Muscarinic acetylcholine receptor M1 and M3 subtypes mediate acetylcholine-induced endothelium-independent vasodilatation in rat mesenteric arteries.

PubMed

Tangsucharit, Panot; Takatori, Shingo; Zamami, Yoshito; Goda, Mitsuhiro; Pakdeechote, Poungrat; Kawasaki, Hiromu; Takayama, Fusako

2016-01-01

The present study investigated pharmacological characterizations of muscarinic acetylcholine receptor (AChR) subtypes involving ACh-induced endothelium-independent vasodilatation in rat mesenteric arteries. Changes in perfusion pressure to periarterial nerve stimulation and ACh were measured before and after the perfusion of Krebs solution containing muscarinic receptor antagonists. Distributions of muscarinic AChR subtypes in mesenteric arteries with an intact endothelium were studied using Western blotting. The expression level of M1 and M3 was significantly greater than that of M2. Endothelium removal significantly decreased expression levels of M2 and M3, but not M1. In perfused mesenteric vascular beds with intact endothelium and active tone, exogenous ACh (1, 10, and 100 nmol) produced concentration-dependent and long-lasting vasodilatations. In endothelium-denuded preparations, relaxation to ACh (1 nmol) disappeared, but ACh at 10 and 100 nmol caused long-lasting vasodilatations, which were markedly blocked by the treatment of pirenzepine (M1 antagonist) or 4-DAMP (M1 and M3 antagonist) plus hexamethonium (nicotinic AChR antagonist), but not methoctramine (M2 and M4 antagonist). These results suggest that muscarinic AChR subtypes, mainly M1, distribute throughout the rat mesenteric arteries, and that activation of M1 and/or M3 which may be located on CGRPergic nerves releases CGRP, causing an endothelium-independent vasodilatation. Copyright © 2015 Japanese Pharmacological Society. Production and hosting by Elsevier B.V. All rights reserved.

Resveratrol Protects and Restores Endothelium-Dependent Relaxation in Hypercholesterolemic Rabbit Corpus Cavernosum.

PubMed

Murat, Nergiz; Korhan, Peyda; Kizer, Onur; Evcim, Sinem; Kefi, Aykut; Demir, Ömer; Gidener, Sedef; Atabey, Neşe; Esen, Ahmet Adil

2016-01-01

Oxidative stress dependent-decrease in nitric oxide (NO) bioavailability plays an integral role in hypercholesterolemia-induced erectile dysfunction (ED). Resveratrol has been demonstrated to exert beneficial effects against oxidative stress and improve NO bioavailability. The protective and restorative potentials of resveratrol on endothelium-dependent relaxations were evaluated in hypercholesterolemic rabbit corpus cavernosum (CC). Hypercholesterolemia was induced by administering 2% cholesterol diet (CD) (w/w) to the rabbits for 6 weeks. Two different protocols were applied to test the effects of resveratrol on hypercholesterolemia-induced ED. In Protocol-1 (P1), resveratrol was administrated to the rabbits simultaneously with CD in order to evaluate the protective effect, and for Protocol-2 (P2), resveratrol was administrated for 6 weeks after termination of CD in order to evaluate the restorative effect. Endothelium-dependent relaxations of CC were evaluated by using organ bath studies. In order to elucidate the possible molecular mechanisms, we measured endothelial NO synthase (eNOS) and phosphovasodilator-stimulated phosphoprotein (VASP) expressions and activations, NADPH oxidase, superoxide dismutase (SOD), and catalase (CAT) and glutathione peroxidase (GPx) activity in cavernosal tissues obtained at the end of the study. Resveratrol showed an improvement in the endothelium-dependent relaxation responses in vitro. We demonstrated significantly increased activatory-phosphorylation (p[S1177]-eNOS) and activated phosphovasodilator-stimulated phosphoprotein (phospho-VASP) levels, but reduced phosphorylation (p[T495]-eNOS) of eNOS and NADPH oxidase activity in the resveratrol-administered HC animals compared with hypercholesterolemic control rabbits in the P1. In the P2, resveratrol exhibited an improvement in endothelium-dependent relaxation responses and more pronounced effects on eNOS activation. Resveratrol administration, either simultaneously with HC diet

