is involved in cardiovascular regulations, in this study the effects of hydroalcoholic extract of Z. jujuba on cardiovascular responses in acute NG-nitro-L-arginine methyl ester (L-NAME) hypertensive rats were evaluated. Rats were divided into 6 group (n=6): 1) saline, 2) L-NAME received (10mg/kg) intravenously, 3) sodium nitroprusside (SNP) (50µg/kg)+L-NAME group received SNP before L-NAME and 4-6) three groups of Z. jujuba (100, 200 and 400mg/kg) that treated for four weeks and on the 28 th day, L-NAME was injected. Femoral artery and vein were cannulated for recording cardiovascular responses and drug injection, respectively. Systolic blood pressure (SBP), Mean arterial pressure (MAP) and heart rate (HR) were recorded continuously. Maximal changes (∆) of SBP, MAP and HR were calculated and compared to control and L-NAME groups. In L-NAME group, maximal ΔSBP (L-NAME: 44.15±4.0 mmHg vs control: 0.71±2.1 mmHg) and ΔMAP (L-NAME: 40.8±4.0 mmHg vs control: 0.57±1.6 mmHg) significantly increased (p<0.001 in both) but ∆HR was not significant as compared to control (p>0.05). All doses of Z. jujuba attenuated maximal ∆SBP and ∆MAP induced by L-NAME but only the lowest dose (100 mg/kg) had significant effects (ΔSBP: 20.36±5.6 mmHg vs L-NAME: 44.1±4.0 mmHg and ΔMAP: 20.8±4.5 mmHg vs L-NAME: 40.8±3.8 mmHg (p<0.05 to p<0.01)). The ∆HR at three doses was not significantly different from that of L-NAME group (p>0.05). Because long-term consumption of Z. jujuba extract, especially its lowest dose, attenuated cardiovascular responses induced by L-NAME, we suggest that Z. jujuba has potential beneficial effects in prevention of hypertension induced by NO deficiency.

A Lactobacillus plantarum Esterase Active on a Broad Range of Phenolic Esters

PubMed Central

Esteban-Torres, María; Landete, José María; Reverón, Inés; Santamaría, Laura; de las Rivas, Blanca

2015-01-01

Lactobacillus plantarum is the lactic acid bacterial species most frequently found in the fermentation of food products of plant origin on which phenolic compounds are abundant. L. plantarum strains showed great flexibility in their ability to adapt to different environments and growth substrates. Of 28 L. plantarum strains analyzed, only cultures from 7 strains were able to hydrolyze hydroxycinnamic esters, such as methyl ferulate or methyl caffeate. As revealed by PCR, only these seven strains possessed the est_1092 gene. When the est_1092 gene was introduced into L. plantarum WCFS1 or L. lactis MG1363, their cultures acquired the ability to degrade hydroxycinnamic esters. These results support the suggestion that Est_1092 is the enzyme responsible for the degradation of hydroxycinnamic esters on the L. plantarum strains analyzed. The Est_1092 protein was recombinantly produced and biochemically characterized. Surprisingly, Est_1092 was able to hydrolyze not only hydroxycinnamic esters, since all the phenolic esters assayed were hydrolyzed. Quantitative PCR experiments revealed that the expression of est_1092 was induced in the presence of methyl ferulate, an hydroxycinnamic ester, but was inhibited on methyl gallate, an hydroxybenzoic ester. As Est_1092 is an enzyme active on a broad range of phenolic esters, simultaneously possessing feruloyl esterase and tannase activities, its presence on some L. plantarum strains provides them with additional advantages to survive and grow on plant environments. PMID:25746986

Age-dependent redox status in the brain stem of NO-deficient hypertensive rats.

PubMed

Majzúnová, Miroslava; Pakanová, Zuzana; Kvasnička, Peter; Bališ, Peter; Čačányiová, Soňa; Dovinová, Ima

2017-09-11

The brain stem contains important nuclei that control cardiovascular function via the sympathetic nervous system (SNS), which is strongly influenced by nitric oxide. Its biological activity is also largely determined by oxygen free radicals. Despite many experimental studies, the role of AT1R-NAD(P)H oxidase-superoxide pathway in NO-deficiency is not yet sufficiently clarified. We determined changes in free radical signaling and antioxidant and detoxification response in the brain stem of young and adult Wistar rats during chronic administration of exogenous NO inhibitors. Young (4 weeks) and adult (10 weeks) Wistar rats were treated with 7-nitroindazole (7-NI group, 10 mg/kg/day), a specific nNOS inhibitor, with N G -nitro-L-arginine-methyl ester (L-NAME group, 50 mg/kg/day), a nonspecific NOS inhibitor, and with drinking water (Control group) during 6 weeks. Systolic blood pressure was measured by non-invasive plethysmography. Expression of genes (AT1R, AT2R, p22phox, SOD and NOS isoforms, HO-1, MDR1a, housekeeper GAPDH) was identified by real-time PCR. NOS activity was detected by conversion of [3H]-L-arginine to [3H]-L-citrulline and SOD activity was measured using UV VIS spectroscopy. We observed a blood pressure elevation and decrease in NOS activity only after L-NAME application in both age groups. Gene expression of nNOS (youngs) and eNOS (adults) in the brain stem decreased after both inhibitors. The radical signaling pathway triggered by AT1R and p22phox was elevated in L-NAME adults, but not in young rats. Moreover, L-NAME-induced NOS inhibition increased antioxidant response, as indicated by the observed elevation of mRNA SOD3, HO-1, AT2R and MDR1a in adult rats. 7-NI did not have a significant effect on AT1R-NADPH oxidase-superoxide pathway, yet it affected antioxidant response of mRNA expression of SOD1 and stimulated total activity of SOD in young rats and mRNA expression of AT2R in adult rats. Our results show that chronic NOS inhibition by two different NOS inhibitors has age-dependent effect on radical signaling and antioxidant/detoxificant response in Wistar rats. While 7-NI had neuroprotective effect in the brain stem of young Wistar rats, L-NAME- induced NOS inhibition evoked activation of AT1R-NAD(P)H oxidase pathway in adult Wistar rats. Triggering of the radical pathway was followed by activation of protective compensation mechanism at the gene expression level.

Effects of Diclofenac, L-NAME, L-Arginine, and Pentadecapeptide BPC 157 on Gastrointestinal, Liver, and Brain Lesions, Failed Anastomosis, and Intestinal Adaptation Deterioration in 24 Hour-Short-Bowel Rats.

PubMed

Lojo, Nermin; Rasic, Zarko; Zenko Sever, Anita; Kolenc, Danijela; Vukusic, Darko; Drmic, Domagoj; Zoricic, Ivan; Sever, Marko; Seiwerth, Sven; Sikiric, Predrag

2016-01-01

Stable gastric pentadecapeptide BPC 157 was previously used to ameliorate wound healing following major surgery and counteract diclofenac toxicity. To resolve the increasing early risks following major massive small bowel resectioning surgery, diclofenac combined with nitric oxide (NO) system blockade was used, suggesting therapy with BPC 157 and the nitric oxide synthase (NOS substrate) L-arginine, is efficacious. Immediately after anastomosis creation, short-bowel rats were untreated or administered intraperitoneal diclofenac (12 mg/kg), BPC 157 (10 μg/kg or 10 ng/kg), L-NG-nitroarginine methyl ester (L-NAME, 5 mg/kg), L-arginine (100 mg/kg) alone or combined, and assessed 24 h later. Short-bowel rats exhibited poor anastomosis healing, failed intestine adaptation, and gastrointestinal, liver, and brain lesions, which worsened with diclofenac. This was gradually ameliorated by immediate therapy with BPC 157 and L-arginine. Contrastingly, NOS-blocker L-NAME induced further aggravation and lesions gradually worsened. Specifically, rats with surgery alone exhibited mild stomach/duodenum lesions, considerable liver lesions, and severe cerebral/hippocampal lesions while those also administered diclofenac showed widespread severe lesions in the gastrointestinal tract, liver, cerebellar nuclear/Purkinje cells, and cerebrum/hippocampus. Rats subjected to surgery, diclofenac, and L-NAME exhibited the mentioned lesions, worsening anastomosis, and macro/microscopical necrosis. Thus, rats subjected to surgery alone showed evidence of deterioration. Furtheremore, rats subjected to surgery and administered diclofenac showed worse symptoms, than the rats subjected to surgery alone did. Rats subjected to surgery combined with diclofenac and L-NAME showed the worst deterioration. Rats subjected to surgery exhibited habitual adaptation of the remaining small intestine, which was markedly reversed in rats subjected to surgery and diclofenac, and those with surgery, diclofenac, and L-NAME. BPC 157 completely ameliorated symptoms in massive intestinal resection-, massive intestinal resection plus diclofenac-, and massive intestinal resection plus diclofenac plus L-NAME-treated short bowel rats that presented with cyclooxygenase (COX)-NO-system inhibition. L-arginine ameliorated only L-NAME-induced aggravation of symptoms in rats subjected to massive intestinal resection and administered diclofenac plus L-NAME.

Effects of Diclofenac, L-NAME, L-Arginine, and Pentadecapeptide BPC 157 on Gastrointestinal, Liver, and Brain Lesions, Failed Anastomosis, and Intestinal Adaptation Deterioration in 24 Hour-Short-Bowel Rats

PubMed Central

Lojo, Nermin; Rasic, Zarko; Zenko Sever, Anita; Kolenc, Danijela; Vukusic, Darko; Drmic, Domagoj; Zoricic, Ivan; Sever, Marko; Seiwerth, Sven; Sikiric, Predrag

2016-01-01

Stable gastric pentadecapeptide BPC 157 was previously used to ameliorate wound healing following major surgery and counteract diclofenac toxicity. To resolve the increasing early risks following major massive small bowel resectioning surgery, diclofenac combined with nitric oxide (NO) system blockade was used, suggesting therapy with BPC 157 and the nitric oxide synthase (NOS substrate) L-arginine, is efficacious. Immediately after anastomosis creation, short-bowel rats were untreated or administered intraperitoneal diclofenac (12 mg/kg), BPC 157 (10 μg/kg or 10 ng/kg), L-NG-nitroarginine methyl ester (L-NAME, 5 mg/kg), L-arginine (100 mg/kg) alone or combined, and assessed 24 h later. Short-bowel rats exhibited poor anastomosis healing, failed intestine adaptation, and gastrointestinal, liver, and brain lesions, which worsened with diclofenac. This was gradually ameliorated by immediate therapy with BPC 157 and L-arginine. Contrastingly, NOS-blocker L-NAME induced further aggravation and lesions gradually worsened. Specifically, rats with surgery alone exhibited mild stomach/duodenum lesions, considerable liver lesions, and severe cerebral/hippocampal lesions while those also administered diclofenac showed widespread severe lesions in the gastrointestinal tract, liver, cerebellar nuclear/Purkinje cells, and cerebrum/hippocampus. Rats subjected to surgery, diclofenac, and L-NAME exhibited the mentioned lesions, worsening anastomosis, and macro/microscopical necrosis. Thus, rats subjected to surgery alone showed evidence of deterioration. Furtheremore, rats subjected to surgery and administered diclofenac showed worse symptoms, than the rats subjected to surgery alone did. Rats subjected to surgery combined with diclofenac and L-NAME showed the worst deterioration. Rats subjected to surgery exhibited habitual adaptation of the remaining small intestine, which was markedly reversed in rats subjected to surgery and diclofenac, and those with surgery, diclofenac, and L-NAME. BPC 157 completely ameliorated symptoms in massive intestinal resection-, massive intestinal resection plus diclofenac-, and massive intestinal resection plus diclofenac plus L-NAME-treated short bowel rats that presented with cyclooxygenase (COX)-NO-system inhibition. L-arginine ameliorated only L-NAME-induced aggravation of symptoms in rats subjected to massive intestinal resection and administered diclofenac plus L-NAME. PMID:27627764

Involvement of Nitric Oxide in a Rat Model of Carrageenin-Induced Pleurisy

PubMed Central

Iwata, Masahiro; Suzuki, Shigeyuki; Asai, Yuji; Inoue, Takayuki; Takagi, Kenji

2010-01-01

Some evidence indicates that nitric oxide (NO) contributes to inflammation, while other evidence supports the opposite conclusion. To clarify the role of NO in inflammation, we studied carrageenin-induced pleurisy in rats treated with an NO donor (NOC-18), a substrate for NO formation (L-arginine), and/or an NO synthase inhibitor (S-(2-aminoethyl) isothiourea or NG-nitro-L-arginine). We assessed inflammatory cell migration, nitrite/nitrate values, lipid peroxidation and pro-inflammatory mediators. NOC-18 and L-arginine reduced the migration of inflammatory cells and edema, lowered oxidative stress, and normalized antioxidant enzyme activities. NO synthase inhibitors increased the exudate formation and inflammatory cell number, contributed to oxidative stress, induced an oxidant/antioxidant imbalance by maintaining high O2 −, and enhanced the production of pro-inflammatory mediators. L-arginine and NOC-18 reversed the proinflammatory effects of NO synthase inhibitors, perhaps by reducing the expression of adhesion molecules on endothelial cells. Thus, our results indicate that NO is involved in blunting—not enhancing—the inflammatory response. PMID:20592757

Inhibition of the L-arginine-nitric oxide pathway mediates the antidepressant effects of ketamine in rats in the forced swimming test.

PubMed

Zhang, Guang-Fen; Wang, Nan; Shi, Jin-Yun; Xu, Shi-Xia; Li, Xiao-Min; Ji, Mu-Huo; Zuo, Zhi-Yi; Zhou, Zhi-Qiang; Yang, Jian-Jun

2013-09-01

Converging evidence shows that the acute administration of a sub-anaesthetic dose ketamine produces fast-acting and robust antidepressant properties in patients suffering from major depressive disorder. However, the underlying mechanisms have not been fully elucidated. The present study aimed to investigate the role of the L-arginine-nitric oxide pathway in the antidepressant effects of ketamine in rats performing the forced swimming test (FST). Ketamine (10 mg/kg) significantly decreased immobility times in the FST and the activities of total nitric oxide synthases (T-NOS), inducible NOS (iNOS), and endothelial NOS (eNOS) in the rat hippocampus. Interestingly, the plasma activities of T-NOS, iNOS, and eNOS increased after administration of ketamine. Furthermore, the activities of neuronal NOS (nNOS) did not change significantly in either the hippocampus or plasma after ketamine administration. The antidepressant effects of ketamine were prevented by pre-treatment with l-arginine (750 mg/kg). Pre-treatment with the NOS inhibitor L-NG-nitroarginine methyl ester at a sub-antidepressant dose of 50 mg/kg and ketamine at a sub-antidepressant dose of 3 mg/kg reduced immobility time in the FST compared to treatment with either drug alone. None of the drugs affected crossing and rearing scores in the open field test. These results suggest that the L-arginine-nitric oxide pathway is involved in the antidepressant effects of ketamine observed in rats in the FST and this involvement is characterised by the inhibition of brain T-NOS, iNOS, and eNOS activities. Copyright © 2013 Elsevier Inc. All rights reserved.

Anxiolytic action of neuromedin-U and neurotransmitters involved in mice.

PubMed

Telegdy, G; Adamik, A

2013-09-10

Peptide Neuromedin-U (NmU) is widely distributed in the central nervous system and the peripheral tissues. Its physiological effects include the regulation of blood pressure, heart rate, and body temperature, and the inhibition of gastric acid secretion. The action of NmU in rats is mediated by two G-protein-coupled receptors, NmU-1R and NmU-2R. NmU-2R is present mainly in the brain, and NmU-1R mainly in the periphery. Despite the great variety of the physiological action of NmU, little is known about its possible effects in different forms of behavior, such as anxiety. In the present work, NmU-23 (the rodent form of the peptide) was tested for its effect on anxiety in elevated plus maze test in mice. For detection of the possible involvement of neurotransmitters, the mice were pretreated with receptor blockers: haloperidol (a D2, dopamine receptor antagonist), propranolol (a β-adrenergic receptor antagonist), atropine (a nonselective muscarinic acetylcholine receptor antagonist), phenoxybenzamine (a nonselective α-adrenergic receptor antagonist) or nitro-l-arginine (a nitric oxide synthase inhibitor). The peptide and nitro-l-arginine were administered into the lateral brain ventricle, while the receptor blockers were applied intraperitoneally. An NmU-23 dose 0.5μg elicited anxiolytic action, whereas this action is faded away when the dose was increased. For further testing therefore 0.5μg i.c.v. was used. Propranolol and atropine fully blocked the NmU-induced anxiolytic action, while haloperidol, phenoxybenzamine and nitro-l-arginine were ineffective. The results suggest that β-adrenergic and cholinergic mechanisms are involved in the anxiolytic action of NmU. © 2013.

Role of Heat Shock Protein 90 and Endothelial Nitric Oxide Synthase during Early Anesthetic and Ischemic Preconditioning

PubMed Central

Amour, Julien; Brzezinska, Anna K.; Weihrauch, Dorothee; Billstrom, Amie R.; Zielonka, Jacek; Krolikowski, John G.; Bienengraeber, Martin W.; Warltier, David C.; Pratt, Philip F.; Kersten, Judy R.

2009-01-01

Background Nitric oxide is known to be essential for early anesthetic (APC) and ischemic (IPC) preconditioning of myocardium. Heat shock protein 90 (Hsp90) regulates endothelial nitric oxide synthase (eNOS) activity. In this study, we tested the hypothesis that Hsp90-eNOS interactions modulate APC and IPC. Methods Myocardial infarct size was measured in rabbits after coronary occlusion and reperfusion in the absence or presence of preconditioning with 30 min of isoflurane (APC) or 5 min of coronary artery occlusion (IPC), and with or without pre-treatment with geldanamycin or radicicol, two chemically distinct Hsp90 inhibitors, or NG-nitro-L-arginine methylester, a non-specific NOS inhibitor. Isoflurane-dependent nitric oxide production was measured (ozone chemiluminescence) in human coronary artery endothelial cells or mouse cardiomyocytes, in the absence or presence of Hsp90 inhibitors or NG-nitro-L-arginine methylester. Interactions between Hsp90 and eNOS, and eNOS activation were assessed with immunoprecipitation, immunoblotting, and confocal microscopy. Results APC and IPC decreased infarct size (50% and 59%, respectively) and this action was abolished by Hsp90 inhibitors. NG-nitro-L-arginine methylester blocked APC but not IPC. Isoflurane increased nitric oxide production in human coronary artery endothelial cells, concomitantly with an increase in Hsp90-eNOS interaction (immunoprecipitation, immunoblotting, and immunohistochemistry). Pretreatment with Hsp90 inhibitors abolished isoflurane-dependent nitric oxide production and decreased Hsp90-eNOS interactions. Isoflurane did not increase nitric oxide production in mouse cardiomyocytes and eNOS was below the level of detection. Conclusion The results indicate that Hsp90 plays a critical role in mediating APC and IPC through protein-protein interactions, and suggest that endothelial cells are important contributors to nitric oxide-mediated signalling during APC. PMID:19194158

Evaluation of nitrate-substituted pseudocholine esters of aspirin as potential nitro-aspirins.

PubMed

Gilmer, John F; Moriarty, Louise M; Clancy, John M

2007-06-01

Herein we explore some designs for nitro-aspirins, compounds potentially capable of releasing both aspirin and nitric oxide in vivo. A series of nitrate-bearing alkyl esters of aspirin were prepared based on the choline ester template preferred by human plasma butyrylcholinesterase. The degradation kinetics of the compounds were followed in human plasma solution. All compounds underwent hydrolysis rapidly (t(1/2) approximately 1min) but generating exclusively the corresponding nitro-salicylate. The one exception, an N-propyl, N-nitroxyethyl aminoethanol ester produced 9.2% aspirin in molar terms indicating that the nitro-aspirin objective is probably achievable if due cognisance can be paid to the demands of the activating enzyme. Even at this low level of aspirin release, this compound is the most successful nitro-aspirin reported to date in the key human plasma model.

Myoendothelial coupling in the mesenteric arterial bed; segmental differences and interplay between nitric oxide and endothelin-1

PubMed Central

Hilgers, RHP; De Mey, JGR

2009-01-01

Background and purpose: We tested the hypothesis that activated arterial smooth muscle (ASM) stimulates endothelial vasomotor influences via gap junctions and that the significance of this myoendothelial coupling increases with decreasing arterial diameter. Experimental approach: From WKY rats, first-, second-, third-and fourth-order branches of the superior mesenteric artery (MA1, MA2, MA3 and MA4 respectively) were isolated and mounted in wire-myographs to record vasomotor responses to 0.16–20 µmol·L−1 phenylephrine. Key results: Removal of endothelium increased the sensitivity (pEC50) to phenylephrine in all arteries. The nitric oxide (NO) synthase inhibitor Nω-nitro-L-arginine methyl ester (L-NAME) (100 µmol·L−1) did not modify pEC50 to phenylephrine in all denuded arteries, and increased it in intact MA1, MA2 and MA3 to the same extent as denudation. However, in intact MA4, the effect of L-NAME was significantly larger (ΔpEC50 0.57 ± 0.02) than the effect of endothelium removal (ΔpEC50 0.20 ± 0.06). This endothelium-dependent effect of L-NAME in MA4 was inhibited by (i) steroidal and peptidergic uncouplers of gap junctions; (ii) a low concentration of the NO donor sodium nitroprusside; and (iii) by the endothelin-receptor antagonist bosentan. It was also observed during contractions induced by (i) calcium channel activation (BayK 8644, 0.001–1 µmol·L−1); (ii) depolarization (10–40 mmol·L−1 K+); and (iii) sympathetic nerve stimulation (0.25–32 Hz). Conclusions and implications: These pharmacological observations indicated feedback control by endothelium of ASM reactivity involving gap junctions and a balance between endothelium-derived NO and endothelin-1. This myoendothelial coupling was most prominent in distal resistance arteries. PMID:19302591

Acute effect of the dual angiotensin-converting enzyme and neutral endopeptidase 24-11 inhibitor mixanpril on insulin sensitivity in obese Zucker rat

PubMed Central

Arbin, V; Claperon, N; Fournié-Zaluski, M -C; Roques, B P; Peyroux, J

2001-01-01

The aim of this study was to determine whether acute dual angiotensin-converting enzyme (ACE)/neutral endopeptidase 24-11 (NEP) inhibition could improve whole body insulin-mediated glucose disposal (IMGD) more than ACE inhibition alone and whether this effect was mediated by the kinin-nitric oxide (NO) pathway activation.We therefore compared in anaesthetized obese (fa/fa) Zucker rats (ZOs) the effects of captopril (2 mg kg−1, i.v.+2 mg kg−1 h−1), retrothiorphan (25 mg kg−1, i.v. +25 mg  kg−1 h−1), a selective NEP inhibitor, and mixanpril (25 mg kg−1, i.v.+25 mg kg−1 h−1), a dual ACE/NEP inhibitor, on IMGD using hyperinsulinaemic euglycaemic clamp technique. The role of the kinin-NO pathway in the effects of mixanpril was tested using a bradykinin B2 receptor antagonist (Hoe-140, 300 μg kg−1) and a NO-synthase inhibitor (Nω-nitro-L-arginine methyl ester, L-NAME, 10 mg kg−1 i.v. +10 mg kg−1 h−1) as pretreatments.Insulin sensitivity index (ISI) was lower in ZO controls than in lean littermates. Increases in ISI were observed in captopril- and retrothiorphan-treated ZOs. In mixanpril-treated ZOs, ISI was further increased, compared to captopril- and retrothiorphan-treated ZOs.In ZOs, Hoe-140 and L-NAME alone did not significantly alter and slightly reduced the ISI respectively. Hoe-140 and L-NAME markedly inhibited the ISI improvement induced by mixanpril.These results show that in obese insulin-resistant Zucker rats, under acute conditions, NEP or ACE inhibition can improve IMGD and that dual ACE/NEP inhibition improves IMGD more effectively than does either single inhibition. This effect is linked to an increased activation of the kinin-NO pathway. PMID:11399666

Effects of combined neutral endopeptidase 24-11 and angiotensin-converting enzyme inhibition on femoral vascular conductance in streptozotocin-induced diabetic rats

PubMed Central

Arbin, V; Claperon, N; Fournié-Zaluski, M -C; Roques, B P; Peyroux, J

2000-01-01

The successive effects of the angiotensin-converting enzyme inhibitor captopril (CAP, 2 mg kg−1+1 mg kg−1 30 min−1 infusion) and the neutral endopeptidase 24-11 inhibitor retrothiorphan (RT, 25 mg kg−1+12.5 mg kg−1 30 min−1 infusion) were studied on femoral vascular conductance (FVC) in streptozotocin-induced diabetic (STZ-SD) and control Sprague-Dawley (C-SD) rats. The role of the kinin-nitric oxide (NO) pathway was assessed by (1) using pre-treatments: a bradykinin (BK) B2 receptor antagonist (Hoe-140, 300 μg kg−1), a NO-synthase inhibitor (Nω-nitro-L-arginine methyl ester, L-NAME, 10 mg kg−1), a kininase I inhibitor (DL-2-mercaptomethyl-3-guanidinoethylthiopropanoic acid, MGTA, 10 mg kg−1+20 mg kg−1 20 min−1 infusion) and (2) comparing the effects in STZ-induced diabetic (STZ-BN) and control Brown-Norway kininogen-deficient (C-BN) rats.In C-SDs, CAP and CAP+RT increased FVC similarly. In STZ-SDs, FVC and FBF were decreased compared to C-SDs. CAP+RT increased them more effectively than CAP alone.In both C-SDs and STZ-SDs, the femoral bed vasodilatation elicited by CAP was inhibited by Hoe-140 and L-NAME. The FVC increase elicited by CAP+RT was not significantly reduced by Hoe-140 but was inhibited by L-NAME and Hoe-140+MGTA.In C-BNs, the vasodilatator responses to CAP and CAP+RT were abolished and highly reduced, respectively. In STZ-BNs, these responses were abolished.These results show that in STZ-SDs, CAP+RT improve FBF and FVC more effectively than CAP alone. These effects are linked to an increased activation of the kinin-NO pathway. BK could lead to NO production by BK B2 receptor activation and another pathway in which kininase I may be involved. PMID:10903969

Sodium nitrite attenuates hypertension-in-pregnancy and blunts increases in soluble fms-like tyrosine kinase-1 and in vascular endothelial growth factor.