Brazilin isolated from the heartwood of Caesalpinia sappan L induces endothelium-dependent and -independent relaxation of rat aortic rings

PubMed Central

Yan, Yu; Chen, Yu-cai; Lin, Yi-huang; Guo, Jing; Niu, Zi-ran; Li, Li; Wang, Shou-bao; Fang, Lian-hua; Du, Guan-hua

2015-01-01

Aim: Brazilin is one of the major constituents of Caesalpinia sappan L with various biological activities. This study sought to investigate the vasorelaxant effect of brazilin on isolated rat thoracic aorta and explore the underlying mechanisms. Methods: Endothelium-intact and -denuded aortic rings were prepared from rats. The tension of the preparations was recorded isometrically with a force displacement transducer connected to a polygraph. The phosphorylation levels of ERK1/2 and myosin light chain (MLC) were analyzed using Western blotting assay. Results: Application of brazilin (10–100 μmol/L) dose-dependently relaxed the NE- or high K+-induced sustained contraction of endothelium-intact aortic rings (the EC50 was 83.51±5.6 and 79.79±4.57 μmol/L, respectively). The vasorelaxant effect of brazilin was significantly attenuated by endothelium removal or by pre-incubation with L-NAME, methylene blue or indomethacin. In addition, pre-incubation with brazilin dose-dependently attenuated the vasoconstriction induced by KCl, NE or Ang II. Pre-incubation with brazilin also markedly suppressed the high K+-induced extracellular Ca2+ influx and NE-induced intracellular Ca2+ release in endothelium-denuded aortic rings. Pre-incubation with brazilin dose-dependently inhibited the NE-stimulated phosphorylation of ERK1/2 and MLC in both endothelium-intact and -denuded aortic rings. Conclusion: Brazilin induces relaxation in rat aortic rings via both endothelium-dependent and -independent ways as well as inhibiting NE-stimulated phosphorylation of ERK1/2 and MLC. Brazilin also attenuates vasoconstriction via blocking voltage- and receptor-operated Ca2+ channels. PMID:26564314

Excess L-arginine restores endothelium-dependent relaxation impaired by monocrotaline pyrrole

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

Cheng Wei; Oike, Masahiro; Hirakawa, Masakazu

2005-09-15

The pyrrolizidine alkaloid plant toxin monocrotaline pyrrole (MCTP) causes pulmonary hypertension in experimental animals. The present study aimed to examine the effects of MCTP on the endothelium-dependent relaxation. We constructed an in vitro disease model of pulmonary hypertension by overlaying MCTP-treated bovine pulmonary artery endothelial cells (CPAEs) onto pulmonary artery smooth muscle cell-embedded collagen gel lattice. Acetylcholine (Ach) induced a relaxation of the control CPAEs-overlaid gels that were pre-contracted with noradrenaline, and the relaxation was inhibited by L-NAME, an inhibitor of NO synthase (NOS). In contrast, when MCTP-treated CPAEs were overlaid, the pre-contracted gels did not show a relaxation inmore » response to Ach in the presence of 0.5 mM L-arginine. Expression of endothelial NOS protein, Ach-induced Ca{sup 2+} transients and cellular uptake of L-[{sup 3}H]arginine were significantly smaller in MCTP-treated CPAEs than in control cells, indicating that these changes were responsible for the impaired NO production in MCTP-treated CPAEs. Since cellular uptake of L-[{sup 3}H]arginine linearly increased according to its extracellular concentration, we hypothesized that the excess concentration of extracellular L-arginine might restore NO production in MCTP-treated CPAEs. As expected, in the presence of 10 mM L-arginine, Ach showed a relaxation of the MCTP-treated CPAEs-overlaid gels. These results indicate that the impaired NO production in damaged endothelial cells can be reversed by supplying excess L-arginine.« less

Butanolic fraction from Cuphea carthagenensis Jacq McBride relaxes rat thoracic aorta through endothelium-dependent and endothelium-independent mechanisms.