PubMed

Gonçalves-Rizzi, Victor Hugo; Possomato-Vieira, Jose Sergio; Sales Graça, Tamiris Uracs; Nascimento, Regina Aparecida; Dias-Junior, Carlos A

2016-07-01

Preeclampsia is a pregnancy-associated disorder characterized by hypertension with uncertain pathogenesis. Increases in antiangiogenic soluble fms-like tyrosine kinase-1 (sFlt-1) and reductions in nitric oxide (NO) bioavailability have been observed in preeclamptic women. However, the specific mechanisms linking these detrimental changes to the hypertension-in-pregnancy are not clearly understood. In this regard, while recent findings have suggested that nitrite-derived NO formation exerts antihypertensive and antioxidant effects, no previous study has examined these responses to orally administered nitrite in hypertension-in-pregnancy. We then hypothesized restoring NO bioavailability with sodium nitrite in pregnant rats upon NO synthesis inhibition with N(omega)-nitro-l-arginine methyl ester (L-NAME) attenuates hypertension and high circulating levels of sFlt-1. Number and weight of pups and placentae were recorded to assess maternal-fetal interface. Plasma sFlt-1, vascular endothelial growth factor (VEGF) and biochemical determinants of NO formation and of antioxidant function were measured. We found that sodium nitrite blunts the hypertension-in-pregnancy and restores the NO bioavailability, and concomitantly prevents the L-NAME-induced high circulating sFlt-1 and VEGF levels. Also, our results suggest that nitrite-derived NO protected against reductions in litter size and placental weight caused by L-NAME, improving number of viable and resorbed fetuses and antioxidant function. Therefore, the present findings are consistent with the hypothesis that nitrite-derived NO may possibly be the driving force behind the maternal and fetal beneficial effects observed with sodium nitrite during hypertension-in-pregnancy. Certainly further investigations are required in preeclampsia, since counteracting the damages to the mother and fetal sides resulting from hypertension and elevated sFlt-1 levels may provide a great benefit in this gestational hypertensive disease. Copyright © 2016 Elsevier Inc. All rights reserved.

Nitric oxide bioavailability modulates the dynamics of microvascular oxygen exchange during recovery from contractions.

PubMed

Hirai, D M; Copp, S W; Ferreira, L F; Musch, T I; Poole, D C

2010-10-01

lowered microvascular PO(2) (PO(2) mv) during the exercise off-transient likely impairs muscle metabolic recovery and limits the capacity to perform repetitive tasks. The current investigation explored the impact of altered nitric oxide (NO) bioavailability on PO(2) mv during recovery from contractions in healthy skeletal muscle. We hypothesized that increased NO bioavailability (sodium nitroprusside: SNP) would enhance PO(2) mv and speed its recovery kinetics while decreased NO bioavailability (l-nitro arginine methyl ester: l-NAME) would reduce PO(2) mv and slow its recovery kinetics.   PO(2) mv was measured by phosphorescence quenching during transitions (rest-1 Hz twitch-contractions for 3 min-recovery) in the spinotrapezius muscle of Sprague-Dawley rats under SNP (300 microm), Krebs-Henseleit (CONTROL) and l-NAME (1.5 mm) superfusion conditions. relative to recovery in CONTROL, SNP resulted in greater overall microvascular oxygenation as assessed by the area under the PO(2) mv curve (PO(2 AREA) ; 3471 ± 292 mmHg s; SNP: 4307 ± 282 mmHg s; P < 0.05) and faster off-kinetics as evidenced by the mean response time (MRToff; 60.2 ± 6.9 s; SNP: 34.8 ± 5.7 s; P < 0.05), whereas l-NAME produced lower PO(2 AREA) (2339 ± 444 mmHg s; P < 0.05) and slower MRToff (86.6 ± 14.5s; P < 0.05). no bioavailability plays a key role in determining the matching of O(2) delivery-to-O(2) uptake and thus the upstream O(2) pressure driving capillary-myocyte O(2) flux (i.e. PO(2) mv) following cessation of contractions in healthy skeletal muscle. Additionally, these data support a mechanistic link between reduced NO bioavailability and prolonged muscle metabolic recovery commonly observed in ageing and diseased populations. © 2010 The Authors. Journal compilation © 2010 Scandinavian Physiological Society.

Evidence for cyclooxygenase-dependent sweating in young males during intermittent exercise in the heat

PubMed Central

Fujii, Naoto; McGinn, Ryan; Stapleton, Jill M; Paull, Gabrielle; Meade, Robert D; Kenny, Glen P

2014-01-01

Our recent work implicated nitric oxide (NO) in the control of sweating during intermittent exercise; however, it is unclear if cyclooxygenase (COX) is also involved. On separate days, ten healthy young (24 ± 4 years) males cycled in the heat (35°C). Two 30 min exercise bouts were performed at either a moderate (400 W, moderate heat load) or high (700 W, high heat load) rate of metabolic heat production and were followed by 20 and 40 min of recovery, respectively. Forearm sweating (ventilated capsule) was evaluated at four skin sites that were continuously perfused via intradermal microdialysis with: (1) lactated Ringer solution (Control), (2) 10 mm ketorolac (a non-selective COX inhibitor), (3) 10 mm NG-nitro-l-arginine methyl ester (l-NAME; a non-selective NO synthase inhibitor) or (4) a combination of 10 mm ketorolac + 10 mml-NAME. During the last 5 min of the first exercise at moderate heat load, forearm sweating (mg min−1 cm−2) was equivalently reduced with ketorolac (0.54 ± 0.08), l-NAME (0.55 ± 0.07) and ketorolac+l-NAME (0.56 ± 0.08) compared to Control (0.67 ± 0.06) (all P < 0.05). Similar results were obtained for the second exercise at moderate heat load (all P < 0.05). However, forearm sweating was similar between the four sites during exercise at high heat load and during recovery regardless of exercise intensity (all P > 0.05). We show that (1) although both COX and NO modulate forearm sweating during intermittent exercise bouts in the heat at a moderate heat load, the effects are not additive, and (2) the contribution of both enzymes to forearm sweating is less evident during intermittent exercise when the heat load is high and during recovery. PMID:25326453

A Lactobacillus plantarum esterase active on a broad range of phenolic esters.

PubMed

Esteban-Torres, María; Landete, José María; Reverón, Inés; Santamaría, Laura; de las Rivas, Blanca; Muñoz, Rosario

2015-05-01

Lactobacillus plantarum is the lactic acid bacterial species most frequently found in the fermentation of food products of plant origin on which phenolic compounds are abundant. L. plantarum strains showed great flexibility in their ability to adapt to different environments and growth substrates. Of 28 L. plantarum strains analyzed, only cultures from 7 strains were able to hydrolyze hydroxycinnamic esters, such as methyl ferulate or methyl caffeate. As revealed by PCR, only these seven strains possessed the est_1092 gene. When the est_1092 gene was introduced into L. plantarum WCFS1 or L. lactis MG1363, their cultures acquired the ability to degrade hydroxycinnamic esters. These results support the suggestion that Est_1092 is the enzyme responsible for the degradation of hydroxycinnamic esters on the L. plantarum strains analyzed. The Est_1092 protein was recombinantly produced and biochemically characterized. Surprisingly, Est_1092 was able to hydrolyze not only hydroxycinnamic esters, since all the phenolic esters assayed were hydrolyzed. Quantitative PCR experiments revealed that the expression of est_1092 was induced in the presence of methyl ferulate, an hydroxycinnamic ester, but was inhibited on methyl gallate, an hydroxybenzoic ester. As Est_1092 is an enzyme active on a broad range of phenolic esters, simultaneously possessing feruloyl esterase and tannase activities, its presence on some L. plantarum strains provides them with additional advantages to survive and grow on plant environments. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Effects of local infusions of apomorphine on the extracellular citrulline level in the striatum: Involvement of D1 and D2 dopamine receptors.

PubMed

Savel'ev, S A

2006-11-01

Studies using vital microdialysis and high-performance liquid chromatography showed that local infusion of the NO synthase inhibitor N-nitro-L-arginine (1 mM) into the striatum decreased, while infusion of the dopamine receptor agonist apomorphine (100 microM) increased the level of citrulline (a side product of nitric oxide synthesis) in the intercellular space of this structure in Sprague-Dawley rats. The increase in the citrulline level induced by infusions of apomorphine was completely prevented by local infusions of N-nitro-L-arginine (1 mM) and raclopride (10 microm), a dopamine D2 receptor blocker, but not by infusion of SCH-23390 (50 microm), a dopamine D1 receptor blocker. These data suggest that the increase in extracellular citrulline in the striatum induced by dopaminergic stimulation results from local increases in NO synthase activity and that this effect involves D2, but not D1 dopamine receptors.

Hydroxyethyl starch inhibits endothelium-derived relaxation in porcine coronary arteries.

PubMed

Dagtekin, Oguzhan; Krep, Henning; Fischer, Jürgen Hartmut

2008-01-01

Hydroxyethyl starch (HES) solutions are widely used for fluid resuscitation. We studied the effects of HES on endothelium-dependent relaxation (EDR), especially on the endothelium-derived hyperpolarizing factor (EDHF). Four-millimeter-long rings of fresh porcine coronary arteries from the local slaughterhouse were consecutively tested with or without HES (6 mg/ml). Indomethacin (10 micromol/l) was added in all measurements to eliminate prostacyclin effects. Prostaglandin F2alpha (10 micromol/l) was used for contraction and bradykinin (10(-10) to 10(-5) mol/l) for inducing EDR, which was calculated in percentage of the precontraction. After blocking all nitric oxide formation by N-nitro-L-arginine (300 micromol/l), the experiments were repeated to assess the EDHF-mediated relaxation response to bradykinin. HES 6 mg/ml induced a significant (p < 0.01) reduction in EDR (n = 8). After incubation with HES and nitric oxide blockage with N-nitro-L-arginine, the relaxation response was reduced especially for the bradykinin concentrations of 10(-6) mol/l (p < 0.05) and 10(-5) mol/l (p < 0.01). For the clinically relevant concentration of 6 mg/ml HES, a significant reduction in EDR and the EDHF can be found in epicardial coronary arteries of the pig. Copyright 2008 S. Karger AG, Basel.

Regulation of NANC neural bronchoconstriction in vivo in the guinea-pig: involvement of nitric oxide, vasoactive intestinal peptide and soluble guanylyl cyclase.

PubMed

Lei, Y H; Barnes, P J; Rogers, D F

1993-01-01

1. We investigated the effect of the nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) and the peptidase alpha-chymotrypsin on non-adrenergic, non-cholinergic (NANC neural) bronchoconstriction induced by electrical stimulation of the vagus nerves and by capsaicin in anaesthetized guinea-pigs in vivo using pulmonary insufflation pressure (PIP) as an index of bronchial tone. We also investigated the contribution of soluble guanylyl cyclase (SGC) to NANC neural relaxant mechanisms. 2. In the presence of atropine and propranolol, electrical stimulation of the vagus nerves induced a frequency-dependent increase in PIP above baseline of 67% at 2.5 Hz, of 128% at 5 Hz and of 230% at 10 Hz. L-NAME (1-50 mg kg-1, i.v.), at doses inducing increases in systemic blood pressure, dose-relatedly potentiated NANC bronchoconstriction. At 10 mg kg-1 i.v., L-NAME significantly (P < 0.05) potentiated NANC bronchoconstriction by a further 106% at 2.5 Hz and a further 147% at 5 Hz but did not potentiate the increase in PIP at 10 Hz. L-NAME did not induce bronchoconstriction in sham-stimulated control animals. D-NAME did not potentiate NANC bronchoconstriction. Raising systemic blood pressure with phenylephrine did not potentiate vagally-induced bronchoconstriction (2.5 Hz). 3. The NO precursor L-arginine, but not D-arginine, (100 mg kg-1, i.v.) significantly reversed the potentiation by L-NAME of NANC bronchoconstriction. L-Arginine alone significantly inhibited neurogenic bronchoconstriction at 10 Hz (by 74%); the inhibition of 25% at 2.5 Hz was not significant. 4. L-NAME did not significantly affect the increases in PIP induced by intravenous substance P. neurokinin A (NKA) or capsaicin. 5. The inhibitor of SGC, methylene blue (10 mg kg', i.v.) potentiated (by 110-140%) NANC neural bronchoconstriction induced by lower frequencies of nerve stimulation and reversed the reduction in PIP induced by the SGC activator, sodium nitroprusside (SNP, 1.05 mg kg- 1, i.v.). SNP significantly (P <0.05) reduced by 65% the bronchoconstriction induced by nerve stimulation at 10 Hz. Methylene blue did not effect baseline PIP in sham-stimulated controls. The airway effects of methylene blue and SNP were not associated with their cardiovascular effects. 6. a-Chymotrypsin (2 units kg-', i.v.) significantly potentiated vagally-induced bronchoconstriction by a further 63% at 2.5 Hz, by a further 95.6% at 5 Hz but did not potentiate the increase in PIP at 10 Hz. alpha-Chymotrypsin also potentiated (by 116%) capsaicin-induced bronchoconstriction. Vasoactive intestinal peptide (VIP, 10 ig kg-' i.v. infused over min) significantly reduced by 70% the increase in PIP induced by NKA (0.1 .Lmol kg-' i.v., infused over 30 s). 7. The combination of a-chymotrypsin (2 units kg-', i.v.) and L-NAME (5 mg kg-', i.v.) significantly potentiated NANC bronchoconstriction by a further 304% at 2.5 Hz, an increase in PIP which was greater than that induced by either a-chymotrypsin or L-NAME alone (P <0.05). 8. We conclude that endogenous NO and a bronchodilator peptide, possibly VIP, released in association with nerve stimulation, as well as activation of soluble guanylyl cyclase, regulate the magnitude of NANC neurogenic bronchoconstriction in guinea-pigs in vivo.

Novel Strategy of Using Methyl Esters as Slow Release Methanol Source during Lipase Expression by mut+ Pichia pastoris X33

PubMed Central

Kumari, Arti; Gupta, Rani

2014-01-01

One of the major issues with heterologous production of proteins in Pichia pastoris X33 under AOX1 promoter is repeated methanol induction. To obviate repeated methanol induction, methyl esters were used as a slow release source of methanol in lipase expressing mut+ recombinant. Experimental design was based on the strategy that in presence of lipase, methyl esters can be hydrolysed to release their products as methanol and fatty acid. Hence, upon break down of methyl esters by lipase, first methanol will be used as a carbon source and inducer. Then P. pastoris can switch over to fatty acid as a carbon source for multiplication and biomass maintenance till further induction by methyl esters. We validated this strategy using recombinant P. pastoris expressing Lip A, Lip C from Trichosporon asahii and Lip11 from Yarrowia lipolytica. We found that the optimum lipase yield under repeated methanol induction after 120 h was 32866 U/L, 28271 U/L and 21978 U/L for Lip C, Lip A and Lip 11 respectively. In addition, we found that a single dose of methyl ester supported higher production than repeated methanol induction. Among various methyl esters tested, methyl oleate (0.5%) caused 1.2 fold higher yield for LipA and LipC and 1.4 fold for Lip11 after 120 h of induction. Sequential utilization of methanol and oleic acid by P. pastoris was observed and was supported by differential peroxisome proliferation studies by transmission electron microscopy. Our study identifies a novel strategy of using methyl esters as slow release methanol source during lipase expression. PMID:25170843

Quantification of Anti-Aggregation Activity of Chaperones: A Test-System Based on Dithiothreitol-Induced Aggregation of Bovine Serum Albumin

PubMed Central

Borzova, Vera A.; Markossian, Kira A.; Kara, Dmitriy A.; Chebotareva, Natalia A.; Makeeva, Valentina F.; Poliansky, Nikolay B.; Muranov, Konstantin O.; Kurganov, Boris I.

2013-01-01

The methodology for quantification of the anti-aggregation activity of protein and chemical chaperones has been elaborated. The applicability of this methodology was demonstrated using a test-system based on dithiothreitol-induced aggregation of bovine serum albumin at 45°C as an example. Methods for calculating the initial rate of bovine serum albumin aggregation (v agg) have been discussed. The comparison of the dependences of v agg on concentrations of intact and cross-linked α-crystallin allowed us to make a conclusion that a non-linear character of the dependence of v agg on concentration of intact α-crystallin was due to the dynamic mobility of the quaternary structure of α-crystallin and polydispersity of the α-crystallin–target protein complexes. To characterize the anti-aggregation activity of the chemical chaperones (arginine, arginine ethyl ester, arginine amide and proline), the semi-saturation concentration [L]0.5 was used. Among the chemical chaperones studied, arginine ethyl ester and arginine amide reveal the highest anti-aggregation activity ([L]0.5 = 53 and 58 mM, respectively). PMID:24058554

Nitric Oxide Is Associated with Long-Term Zinc Tolerance in Solanum nigrum1[W

PubMed Central

Xu, Jin; Yin, Hengxia; Li, Yulong; Liu, Xiaojing

2010-01-01

Nitric oxide (NO) has been identified as a signal molecule that interplays with reactive oxygen species in response to heavy metal stresses. Roles of NO in regulating cadmium toxicity and iron deficiency have been proposed; however, the function of NO in zinc (Zn) tolerance in plants remains unclear. Here, we investigated NO accumulation and its role in plant Zn tolerance. Zn-induced NO production promoted an increase in reactive oxygen species accumulation in Solanum nigrum roots by modulating the expression and activity of antioxidative enzymes. Subsequently, programmed cell death (PCD) was observed in primary root tips. Inhibiting NO accumulation by 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (a specific NO scavenger) or NG-nitro-l-arginine-methyl ester (a NO synthase inhibitor) prevented the increase of superoxide radical and hydrogen peroxide as well as the subsequent cell death in the root tips, supporting the role of NO in Zn-induced PCD in the root tips. Zn-induced NO production affected the length of primary roots, the number of lateral roots, and root hair growth and thereby modulated root system architecture and activity. Investigation of metal contents in Zn-treated roots suggests that NO is required for metal (especially iron) uptake and homeostasis in plants exposed to excess Zn. Taken together, our results indicate that NO production and the subsequent PCD in root tips exposed to excess Zn are favorable for the S. nigrum seedling response to long-term Zn toxicity by modulating root system architecture and subsequent adaptation to Zn stress. PMID:20855519

Influence of Repeated Senna Laxative Use on Skin Barrier Function in Mice.

PubMed

Yokoyama, Satoshi; Hiramoto, Keiichi; Yamate, Yurika; Ooi, Kazuya

2017-08-01

Senna, one of the major stimulant laxatives, is widely used for treating constipation. Chronic senna use has been reported to be associated with colonic disorders such as melanosis coli and/or epithelial hyperplasia. However, there is no obvious information on the influence of chronic senna use on organs except for the intestine. To clarify the influence of senna laxative use on skin barrier function by repeated senna administration. Eight-week-old male hairless mice received senna (10 mg/kg/day) for 21 days. After administration, we evaluated transepidermal water loss (TEWL), and investigated the biomarkers in plasma and skin using protein analysis methods. Fecal water content on day seven was significantly increased; however, on day 21, it was significantly decreased after repeated senna administration. In the senna-administered group, TEWL was significantly higher compared to the control on days seven and 21. Plasma acetylcholine concentration and NO 2 - /NO 3 - were increased on days seven and 21, respectively. In skin, tryptase-positive mast cells and inducible nitric oxide synthase (iNOS)-positive cells were increased on days seven and 21, respectively. The increase of TEWL on days seven and 21 was suppressed by the administration of atropine and N(G)-nitro-L-arginine methyl ester, respectively. It was suggested that diarrhea or constipation induced by repeated senna administration caused the impairment of skin barrier function. There is a possibility that this impaired skin barrier function occurred due to degranulation of mast cells via cholinergic signals or oxidative stress derived from iNOS.

(−)-Epicatechin induces calcium and translocation independent eNOS activation in arterial endothelial cells

PubMed Central

Ramirez-Sanchez, Israel; Maya, Lisandro; Ceballos, Guillermo

2011-01-01

The consumption of cacao-derived (i.e., cocoa) products provides beneficial cardiovascular effects in healthy subjects as well as individuals with endothelial dysfunction such as smokers, diabetics, and postmenopausal women. The vascular actions of cocoa are related to enhanced nitric oxide (NO) production. These actions can be reproduced by the administration of the cacao flavanol (−)-epicatechin (EPI). To further understand the mechanisms behind the vascular action of EPI, we investigated the effects of Ca2+ depletion on endothelial nitric oxide (NO) synthase (eNOS) activation/phosphorylation and translocation. Human coronary artery endothelial cells were treated with EPI or with bradykinin (BK), a well-known Ca2+-dependent eNOS activator. Results demonstrate that both EPI and BK induce increases in intracellular calcium and NO levels. However, under Ca2+-free conditions, EPI (but not BK) is still capable of inducing NO production through eNOS phosphorylation at serine 615, 633, and 1177. Interestingly, EPI-induced translocation of eNOS from the plasmalemma was abolished upon Ca2+ depletion. Thus, under Ca2+-free conditions, EPI can stimulate NO synthesis independent of calmodulin binding to eNOS and of its translocation into the cytoplasm. We also examined the effect of EPI on the NO/cGMP/vasodilator-stimulated phosphoprotein (VASP) pathway activation in isolated Ca2+-deprived canine mesenteric arteries. Results demonstrate that under these conditions, EPI induces the activation of this vasorelaxation-related pathway and that this effect is inhibited by pretreatment with nitro-l-arginine methyl ester, suggesting a functional relevance for this phenomenon. PMID:21209365

Reduced Cystathionine γ-Lyase and Increased miR-21 Expression Are Associated with Increased Vascular Resistance in Growth-Restricted Pregnancies

PubMed Central

Cindrova-Davies, Tereza; Herrera, Emilio A.; Niu, Youguo; Kingdom, John; Giussani, Dino A.; Burton, Graham J.

2013-01-01

Increased vascular impedance in the fetoplacental circulation is associated with fetal hypoxia and growth restriction. We sought to investigate the role of hydrogen sulfide (H2S) in regulating vasomotor tone in the fetoplacental vasculature. H2S is produced endogenously by catalytic activity of cystathionine β-synthase and cystathionine γ-lyase (CSE). Immunohistochemical analysis localized CSE to smooth muscle cells encircling arteries in stem villi. Immunoreactivity was reduced in placentas from pregnancies with severe early-onset growth-restriction and preeclampsia displaying abnormal umbilical artery Doppler waveforms compared with preeclamptic placentas with normal waveforms and controls. These findings were confirmed at the protein and mRNA levels. MicroRNA-21, which negatively regulates CSE expression, was increased in placentas with abnormal Doppler waveforms. Exposure of villus explants to hypoxia-reoxygenation significantly reduced CSE protein and mRNA and increased microRNA-21 expression. No changes were observed in cystathionine β-synthase expression, immunolocalized principally to the trophoblast, in pathologic placentas or in vitro. Finally, perfusion of normal placentas with an H2S donor, after preconstriction with a thromboxane mimetic, resulted in dose-dependent vasorelaxation. Glibenclamide and NG-nitro-l-arginine methyl ester partially blocked the effect, indicating that H2S acts through ATP-sensitive K+ channels and nitric oxide synthesis. These results demonstrate that H2S is a powerful vasodilator of the placental vasculature and that expression of CSE is reduced in placentas associated with increased vascular resistance. PMID:23410520

Endothelial dysfunction in rat mesenteric resistance artery after transient middle cerebral artery occlusion.

PubMed

Martinez-Revelles, Sonia; Jiménez-Altayó, Francesc; Caracuel, Laura; Pérez-Asensio, Fernando J; Planas, Anna M; Vila, Elisabet

2008-05-01

Stroke triggers a local and systemic inflammatory response leading to the production of cytokines that can influence blood vessel reactivity. In this study, we aimed to assess whether cerebral ischemia/reperfusion could affect vasoconstriction and vasodilatation on mesenteric resistance arteries (MRA) from Wistar Kyoto rats. The right middle cerebral artery was occluded (90 min) and reperfused (24 h). Sham-operated animals were used as controls. Plasma levels of interleukin (IL)-6 and IL-1beta were measured at 24 h. Vasoconstrictor and vasodilator responses were recorded in a wire myograph. Protein expression was determined by Western blot and immunofluorescence, and superoxide anion (O(2)(.)) production was evaluated by ethidium fluorescence. In MRA, ischemia/reperfusion increased plasma levels of IL-6, O2. production, protein expression of cyclooxygenase-2, and protein tyrosine nitrosylation, but it impaired acetylcholine (ACh) vasodilatation without modifying the vasodilatations to sodium nitroprusside or the contractions to phenylephrine and KCl. Superoxide dismutase (SOD) and indomethacin reversed the impairment of ACh relaxation induced by ischemia/reperfusion. However, N(omega)-nitro-l-arginine methyl ester affected similarly ACh-induced vasodilatations in MRA of ischemic and sham-operated rats. Protein expression of endothelial and inducible nitric-oxide synthase, copper/zinc SOD, manganese SOD, and extracellular SOD was similar in both groups of rats. Our results show MRA endothelial dysfunction 24 h after brain ischemia/reperfusion. Excessive production of O2. in MRA mediates endothelial dysfunction, and the increase in plasma cytokine levels after brain ischemia/reperfusion might be involved in this effect.

Lung heparan sulfates modulate Kfc during increased vascular pressure: evidence for glycocalyx-mediated mechanotransduction

PubMed Central

Cluff, Mark; Kingston, Joseph; Hill, Denzil; Chen, Haiyan; Hoehne, Soeren; Malleske, Daniel T.; Kaur, Rajwinederjit

2012-01-01

Lung endothelial cells respond to changes in vascular pressure through mechanotransduction pathways that alter barrier function via non-Starling mechanism(s). Components of the endothelial glycocalyx have been shown to participate in mechanotransduction in vitro and in systemic vessels, but the glycocalyx's role in mechanosensing and pulmonary barrier function has not been characterized. Mechanotransduction pathways may represent novel targets for therapeutic intervention during states of elevated pulmonary pressure such as acute heart failure, fluid overload, and mechanical ventilation. Our objective was to assess the effects of increasing vascular pressure on whole lung filtration coefficient (Kfc) and characterize the role of endothelial heparan sulfates in mediating mechanotransduction and associated increases in Kfc. Isolated perfused rat lung preparation was used to measure Kfc in response to changes in vascular pressure in combination with superimposed changes in airway pressure. The roles of heparan sulfates, nitric oxide, and reactive oxygen species were investigated. Increases in capillary pressure altered Kfc in a nonlinear relationship, suggesting non-Starling mechanism(s). nitro-l-arginine methyl ester and heparanase III attenuated the effects of increased capillary pressure on Kfc, demonstrating active mechanotransduction leading to barrier dysfunction. The nitric oxide (NO) donor S-nitrosoglutathione exacerbated pressure-mediated increase in Kfc. Ventilation strategies altered lung NO concentration and the Kfc response to increases in vascular pressure. This is the first study to demonstrate a role for the glycocalyx in whole lung mechanotransduction and has important implications in understanding the regulation of vascular permeability in the context of vascular pressure, fluid status, and ventilation strategies. PMID:22160307

Antioxidative and myocardial protective effects of L-arginine in oxygen radical-induced injury of isolated perfused rat hearts.

PubMed

Suessenbacher, Astrid; Lass, Achim; Mayer, Bernd; Brunner, Friedrich

2002-04-01

Oxygen-derived free radicals and oxidants (reactive oxygen intermediates, ROI) have been implicated in cardiovascular diseases. The protective role of nitric oxide (NO) against ROI-mediated tissue injury is not resolved. We tested the effects of exogenous NO, L- and D-arginine and a NO synthase inhibitor on electrolysis-induced cardiac injury and the generation of ROI by electrolysis. Superoxide dismutase (SOD) and catalase were used for comparison. Hearts ( n=7) from male rats (350+/-30 g) were perfused in vitro at 10 ml min(-1) g(-1), ROI generated by electrolysis of the perfusion medium (15 mA, 10 s), and cardiac function and the level of isoluminol-derived chemiluminescence in electrolysed perfusion medium documented for 15 min ( n=4). The ROI-induced maximal reduction of left ventricular developed pressure to 55+/-5% of baseline, and a 2.2+/-0.1-fold rise in coronary perfusion pressure 3 min after electrolysis, were prevented by SOD (50 U ml(-1)), catalase (100 U ml(-1)), S-nitroso- N-acetyl- D,L-penicillamine (SNAP, 100 nmol l(-1)); L-arginine (1 mmol l(-1)), N(G)-nitro- L-arginine (L-NNA, 200 micromol l(-1)) or D-arginine (1 mmol l(-1)). The effect of L-arginine was concentration dependent. In all cases, the beneficial effects were closely matched by a near-total reduction of ROI in the perfusion medium.We conclude that, besides mimicking or enhancing NO activity, L-arginine and donor-derived exogenous NO are cardioprotective by reducing ROI-mediated tissue injury. The protective effect of L-NNA and D-arginine implies that the protection results from a direct chemical interaction between the drug and the oxidizing species.

Vasorelaxant properties of Vernonia amygdalina ethanol extract and its possible mechanism.

PubMed

Ch'ng, Yung Sing; Loh, Yean Chun; Tan, Chu Shan; Ahmad, Mariam; Asmawi, Mohd Zaini; Wan Omar, Wan Maznah; Yam, Mun Fei

2017-12-01

Vernonia amygdalina Del. (VA) (Asteraceae) is commonly used to treat hypertension in Malaysia. This study investigates the vasorelaxant mechanism of VA ethanol extract (VAE) and analyzes its tri-step FTIR spectroscopy fingerprint. Dried VA leaves were extracted with ethanol through maceration and concentrated using rotary evaporator before freeze-dried. The vasorelaxant activity and the underlying mechanisms of VAE using the cumulative concentration (0.01-2.55 mg/mL at 20-min intervals) were evaluated on aortic rings isolated from Sprague Dawley rats in the presence of antagonists. The tri-step FTIR spectroscopy showed that VAE contains alkaloids, flavonoids, and saponins. VAE caused the relaxation of pre-contracted aortic rings in the presence and absence of endothelium with EC 50 of 0.057 ± 0.006 and 0.430 ± 0.196 mg/mL, respectively. In the presence of Nω-nitro-l-arginine methyl ester (EC 50 0.971 ± 0.459 mg/mL), methylene blue (EC 50 1.203 ± 0.426 mg/mL), indomethacin (EC 50 2.128 ± 1.218 mg/mL), atropine (EC 50 0.470 ± 0.325 mg/mL), and propranolol (EC 50 0.314 ± 0.032 mg/mL), relaxation stimulated by VAE was significantly reduced. VAE acted on potassium channels, with its vasorelaxation effects significantly reduced by tetraethylammonium, 4-aminopyridine, barium chloride, and glibenclamide (EC 50 0.548 ± 0.184, 0.158 ± 0.012, 0.847 ± 0.342, and 0.304 ± 0.075 mg/mL, respectively). VAE was also found to be active in reducing Ca 2+ released from the sarcoplasmic reticulum and blocking calcium channels. The vasorelaxation effect of VAE involves upregulation of NO/cGMP and PGI 2 signalling pathways, and modulation of calcium/potassium channels, and muscarinic and β 2 -adrenergic receptor levels.

Tumor necrosis factor regulates NMDA receptor-mediated airway smooth muscle contractile function and airway responsiveness.

PubMed

Anaparti, Vidyanand; Pascoe, Christopher D; Jha, Aruni; Mahood, Thomas H; Ilarraza, Ramses; Unruh, Helmut; Moqbel, Redwan; Halayko, Andrew J

2016-08-01

We have shown that N-methyl-d-aspartate receptors (NMDA-Rs) are receptor-operated calcium entry channels in human airway smooth muscle (HASM) during contraction. Tumor necrosis factor (TNF) augments smooth muscle contractility by influencing pathways that regulate intracellular calcium flux and can alter NMDA-R expression and activity in cortical neurons and glial cells. We hypothesized that NMDA-R-mediated Ca(2+) and contractile responses of ASM can be altered by inflammatory mediators, including TNF. In cultured HASM cells, we assessed TNF (10 ng/ml, 48 h) effect on NMDA-R subunit abundance by quantitative PCR, confocal imaging, and immunoblotting. We observed dose- and time-dependent changes in NMDA-R composition: increased obligatory NR1 subunit expression and altered regulatory NR2 and inhibitory NR3 subunits. Measuring intracellular Ca(2+) flux in Fura-2-loaded HASM cultures, we observed that TNF exposure enhanced cytosolic Ca(2+) mobilization and changed the temporal pattern of Ca(2+) flux in individual myocytes induced by NMDA, an NMDA-R selective analog of glutamate. We measured airway responses to NMDA in murine thin-cut lung slices (TCLS) from allergen-naive animals and observed significant airway contraction. However, NMDA acted as a bronchodilator in TCLS from house dust mice-challenged mice and in allergen-naive TCLS subjected to TNF exposure. All contractile or bronchodilator responses were blocked by a selective NMDA-R antagonist, (2R)-amino-5-phosphonopentanoate, and bronchodilator responses were prevented by N(G)-nitro-l-arginine methyl ester (nitric oxide synthase inhibitor) or indomethacin (cyclooxygenase inhibitor). Collectively, we show that TNF augments NMDA-R-mediated Ca(2+) mobilization in HASM cells, whereas in multicellular TCLSs allergic inflammation and TNF exposure leads to NMDA-R-mediated bronchodilation. These findings reveal the unique contribution of ionotrophic NMDA-R to airway hyperreactivity. Copyright © 2016 the American Physiological Society.

Effects of melatonin on rat pial arteriolar diameter in vivo

PubMed Central

Régrigny, Olivier; Delagrange, Philippe; Scalbert, Elizabeth; Lartaud-Idjouadiene, Isabelle; Atkinson, Jeffrey; Chillon, Jean-Marc

1999-01-01

Based on our finding that melatonin decreased the lower limit of cerebral blood flow autoregulation in rat, we previously suggested that melatonin constricts cerebral arterioles. The goal of this study was to demonstrate this vasoconstrictor action and investigate the mechanisms involved.The effects of cumulative doses of melatonin (10−10 to 10−6 M) were examined in cerebral arterioles (30–50 μM) of male Wistar rats using an open skull preparation. Cerebral arterioles were exposed to two doses of melatonin (3×10−9 and 3×10−8 M) in the absence and presence of the mt1 and/or MT2 receptor antagonist, luzindole (2×10−6 M) and the Ca2+-activated K+ (BKCa) channel blocker, tetraethylammonium (TEA+, 10−4 M). The effect of L-nitro arginine methyl ester (L-NAME, 10−8 M) was examined on arterioles after TEA+ superfusion. Cerebral arterioles were also exposed to the BKCa activator, NS1619 (10−5 M), and to sodium nitroprusside (SNP, 10−8 M) in the absence and presence of melatonin (3×10−8 M).Melatonin induced a dose-dependent constriction with an EC50 of 3.0±0.1 nM and a maximal constriction of −15±1%. Luzindole abolished melatonin-induced vasoconstriction. TEA+ induced significant vasoconstriction (−10±2%). No additional vasoconstriction was observed when melatonin was added to the aCSF in presence of TEA+, whereas L-NAME still induced vasoconstriction (−10±1%). NS1619 induced vasodilatation (+11±1%) which was 50% less in presence of melatonin. Vasodilatation induced by SNP (+12±2%) was not diminished by melatonin.Melatonin directly constricts small diameter cerebral arterioles in rats. This vasoconstrictor effect is mediated by inhibition of BKCa channels following activation of mt1 and/or MT2 receptors. PMID:10455324

Neuropeptide S reduces duodenal bicarbonate secretion and ethanol-induced increases in duodenal motility in rats

PubMed Central

Wan Saudi, Wan Salman

2017-01-01

Alcohol disrupts the intestinal mucosal barrier by inducing metabolic and functional changes in epithelial cells. Recently, we showed that neuropeptide S (NPS) decreases duodenal motility and increases mucosal paracellular permeability, suggesting a role of NPS in the pathogenesis of disorders and dysfunctions in the small intestine. The aim of the present study was to investigate the effects of NPS on ethanol- and HCl-induced changes of duodenal mucosal barrier function and motility. Rats were anaesthetized with thiobarbiturate, and a 30-mm segment of the proximal duodenum with an intact blood supply was perfused in situ. The effects on duodenal bicarbonate secretion, the blood-to-lumen clearance of 51Cr-EDTA, motility and transepithelial net fluid flux were investigated. Intravenous (i.v.) administration of NPS significantly reduced duodenal mucosal bicarbonate secretion and stimulated mucosal transepithelial fluid absorption, mechanisms dependent on nitrergic signaling. NPS dose-dependently reduced ethanol-induced increases in duodenal motility. NPS (83 pmol·kg-1·min-1, i.v.) reduced the bicarbonate and fluid secretory response to luminal ethanol, whereas a 10-fold higher dose stimulated fluid secretion but did not influence bicarbonate secretion. In NPS-treated animals, duodenal perfusion of acid (pH 3) induced greater bicarbonate secretory rates than in controls. Pre-treating animals with Nω-nitro-L-arginine methyl ester (L-NAME) inhibited the effect of NPS on bicarbonate secretion. In response to luminal acid, NPS-treated animals had significantly higher paracellular permeability compared to controls, an effect that was abolished by L-NAME. Our findings demonstrate that NPS reduces basal and ethanol-induced increases in duodenal motility. In addition, NPS increases luminal alkalinization and mucosal permeability in response to luminal acid via mechanisms that are dependent on nitric oxide signaling. The data support a role for NPS in neurohumoral regulation of duodenal mucosal barrier function and motility. PMID:28384243

Effects of different levels of exercise volume on endothelium-dependent vasodilation: roles of nitric oxide synthase and heme oxygenase.

PubMed

Sun, Meng-Wei; Zhong, Mei-Fang; Gu, Jun; Qian, Feng-Lei; Gu, Jian-Zhong; Chen, Hong

2008-04-01

The objective of this study was to examine the effects of moderate and high levels of exercise volume on endothelium-dependent vasodilation and associated changes in vascular endothelial/inducible nitric oxide synthase (eNOS and iNOS) and heme oxygenase (HO). Male Sprague-Dawley rats were assigned to sedentary control, acute (2 weeks), or chronic (6 weeks) treadmill running at moderate intensity (50% maximal aerobic velocity) with different durations of exercise episodes: 2 h/d (endurance training, moderate volume) and 3 h/d (intense training, high volume). Endothelium-dependent vascular function was examined in isolated thoracic aorta. Co-localization and contents of aortic eNOS/iNOS and HO-1/HO-2 were determined with immunofluorescence and Western blotting. Compared with sedentary controls, rats subjected to acute and chronic endurance training showed enhanced endothelium-dependent relaxation (p<0.01). Whereas acetylcholine-induced dilation was inhibited completely by NOS inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) in sedentary controls, the dilation in the training groups was only partly blocked by L-NAME (inhibition was 98+/-3%, 79+/-6%, and 77+/-5% in sedentary control, acute, and chronic training groups, respectively, p<0.01). The remnant dilation in the training groups was further inhibited by HO inhibitor protoporphyrin IX zinc, with concomitant elevation in aortic eNOS as well as HO-1 and HO-2. In contrast to endurance exercise, high-volume intense training resulted in mild hypertension with significant impairment in endothelium-dependent vasodilation and profuse increases in aortic iNOS and eNOS (p<0.01). In conclusion, endothelium-dependent vasodilation is improved by endurance exercise but impaired by chronic intense training. Elevations of vascular eNOS and HO-1/HO-2 may contribute to enhanced vasodilation, which can be offset by intense training and elevation in vascular iNOS.

CGRP and nitric oxide of neuronal origin and their involvement in neurogenic vasodilatation in rat skin microvasculature

PubMed Central

Merhi, Merhi; Dusting, Greg J; Khalil, Zeinab

1998-01-01

Sensory nerves are important for the initiation of neurogenic inflammation and tissue repair. Both calcitonin gene-related peptide (CGRP) and nitric oxide (NO) have been implicated in neurogenic vasodilatation and inflammatory responses.A blister model in the rat hind footpad was used as a site to induce neurogenic vasodilatation in response to antidromic electrical stimulation of the sciatic nerve. Blood flux was monitored with a laser Doppler flow monitor.The quantitative contributions of CGRP and NO to vasodilatation were examined by use of the CGRP receptor antagonist CGRP8-37 and NO synthase inhibitors 7-nitroindazole (7-NI), 3-bromo 7-NI and NG-nitro L-arginine methyl ester (L-NAME). The potential modulatory role of endothelin was examined by use of the ETA receptor antagonist BQ-123.CGRP8-37 (10 μM) was perfused over the blister base before nerve stimulation and continuously throughout the post-stimulation period, resulting in a significant reduction (41%) in the blood flux vascular response.Pretreatment with the specific neuronal NO synthase inhibitors, 7-NI and 3-bromo 7-NI (10 mg kg−1, i.v.), and of the non-specific L-NAME (100 μM), resulted in significant inhibition of the blood flux response (36%, 72% and 57% decrease, respectively). In contrast, 7-NI treatment in young rats pretreated with capsaicin had no further effect on the vascular response, suggesting that the source of NO is the sensory nerves.BQ-123 (10 μM) significantly enhanced the stimulation-induced blood flux response (61% increase). When 7-NI was co-administered with either CGRP8-37 or BQ-123, the drug actions were additive, suggesting that there was no interaction between NO and CGRP or endothelin.These data suggest that both NO and CGRP participate in neurogenic vasodilatation in rat skin microvasculature and that this response is modulated by endogenous endothelin. PMID:9535014

The influence of human neutrophils on N-nitrosodimethylamine (NDMA) synthesis.

PubMed

Jabłoński, Jakub; Jabłońska, Ewa; Iwanowska, Jolanta; Marcińczyk, Magda; Moniuszko-Jakoniuk, Janina

2006-01-01

N-nitrozodimethyloamine (NDMA) is a carcinogenic compound that can be formed in vivo. NDMA is synthesized from precursors-amines and nitrosating agents. Nitrosating agents are formed through the reaction of oxide, reactive oxygen species and nitric oxide (NO). Human neutrophils (PMN) are an important source of the most reactive oxygen species as well as of the nitric oxide. The increase in oxygen metabolism of PMN can lead to the increase nitrosating agent and nitroso-forms. Inflammatory process is associated with locally decreased pH that may favor nitrosation reaction. In the present study, we estimated the NDMA synthesis by LPS-stimulated PMN in the presence of the iNOS inhibitor--N-nitro-L-arginine methyl ester (L-NAME). In the nitrosation reaction dimethylamine (DMA) was used as substrat. The viability of the cells was measured by cytometric method. NDMA concentrations the culture media was measured by GCMS method. NO production was estimated by Griess's method. Expression of iNOS was determined by western blotting. Results obtained showed that DMA nitrosation is most effective in pH between 3-4.5. Nonstimulated PMN produced lower concentrations of NO than LPS-stimulated cells (1.27 microg/cm3 and 1.57 microg/cm3, respectively). In the culture of nonstimulated PMN supplemented with DMA, there was NDMA (mean--0.99 ng/cm3). In the culture of LPS-stimulated PMN in the presence of DMA, the concentration of NDMA was higher than in the culture of nonstimulated PMN (median--1.45 ng/cm3). In the supernatants of cells incubated without DMA and with DMA, LPS and L-NAME, no NDMA was detected. These results indicate that PMN can be one of sources of nitrosating agents and can play a role in endogenous NDMA synthesis. Stimulation of PMN can lead to the increase of NDMA concentration following the increase of NO production. Different pathological conditions associated with PMN activation as well as the decreased pH may favor endogenous NDMA synthesis.