PubMed

Schuldt, E Z; Ckless, K; Simas, M E; Farias, M R; Ribeiro-Do-Valle, R M

2000-02-01

This study evaluated the vasorelaxant properties of the crude hydroalcoholic extract (CE) of Cuphea carthagenensis, as well as its butanolic (BF) and ethyl acetate (EA) fractions, in rings of rat thoracic aorta. In endothelium-intact rings contracted with phenylephrine (30-100 nM), cumulative additions of increasing concentrations of CE, BF, and EA of C. carthagenensis (0.1 microg/ml-3 mg/ml) caused graded relaxations, with BF displaying the lowest median inhibitory concentration (IC5; mean, 6.8 microg/ml; 95% confidence limits, 3.3-14.2). BF-induced relaxations of endothelium-intact rings were virtually abolished by prior incubation with the NO-synthase inhibitor N(omega)-nitro-L-arginine (L-NOARG; 10 or 30 microM), and were markedly reduced after guanylate cyclase inhibition with either methylene blue (10 microM) or ODQ (1 microM; 1H[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one). The inhibition of BF-induced relaxation by L-NOARG was prevented to a large extent by simultaneous incubation with L-arginine (1 mM). In endothelium-denuded rings contracted with phenylephrine, CE and BF caused graded relaxations only at doses >100 microg/ml, whereas the NO-donors SNAP (S-nitroso-N-acetyl-penicillamine) and SIN-1 (3-morpholino-sydnonimine) induced full relaxation at 1 microM. BF (100 microg/ml), which caused little relaxation per se of endothelium-denuded rings, potentiated the relaxant effects of SNAP and even more so of SIN-1 (which, unlike SNAP, also releases superoxide anion O2- in addition to NO), in a manner qualitatively similar to that seen with SOD (superoxide dismutase) against SIN-1. These data indicate that the BF of C. carthagenensis induces relaxation of the rat thoracic aorta by two mechanisms: (a) an endothelium-dependent component of action, which clearly depends on the NO/cyclic guanosine monophosphate (cGMP) pathway and can be attributed, at least in part, to free radical-scavenging properties; and (b) an endothelium-independent component of action, which

Mechanisms underlying the reduced endothelium-dependent relaxation in human omental resistance artery in pre-eclampsia

PubMed Central

Suzuki, Yoshikatsu; Kajikuri, Junko; Suzumori, Kaoru; Itoh, Takeo

2000-01-01

In pre-eclampsia, a functional change occurs in the role played by endothelium-derived nitric oxide (NO) in the regulation of smooth muscle contraction in resistance arteries. We investigated the underlying mechanism in human omental resistance arteries from normotensive pregnant and pre-eclamptic women in the presence of diclofenac (an inhibitor of cyclo-oxygenase).In endothelium-intact strips, the sensitivity to 9,11-epithio-11,12-methano-thromboxane A2 (STA2) was significantly higher in pre-eclampsia, and this was not modified by either NG-nitro-l-arginine (l-NNA, an inhibitor of NO synthase) or removal of the endothelium.Bradykinin and substance P each produced an endothelium-dependent relaxation of the STA2-induced contraction in both groups, although the relaxation was significantly smaller for pre-eclampsia. l-NNA markedly attenuated the endothelium-dependent relaxation in the normotensive pregnant group but not in the pre-eclamptic group.In the presence of l-NNA, the relaxation induced by sodium nitroprusside (SNP) on the STA2 contraction was significantly smaller for pre-eclamptic than for normotensive pregnant women.In endothelium-denuded strips, the relaxation induced by 8-para- chlorophenyl thio-guanosine-3′,5′-cyclic monophosphate (8-pCPT-cGMP) on the STA2 contraction was significantly less for pre-eclampsia.In β-escin-skinned strips from both groups of women, 8-pCPT-cGMP (1–10 μm) concentration-dependently attenuated the contraction induced by 0.5 μm Ca2+. However, its relaxing action was significantly weaker in pre-eclampsia.It is suggested that the weaker responsiveness to NO seen in strips from pre-eclamptic women may be partly due to a reduced smooth muscle responsiveness to cyclic GMP. PMID:10944179

Comparison of the relaxing actions of acetylcholine and substance P in smooth muscle of the guinea-pig aorta.