Cilostazol enhances atorvastatin-induced vasodilation of female rat aorta during aging.

PubMed

Nurullahoğlu-Atalık, K E; Kutlu, S; Solak, H; Koca, R Özen

2017-09-01

Statins have cholesterol-independent effects including an increased vascular nitric oxide activity and are commonly used by patients with cardiovascular disease. Such patients frequently have cardiovascular diseases, which may be treated with cilostazol, a platelet aggregation inhibitor. This study was designed to investigate whether combined use of cilostazol would increase the inhibitory effect of statin on vascular smooth muscle and how maturation would affect these responses. Female Wistar rats, aged 3-4 months (young) and 14-15 months (adult), were sacrificed by cervical dislocation and the thoracic aorta was dissected and cut into 3- to 4-mm-long rings. The rings were mounted under a resting tension of 1 g in a 20-ml organ bath filled with Krebs-Henseleit solution. Rings were precontracted with phenylephrine (10 -6  M), and the presence of endothelium was confirmed with acetylcholine (10 -6  M). Then, the concentration-response curves were obtained for atorvastatin alone (10 -10 to 3 × 10 -4  M; control) and in the presence of cilostazol (10 -6  M) in young and adult rat aortas. This experimental protocol was also carried out in aorta rings, which had been pretreated with N G -nitro-l-arginine methyl ester (l-NAME, 10 -4  M). Atorvastatin induced concentration-dependent relaxations in young and adult rat thoracic aorta rings precontracted with phenylephrine. The pIC 50 value of atorvastatin was significantly decreased in adult rat aortas. In addition, pretreatment of aortas with cilostazol enhanced the potency of atorvastatin in both young and adult aortas. Incubation with l-NAME did not completely eliminate the relaxations to atorvastatin in the presence of cilostazol. These results suggest that combined application of cilostazol with atorvastatin was significantly more potent than atorvastatin alone. Combined drug therapy may be efficacious in delaying the occurrence of cardiovascular events.

Exercise training and muscle microvascular oxygenation: functional role of nitric oxide

PubMed Central

Hirai, Daniel M.; Copp, Steven W.; Ferguson, Scott K.; Holdsworth, Clark T.; McCullough, Danielle J.; Behnke, Bradley J.; Musch, Timothy I.

2012-01-01

Exercise training induces multiple adaptations within skeletal muscle that may improve local O2 delivery-utilization matching (i.e., Po2mv). We tested the hypothesis that increased nitric oxide (NO) function is intrinsic to improved muscle Po2mv kinetics from rest to contractions after exercise training. Healthy young Sprague-Dawley rats were assigned to sedentary (n = 18) or progressive treadmill exercise training (n = 10; 5 days/wk, 6–8 wk, final workload of 60 min/day at 35 m/min, −14% grade) groups. Po2mv was measured via phosphorescence quenching in the spinotrapezius muscle at rest and during 1-Hz twitch contractions under control (Krebs-Henseleit solution), sodium nitroprusside (SNP, NO donor; 300 μM), and NG-nitro-l-arginine methyl ester (l-NAME, nonspecific NO synthase blockade; 1.5 mM) superfusion conditions. Exercise-trained rats had greater peak oxygen uptake (V̇o2peak) than their sedentary counterparts (81 ± 1 vs. 72 ± 2 ml·kg−1·min−1, respectively; P < 0.05). Exercise-trained rats had significantly slower Po2mv fall throughout contractions (τ1; time constant for the first component) during control (sedentary: 8.1 ± 0.6; trained: 15.2 ± 2.8 s). Compared with control, SNP slowed τ1 to a greater extent in sedentary rats (sedentary: 38.7 ± 5.6; trained: 26.8 ± 4.1 s; P > 0.05) whereas l-NAME abolished the differences in τ1 between sedentary and trained rats (sedentary: 12.0 ± 1.7; trained: 11.2 ± 1.4 s; P < 0.05). Our results indicate that endurance exercise training leads to greater muscle microvascular oxygenation across the metabolic transient following the onset of contractions (i.e., slower Po2mv kinetics) partly via increased NO-mediated function, which likely constitutes an important mechanism for training-induced metabolic adaptations. PMID:22678970

Hyperfiltration and effect of nitric oxide inhibition on renal and endothelial function in humans with uncomplicated type 1 diabetes mellitus

PubMed Central

Reich, Heather N.; Jiang, Shan; Har, Ronnie; Nasrallah, Rania; Hébert, Richard L.; Lai, Vesta; Scholey, James W.; Sochett, Etienne B.

2012-01-01

Studies of experimental diabetes mellitus (DM) suggest that increased nitric oxide (NO) bioactivity contributes to renal hyperfiltration. However, the role of NO in mediating hyperfiltration has not been fully elucidated in humans. Our aim was to examine the effect of NO synthase inhibition on renal and peripheral vascular function in normotensive subjects with uncomplicated type 1 DM. Renal function and brachial artery flow-mediated vasodilatation (FMD) were measured before and after an intravenous infusion of the NO synthase inhibitor NG-nitro-l-arginine methyl ester (l-NMMA) in 21 healthy control and 37 type 1 DM patients. Measurements in DM participants were made under clamped euglycemic conditions. The effect of l-NMMA on circulating and urinary NO metabolites (NOx) and cGMP and on urinary prostanoids was also determined. Baseline characteristics were similar in the two groups. For analysis, the DM patients were divided into those with hyperfiltration (DM-H, n = 18) and normal glomerular filtration rate (GFR) levels (DM-N, n = 19). Baseline urine NOx and cGMP were highest in DM-H. l-NMMA led to a decline in GFR in DM-H (152 ± 16 to 140 ± 11 ml·min−1·1.73 m−2) but not DM-N or healthy control participants. The decline in effective renal plasma flow in response to l-NMMA (806 ± 112 to 539 ± 80 ml·min−1·1.73 m−2) in DM-H was also exaggerated compared with the other groups (repeated measures ANOVA, P < 0.05), along with declines in urinary NOx metabolites and cGMP. Baseline FMD was lowest in DM-H compared with the other groups and did not change in response to l-NMMA. l-NMMA reduced FMD and plasma markers of NO bioactivity in the healthy control and DM-N groups. In patients with uncomplicated type 1 DM, renal hyperfiltration is associated with increased NO bioactivity in the kidney and reduced NO bioactivity in the systemic circulation, suggesting a paradoxical state of high renal and low systemic vascular NO bioactivity. PMID:22855276

40 CFR 721.4080 - MNNG (N-methyl-N′-nitro-N-nitrosoguanidine).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false MNNG (N-methyl-Nâ²-nitro-N... Specific Chemical Substances § 721.4080 MNNG (N-methyl-N′-nitro-N-nitrosoguanidine). (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance MNNG (N-methyl-N′-nitro-N...

40 CFR 721.4080 - MNNG (N-methyl-N′-nitro-N-nitrosoguanidine).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false MNNG (N-methyl-Nâ²-nitro-N... Specific Chemical Substances § 721.4080 MNNG (N-methyl-N′-nitro-N-nitrosoguanidine). (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance MNNG (N-methyl-N′-nitro-N...

Nitric Oxide Mediates Glutamate-Linked Enhancement of cGMP Levels in the Cerebellum

NASA Astrophysics Data System (ADS)

Bredt, David S.; Snyder, Solomon H.

1989-11-01

Nitric oxide, which mediates influences of numerous neurotransmitters and modulators on vascular smooth muscle and leukocytes, can be formed in the brain from arginine by an enzymatic activity that stoichiometrically generates citrulline. We show that glutamate and related amino acids, such as N-methyl-D-aspartate, markedly stimulate arginine-citrulline transformation in cerebellar slices stoichiometrically with enhancement of cGMP levels. Nω-monomethyl-L-arginine blocks the augmentation both of citrulline and cGMP with identical potencies. Arginine competitively reverses both effects of Nω-monomethyl-L-arginine with the same potencies. Hemoglobin, which complexes nitric oxide, prevents the stimulation by N-methyl-D-aspartate of cGMP levels, and superoxide dismutase, which elevates nitric oxide levels, increases cGMP formation. These data establish that nitric oxide mediates the stimulation by glutamate of cGMP formation.

Agmatine exerts anticonvulsant effect in mice: modulation by alpha 2-adrenoceptors and nitric oxide.

PubMed

Demehri, Shadpour; Homayoun, Houman; Honar, Hooman; Riazi, Kiarash; Vafaie, Kourosh; Roushanzamir, Farshad; Dehpour, Ahmad Reza

2003-09-01

The effect of agmatine, an endogenous polyamine metabolite, on seizure susceptibility was investigated in mice. Acute intraperitoneal administration of agmatine (5, 10, 20, 40 mg/kg) had a significant and dose-dependent inhibitory effect on pentylenetetrazole (PTZ)-induced seizures. The peak of this anticonvulsant effect was 45 min after agmatine administration. We further investigated the possible involvement of the alpha(2)-adrenoceptors and L-arginine/NO pathway in this effect of agmatine. The alpha(2)-adrenoceptor antagonist, yohimbine (0.5-2 mg/kg), induced a dose-dependent blockade of the anticonvulsant effect of agmatine. The nitric oxide synthase (NOS) substrate, L-arginine (60 mg/kg), inhibited the anticonvulsant property of agmatine and this effect was significantly reversed by NOS inhibitor N(G)-nitro-L-arginine (L-NAME, 30 mg/kg), implying an NO-dependent mechanism for L-arginine effect. We further examined a possible additive effect between agmatine (1 or 5 mg/kg) and L-NAME (10 mg/kg). The combination of L-NAME (10 mg/kg) with agmatine (5 but not 1 mg/kg) induced a significantly higher level of seizure protection as compared with each drug alone. Moreover, a combination of lower doses of yohimbine (0.5 mg/kg) and L-arginine (30 mg/kg) also significantly decreased the anticonvulsant effect of agmatine. In conclusion, the present data suggest that agmatine may be of potential use in seizure treatment.

Efficient and Selective N-Methylation of Nitroarenes under Mild Reaction Conditions.

PubMed

Pedrajas, Elena; Sorribes, Iván; Guillamón, Eva; Junge, Kathrin; Beller, Matthias; Llusar, Rosa

2017-09-21

Herein, we report a straightforward protocol for the preparation of N,N-dimethylated amines from readily available nitro starting materials using formic acid as a renewable C 1 source and silanes as reducing agents. This tandem process is efficiently accomplished in the presence of a cubane-type Mo 3 PtS 4 catalyst. For the preparation of the novel [Mo 3 Pt(PPh 3 )S 4 Cl 3 (dmen) 3 ] + (3 + ) (dmen: N,N'-dimethylethylenediamine) compound we have followed a [3+1] building block strategy starting from the trinuclear [Mo 3 S 4 Cl 3 (dmen) 3 ] + (1 + ) and Pt(PPh 3 ) 4 (2) complexes. The heterobimetallic 3 + cation preserves the main structural features of its 1 + cluster precursor. Interestingly, this catalytic protocol operates at room temperature with high chemoselectivity when the 3 + catalyst co-exists with its trinuclear 1 + precursor. N-heterocyclic arenes, double bonds, ketones, cyanides and ester functional groups are well retained after N-methylation of the corresponding functionalized nitroarenes. In addition, benzylic-type as well as aliphatic nitro compounds can also be methylated following this protocol. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ameliorated effect of L-arginine supplementation on gingival morphology in cyclosporin-treated rats.

PubMed

Fu, E; Tz-Chong, C; Liu, D; Chiu, S C

2000-11-01

The role of nitric oxide (NO) in the pathogenesis of cyclosporin (CsA)-induced gingival overgrowth is unknown. The purpose of the present study was to evaluate the effect of NO substrate (L-arginine) and blockade (N-nitro-L-arginine methylester-hydrochloride, L-NAME) on the gingival morphology in CsA-fed rats. Sixty CsA-fed (10 mg/kg/day) male Sprague-Dawley rats were assigned to 3 groups. Animals in 2 experimental groups received L-arginine (1% weight/weight) in rat chowder or L-NAME (50 mg/l) in drinking water, respectively, for 4 weeks. Rats in the control group were fed a normal diet and water. At week 0, 2, and 4, dental stone models were made from the mandibular anterior region and the gingival dimensions (width, depth, and height) were measured. The tail cuff blood pressure and the plasma nitrate level were also measured at week 4 to monitor the effects of L-arginine and L-NAME treatment. No significant difference in the gingival dimensions was noticed at week 0; however, significant differences were observed at weeks 2 and 4, except the buccolingual depth at week 2. While the magnitude of gingival dimensions was large, moderate, and small in control, L-NAME, and L-arginine groups, respectively, we found significantly reduced gingival dimensions in both L-arginine supplement and L-NAME groups. Nevertheless, the reduced gingival overgrowth in the L-NAME treatment group was far less than that in the exogenous NO treatment group. Plasma NO2-/NO3- concentrations were also significantly different; i.e., from the highest to the lowest levels were the L-arginine, CsA control, and L-NAME group, respectively. A significantly increased mean and diastolic blood pressure was found in the L-NAME group compared to the L-arginine group. Gingival morphology in CsA-fed rats was evaluated after NO substrate (L-arginine) and blockade (L-NAME) treatment for 4 weeks. Significantly decreased dimensions were noted in the L-arginine group compared to the CsA group at weeks 2 and 4. Although an inhibitory effect on the gingival morphology was also observed in the L-NAME group, another unknown mechanism might be involved. Within the limitations of the study, we suggest that NO may have an important role in the mechanism of CsA-induced gingival overgrowth.

Pendrin protein abundance in the kidney is regulated by nitric oxide and cAMP.

PubMed

Thumova, Monika; Pech, Vladimir; Froehlich, Otto; Agazatian, Diana; Wang, Xiaonan; Verlander, Jill W; Kim, Young Hee; Wall, Susan M

2012-09-15

Pendrin is a Cl(-)/HCO(3)(-) exchanger, expressed in the apical regions of some intercalated cell subtypes, and is critical in the pressor response to angiotensin II. Since angiotensin type 1 receptor inhibitors reduce renal pendrin protein abundance in mice in vivo through a mechanism that is dependent on nitric oxide (NO), we asked if NO modulates renal pendrin expression in vitro and explored the mechanism by which it occurs. Thus we quantified pendrin protein abundance by confocal fluorescent microscopy in cultured mouse cortical collecting ducts (CCDs) and connecting tubules (CNTs). After overnight culture, CCDs maintain their tubular structure and maintain a solute gradient when perfused in vitro. Pendrin protein abundance increased 67% in CNT and 53% in CCD when NO synthase was inhibited (N(G)-nitro-L-arginine methyl ester, 100 μM), while NO donor (DETA NONOate, 200 μM) application reduced pendrin protein by ∼33% in the CCD and CNT. When CNTs were cultured in the presence of the guanylyl cyclase inhibitor 1H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one (10 μM), NO donors did not alter pendrin abundance. Conversely, pendrin protein abundance rose when cAMP content was increased by the application of an adenylyl cyclase agonist (forskolin, 10 μM), a cAMP analog (8-bromo-cAMP, 1 mM), or a phosphodiesterase inhibitor (BAY60-7550, 50 μM). Since NO reduces cellular cAMP in the CNT, we asked if NO reduces pendrin abundance by reducing cAMP. With blockade of cGMP-stimulated phosphodiesterase II, NO did not alter pendrin protein abundance. We conclude that NO acts through cAMP to reduce pendrin total protein abundance by enhancing cAMP degradation.

Pendrin protein abundance in the kidney is regulated by nitric oxide and cAMP

PubMed Central

Thumova, Monika; Pech, Vladimir; Froehlich, Otto; Agazatian, Diana; Wang, Xiaonan; Verlander, Jill W.; Kim, Young Hee

2012-01-01

Pendrin is a Cl−/HCO3− exchanger, expressed in the apical regions of some intercalated cell subtypes, and is critical in the pressor response to angiotensin II. Since angiotensin type 1 receptor inhibitors reduce renal pendrin protein abundance in mice in vivo through a mechanism that is dependent on nitric oxide (NO), we asked if NO modulates renal pendrin expression in vitro and explored the mechanism by which it occurs. Thus we quantified pendrin protein abundance by confocal fluorescent microscopy in cultured mouse cortical collecting ducts (CCDs) and connecting tubules (CNTs). After overnight culture, CCDs maintain their tubular structure and maintain a solute gradient when perfused in vitro. Pendrin protein abundance increased 67% in CNT and 53% in CCD when NO synthase was inhibited (NG-nitro-l-arginine methyl ester, 100 μM), while NO donor (DETA NONOate, 200 μM) application reduced pendrin protein by ∼33% in the CCD and CNT. When CNTs were cultured in the presence of the guanylyl cyclase inhibitor 1H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one (10 μM), NO donors did not alter pendrin abundance. Conversely, pendrin protein abundance rose when cAMP content was increased by the application of an adenylyl cyclase agonist (forskolin, 10 μM), a cAMP analog (8-bromo-cAMP, 1 mM), or a phosphodiesterase inhibitor (BAY60-7550, 50 μM). Since NO reduces cellular cAMP in the CNT, we asked if NO reduces pendrin abundance by reducing cAMP. With blockade of cGMP-stimulated phosphodiesterase II, NO did not alter pendrin protein abundance. We conclude that NO acts through cAMP to reduce pendrin total protein abundance by enhancing cAMP degradation. PMID:22811483

High-fat diet-induced obesity leads to increased NO sensitivity of rat coronary arterioles: role of soluble guanylate cyclase activation.

PubMed

Jebelovszki, Eva; Kiraly, Csaba; Erdei, Nora; Feher, Attila; Pasztor, Eniko T; Rutkai, Ibolya; Forster, Tamas; Edes, Istvan; Koller, Akos; Bagi, Zsolt

2008-06-01

The impact of obesity on nitric oxide (NO)-mediated coronary microvascular responses is poorly understood. Thus NO-mediated vasomotor responses were investigated in pressurized coronary arterioles ( approximately 100 microm) isolated from lean (on normal diet) and obese (fed with 60% of saturated fat) rats. We found that dilations to acetylcholine (ACh) were not significantly different in obese and lean rats (lean, 83 +/- 4%; and obese, 85 +/- 3% at 1 microM), yet the inhibition of NO synthesis with N(omega)-nitro-l-arginine methyl ester reduced ACh-induced dilations only in vessels of lean controls. The presence of the soluble guanylate cyclase (sGC) inhibitor oxadiazolo-quinoxaline (ODQ) elicited a similar reduction in ACh-induced dilations in the two groups of vessels (lean, 60 +/- 11%; and obese, 57 +/- 3%). Dilations to NO donors, sodium nitroprusside (SNP), and diethylenetriamine (DETA)-NONOate were enhanced in coronary arterioles of obese compared with lean control rats (lean, 63 +/- 6% and 51 +/- 5%; and obese, 78 +/- 5% and 70 +/- 5%, respectively, at 1 microM), whereas dilations to 8-bromo-cGMP were not different in the two groups. In the presence of ODQ, both SNP and DETA-NONOate-induced dilations were reduced to a similar level in lean and obese rats. Moreover, SNP-stimulated cGMP immunoreactivity in coronary arterioles and also cGMP levels in carotid arteries were enhanced in obese rats, whereas the protein expression of endothelial NOS and the sGC beta1-subunit were not different in the two groups. Collectively, these findings suggest that in coronary arterioles of obese rats, the increased activity of sGC leads to an enhanced sensitivity to NO, which may contribute to the maintenance of NO-mediated dilations and coronary perfusion in obesity.

Heme oxygenase-1 overexpression fails to attenuate hypertension when the nitric oxide synthase system is not fully operative.

PubMed

Polizio, Ariel H; Santa-Cruz, Diego M; Balestrasse, Karina B; Gironacci, Mariela M; Bertera, Facundo M; Höcht, Christian; Taira, Carlos A; Tomaro, Maria L; Gorzalczany, Susana B

2011-01-01

Heme oxygenase (HO) is an enzyme that is involved in numerous secondary actions. One of its products, CO, seems to have an important but unclear role in blood pressure regulation. CO exhibits a vasodilator action through the activation of soluble guanylate cyclase and the subsequent production of cyclic guanosine monophosphate (cGMP). The aim of the present study was to determine whether pathological and pharmacological HO-1 overexpression has any regulatory role on blood pressure in a renovascular model of hypertension. We examined the effect of zinc protoporyphyrin IX (ZnPP-IX) administration, an inhibitor of HO activity, on mean arterial pressure (MAP) and heart rate in sham-operated and aorta-coarcted (AC) rats and its interaction with the nitric oxide synthase (NOS) pathway. Inhibition of HO increased MAP in normotensive rats with and without hemin pretreatment but not in hypertensive rats. Pretreatment with NG-nitro-L-arginine methyl ester blocked the pressor response to ZnPP-IX, suggesting a key role of NOS in the cardiovascular action of HO inhibition. In the same way, AC rats, an experimental model of hypertension with impaired function and low expression of endothelial NOS (eNOS), did not show any cardiovascular response to inhibition or induction of HO. This finding suggests that eNOS was necessary for modulating the CO response in the hypertensive group. In conclusion, the present study suggests that HO regulates blood pressure through CO only when the NOS pathway is fully operative. In addition, chronic HO induction fails to attenuate the hypertensive stage induced by coarctation as a consequence of the impairment of the NOS pathway. Copyright © 2011 S. Karger AG, Basel.

Leptin resistance extends to the coronary vasculature in prediabetic dogs and provides a protective adaptation against endothelial dysfunction.

PubMed

Knudson, Jarrod D; Dincer, U Deniz; Dick, Gregory M; Shibata, Haruki; Akahane, Rie; Saito, Masayuki; Tune, Johnathan D

2005-09-01

Hyperleptinemia, associated with prediabetes, is an independent risk factor for coronary artery disease and a mediator of coronary endothelial dysfunction. We previously demonstrated that acutely raising the leptin concentration to levels comparable with those observed in human obesity significantly attenuates coronary dilation/relaxation to acetylcholine (ACh) both in vivo in anesthetized dogs and in vitro in isolated canine coronary rings. Accordingly, the purpose of this investigation was to extend these studies to a model of prediabetes with chronic hyperleptinemia. In the present investigation, experiments were conducted on control and high-fat-fed dogs. High-fat feeding caused a significant increase (131%) in plasma leptin concentration. Furthermore, in high-fat-fed dogs, exogenous leptin did not significantly alter vascular responses to ACh in vivo or in vitro. Coronary vasodilator responses to ACh (0.3-30.0 microg/min) and sodium nitroprusside (1.0-100.0 microg/min) were not significantly different from those observed in control dogs. Also, high-fat feeding did not induce a switch to an endothelium-derived hyperpolarizing factor as a major mediator of muscarinic coronary vasodilation, because dilation to ACh was abolished by combined pretreatment with N(omega)-nitro-l-arginine methyl ester (150 microg/min ic) and indomethacin (10 mg/kg iv). Quantitative, real-time PCR revealed no significant difference in coronary artery leptin receptor gene expression between control and high-fat-fed dogs. In conclusion, high-fat feeding induces resistance to the coronary vascular effects of leptin, and this represents an early protective adaptation against endothelial dysfunction. The resistance is not due to altered endothelium-dependent or -independent coronary dilation, increased endothelium-derived hyperpolarizing factor, or changes in coronary leptin receptor mRNA levels.

Heart-rate reduction by If-channel inhibition with ivabradine restores collateral artery growth in hypercholesterolemic atherosclerosis.

PubMed

Schirmer, Stephan H; Degen, Achim; Baumhäkel, Magnus; Custodis, Florian; Schuh, Lisa; Kohlhaas, Michael; Friedrich, Erik; Bahlmann, Ferdinand; Kappl, Reinhard; Maack, Christoph; Böhm, Michael; Laufs, Ulrich

2012-05-01

Collateral arteries protect tissue from ischaemia. Heart rate correlates with vascular events in patients with arterial obstructive disease. Here, we tested the effect of heart-rate reduction (HRR) on collateral artery growth. The I(f)-channel inhibitor ivabradine reduced heart rate by 11% in wild-type and 15% in apolipoprotein E (ApoE)(-/-) mice and restored endothelium-dependent relaxation in aortic rings of ApoE(-/-) mice. Microsphere perfusion and angiographies demonstrated that ivabradine did not change hindlimb perfusion in wild-type mice but improved perfusion in ApoE(-/-) mice from 40.5 ± 15.8-60.2 ± 18.5% ligated/unligated hindlimb. Heart rate reduction (13%) with metoprolol failed to improve endothelial function and perfusion. Protein expression of endothelial nitric oxide synthase (eNOS), phosphorylated eNOS, and eNOS activity were increased in collateral tissue following ivabradine treatment of ApoE(-/-) mice. Co-treatment with nitric oxide-inhibitor N (G)-nitro-L-arginine methyl ester abolished the effects of ivabradine on arteriogenesis. Following ivabradine, classical inflammatory cytokine expression was lowered in ApoE(-/-) circulating mononuclear cells and in plasma, but unaltered in collateral-containing hindlimb tissue, where numbers of perivascular macrophages also remained unchanged. However, ivabradine reduced expression of anti-arteriogenic cytokines CXCL10and CXCL11 and of smooth muscle cell markers smoothelin and desmin in ApoE(-/-) hindlimb tissue. Endothelial nitric oxide synthase and inflammatory cytokine expression were unchanged in wild-type mice. Ivabradine did not affect cytokine production in HUVECs and THP1 mononuclear cells and had no effect on the membrane potential of HUVECs in patch-clamp experiments. Ivabradine-induced HRR stimulates adaptive collateral artery growth. Important contributing mechanisms include improved endothelial function, eNOS activity, and modulation of inflammatory cytokine gene expression.

Hydrogen sulfide inhibits high glucose-induced NADPH oxidase 4 expression and matrix increase by recruiting inducible nitric oxide synthase in kidney proximal tubular epithelial cells.

PubMed

Lee, Hak Joo; Lee, Doug Yoon; Mariappan, Meenalakshmi M; Feliers, Denis; Ghosh-Choudhury, Goutam; Abboud, Hanna E; Gorin, Yves; Kasinath, Balakuntalam S

2017-04-07

High-glucose increases NADPH oxidase 4 (NOX4) expression, reactive oxygen species generation, and matrix protein synthesis by inhibiting AMP-activated protein kinase (AMPK) in renal cells. Because hydrogen sulfide (H 2 S) inhibits high glucose-induced matrix protein increase by activating AMPK in renal cells, we examined whether H 2 S inhibits high glucose-induced expression of NOX4 and matrix protein and whether H 2 S and NO pathways are integrated. High glucose increased NOX4 expression and activity at 24 h in renal proximal tubular epithelial cells, which was inhibited by sodium hydrosulfide (NaHS), a source of H 2 S. High glucose decreased AMPK phosphorylation and activity, which was restored by NaHS. Compound C, an AMPK inhibitor, prevented NaHS inhibition of high glucose-induced NOX4 expression. NaHS inhibition of high glucose-induced NOX4 expression was abrogated by N (ω)-nitro-l-arginine methyl ester, an inhibitor of NOS. NaHS unexpectedly augmented the expression of inducible NOS (iNOS) but not endothelial NOS. iNOS siRNA and 1400W, a selective iNOS inhibitor, abolished the ameliorative effects of NaHS on high glucose-induced NOX4 expression, reactive oxygen species generation, and, matrix laminin expression. Thus, H 2 S recruits iNOS to generate NO to inhibit high glucose-induced NOX4 expression, oxidative stress, and matrix protein accumulation in renal epithelial cells; the two gasotransmitters H 2 S and NO and their interaction may serve as therapeutic targets in diabetic kidney disease. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Chronic hydroxychloroquine improves endothelial dysfunction and protects kidney in a mouse model of systemic lupus erythematosus.

PubMed

Gómez-Guzmán, Manuel; Jiménez, Rosario; Romero, Miguel; Sánchez, Manuel; Zarzuelo, María José; Gómez-Morales, Mercedes; O'Valle, Francisco; López-Farré, Antonio José; Algieri, Francesca; Gálvez, Julio; Pérez-Vizcaino, Francisco; Sabio, José Mario; Duarte, Juan

2014-08-01

Hydroxychloroquine has been shown to be efficacious in the treatment of autoimmune diseases, including systemic lupus erythematosus. Hydroxychloroquine-treated lupus patients showed a lower incidence of thromboembolic disease. Endothelial dysfunction, the earliest indicator of the development of cardiovascular disease, is present in lupus. Whether hydroxychloroquine improves endothelial function in lupus is not clear. The aim of this study was to analyze the effects of hydroxychloroquine on hypertension, endothelial dysfunction, and renal injury in a female mouse model of lupus. NZBWF1 (lupus) and NZW/LacJ (control) mice were treated with hydroxychloroquine 10 mg/kg per day by oral gavage, or with tempol and apocynin in the drinking water, for 5 weeks. Hydroxychloroquine treatment did not alter lupus disease activity (assessed by plasma double-stranded DNA autoantibodies) but prevented hypertension, cardiac and renal hypertrophy, proteinuria, and renal injury in lupus mice. Aortae from lupus mice showed reduced endothelium-dependent vasodilator responses to acetylcholine and enhanced contraction to phenylephrine, which were normalized by hydroxychloroquine or antioxidant treatments. No differences among all experimental groups were found in both the relaxant responses to acetylcholine and the contractile responses to phenylephrine in rings incubated with the nitric oxide synthase inhibitor N(G)-nitro-l-arginine methyl ester. Vascular reactive oxygen species content and mRNA levels of nicotinamide adenine dinucleotide phosphate oxidase subunits NOX-1 and p47(phox) were increased in lupus mice and reduced by hydroxychloroquine or antioxidants. Chronic hydroxychloroquine treatment reduced hypertension, endothelial dysfunction, and organ damage in severe lupus mice, despite the persistent elevation of anti-double-stranded DNA, suggesting the involvement of new additional mechanisms to improve cardiovascular complications. © 2014 American Heart Association, Inc.

Central exogenous nitric oxide decreases cardiac sympathetic drive and improves baroreflex control of heart rate in ovine heart failure.

PubMed

Ramchandra, Rohit; Hood, Sally G; May, Clive N

2014-08-01

Heart failure (HF) is associated with increased cardiac and renal sympathetic drive, which are both independent predictors of poor prognosis. A candidate mechanism for the centrally mediated sympathoexcitation in HF is reduced synthesis of the inhibitory neuromodulator nitric oxide (NO), resulting from downregulation of neuronal NO synthase (nNOS). Therefore, we investigated the effects of increasing the levels of NO in the brain, or selectively in the paraventricular nucleus of the hypothalamus (PVN), on cardiac sympathetic nerve activity (CSNA) and baroreflex control of CSNA and heart rate in ovine pacing-induced HF. The resting level of CSNA was significantly higher in the HF than in the normal group, but the resting level of RSNA was unchanged. Intracerebroventricular infusion of the NO donor sodium nitroprusside (SNP; 500 μg · ml(-1)· h(-1)) in conscious normal sheep and sheep in HF inhibited CSNA and restored baroreflex control of heart rate, but there was no change in RSNA. Microinjection of SNP into the PVN did not cause a similar cardiac sympathoinhibition in either group, although the number of nNOS-positive cells was decreased in the PVN of sheep in HF. Reduction of endogenous NO with intracerebroventricular infusion of N(ω)-nitro-l-arginine methyl ester decreased CSNA in normal but not in HF sheep and caused no change in RSNA in either group. These findings indicate that endogenous NO in the brain provides tonic excitatory drive to increase resting CSNA in the normal state, but not in HF. In contrast, exogenously administered NO inhibited CSNA in both the normal and HF groups via an action on sites other than the PVN. Copyright © 2014 the American Physiological Society.

Vasorelaxant and cardiovascular properties of the essential oil of Pogostemon elsholtzioides.

PubMed

Shiva Kumar, Arumugasamy; Jeyaprakash, Karnan; Chellappan, David Raj; Murugan, Ramar

2017-03-06

Pogostemon elsholtzioides Benth. (Lamiaceae) is an aromatic shrub, endemic to eastern Himalaya region. The leaves are used for treating goiter and high blood pressure (BP) by indigenous people in Arunachal Pradesh, India. Young leaves are used as vegetable and leaf decoction is also used for cough, cold and headache by some indigenous communities in Northeast India. This species is used for treating hypertension and the genus Pogostemon is rich in essential oil. Therefore, the present study was aimed at investigation of the chemical constituents, vasorelaxant and cardiovascular effects of the essential oil of P. elsholtzioides. P. elsholtzioides was collected from Pasighat, Arunachal Pradesh, India and essential oil was extracted from shade dried leaves. Essential oil was analyzed by GC-FID and GC-MS and the volatile constituents were identified. Vasorelaxant and cardiovascular properties of the essential oil were studied against phenylephrine induced contraction in isolated endothelium intact aortic preparations and by measuring systolic and diastolic BP, mean arterial pressure (MAP) and heart rate (HR) after carotid artery cannulation in Wistar rats. The essential oil was rich in sesquiterpenes and curzerene, benzophenone, α-cadinol and germacrone were major constituents. The essential oil exhibited significant vasodilation effect in phenylephrine induced contracted aortic rings. Vasorelaxant effect of the essential oil was also observed both in the presence and absence of Nitro-L-arginine methyl ester against phenylephrine-contracted aortic rings. It also induced reduction of systolic and diastolic BP, MAP and HR. Essential oil of P. elsholtzioides exhibited significant vasorelaxant effect against endothelium intact aortic preparation mediated through nitric oxide dependent pathway and also reduced BP. However, further study is needed to screen the role of calcium ions in both intracellular and extracellular pathway. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

Agonistic autoantibodies as vasodilators in orthostatic hypotension: a new mechanism.

PubMed

Li, Hongliang; Kem, David C; Reim, Sean; Khan, Muneer; Vanderlinde-Wood, Megan; Zillner, Caitlin; Collier, Daniel; Liles, Campbell; Hill, Michael A; Cunningham, Madeleine W; Aston, Christopher E; Yu, Xichun

2012-02-01

Agonistic autoantibodies to the β-adrenergic and muscarinic receptors are a novel investigative and therapeutic target for certain orthostatic disorders. We have identified the presence of autoantibodies to β2-adrenergic and/or M3 muscarinic receptors by ELISA in 75% (15 of 20) of patients with significant orthostatic hypotension. Purified serum IgG from all 20 of the patients and 10 healthy control subjects were examined in a receptor-transfected cell-based cAMP assay for β2 receptor activation and β-arrestin assay for M3 receptor activation. There was a significant increase in IgG-induced activation of β2 and M3 receptors in the patient group compared with controls. A dose response was observed for both IgG activation of β2 and M3 receptors and inhibition of their activation with the nonselective β blocker propranolol and muscarinic blocker atropine. The antibody effects on β2 and/or M3 (via production of NO) receptor-mediated vasodilation were studied in a rat cremaster resistance arteriole assay. Infusion of IgG from patients with documented β2 and/or M3 receptor agonistic activity produced a dose-dependent vasodilation. Sequential addition of the β-blocker propranolol and the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester partially inhibited IgG-induced vasodilation (percentage of maximal dilatory response: from 57.7±10.4 to 35.3±4.6 and 24.3±5.8, respectively; P<0.01; n=3), indicating that antibody activation of vascular β2 and/or M3 receptors may contribute to systemic vasodilation. These data support the concept that circulating agonistic autoantibodies serve as vasodilators and may cause or exacerbate orthostatic hypotension.

Exercise training improves functional sympatholysis in spontaneously hypertensive rats through a nitric oxide-dependent mechanism

PubMed Central

Mizuno, Masaki; Iwamoto, Gary A.; Vongpatanasin, Wanpen; Mitchell, Jere H.

2014-01-01

Functional sympatholysis is impaired in hypertensive animals and patients. Exercise training (ET) improves functional sympatholysis through a nitric oxide (NO)-dependent mechanism in normotensive rats. However, whether ET has similar physiological benefits in hypertension remains to be elucidated. Thus we tested the hypothesis that the impairment in functional sympatholysis in hypertension is reversed by ET through a NO-dependent mechanism. In untrained normotensive Wistar-Kyoto rats (WKYUT; n = 13), untrained spontaneously hypertensive rats (SHRUT; n = 13), and exercise-trained SHR (SHRET; n = 6), changes in femoral vascular conductance (FVC) were examined during lumbar sympathetic nerve stimulation (1, 2.5, and 5 Hz) at rest and during muscle contraction. The magnitude of functional sympatholysis (Δ%FVC = Δ%FVC muscle contraction − Δ%FVC rest) in SHRUT was significantly lower than WKYUT (1 Hz: −2 ± 4 vs. 13 ± 3%; 2.5 Hz: 9 ± 3 vs. 21 ± 3%; and 5 Hz: 12 ± 3 vs. 26 ± 3%, respectively; P < 0.05). Three months of voluntary wheel running significantly increased maximal oxygen uptake in SHRET compared with nontrained SHRUT (78 ± 6 vs. 62 ± 4 ml·kg−1·min−1, respectively; P < 0.05) and restored the magnitude of functional sympatholysis in SHRET (1 Hz: 9 ± 2%; 2.5 Hz: 20 ± 4%; and 5 Hz: 34 ± 5%). Blockade of NO synthase (NOS) by NG-nitro-l-arginine methyl ester attenuated functional sympatholysis in WKYUT but not SHRUT. Furthermore, NOS inhibition significantly diminished the improvements in functional sympatholysis in SHRET. These data demonstrate that impairments in functional sympatholysis are normalized via a NO mechanism by voluntary wheel running in hypertensive rats. PMID:24816260

Mitigating peroxynitrite mediated mitochondrial dysfunction in aged rat brain by mitochondria-targeted antioxidant MitoQ.

PubMed

Maiti, Arpan Kumar; Spoorthi, B C; Saha, Nimai Chandra; Panigrahi, Ashis Kumar

2018-05-17

Although reactive oxygen species mediated oxidative stress is a well-documented mechanism of aging, recent evidences indicate involvement of nitrosative stress in the same. As mitochondrial dysfunction is considered as one of the primary features of aging, the present study was designed to understand the involvement of nitrosative stress by studying the impact of a mitochondria-targeted antioxidant MitoQ, a peroxynitrite (ONOO - ) scavenger, on mitochondrial functions. Four groups of rats were included in this study: Group I: Young-6 months (-MitoQ), Group II: Aged-22 months (- MitoQ), Group III: Young-6 months (+ MitoQ), Group IV: Aged-22 months (+ MitoQ). The rats belonging to group III and IV were treated with oral administration of MitoQ (500 μM) daily through drinking water for 5 weeks. MitoQ efficiently suppressed synaptosomal lipid peroxidation and protein oxidation accompanied by diminution of nitrite production and protein bound 3-nitrotyrosine. MitoQ normalized enhanced caspase 3 and 9 activities in aged rat brains and efficiently reversed ONOO - mediated mitochondrial complex I and IV inhibition, restored mitochondrial ATP production and lowered mitochondrial membrane potential loss. To ascertain these findings, a mitochondrial in vitro model (iron/ascorbate) was used involving different free radical scavengers and anti-oxidants. MitoQ provided better protection compared to mercaptoethylguanidine, N-nitro-L-arginine-methyl ester and superoxide dismutase establishing the predominancy of ONOO - in the process compared to • NO and O 2 •- . These results clearly highlight the involvement of nitrosative stress in aging process with MitoQ having therapeutic potential to fight against ONOO - mediated aging deficits.

Insulin induces the correlation between renal blood flow and glomerular filtration rate in diabetes: implications for mechanisms causing hyperfiltration.

PubMed

Pihl, Liselotte; Persson, Patrik; Fasching, Angelica; Hansell, Peter; DiBona, Gerald F; Palm, Fredrik

2012-07-01

Glomerular filtration rate (GFR) and renal blood flow (RBF) are normally kept constant via renal autoregulation. However, early diabetes results in increased GFR and the potential mechanisms are debated. Tubuloglomerular feedback (TGF) inactivation, with concomitantly increased RBF, is proposed but challenged by the finding of glomerular hyperfiltration in diabetic adenosine A(1) receptor-deficient mice, which lack TGF. Furthermore, we consistently find elevated GFR in diabetes with only minor changes in RBF. This may relate to the use of a lower streptozotocin dose, which produces a degree of hyperglycemia, which is manageable without supplemental suboptimal insulin administration, as has been used by other investigators. Therefore, we examined the relationship between RBF and GFR in diabetic rats with (diabetes + insulin) and without suboptimal insulin administration (untreated diabetes). As insulin can affect nitric oxide (NO) release, the role of NO was also investigated. GFR, RBF, and glomerular filtration pressures were measured. Dynamic RBF autoregulation was examined by transfer function analysis between arterial pressure and RBF. Both diabetic groups had increased GFR (+60-67%) and RBF (+20-23%) compared with controls. However, only the diabetes + insulin group displayed a correlation between GFR and RBF (R(2) = 0.81, P < 0.0001). Net filtration pressure was increased in untreated diabetes compared with both other groups. The difference between untreated and insulin-treated diabetic rats disappeared after administering N(ω)-nitro-l-arginine methyl ester to inhibit NO synthase and subsequent NO release. In conclusion, mechanisms causing diabetes-induced glomerular hyperfiltration are animal model-dependent. Supplemental insulin administration results in a RBF-dependent mechanism, whereas elevated GFR in untreated diabetes is mediated primarily by a tubular event. Insulin-induced NO release partially contributes to these differences.

The atypical structure and function of newborn arterial endothelium is mediated by Rho/Rho kinase signaling.

PubMed

Flavahan, Sheila; Flavahan, Nicholas A

2014-08-15

Endothelium of fetal or newborn arteries is atypical, displaying actin stress fibers and reduced nitric oxide (NO)-mediated dilatation. This study tested the hypothesis that Rho/Rho kinase signaling, which promotes endothelial stress fibers and inhibits endothelial dilatation, contributed to this phenotype. Carotid arteries were isolated from newborn [postnatal day 1 (P1)], P7, and P21 mice. Endothelial dilatation to acetylcholine (pressure myograph) was minimal at P1, increased at P7, and further increased at P21. Inhibition of Rho (C3 transferase) or Rho kinase (Y27632, fasudil) significantly increased dilatation to acetylcholine in P1 arteries but had no effect in P7 or P21 arteries. After inhibition of NO synthase (N(G)-nitro-l-arginine methyl ester), Rho kinase inhibition no longer increased acetylcholine responses in P1 arteries. Rho kinase inhibition did not affect dilatation to the NO donor DEA-NONOate. The endothelial actin cytoskeleton was labeled with phalloidin and visualized by laser-scanning microscopy. In P1 arteries, the endothelium had prominent transcytoplasmic stress fibers, whereas in P7 and P21 arteries, the actin fibers had a significantly reduced intensity and were restricted to cell borders. Phosphorylation of myosin light chains, a Rho kinase substrate, was highest in P1 endothelium and significantly reduced in P7 and P21 endothelium (laser-scanning microscopy). In P1 arteries, inhibition of Rho (C3 transferase) or Rho kinase (Y27632) significantly reduced the intensity of actin fibers, which were restricted to cell borders. Similarly, in P1 arteries, Rho inhibition significantly reduced endothelial levels of phosphorylated myosin light chains. These results indicate that the atypical function and morphology of newborn endothelium is mediated by Rho/Rho kinase signaling. Copyright © 2014 the American Physiological Society.

Endothelial Cell Tetrahydrobiopterin Modulates Sensitivity to Ang (Angiotensin) II-Induced Vascular Remodeling, Blood Pressure, and Abdominal Aortic Aneurysm.

PubMed

Chuaiphichai, Surawee; Rashbrook, Victoria S; Hale, Ashley B; Trelfa, Lucy; Patel, Jyoti; McNeill, Eileen; Lygate, Craig A; Channon, Keith M; Douglas, Gillian

2018-07-01

GTPCH (GTP cyclohydrolase 1, encoded by Gch1 ) is required for the synthesis of tetrahydrobiopterin; a critical regulator of endothelial NO synthase function. We have previously shown that mice with selective loss of Gch1 in endothelial cells have mild vascular dysfunction, but the consequences of endothelial cell tetrahydrobiopterin deficiency in vascular disease pathogenesis are unknown. We investigated the pathological consequence of Ang (angiotensin) II infusion in endothelial cell Gch1 deficient ( Gch1 fl/fl Tie2cre) mice. Ang II (0.4 mg/kg per day, delivered by osmotic minipump) caused a significant decrease in circulating tetrahydrobiopterin levels in Gch1 fl/fl Tie2cre mice and a significant increase in the Nω-nitro-L-arginine methyl ester inhabitable production of H 2 O 2 in the aorta. Chronic treatment with this subpressor dose of Ang II resulted in a significant increase in blood pressure only in Gch1 fl/fl Tie2cre mice. This finding was mirrored with acute administration of Ang II, where increased sensitivity to Ang II was observed at both pressor and subpressor doses. Chronic Ang II infusion in Gch1 fl/fl Tie2ce mice resulted in vascular dysfunction in resistance mesenteric arteries with an enhanced constrictor and decreased dilator response and medial hypertrophy. Altered vascular remodeling was also observed in the aorta with an increase in the incidence of abdominal aortic aneurysm formation in Gch1 fl/fl Tie2ce mice. These findings indicate a specific requirement for endothelial cell tetrahydrobiopterin in modulating the hemodynamic and structural changes induced by Ang II, through modulation of blood pressure, structural changes in resistance vessels, and aneurysm formation in the aorta. © 2018 The Authors.

Rate dependency and role of nitric oxide in the vascular response to direct cooling in human skin.

PubMed

Yamazaki, Fumio; Sone, Ryoko; Zhao, Kun; Alvarez, Guy E; Kosiba, Wojciech A; Johnson, John M

2006-01-01

Local cooling of nonglabrous skin without functional sympathetic nerves causes an initial vasodilation followed by vasoconstriction. To further characterize these responses to local cooling, we examined the importance of the rate of local cooling and the effect of nitric oxide synthase (NOS) inhibition in intact skin and in skin with vasoconstrictor function inhibited. Release of norepinephrine was blocked locally (iontophoresis) with bretylium tosylate (BT). Skin blood flow was monitored from the forearm by laser-Doppler flowmetry (LDF). Cutaneous vascular conductance (CVC) was calculated as the ratio of LDF to blood pressure. Local temperature was controlled over 6.3 cm2 around the sites of LDF measurement. Local cooling was applied at -0.33 or -4 degrees C/min. At -4 degrees C/min, CVC increased (P < 0.05) at BT sites in the early phase. At -0.33 degrees C/min, there was no early vasodilator response, but there was a delay in the onset of vasoconstriction relative to intact skin. The NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) (intradermal microdialysis) decreased (P < 0.05) CVC by 28.3 +/- 3.8% at untreated sites and by 46.9 +/- 6.3% at BT-treated sites from the value before infusion. Rapid local cooling (-4 degrees C/min) to 24 degrees C decreased (P < 0.05) CVC at both untreated (saline) sites and L-NAME only sites from the precooling levels, but it transiently increased (P < 0.05) CVC at both BT + saline sites and BT + L-NAME sites in the early phase. After 35-45 min of local cooling, CVC decreased at BT + saline sites relative to the precooling levels (P < 0.05), but at BT + L-NAME sites CVC was not reduced below the precooling level (P = 0.29). These findings suggest that the rate of local cooling, but not functional NOS, is an important determinant of the early non-adrenergic vasodilator response to local cooling and that functional NOS, adrenergic nerves, as well as other mechanisms play roles in vasoconstriction during prolonged local cooling of skin.

Kinetics and thermodynamics of oxidation mediated reaction in L-cysteine and its methyl and ethyl esters in dimethyl sulfoxide-d6 by NMR spectroscopy

NASA Astrophysics Data System (ADS)

Dougherty, Ryan J.; Singh, Jaideep; Krishnan, V. V.

2017-03-01

L-Cysteine (L-Cys), L-Cysteine methyl ester (L-CysME) or L-Cysteine ethyl ester (L-CysEE), when dissolved in dimethyl sulfoxide, undergoes an oxidation process. This process is slow enough and leads to nuclear magnetic resonance (NMR) spectral changes that could be monitored in real time. The oxidation mediated transition is modeled as a pseudo-first order kinetics and the thermodynamic parameters are estimated using the Eyring's formulation. L-Cysteine and their esters are often used as biological models due to the remarkable thiol group that can be found in different oxidation states. This oxidation mediated transition is due to the combination of thiol oxidation to a disulfide followed by solvent-induced effects may be relevant in designing cysteine-based molecular models.

N-mustard analogs of S-adenosyl-L-methionine as biochemical probes of protein arginine methylation.

PubMed

Hymbaugh Bergman, Sarah J; Comstock, Lindsay R

2015-08-01

Nucleosomes, the fundamental building blocks of eukaryotic chromatin, undergo post-synthetic modifications and play a major role in the regulation of transcriptional processes. Combinations of these modifications, including methylation, regulate chromatin structure, determining its different functional states and playing a central role in differentiation. The biological significance of cellular methylation, particularly on chromatin, is widely recognized, yet we know little about the mechanisms that link biological methylation events. To characterize and fully understand protein methylation, we describe here novel N-mustard analogs of S-adenosyl-l-methionine (SAM) as biochemical tools to better understand protein arginine methylation events using protein arginine methyltransferase 1 (PRMT1). Specifically, azide- and alkyne-functionalized N-mustard analogs serve as cofactor mimics of SAM and are enzymatically transferred to a model peptide substrate in a PRMT1-dependent fashion. Once incorporated, the resulting alkynes and azides can be modified through chemoselective ligations, including click chemistry and the Staudinger ligation. These results readily demonstrate the feasibility of utilizing N-mustard analogs as biochemical tools to site-specifically label substrates of PRMT1 and serve as an alternative approach to study protein methylation events. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Effects of L-arginine pre-treatment in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinson’s diseases in Balb/c mice

PubMed Central

Hami, Javad; Hosseini, Mehran; Shahi, Sekineh; Lotfi, Nassim; Talebi, Abolfazl; Afshar, Mohammad

2015-01-01

Background: Parkinson’s disease (PD) is a common neurodegenerative disease resulting from the degeneration of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc). Increasing evidence demonstrated that mice treated intranasally with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) suffered impairments in motor functions associated with disruption of DA neurons in SNc conceivably analogous to those observed in PD. L-arginine has been proposed as a novel neuroprotective agent that plays protective roles in several models of neuronal cellular damage. This study aimed to evaluate the effects of L-arginine on the numerical density of dark neurons (DNs) in the SNc of Balb/c mice subjected to MPTP administration. Methods: In the present study, we demonstrated that repeated treatment with L-arginine (300 mg/kg, i.p.) during 7 consecutive days attenuated the production of DNs in SNc of adult male Balb/c mice infused with a single intranasal administration of MPTP (1 mg/nostril). Results: Pre-treatment with L-arginine significantly decreased the numerical density of DNs in SNc of mice 21 days after intranasal MPTP administration. Conclusion: This investigation provides new insights in experimental models of PD, indicating that L-arginine represents a potential neuroprotective agent for the prevention of DA neuron degeneration in SNc observed in PD patients. PMID:26885338

Perfusion of isolated carotid sinus with hydrogen sulfide attenuated the renal sympathetic nerve activity in anesthetized male rats.

PubMed

Guo, Q; Wu, Y; Xue, H; Xiao, L; Jin, S; Wang, R

2016-07-18

The purpose of the present study was to define the indirect central effect of hydrogen sulfide (H(2)S) on baroreflex control of sympathetic outflow. Perfusing the isolated carotid sinus with sodium hydrosulfide (NaHS), a H(2)S donor, the effect of H(2)S was measured by recording changes of renal sympathetic nerve activity (RSNA) in anesthetized male rats. Perfusion of isolated carotid sinus with NaHS (25, 50, 100 micromol/l) dose and time-dependently inhibited sympathetic outflow. Preconditioning of glibenclamide (20 micromol/l), a ATP-sensitive K(+) channels (K(ATP)) blocker, the above effect of NaHS was removed. With 1, 4-dihydro-2, 6-dimethyl-5-nitro-4-(2-[trifluoromethyl] phenyl) pyridine-3-carboxylic acid methyl ester (Bay K8644, 500 nmol/l) pretreatment, which is an agonist of L-calcium channels, the effect of NaHS was eliminated. Perfusion of cystathionine gamma-lyase (CSE) inhibitor, DL-propargylglycine (PPG, 200 micromol/l), increased sympathetic outflow. The results show that exogenous H(2)S in the carotid sinus inhibits sympathetic outflow. The effect of H(2)S is attributed to opening K(ATP) channels and closing the L-calcium channels.

Potential role of eNOS in the therapeutic control of myocardial oxygen consumption by ACE inhibitors and amlodipine.

PubMed

Loke, K E; Messina, E J; Shesely, E G; Kaley, G; Hintze, T H

2001-01-01

Our aim was to investigate the potential therapeutic role of endothelial nitric oxide synthase (eNOS) in the modulation of cardiac O(2) consumption induced by the angiotensin converting enzyme (ACE) inhibitor ramiprilat and amlodipine. Three different groups of mice were used; wild type, wild type in the presence of N-nitro-L-arginine methyl ester (L-NAME, 10(-4) mol/l) or genetically altered mice lacking the eNOS gene (eNOS -/-). Myocardial O(2) consumption was measured using a Clark-type O(2) electrode in an air-tight stirred bath. Concentration-response curves to ramiprilat (RAM), amlodipine (AMLO), diltiazem (DIL), carbachol (CCL), substance P (SP) and S-nitroso-N-acetyl-penicillamine (SNAP) were performed. The rate of decrease in O(2) concentration was expressed as a percentage of the baseline. Baseline O(2) consumption was not different between the three groups of mice. In tissues from wild type mice, RAM (10(-5) mol/l), AMLO (10(-5) mol/l), DIL (10(-4) mol/l), CCL (10(-4) mol/l), SP (10(-7) mol/l) and SNAP (10(-4) mol/l) reduced myocardial O(2) consumption by -32+/-4, -27+/-10, -20+/-6, -25+/-2, -22+/-4 and -42+/-4%, respectively. The responses to RAM, AMLO, CCL and SP were absent in tissues taken from eNOS -/- mice (-7.1+/-4.3, -5.0+/-6.0, -5.2+/-5.1 and -0.4+/-0.2%, respectively). In addition, L-NAME significantly (P<0.05) inhibited the reduction in O(2) consumption induced by RAM (-9.8+/-4.4%), AMLO (-1.0+/-6.0%), CCL (-8.8+/-3.7%) and SP (-6.6+/-4.9%) in cardiac tissues from wild type mice. In contrast, NO-independent responses to the calcium channel antagonist, DIL, and responses to the NO donor, SNAP, were not affected in cardiac tissues taken from eNOS -/- (DIL: -20+/-4%; SNAP: -46+/-6%) or L-NAME-treated (DIL: -17+/-2%; SNAP: -33+/-5%) mice. These results suggest that endogenous endothelial NO synthase derived NO serves an important role in the regulation of myocardial O(2) consumption. This action may contribute to the therapeutic action of ACE inhibitors and amlodipine.

Identification of trace-amine-associated receptors (TAAR) in the rat aorta and their role in vasoconstriction by β-phenylethylamine.

PubMed

Fehler, Martina; Broadley, Kenneth J; Ford, William R; Kidd, Emma J

2010-10-01

Trace amines including tyramine and β-phenylethylamine (β-PEA) increase blood pressure and cause vasoconstriction which is attributed to indirect sympathomimetic actions. However, there is evidence that they may also have non-sympathomimetic mechanisms. This study examined whether β-PEA causes vasoconstriction of rat aorta by a sympathomimetic action or through the recently described trace-amine-associated receptors (TAAR). Concentration-response curves (CRCs) for β-PEA were constructed either cumulatively or non-cumulatively in rat isolated aortic rings. TAAR-1 and TAAR-4 protein expression was determined in rat aorta by Western blotting and TAAR-1 mRNA by reverse transcriptase polymerase chain reaction (RT-PCR). β-PEA caused concentration-related constriction of rat aorta. The contractions were unaffected by endothelium removal or the nitric oxide synthase inhibitor, N(ω)-nitro-L-arginine methyl ester (L-NAME, 100 μM) or the cyclooxygenase inhibitor, indomethacin (10 μM). Non-cumulative CRCs showed greater contractions and sensitivity to β-PEA than cumulative. The α(1)-adrenoceptor antagonist, prazosin, failed to inhibit either curve. The β-adrenoceptor antagonist, propranolol, the adrenergic neuronal transport inhibitor, cocaine, and the monoamine oxidase inhibitor, pargyline, also failed to alter the CRC. In the combined presence of prazosin, cocaine, pargyline, and the selective β(2)-adrenoceptor antagonist, ICI-118,551, the trace amine contractile potency order was tryptamine > β-PEA > octopamine > D: -amphetamine > tyramine. Western blotting and RT-PCR revealed the presence of TAAR-1 in rat aorta, but TAAR-4 was poorly expressed. Vasoconstriction of rat aorta by β-PEA appears not to be an indirect sympathomimetic action. The presence of TAAR-1 suggests that vasoconstriction may be via these receptors; however, the potency order differed from that reported for transfected cells expressing rat TAAR-1.

Impaired vascular function in normoglycemic mice prone to autoimmune diabetes: role of nitric oxide.

PubMed

Traupe, Tobias; Nett, Philipp C; Frank, Beat; Tornillo, Luigi; Hofmann-Lehmann, Regina; Terracciano, Luigi M; Barton, Matthias

2007-02-28

Type 1 diabetes is an immuno-inflammatory condition which increases the risk of cardiovascular disease, particularly in young adults. This study investigated whether vascular function is altered in mice prone to autoimmune diabetes and whether the nitric oxide (NO)-cyclic GMP axis is involved. Aortic rings suspended in organ chambers and precontracted with phenylephrine were exposed to cumulative concentrations of acetylcholine. To investigate the role of NO, some experiments were performed in the presence of either 1400W (N-(3-aminomethyl)benzyl-acetamidine hydrochloride), a selective inhibitor of the iNOS-isoform, L-NAME (N(G)-nitro-L-arginine methyl ester hydrochloride), an inhibitor of all three NOS-isoforms, or ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one), a selective inhibitor of guanylate cyclase. Moreover, contractility to phenylephrine, big endothelin-1, and endothelin-1 was assessed and histological analysis and iNOS immunohistochemistry were performed. Endothelium-dependent relaxation was reduced in prediabetic NOD mice (78+/-4 vs. 88+/-2%, respectively, P<0.05 vs. control) despite normal plasma glucose levels (n.s. vs. control). Preincubation with 1400W further attenuated responses in prediabetic (P<0.05 vs. untreated) but not in diabetic or in control mice. In contrast, basal NO bioactivity remained unaffected until the onset of diabetes in NOD mice. Contractile responses to big endothelin-1 and endothelin-1 were reduced in prediabetic animals (P<0.05 vs. control), whereas in diabetic mice only responses to big endothelin-1 were decreased (P<0.05 vs. control). These data demonstrate that endothelium-dependent and -independent vascular function in NOD mice is abnormal already in prediabetes in the absence of structural injury. Early proinflammatory activation due to iNOS in diabetes-prone NOD mice appears to be one of the mechanisms contributing to impaired vasoreactivity.

Dahl SS rats demonstrate enhanced aortic perivascular adipose tissue-mediated buffering of vasoconstriction through activation of NOS in the endothelium

PubMed Central

Spradley, Frank T.; Ho, Dao H.

2015-01-01

Perivascular adipose tissue (PVAT) mediates buffering of vasoconstriction through activation of endothelium-derived factors. We hypothesized that the PVAT of Dahl salt-sensitive (Dahl SS) rats has reduced ability to buffer vasoconstriction. Vascular reactivity experiments were performed on aortic rings with PVAT intact (+PVAT) or removed (−PVAT), and endothelium intact (+ENDO) or removed (−ENDO) from Dahl SS rats and control SS.13BN rats (Dahl SS rats that have had chromosome 13 completely replaced with that of the Brown Norway rat, rendering this strain insensitive to high-salt or high-fat diet-induced hypertension). Endothelial dysfunction, assessed by ACh-mediated vasorelaxation, was confirmed in aortic rings of Dahl SS rats. The +PVAT+ENDO aortic rings had indistinguishable phenylephrine-induced vasoconstriction between genotypes. In both strains, removal of PVAT significantly enhanced vasoconstriction. Dahl SS rat −PVAT+ENDO aortic rings displayed exaggerated vasoconstriction to phenylephrine vs. SS.13BN rats, indicating that PVAT-mediated buffering of vasoconstriction was greater in Dahl SS rats. Removal of both the ENDO and PVAT restored vasoconstriction in both strains. The nitric oxide synthase (NOS) inhibitor, Nω-nitro-l-arginine methyl ester (l-NAME), produced a similar effect as that seen with −ENDO. These data indicate that the function of the PVAT to activate endothelium-derived NOS is enhanced in Dahl SS compared with SS.13BN rats and, most likely, occurs through a pathway that is distinct from ACh-mediated activation of NOS. PVAT weight and total PVAT leptin levels were greater in Dahl SS rats. Leptin induced a significantly decreased vasoconstriction in −PVAT+ENDO aortic rings from Dahl SS rats, but not SS.13BN rats. In contrast to our initial hypothesis, PVAT in Dahl SS rats buffers vasoconstriction by activating endothelial NOS via mechanisms that may include the involvement of leptin. Thus, the PVAT serves a vasoprotective role in Dahl SS rats on normal-salt diet. PMID:26608658

The effect of chronic hyperthyroidism and restored euthyroid state by methimazole therapy in rat small mesenteric arteries.

PubMed

Khorshidi-Behzadi, Mahdi; Alimoradi, Houman; Haghjoo-Javanmard, Shaghayegh; Reza Sharifi, Mohammad; Rahimi, Nastaran; Dehpour, Ahmad Reza

2013-02-15

Not much has been reported about the effects of hyperthyroidism and its correction on resistance vessels, and just two inconsistent studies have investigated the impacts of restored euthyroidism on vascular reactivity. In this regard, we designed the current study to evaluate the vascular reactivity of the mesenteric arteries of hyperthyroid and restore euthyroid rats. Hyperthyroidism was induced by administration of triiodothyronine (T3; 300μg/kg, i.p., for 12 weeks in T3 group). Euthyroidism was restored by administration of T3 for 8 weeks and then T3+Methimazole (0.003% in drinking water) for 4 weeks (T3+MMI group). According to the McGregor method, vascular relaxation and contractility response were measured in response to acetylcholine or phenylephrine respectively. We found that maximal contractility response (Emax) to phenylephrine in the T3 group was significantly decreased (P<0.001), and Emax to acetylcholine was significantly increased compared with the saline group (P<0.05). When N(G)-nitro-L-arginine methyl ester (L-NAME, 3×10(-4)M) was used, Emax to acetylcholine in the T3 group was still higher than the saline group (P<0.05). However, decrease in maximal response of the T3 group was significantly greater than the saline group (P<0.01). We also showed that when euthyroidism is restored by methimazole therapy, enhanced acetylcholine-induced vasorelaxation and impaired contractility response to phenylephrine were normalized, as there was no significant difference in Emax of the T3+MMI group versus the saline group (P>0.05). In conclusion, synthesis of both nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF) in mesenteric arteries significantly increased as a consequence of hyperthyroidism, and this abnormal vascular reactivity is corrected by methimazole therapy. Copyright © 2012 Elsevier B.V. All rights reserved.

Renal Phenotype of UT-A Urea Transporter Knockout Mice

PubMed Central

Fenton, Robert A.; Flynn, Anneliese; Shodeinde, Adetola; Smith, Craig P.; Schnermann, Jurgen; Knepper, Mark A.

2006-01-01

The urea transporters UT-A1 and UT-A3 mediate rapid transepithelial urea transport across the inner medullary collecting duct (IMCD). In a previous study, using a new mouse model in which both UT-A1 and UT-A3 were genetically deleted from the IMCD (UT-A1/3−/− mice), we investigated the role of these transporters in the function of the renal inner medulla. Here we report a series of studies investigating more generally the renal phenotype of UT-A1/3−/− mice. Pathological screening revealed abnormalities in both the testis (increased size) and kidney (decreased size and vascular congestion) of UT-A1/3−/− mice. Total urinary nitrate and nitrite excretion rates in UT-A1/3−/− mice were more than double those in wildtype mice. Total renal blood flow was not different between UT-A1/3−/− and wildtype mice, but underwent a greater percentage decrease in response to NG-Nitro-L-arginine Methyl Ester Hydrochloride (L-NAME) infusion. Whole kidney glomerular filtration rate was not different in UT-A1/3−/− mice compared to controls and underwent a similar increase in response to a greater dietary protein intake. Fractional urea excretion was markedly elevated in UT-A1/3−/− mice on a 40% protein diet, reaching 102.4 ± 8.8% of the filtered load, suggesting that there may be active urea secretion along the renal tubule. Although there was a marked urinary concentrating defect in UT-A1/3−/− mice, there was no decrease in aquaporin-2 or -3 expression. Furthermore, although urea accumulation in the inner medulla was markedly attenuated, there was no decrease in NaCl concentration in tissue from outer medulla or 2 levels of the inner medulla. PMID:15829709

Herpes Simplex Virus Type 1 Infects Enteric Neurons and Triggers Gut Dysfunction via Macrophage Recruitment.

PubMed

Brun, Paola; Qesari, Marsela; Marconi, Peggy C; Kotsafti, Andromachi; Porzionato, Andrea; Macchi, Veronica; Schwendener, Reto A; Scarpa, Marco; Giron, Maria C; Palù, Giorgio; Calistri, Arianna; Castagliuolo, Ignazio

2018-01-01

Herpes Simplex Virus type 1 (HSV-1), a neurotropic pathogen widespread in human population, infects the enteric nervous system (ENS) in humans and rodents and causes intestinal neuromuscular dysfunction in rats. Although infiltration of inflammatory cells in the myenteric plexus and neurodegeneration of enteric nerves are common features of patients suffering from functional intestinal disorders, the proof of a pathogenic link with HSV-1 is still unsettled mainly because the underlying mechanisms are largely unknown. In this study we demonstrated that following intragastrical administration HSV-1 infects neurons within the myenteric plexus resulting in functional and structural alterations of the ENS. By infecting mice with HSV-1 replication-defective strain we revealed that gastrointestinal neuromuscular anomalies were however independent of viral replication. Indeed, enteric neurons exposed to UV-inactivated HSV-1 produced monocyte chemoattractant protein-1 (MCP-1/CCL2) to recruit activated macrophages in the longitudinal muscle myenteric plexus. Infiltrating macrophages produced reactive oxygen and nitrogen species and directly harmed enteric neurons resulting in gastrointestinal dysmotility. In HSV-1 infected mice intestinal neuromuscular dysfunctions were ameliorated by in vivo administration of (i) liposomes containing dichloromethylene bisphosphonic acid (clodronate) to deplete tissue macrophages, (ii) CCR2 chemokine receptor antagonist RS504393 to block the CCL2/CCR2 pathway, (iii) Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME) and AR-C 102222 to quench production of nitrogen reactive species produced via iNOS. Overall these data demonstrate that HSV-1 infection makes enteric neurons recruit macrophages via production of a specific chemoattractant factor. The resulting inflammatory reaction is mandatory for intestinal dysmotility. These findings provide insights into the neuro-immune communication that occurs in the ENS following HSV-1 infection and allow recognition of an original pathophysiologic mechanism underlying gastrointestinal diseases as well as identification of novel therapeutic targets.

No effect of NOS inhibition on skeletal muscle glucose uptake during in situ hindlimb contraction in healthy and diabetic Sprague-Dawley rats.

PubMed

Hong, Yet Hoi; Betik, Andrew C; Premilovac, Dino; Dwyer, Renee M; Keske, Michelle A; Rattigan, Stephen; McConell, Glenn K

2015-05-15

Nitric oxide (NO) has been shown to be involved in skeletal muscle glucose uptake during contraction/exercise, especially in individuals with Type 2 diabetes (T2D). To examine the potential mechanisms, we examined the effect of local NO synthase (NOS) inhibition on muscle glucose uptake and muscle capillary blood flow during contraction in healthy and T2D rats. T2D was induced in Sprague-Dawley rats using a combined high-fat diet (23% fat wt/wt for 4 wk) and low-dose streptozotocin injections (35 mg/kg). Anesthetized animals had one hindlimb stimulated to contract in situ for 30 min (2 Hz, 0.1 ms, 35 V) with the contralateral hindlimb rested. After 10 min, the NOS inhibitor, N(G)-nitro-l-arginine methyl ester (l-NAME; 5 μM) or saline was continuously infused into the femoral artery of the contracting hindlimb until the end of contraction. Surprisingly, there was no increase in skeletal muscle NOS activity during contraction in either group. Local NOS inhibition had no effect on systemic blood pressure or muscle contraction force, but it did cause a significant attenuation of the increase in femoral artery blood flow in control and T2D rats. However, NOS inhibition did not attenuate the increase in muscle capillary recruitment during contraction in these rats. Muscle glucose uptake during contraction was significantly higher in T2D rats compared with controls but, unlike our previous findings in hooded Wistar rats, NOS inhibition had no effect on glucose uptake during contraction. In conclusion, NOS inhibition did not affect muscle glucose uptake during contraction in control or T2D Sprague-Dawley rats, and this may have been because there was no increase in NOS activity during contraction. Copyright © 2015 the American Physiological Society.

Elucidation of the profound antagonism of contractile action of phenylephrine in rat aorta effected by an atypical sympathomimetic decongestant

PubMed Central

Rizvić, Eldina; Janković, Goran

2017-01-01

Vasoconstrictive properties of sympathomimetic drugs are the basis of their widespread use as decongestants and possible source of adverse responses. Insufficiently substantiated practice of combining decongestants in some marketed preparations, such are those containing phenylephrine and lerimazoline, may affect the overall contractile activity, and thus their therapeutic utility. This study aimed to examine the interaction between lerimazoline and phenylephrine in isolated rat aortic rings, and also to assess the substrate of the obtained lerimazoline-induced attenuation of phenylephrine contraction. Namely, while lower concentrations of lerimazoline (10−6 M and especially 10−7 M) expectedly tended to potentiate the phenylephrine-induced contractions, lerimazoline in higher concentrations (10−4 M and above) unexpectedly and profoundly depleted the phenylephrine concentration-response curve. Suppression of NO with NO synthase (NOS) inhibitor Nw-nitro-L-arginine methyl ester (L-NAME; 10−4 M) or NO scavanger OHB12 (10−3 M), as well as non-specific inhibition of K+-channels with tetraethylammonium (TEA; 10−3 M), have reversed lerimazoline-induced relaxation of phenylephrine contractions, while cyclooxygenase inhibitor indomethacin (10−5 M) did not affect the interaction between two vasoconstrictors. At the receptor level, non-selective 5-HT receptor antagonist methiothepin reversed the attenuating effect of lerimazoline on phenylephrine contraction when applied at 3×10−7 and 10−6 M, but not at the highest concentration (10−4 M). Neither the 5-HT1D-receptor selective antagonist BRL 15572 (10−6 M) nor 5-HT7 receptor selective antagonist SB 269970 (10−6 M) affected the lerimazoline-induced attenuation of phenylephrine activity. The mechanism of lerimazoline-induced suppression of phenylephrine contractions may involve potentiation of activity of NO and K+-channels and activation of some methiothepin-sensitive receptors, possibly of the 5-HT2B subtype. PMID:28706452

Elucidation of the profound antagonism of contractile action of phenylephrine in rat aorta effected by an atypical sympathomimetic decongestant.

PubMed

Rizvić, Eldina; Janković, Goran; Savić, Miroslav M

2017-07-01

Vasoconstrictive properties of sympathomimetic drugs are the basis of their widespread use as decongestants and possible source of adverse responses. Insufficiently substantiated practice of combining decongestants in some marketed preparations, such are those containing phenylephrine and lerimazoline, may affect the overall contractile activity, and thus their therapeutic utility. This study aimed to examine the interaction between lerimazoline and phenylephrine in isolated rat aortic rings, and also to assess the substrate of the obtained lerimazoline-induced attenuation of phenylephrine contraction. Namely, while lower concentrations of lerimazoline (10 -6 M and especially 10 -7 M) expectedly tended to potentiate the phenylephrine-induced contractions, lerimazoline in higher concentrations (10 -4 M and above) unexpectedly and profoundly depleted the phenylephrine concentration-response curve. Suppression of NO with NO synthase (NOS) inhibitor N w -nitro-L-arginine methyl ester (L-NAME; 10 -4 M) or NO scavanger OHB 12 (10 -3 M), as well as non-specific inhibition of K + -channels with tetraethylammonium (TEA; 10 -3 M), have reversed lerimazoline-induced relaxation of phenylephrine contractions, while cyclooxygenase inhibitor indomethacin (10 -5 M) did not affect the interaction between two vasoconstrictors. At the receptor level, non-selective 5-HT receptor antagonist methiothepin reversed the attenuating effect of lerimazoline on phenylephrine contraction when applied at 3×10 -7 and 10 -6 M, but not at the highest concentration (10 -4 M). Neither the 5-HT 1D -receptor selective antagonist BRL 15572 (10 -6 M) nor 5-HT 7 receptor selective antagonist SB 269970 (10 -6 M) affected the lerimazoline-induced attenuation of phenylephrine activity. The mechanism of lerimazoline-induced suppression of phenylephrine contractions may involve potentiation of activity of NO and K + -channels and activation of some methiothepin-sensitive receptors, possibly of the 5-HT 2B subtype.

In vitro vascular effects produced by crude aqueous extract of green marine algae, Cladophora patentiramea (Mont.) Kützing, in aorta from normotensive rats.

PubMed

Lim, Yee-Ling; Mok, Shiueh-Lian

2010-01-01

To investigate the antihypertensive activity of aqueous extracts obtained from Malaysian coastal seaweeds and to determine the pharmacological mechanisms of the extracts on rat aorta in vitro. The antihypertensive activity of 11 species of seaweeds (5 brown, 1 red and 5 green algae) were tested by cumulative addition of the extracts to phenylephrine (PE)-precontracted Wistar-Kyoto (WKY) aortic rings in in vitro isometric contraction studies. Mechanisms for vasorelaxant effect were investigated in the presence of various antagonists. Of the 11 species tested, 2 showed a vasorelaxant effect. Further investigation of the mechanisms of action of the aqueous extract of green alga, Cladophora patentiramea (AECP),showed that the vascular relaxant effect was endothelium- and concentration-dependent. A maximum relaxation of 45.8 +/- 4.6% (n = 8, p < 0.001) was obtained at 0.1 mg/ml of extract, after which the response was found to reduce in a concentration-dependent manner to 15.7 +/- 4.9% (n = 8, p < 0.001) at the highest extract concentration tested. Pretreatment of endothelium-intact aortic rings with Nomega-nitro-L-arginine methyl ester (L-NAME, 30 microM), (1)H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 10 microM) and methylene blue (100 microM) resulted in a complete blockade of AECP-induced vasorelaxation. However, the relaxant effects of the extract were not blocked by atropine (1 microM), indomethacin (10 microM) and glibenclamide (10 microM), although the maximum relaxant responses were enhanced in the presence of glibenclamide. Our data showed that the in vitro vascular relaxant effect of AECPwas mediated through endothelium-dependent nitric oxide-cGMP pathway, and was not associated with the release of vasodilator prostaglandins, activation of muscarinic receptors, or ATP-sensitive potassium channels opening. Copyright 2010 S. Karger AG, Basel.

Vasoresponsiveness of collateral vessels in the rat hindlimb: influence of training.

PubMed

Colleran, Patrick N; Li, Zeyi; Yang, Hsiao T; Laughlin, M Harold; Terjung, Ronald L

2010-04-15

Exercise training is known to be an effective means of improving functional capacity and quality of life in patients with peripheral arterial insufficiency (PAI). However, the specific training-induced physiological adaptations occurring within collateral vessels remain to be clearly defined. The purpose of this study was to determine the effect of exercise training on vasomotor properties of isolated peripheral collateral arteries. We hypothesized that daily treadmill exercise would improve the poor vasodilatory capacity of collateral arteries isolated from rats exposed to surgical occlusion of the femoral artery. Following femoral artery ligation, animals were either kept sedentary or exercise trained daily for a period of 3 weeks. Hindlimb collateral arteries were then isolated, cannulated and pressurized via hydrostatic reservoirs to an intravascular pressure of either 45 or 120 cmH(2)O. Non-occluded contralateral vessels of the sedentary animals served as normal Control. Vasodilatory responses to acetylcholine (ACh; 1 x 10(9)-1 x 10(5)m) and sodium nitroprusside (SNP; 1 x 10(9)-1 x 10(4)m), constrictor responses to phenylephrine (PE; 1 x 10(9)-1 x 10(4)m), and flow-induced vasodilatation were determined. Endothelium-mediated vasodilatation responses were significantly greater to either ACh (P < 0.02) or intravascular flow (P < 0.001) in collateral arteries of trained rats. Neither blockade of cyclooxygenase with indomethacin (Indo; 5 microm) nor blockade of endothelial nitric oxide synthase with N(G)-nitro-L-arginine methyl ester (L-NAME; 300 microm) eliminated this ACh- or flow-induced vasodilatation. The depressed vasodilatory response to SNP caused by vascular occlusion was reversed with training. These data indicate that exercise training improves endothelium-mediated vasodilatory capacity of hindlimb collateral arteries, apparently by enhanced production of the putative endothelium-derived hyperpolarizing factor(s). If these findings were applicable to patients with PAI, they could contribute to an improved collateral vessel function and enhance exercise tolerance during routine physical activity.

Interferon-γ regulates chemokine expression and release in the human mast cell line HMC1: role of nitric oxide

PubMed Central

Gilchrist, M; Befus, A D

2008-01-01

Mast cells (MCs) are critical immune effector cells that release cytokines and chemokines involved in both homeostasis and disease. Interferon-γ (IFN-γ) is a pleiotropic cytokine that regulates multiple cellular activities. IFN-γ modulates rodent MC responsiveness via production of nitric oxide (NO), although the effects in human MC populations is unknown. We sought to investigate the effects of IFN-γ on expression of the chemokines interleukin-8 (IL-8) and CCL1 (I-309) in a human mast cell line (HMC1) and to determine the underlying regulatory mechanism. Nitric oxide synthase (NOS), IL-8 and CCL1 expression was determined using real-time polymerase chain reaction (PCR). NOS protein expression was analysed using western blot. NOS activity was determined using the citrulline assay. IL-8 and CCL1 release was measured by specific enzyme-linked immunosorbent assay (ELISA). IFN-γ inhibited phorbol 12-myristate 13-acetate (PMA)-induced release of IL-8 and CCL1 (by 47 and 38%). Real-time PCR analysis of IFN-γ-treated HMC1 showed a significant (P < 0·05) time-dependent increase in NOS1 and NOS3 mRNA. NOS3 protein was significantly increased at 18 hr, which correlated with a significant (P < 0·05) increase in constitutive NOS (cNOS) activity. IFN-γ-induced inhibition of chemokine expression and release was NO dependent, as treatment with the NOS inhibitor NG-nitro-l-arginine methyl ester (l-NAME) reduced the IFN-γ inhibitory effect on IL-8 and CCL1 mRNA expression. NO donors mimicked the IFN-γ effect. IFN-γ inhibited PMA-induced cAMP response element binding protein (CREB) phosphorylation and DNA-binding activity. Our observations indicate for the first time that IFN-γ enhances endogenous NO formation through NOS3 activity, and that NO regulates the transcription and release of IL-8 and CCL1 in a human MC line. PMID:17662042

Nitric oxide/cGMP/PKG signaling pathway activated by M1-type muscarinic acetylcholine receptor cascade inhibits Na+-activated K+ currents in Kenyon cells

PubMed Central

Hasebe, Masaharu

2016-01-01

The interneurons of the mushroom body, known as Kenyon cells, are essential for the long-term memory of olfactory associative learning in some insects. Some studies have reported that nitric oxide (NO) is strongly related to this long-term memory in Kenyon cells. However, the target molecules and upstream and downstream NO signaling cascades are not completely understood. Here we analyzed the effect of the NO signaling cascade on Na+-activated K+ (KNa) channel activity in Kenyon cells of crickets (Gryllus bimaculatus). We found that two different NO donors, S-nitrosoglutathione (GSNO) and S-nitroso-N-acetyl-dl-penicillamine (SNAP), strongly suppressed KNa channel currents. Additionally, this inhibitory effect of GSNO on KNa channel activity was diminished by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), an inhibitor of soluble guanylate cyclase (sGC), and KT5823, an inhibitor of protein kinase G (PKG). Next, we analyzed the role of ACh in the NO signaling cascade. ACh strongly suppressed KNa channel currents, similar to NO donors. Furthermore, this inhibitory effect of ACh was blocked by pirenzepine, an M1 muscarinic ACh receptor antagonist, but not by 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide (4-DAMP) and mecamylamine, an M3 muscarinic ACh receptor antagonist and a nicotinic ACh receptor antagonist, respectively. The ACh-induced inhibition of KNa channel currents was also diminished by the PLC inhibitor U73122 and the calmodulin antagonist W-7. Finally, we found that ACh inhibition was blocked by the nitric oxide synthase (NOS) inhibitor NG-nitro-l-arginine methyl ester (l-NAME). These results suggested that the ACh signaling cascade promotes NO production by activating NOS and NO inhibits KNa channel currents via the sGC/cGMP/PKG signaling cascade in Kenyon cells. PMID:26984419

Ghrelin-Related Peptides Exert Protective Effects in the Cerebral Circulation of Male Mice Through a Nonclassical Ghrelin Receptor(s)

PubMed Central

Ku, Jacqueline M.; Andrews, Zane B.; Barsby, Tom; Reichenbach, Alex; Lemus, Moyra B.; Drummond, Grant R.; Sleeman, Mark W.; Spencer, Sarah J.; Sobey, Christopher G.

2015-01-01

The ghrelin-related peptides, acylated ghrelin, des-acylated ghrelin, and obestatin, are novel gastrointestinal hormones. We firstly investigated whether the ghrelin gene, ghrelin O-acyltransferase, and the ghrelin receptor (GH secretagogue receptor 1a [GHSR1a]) are expressed in mouse cerebral arteries. Secondly, we assessed the cerebrovascular actions of ghrelin-related peptides by examining their effects on vasodilator nitric oxide (NO) and superoxide production. Using RT-PCR, we found the ghrelin gene and ghrelin O-acyltransferase to be expressed at negligible levels in cerebral arteries from male wild-type mice. mRNA expression of GHSR1a was also found to be low in cerebral arteries, and GHSR protein was undetectable in GHSR-enhanced green fluorescent protein mice. We next found that exogenous acylated ghrelin had no effect on the tone of perfused cerebral arteries or superoxide production. By contrast, exogenous des-acylated ghrelin or obestatin elicited powerful vasodilator responses (EC50 < 10 pmol/L) that were abolished by the NO synthase inhibitor Nω-nitro-L-arginine methyl ester. Furthermore, exogenous des-acylated ghrelin suppressed superoxide production in cerebral arteries. Consistent with our GHSR expression data, vasodilator effects of des-acylated ghrelin or obestatin were sustained in the presence of YIL-781 (GHSR1a antagonist) and in arteries from Ghsr-deficient mice. Using ghrelin-deficient (Ghrl−/−) mice, we also found that endogenous production of ghrelin-related peptides regulates NO bioactivity and superoxide levels in the cerebral circulation. Specifically, we show that NO bioactivity was markedly reduced in Ghrl−/− vs wild-type mice, and superoxide levels were elevated. These findings reveal protective actions of exogenous and endogenous ghrelin-related peptides in the cerebral circulation and show the existence of a novel ghrelin receptor(s) in the cerebral endothelium. PMID:25322462

40 CFR 721.1325 - Benzene, 1-(1-methyl-bu-toxy)-4-nitro-.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Benzene, 1-(1-methyl-bu-toxy)-4-nitro... Substances § 721.1325 Benzene, 1-(1-methyl-bu-toxy)-4-nitro-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1-(1-methylbutoxy)-4-nitro- (PMN P...

40 CFR 721.1325 - Benzene, 1-(1-methyl-bu-toxy)-4-nitro-.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Benzene, 1-(1-methyl-bu-toxy)-4-nitro... Substances § 721.1325 Benzene, 1-(1-methyl-bu-toxy)-4-nitro-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1-(1-methylbutoxy)-4-nitro- (PMN P...

40 CFR 721.1325 - Benzene, 1-(1-methyl-bu-toxy)-4-nitro-.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, 1-(1-methyl-bu-toxy)-4-nitro... Substances § 721.1325 Benzene, 1-(1-methyl-bu-toxy)-4-nitro-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1-(1-methylbutoxy)-4-nitro- (PMN P...

40 CFR 721.1325 - Benzene, 1-(1-methyl-bu-toxy)-4-nitro-.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Benzene, 1-(1-methyl-bu-toxy)-4-nitro... Substances § 721.1325 Benzene, 1-(1-methyl-bu-toxy)-4-nitro-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1-(1-methylbutoxy)-4-nitro- (PMN P...

40 CFR 721.1325 - Benzene, 1-(1-methyl-bu-toxy)-4-nitro-.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Benzene, 1-(1-methyl-bu-toxy)-4-nitro... Substances § 721.1325 Benzene, 1-(1-methyl-bu-toxy)-4-nitro-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1-(1-methylbutoxy)-4-nitro- (PMN P...

Muscarinic receptors, nitric oxide formation and cyclooxygenase pathway involved in tracheal smooth muscle relaxant effect of hydro-ethanolic extract of Lavandula angustifolia flowers.

PubMed

Naghdi, Farzaneh; Gholamnezhad, Zahra; Boskabady, Mohammad Hossein; Bakhshesh, Morteza

2018-06-01

Lavandula angustifolia (L. angustifolia) Mill. (Common name Lavender) is used in traditional and folk medicines for the treatment of various diseases including respiratory disorders worldwide. The relaxant effect of the plant on the smooth muscle of some tissues was shown previously. The present study has investigated the role of different receptors and pathways in the relaxant effect of L. angustifolia on tracheal smooth muscle. Cumulative concentrations of the hydro-ethanolic extract of L. angustifolia flowers (0.5, 1, 2 and 4 mg/ml) were added on pre-contracted tracheal smooth muscle by methacholine (10 μM) or KCl (60 mM) on non-preincubated or preincubated tissues with atropine, chlorpheniramine, propranolol, diltiazem, glibenclamide, indomethacin, ω-nitro-L-arginine methyl ester (L-NAME) and papaverine. The results compared with of theophylline (0.2, 0.4, 0.6 and 0.8 mM) as positive control and saline (1 ml) as negative control. The extract showed concentration-dependent relaxant effects in non-preincubated tracheal smooth muscle contracted by KCl and methacholine (p < 0.05 to p < 0.001). The relaxant effect ofL. angustifolia was not significantly different between non-preincubated and preincubated tissues with chlorpheniramine, propranolol, diltiazem, glibenclamide, and papaverine. However, two higher concentrations of L. angustifolia in preincubated tissues with L-NAME (p < 0.01), indomethacin (p < 0.05 to p < 0.001) and atropine (p < 0.05) showed significantly lower relaxant effects than non-preincubated tissues. The EC 50 values of L. angustifolia in tissues preincubated with indomethacin was significantly higher than non-preincubated trachea (p < 0.05). The effects of three first concentrations of the extract on KCl and methacholine-induced muscle contraction were significantly lower than those of theophylline (p < 0.05 to p < 0.001). These results indicated a relatively potent relaxant effect ofL. angustifolia that was lower than the effect of theophylline. The possible mechanisms of relaxant effect of this plant on tracheal smooth muscle are muscarinic receptors blockade, inhibition of cyclooxygenase pathways and/or involvement of nitric oxide production. Its clinical applications should be investigated in further studies. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

N-alpha-Cocoyl-L-arginine ethyl ester, DL-pyroglutamic acid salt, as an inactivator of hepatitis B surface antigen.

PubMed Central

Sugimoto, Y; Toyoshima, S

1979-01-01

N-alpha-Cocoyl-L-arginine ethyl ester, DL-pyroglutamic acid salt (CAE), exhibited a strong inactivating effect on hepatitis B surface antigen. Concentrations of CAE required for 50 and 100% inactivation of the antigen were 0.01 to 0.025% and 0.025 to 0.05% respectively. CAE completely inactivated hepatitis B surface antigen at the lowest concentration compared with various compounds including about 500 amino acid derivatives, sodium hypochlorite, 2,4,4'-trichloro-2'-hydroxydiphenyl ether, and some detergents. Furthermore, CAE inactivated vaccinia virus, herpes simplex virus, and influenza virus, whereas poliovirus was not inactivated at all. The results suggest that the inactivating effects of CAE are related to interaction with lipid-containing viral envelopes. PMID:228595

Low-amplitude pulses to the circulation through periodic acceleration induces endothelial-dependent vasodilatation.

PubMed

Uryash, Arkady; Wu, Heng; Bassuk, Jorge; Kurlansky, Paul; Sackner, Marvin A; Adams, Jose A

2009-06-01

Low-amplitude pulses to the vasculature increase pulsatile shear stress to the endothelium. This activates endothelial nitric oxide (NO) synthase (eNOS) to promote NO release and endothelial-dependent vasodilatation. Descent of the dicrotic notch on the arterial pulse waveform and a-to-b ratio (a/b; where a is the height of the pulse amplitude and b is the height of the dicrotic notch above the end-diastolic level) reflects vasodilator (increased a/b) and vasoconstrictor effects (decreased a/b) due to NO level change. Periodic acceleration (pG(z)) (motion of the supine body head to foot on a platform) provides systemic additional pulsatile shear stress. The purpose of this study was to determine whether or not pG(z) applied to rats produced endothelial-dependent vasodilatation and increased NO production, and whether the latter was regulated by the Akt/phosphatidylinositol 3-kinase (PI3K) pathway. Male rats were anesthetized and instrumented, and pG(z) was applied. Sodium nitroprusside, N(G)-nitro-l-arginine methyl ester (l-NAME), and wortmannin (WM; to block Akt/PI3K pathway) were administered to compare changes in a/b and mean aortic pressure. Descent of the dicrotic notch occurred within 2 s of initiating pG(z). Dose-dependent increase of a/b and decrease of mean aortic pressure took place with SNP. l-NAME produced a dose-dependent rise in mean aortic pressure and decrease of a/b, which was blunted with pG(z). In the presence of WM, pG(z) did not decrease aortic pressure or increase a/b. WM also abolished the pG(z) blunting effect on blood pressure and a/b of l-NAME-treated animals. eNOS expression was increased in aortic tissue after pG(z). This study indicates that addition of low-amplitude pulses to circulation through pG(z) produces endothelial-dependent vasodilatation due to increased NO in rats, which is mediated via activation of eNOS, in part, by the Akt/PI3K pathway.

Histone arginine methylations: their roles in chromatin dynamics and transcriptional regulation

PubMed Central

LITT, Michael; QIU, Yi; HUANG, Suming

2017-01-01

Synopsis PRMTs (protein arginine N-methyltransferases) specifically modify the arginine residues of key cellular and nuclear proteins as well as histone substrates. Like lysine methylation, transcriptional repression or activation is dependent upon the site and type of arginine methylation on histone tails. Recent discoveries imply that histone arginine methylation is an important modulator of dynamic chromatin regulation and transcriptional controls. However, under the shadow of lysine methylation, the roles of histone arginine methylation have been under-explored. The present review focuses on the roles of histone arginine methylation in the regulation of gene expression, and the interplays between histone arginine methylation, histone acetylation, lysine methylation and chromatin remodelling factors. In addition, we discuss the dynamic regulation of arginine methylation by arginine demethylases, and how dysregulation of PRMTs and their activities are linked to human diseases such as cancer. PMID:19220199

[The importance of regulation of endogenous methylarginine concentrations in clinical practice].

PubMed

Kopieczna-Grzebieniak, Ewa; Goss, Małgorzata

2005-01-01

Endogenous methylarginines, the catabolism products of proteins containing post-translationally methylated arginine residues, are the modulators of arginine metabolism. Endogenous methylarginines compete with arginine about cationic aminoacid transporter and some of them, e.g. asymmetric dimethylarginine (ADMA) and N-mono-methylarginine (MMA), are competitive inhibitors of nitric oxide synthases. The changes of arginine metabolism, induced by these methylarginines, may have serious consequences, because arginine is the precursor of cell-signalling molecules such as NO, agmatine, glutamate and gamma-aminobutyric acid (GABA) and the regulatory molecules polyamines. ADMA has also prooxidant properties and increases endothelial adhesiveness for monocytes. Asymmetric methyl-arginines induce endothelial dysfunction, which may be reversed by L-arginine supplementation, what is defined as "arginine paradox". The increased plasma concentration of asymmetric methylarginines is induced by hypercholesterolemic or hyperhomocysteinemic diets and by rich sodium chloride intake. The high level of plasma asymmetric methyl-arginines accompanies atherosclerosis, hypertension, chronic renal failure, diabetes, insulin resistence, hyperthyreosis, schizophrenia and sclerosis multiplex. The causes of increased concentration ADMA and MMA in these diseases are just now discovered. The hope in the future is the modulation of methylarginines concentration by regulation of expression and activities of enzymes taking part in the metabolism of these substances, particularly of dimethyl-arginine dimethyl-aminotransferase. The main aim of the present study is to pay attention to possibility of the modulation of asymmetric methyl-arginines concentration, what may be a new way of synthase nitric oxide activity regulation in vivo and may be useful in future therapy of patologies in which synthesis of NO is troubled.

Kenaf methyl esters

USDA-ARS?s Scientific Manuscript database

Additional or alternative feedstocks are one of the major areas of interest regarding biodiesel. In this paper, for the first time, the fuel properties of kenaf (Hibiscus cannabinus L.) seed oil methyl esters are comprehensively reported. This biodiesel is also relatively unique by containing small ...

Preparation and Evaluation of Jojoba Oil Methyl Ester as Biodiesel and as Blend Components in Ultra Low Sulfur Diesel Fuel

USDA-ARS?s Scientific Manuscript database

The jojoba plant (Simmondsia chinensis L.) produces seeds that contain around 50 to 60 weight percent of inedible long-chain wax esters that are suitable as a potential feedstock for biodiesel production. A Jojoba oil methyl ester (JME) was prepared in effort to evaluate an important fuel propertie...

A simple and sensitive fluorescent sensor for methyl parathion based on L-tyrosine methyl ester functionalized carbon dots.

PubMed

Hou, Juying; Dong, Jing; Zhu, Haishuang; Teng, Xue; Ai, Shiyun; Mang, Minglin

2015-06-15

In this paper, a simple and sensitive fluorescent sensor for methyl parathion is developed based on L-tyrosine methyl ester functionalized carbon dots (Tyr-CDs) and tyrosinase system. The carbon dots are obtained by simple hydrothermal reaction using citric acid as carbon resource and L-tyrosine methyl ester as modification reagent. The carbon dots are characterized by transmission electron microscope, high resolution transmission electron microscopy, X-ray diffraction spectrum, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The carbon dots show strong and stable photoluminescence with a quantum yield of 3.8%. Tyrosinase can catalyze the oxidation of tyrosine methyl ester on the surface of carbon dots to corresponding quinone products, which can quench the fluorescence of carbon dots. When organophosphorus pesticides (OPs) are introduced in system, they can decrease the enzyme activity, thus decrease the fluorescence quenching rate. Methyl parathion, as a model of OPs, was detected. Experimental results show that the enzyme inhibition rate is proportional to the logarithm of the methyl parathion concentration in the range 1.0×10(-10)-1.0×10(-4) M with the detection limit (S/N=3) of 4.8×10(-11) M. This determination method shows a low detection limit, wide linear range, good selectivity and high reproducibility. This sensing system has been successfully used for the analysis of cabbage, milk and fruit juice samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Improvement of retinal functions after ischemia with L-arginine and its derivatives.

PubMed

Liu, S X; Chiou, G C; Varma, R S

1995-01-01

Retinal ischemia was created by occlusion of rat central retinal artery for 30 minutes. The loss of retinal function was indicated by the loss of b-wave of electroretinogram. The recovery of retinal function after reperfusion of central retinal artery was observed with the gradual recovery of b-wave amplitude to approximately 20% of original b-wave amplitude. When L-arginine (RVC-579) was administered at the time of retina ischemia, the b-wave amplitudes recovered up to 64% of original height and were significantly higher than corresponding controls at 120, 180, and 240 min after ischemia. When the derivative of L-arginine, N alpha-benzoyl-L-arginine ethyl ester (RVC-578), was administered, the b-wave recovery was significantly higher than corresponding controls at 90, 120, 180, and 240 min after ischemia; the recovery reached 51% of the original b-wave value. These results indicate that the L-arginine and its lipophilic derivatives could be used for the treatment of ischemic retinopathy. Since L-arginine is a natural amino acid, it is not expected to produce major side effects, if any, and could pave the way for the development of a safer drug to be used in the clinics. Compounds which increase the formation of NO in vivo, dilate blood vessels. Both L-arginine and RVC-578 can be placed in this category. They may improve effects of retinal ischemia by increasing NO production.

Vinyl functionalized silica hybrid monolith-based trypsin microreactor for on line digestion and separation via thiol-ene "click" strategy.

PubMed

Chen, Yingzhuang; Wu, Minghuo; Wang, Keyi; Chen, Bo; Yao, Shouzhuo; Zou, Hanfa; Nie, Lihua

2011-11-04

A novel thiol-ene "click" strategy for the preparation of monolithic trypsin microreactor was proposed. The hybrid organic-inorganic monolithic capillary column with ene-functionality was fabricated by sol-gel process using tetramethoxysilane (TMOS) and γ-methacryloxypropyltrimethoxysilane (γ-MAPS) as precursors. The disulfide bonds of trypsin were reduced to form free thiol groups. Then the trypsin containing free thiol groups was attached on the γ-MAPS hybrid monolithic column with ene-functionality via thiol-ene click chemistry to form a trypsin microreactor. The activity of the trypsin microreactor was characterized by detecting the substrate (Nα-p-tosyl-L-arginine methyl ester hydrochloride, TAME) and the product (Nα-p-tosyl-L-arginine, TA) with on-line capillary zone electrophoresis. After investigating various synthesizing conditions, it was found that the microreactor with poly(N,N'-methylenebisacrylamide) as spacer can deliver the highest activity, yielding a rapid reaction rate. After repeatedly sampling and analyzing for 100 times, the monolithic trypsin microreactor still remained 87.5% of its initial activity. It was demonstrated that thiol-ene "click" strategy for the construction of enzyme microreactor is a promising method for the highly selective immobilization of proteins under mild conditions, especially enzymes with free thiol radicals. Copyright © 2011 Elsevier B.V. All rights reserved.

Development of an HPLC Method with an ODS Column to Determine Low Levels of Aspartame Diastereomers in Aspartame

PubMed Central

Ohtsuki, Takashi; Nakamura, Ryoichiro; Kubo, Satoru; Otabe, Akira; Oobayashi, Yoko; Suzuki, Shoko; Yoshida, Mika; Yoshida, Mitsuya; Tatebe, Chiye; Sato, Kyoko; Akiyama, Hiroshi

2016-01-01

α-L-Aspartyl-D-phenylalanine methyl ester (L, D-APM) and α-D-aspartyl-L-phenylalanine methyl ester (D, L-APM) are diastereomers of aspartame (N-L-α-Aspartyl-L-phenylalanine-1-methyl ester, L, L-APM). The Joint FAO/WHO Expert Committee on Food Additives has set 0.04 wt% as the maximum permitted level of the sum of L, D-APM and D, L-APM in commercially available L, L-APM. In this study, we developed and validated a simple high-performance liquid chromatography (HPLC) method using an ODS column to determine L, D-APM and D, L-APM in L, L-APM. The limits of detection and quantification, respectively, of L, D-APM and D, L-APM were found to be 0.0012 wt% and 0.004 wt%. This method gave excellent accuracy, repeatability, and reproducibility in a recovery test performed on five different days. Moreover, the method was successfully applied to the determination of these diastereomers in commercial L, L-APM samples. Thus, the developed method is a simple, useful, and practical tool for determining L, D-APM and D, L-APM levels in L, L-APM. PMID:27015640

Development of an HPLC Method with an ODS Column to Determine Low Levels of Aspartame Diastereomers in Aspartame.

PubMed

Ohtsuki, Takashi; Nakamura, Ryoichiro; Kubo, Satoru; Otabe, Akira; Oobayashi, Yoko; Suzuki, Shoko; Yoshida, Mika; Yoshida, Mitsuya; Tatebe, Chiye; Sato, Kyoko; Akiyama, Hiroshi

2016-01-01

α-L-Aspartyl-D-phenylalanine methyl ester (L, D-APM) and α-D-aspartyl-L-phenylalanine methyl ester (D, L-APM) are diastereomers of aspartame (N-L-α-Aspartyl-L-phenylalanine-1-methyl ester, L, L-APM). The Joint FAO/WHO Expert Committee on Food Additives has set 0.04 wt% as the maximum permitted level of the sum of L, D-APM and D, L-APM in commercially available L, L-APM. In this study, we developed and validated a simple high-performance liquid chromatography (HPLC) method using an ODS column to determine L, D-APM and D, L-APM in L, L-APM. The limits of detection and quantification, respectively, of L, D-APM and D, L-APM were found to be 0.0012 wt% and 0.004 wt%. This method gave excellent accuracy, repeatability, and reproducibility in a recovery test performed on five different days. Moreover, the method was successfully applied to the determination of these diastereomers in commercial L, L-APM samples. Thus, the developed method is a simple, useful, and practical tool for determining L, D-APM and D, L-APM levels in L, L-APM.

Activation of brain nitric oxide synthase in depolarized human temporal cortex slices: differential role of voltage-sensitive calcium channels

PubMed Central

Fontana, Giovanni; Fedele, Ernesto; Cossu, Massimo; Munari, Claudio; Raiteri, Maurizio

1997-01-01

Nitric oxide (NO) synthase activity was studied in slices of human temporal cortex samples obtained in neurosurgery by measuring the conversion of L-[3H]-arginine to L-[3H]-citrulline. Elevation of extracellular K+ to 20, 35 or 60 mM concentration-dependently augmented L-[3H]-citrulline production. The response to 35 mM KCl was abolished by NG-nitro-L-arginine (100 μM) demonstrating NO synthase specific conversion of L-arginine to L-citrulline. Increasing extracellular MgCl2 concentration up to 10 mM also prevented the K+ (35 mM)-induced NO synthase activation, suggesting the absolute requirement of external calcium ions for enzyme activity. However, the effect of high K+ (35 mM) on citrulline synthesis was insensitive to the antagonists of ionotropic and metabotropic glutamate receptors dizocilpine (MK-801), 6-nitro-7-sulphamoylbenzo(f)quinoxaline-2-3-dione (NBQX) or L-2-amino-3-phosphonopropionic acid (L-AP3) as well as to the nicotinic receptor antagonist, mecamylamine. The 35 mM K+ response was insensitive to ω-conotoxin GVIA (1 μM) and nifedipine (100 μM), but could be prevented in part by ω-agatoxin IVA (0.1 and 1 μM). The inhibition caused by 0.1 μM ω-agatoxin IVA (∼30%) was enhanced by adding ω-conotoxin GVIA (1 μM) or nifedipine (100 μM). Further inhibition (up to above 70%) could be observed when the three Ca2+ channel blockers were added together. Similarly, synthetic FTX 3.3 arginine polyamine (sFTX) prevented (50% at 100 μM) the K+-evoked NO synthase activation. This effect of sFTX was further enhanced (up to 70%) by adding 1 μM ω-conotoxin GVIA plus 100 μM nifedipine. No further inhibition could be observed upon addition of MK-801 or/and NBQX. It was concluded that elevation of extracellular [K+] causes NO synthase activation by external Ca+ entering cells mainly through channels of the P/Q-type. Other Ca2+ channels (L- and N-type) appear to contribute when P/Q-channels are blocked. PMID:9384511

Activation of brain nitric oxide synthase in depolarized human temporal cortex slices: differential role of voltage-sensitive calcium channels.

PubMed

Fontana, G; Fedele, E; Cossu, M; Munari, C; Raiteri, M

1997-11-01

1. Nitric oxide (NO) synthase activity was studied in slices of human temporal cortex samples obtained in neurosurgery by measuring the conversion of L-[3H]-arginine to L-[3H]-citrulline. 2. Elevation of extracellular K+ to 20, 35 or 60 mM concentration-dependently augmented L-[3H]-citrulline production. The response to 35 mM KCl was abolished by N(G)-nitro-L-arginine (100 microM) demonstrating NO synthase specific conversion of L-arginine to L-citrulline. Increasing extracellular MgCl2 concentration up to 10 mM also prevented the K+ (35 mM)-induced NO synthase activation, suggesting the absolute requirement of external calcium ions for enzyme activity. 3. However, the effect of high K+ (35 mM) on citrulline synthesis was insensitive to the antagonists of ionotropic and metabotropic glutamate receptors dizocilpine (MK-801), 6-nitro-7-sulphamoylbenzo(f)-quinoxaline-2-3-dione (NBQX) or L-2-amino-3-phosphonopropionic acid (L-AP3) as well as to the nicotinic receptor antagonist, mecamylamine. 4. The 35 mM K+ response was insensitive to omega-conotoxin GVIA (1 microM) and nifedipine (100 microM), but could be prevented in part by omega-agatoxin IVA (0.1 and 1 microM). The inhibition caused by 0.1 microM omega-agatoxin IVA (approximately 30%) was enhanced by adding omega-conotoxin GVIA (1 microM) or nifedipine (100 microM). Further inhibition (up to above 70%) could be observed when the three Ca2+ channel blockers were added together. Similarly, synthetic FTX 3.3 arginine polyamine (sFTX) prevented (50% at 100 microM) the K+-evoked NO synthase activation. This effect of sFTX was further enhanced (up to 70%) by adding 1 microM omega-conotoxin GVIA plus 100 microM nifedipine. No further inhibition could be observed upon addition of MK-801 or/and NBQX. 5. It was concluded that elevation of extracellular [K+] causes NO synthase activation by external Ca2+ entering cells mainly through channels of the P/Q-type. Other Ca2+ channels (L- and N-type) appear to contribute when P/Q-channels are blocked.

Oxygenated N-Acyl Alanine Methyl Esters (NAMEs) from the Marine Bacterium Roseovarius tolerans EL-164.

PubMed

Bruns, Hilke; Herrmann, Jennifer; Müller, Rolf; Wang, Hui; Wagner Döbler, Irene; Schulz, Stefan

2018-01-26

The marine bacterium Roseovarius tolerans EL-164 (Rhodobacteraceae) can produce unique N-acylalanine methyl esters (NAMEs) besides strucutrally related N-acylhomoserine lactones (AHLs), bacterial signaling compounds widespread in the Rhodobacteraceae. The structures of two unprecedented NAMEs carrying a rare terminally oxidized acyl chain are reported here. The compounds (Z)-N-16-hydroxyhexadec-9-enoyl-l-alanine methyl ester (Z9-16-OH-C16:1-NAME, 3) and (Z)-N-15-carboxypentadec-9-enoyl-l-alanine methyl ester (16COOH-C16:1-NAME, 4) were isolated, and the structures were determined by NMR and MS experiments. Both compounds were synthesized to prove assignments and to test their biological activity. Finally, non-natural, structurally related Z9-3-OH-C16:1-NAME (18) was synthesized to investigate the mass spectroscopy of structurally related NAMEs. Compound 3 showed moderate antibacterial activity against microorganisms such as Bacillus, Streptococcus, Micrococcus, or Mucor strains. In contrast to AHLs, quorum-sensing or quorum-quenching activity was not observed.

Transient Receptor Potential Channel Opening Releases Endogenous Acetylcholine, which Contributes to Endothelium-Dependent Relaxation Induced by Mild Hypothermia in Spontaneously Hypertensive Rat but Not Wistar-Kyoto Rat Arteries.

PubMed

Zou, Q; Leung, S W S; Vanhoutte, P M

2015-08-01

Mild hypothermia causes endothelium-dependent relaxations, which are reduced by the muscarinic receptor antagonist atropine. The present study investigated whether endothelial endogenous acetylcholine contributes to these relaxations. Aortic rings of spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats were contracted with prostaglandin F2 α and exposed to progressive mild hypothermia (from 37 to 31°C). Hypothermia induced endothelium-dependent, Nω-nitro-l-arginine methyl ester-sensitive relaxations, which were reduced by atropine, but not by mecamylamine, in SHR but not in WKY rat aortae. The responses in SHR aortae were also reduced by acetylcholinesterase (the enzyme responsible for acetylcholine degradation), bromoacetylcholine (inhibitor of acetylcholine synthesis), hemicholinium-3 (inhibitor of choline uptake), and vesamicol (inhibitor of acetylcholine release). The mild hypothermia-induced relaxations in both SHR and WKY rat aortae were inhibited by AMTB [N-(3-aminopropyl)-2-[(3-methylphenyl)methoxy]-N-(2-thienylmethyl)-benzamide; the transient receptor potential (TRP) M8 inhibitor]; only those in SHR aortae were inhibited by HC-067047 [2-methyl-1-[3-(4-morpholinyl)propyl]-5-phenyl-N-[3-(trifluoromethyl)phenyl]-1H-pyrrole-3-carboxamide; TRPV4 antagonist] while those in WKY rat aortae were reduced by HC-030031 [2-(1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purin-7-yl)-N-(4-isopropylphenyl)acetamide; TRPA1 antagonist]. The endothelial uptake of extracellular choline and release of cyclic guanosine monophosphate was enhanced by mild hypothermia and inhibited by HC-067047 in SHR but not in WKY rat aortae. Compared with WKY rats, the SHR preparations expressed similar levels of acetylcholinesterase and choline acetyltransferase, but a lesser amount of vesicular acetylcholine transporter, located mainly in the endothelium. Thus, mild hypothermia causes nitric oxide-dependent relaxations by opening TRPA1 channels in WKY rat aortae. By contrast, in SHR aortae, TRPV4 channels are opened, resulting in endothelial production of acetylcholine, which, in an autocrine manner, activates muscarinic receptors on neighboring cells to elicit endothelium-dependent relaxations in response to mild hypothermia. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Angiotensin II AT2 receptor decreases AT1 receptor expression and function via nitric oxide/cGMP/Sp1 in renal proximal tubule cells from Wistar–Kyoto rats

PubMed Central

Yang, Jian; Chen, Caiyu; Ren, Hongmei; Han, Yu; He, Duofen; Zhou, Lin; Hopfer, Ulrich; Jose, Pedro A.; Zeng, Chunyu

2013-01-01

Background The renin–angiotensin (Ang) system controls blood pressure, in part, by regulating renal tubular sodium transport. In the kidney, activation of the angiotensin II type 1 (AT1) receptor increases renal sodium reabsorption, whereas the angiotensin II type 2 (AT2) receptor produces the opposite effect. We hypothesized that the AT2 receptor regulates AT1 receptor expression and function in the kidney. Methods and results In immortalized renal proximal tubule (RPT) cells from Wistar–Kyoto rats, CGP42112, an AT2 receptor agonist, decreased AT1 receptor mRNA and protein expression (P < 0.05), as assessed by reverse transcriptase-polymerase chain reaction and immunoblotting. The inhibitory effect of the AT2 receptor on AT1 receptor expression was blocked by the AT2 receptor antagonist, PD123319 (10−6 mol/l), the nitric oxide synthase inhibitor Nw-nitro-l-arginine methyl ester (10−4 mol/l), or the nitric oxide-dependent soluble guanylate cyclase inhibitor 1H-[1,2,4] oxadiazolo-[4,3-a] quinoxalin-1-one (10−5 mol/l), indicating that both nitric oxide and cyclic guanosine monophosphate (cGMP) were involved in the signaling pathway. Furthermore, CGP42112 decreased Sp1 serine phosphorylation and reduced the binding of Sp1 to AT1 receptor DNA. Stimulation with Ang II (10−11 mol/l per 30 min) enhanced Na+-K+-ATPase activity in RPT cells, which was prevented by pretreatment with CGP42112 (10−7 mol/l per 24 h) (P < 0.05). The above-mentioned results were confirmed in RPT cells from AT2 receptor knockout mice; AT1 receptor expression and Ang II-stimulated Na+-K+-ATPase activity were greater in these cells than in RPT cells from wild-type mice (P < 0.05). AT1/AT2 receptors co-localized and co-immunoprecipitated in RPT cells; short-term CGP42112 (10−7 mol/l per 30 min) treatment increased AT1/AT2 receptor co-immunoprecipitation (P < 0.05). Conclusions These results indicate that the renal AT2 receptor, via nitric oxide/cGMP/Sp1 pathway, regulates AT1 receptor expression and function, which may be important in the regulation of sodium excretion and blood pressure. PMID:22504846

The effect of intravenous insulin infusion on renal blood flow in conscious sheep is partially mediated by nitric oxide but not by prostaglandins.

PubMed

Tebot, I; Bonnet, J-M; Paquet, C; Ayoub, J-Y; Da Silva, S M; Louzier, V; Cirio, A

2012-04-01

To test the effect of insulin on renal perfusion and the participation of NO and PG as mediators of this response, renal blood flow (RBF) was measured in sheep (n = 8) implanted with ultrasonic flow probes around renal arteries and with a systemic arterial pressure (SAP, n = 4) telemetry device. Three protocols were performed: 1) RBF and SAP were recorded (0800 to 1800 h) in fed and fasted sheep, with the latter receiving intravenous (i.v.) infusions (0.5 mL/min) of insulin at 2 or 6 mU/(kg·min); 2) fasted sheep received i.v. infusions of either an inhibitor of NO synthesis (N(G)-nitro-L-arginine methyl ester, L-NAME) alone [0.22 mg/(kg·min), 1000 to 1200 h] or L-NAME (1000 to 1200 h) + insulin during the second hour (6 mU/(kg·min), 1100 to 1200 h); and 3) the same protocol was followed as in protocol 2, substituting L-NAME with ketoprofen [0.2 mg/(kg·min)], a cyclooxygenase inhibitor. In all protocols, plasma insulin and glucose were determined. During insulin administration, euglycemia was maintained and hypokalemia was prevented by infusing glucose and KCl solutions. After the onset of meals, a long-lasting 18% increase in RBF and a 48% insulin increase were observed (P < 0.05), without changes in SAP. Low- and high-dose insulin infusions increased RBF by 19 and 40%, respectively (P < 0.05). As after meals, the increases in RBF lasted longer than the insulin increase (P < 0.05). The L-NAME infusion decreased RBF by 15% (P < 0.05); when insulin was added, RBF increased to preinfusion values. Ketoprofen decreased RBF by 9% (P < 0.05); when insulin was added, RBF increased to 13% above preinfusion values (P < 0.05). In no case was a modification in SAP or glucose noted during the RBF changes. In conclusion, insulin infusion mimics the meal-dependent increase in RBF, independent of SAP, and lasts longer than the blood insulin plateau. The RBF increase induced by insulin was only partially prevented by L-NAME. Ketoprofen failed to prevent the insulin-dependent RBF increase. Both facts suggested that complementary vasodilatatory agents accounted for the insulin effect on sheep renal hemodynamics.