PubMed

Hozumi, T; Fukuta, H; Suzuki, H

1997-04-01

The relationship between relaxation produced by acetylcholine (ACh) or substance P (SP) and tissue cyclic GMP content was investigated in the isolated guinea-pig aorta. ACh and SP relaxed aortic rings precontracted with noradrenaline (NA) or high-K solution ([K+]o = 38.8 mM), in an endothelium-dependent manner. The amplitude of relaxation was larger for SP than for ACh. Nitroarginine inhibited ACh-induced but not SP-induced relaxation in NA-contraction, while this chemical inhibited both ACh- and SP-induced relaxations in high-K contraction. The tissue cyclic GMP content was not changed by nitroarginine or by removal of endothelial cells, but was elevated by stimulation with NA, ACh or SP by a factor of about 3, 5 or 11 times, respectively. These actions of ACh or SP were endothelium-dependent, and were inhibited by nitroarginine and remained unaltered by high-K solution. Thus, ACh and SP relax muscles indirectly by releasing endothelial factors, and the former by releasing mainly an endothelium-derived relaxing factor (EDRF), and the latter by releasing EDRF and other unidentified factors. As the relaxing actions of the latter factors are inhibited by high-K solution with no relation to the production of cyclic GMP, an involvement of hyperpolarizing factor, possibly EDHF, is suggested.

Dietary antioxidants preserve endothelium-dependent vessel relaxation in cholesterol-fed rabbits.

PubMed Central

Keaney, J F; Gaziano, J M; Xu, A; Frei, B; Curran-Celentano, J; Shwaery, G T; Loscalzo, J; Vita, J A

1993-01-01

Recent evidence suggests that dietary therapy with lipid-soluble antioxidants may be beneficial for patients with atherosclerotic vascular disease but the potential mechanism(s) for these observations remain obscure. Abnormalities in endothelium-dependent control of vascular tone develop early in the course of atherosclerosis and may result from oxidative modification of low density lipoproteins. We examined the role of dietary antioxidants in preserving normal endothelial cell vasodilator function in cholesterol-fed rabbits with particular attention to possible effects on serum lipoproteins, low density lipoprotein oxidation, and atherogenesis. Male New Zealand White rabbits were fed diets containing no additive (controls), 1% cholesterol (cholesterol group), or 1% cholesterol chow supplemented with either beta-carotene (0.6 g/kg of chow) or alpha-tocopherol (1000 international units/kg of chow) for a 28-day period. After dietary therapy, thoracic aortae were harvested for assay of vascular function and for pathologic examination and tissue antioxidant levels. Compared to controls, acetylcholine- and A23187-mediated endothelium-dependent relaxations were significantly impaired in vessels from the cholesterol group (P < 0.001), whereas vessels from animals treated with beta-carotene or alpha-tocopherol demonstrated normal endothelium-dependent arterial relaxation. Preservation of endothelial function was associated with vascular incorporation of alpha-tocopherol and beta-carotene but was unrelated to plasma lipoprotein levels, smooth muscle cell function, or the extent of atherosclerosis. Increased low density lipoprotein resistance to ex vivo copper-mediated oxidation was observed only in the alpha-tocopherol group. Our results suggest that dietary antioxidants may benefit patients with atherosclerosis by preserving endothelial vasodilator function through a mechanism related to vascular tissue antioxidant content and not reflected by assay of low density

Epoxyeicosatrienoic acids, potassium channel blockers and endothelium-dependent hyperpolarization in the guinea-pig carotid artery

PubMed Central

Chataigneau, Thierry; Félétou, Michel; Duhault, Jacques; Vanhoutte, Paul M

1998-01-01

Using intracellular microelectrodes, we investigated the effects of 17-octadecynoic acid (17-ODYA) on the endothelium-dependent hyperpolarization induced by acetylcholine in the guinea-pig isolated internal carotid artery with endothelium. In the presence of Nω-nitro-L-arginine (L-NOARG, 100 μM) and indomethacin (5 μM) to inhibit nitric oxide synthase and cyclo-oxygenase, acetylcholine (1 μM) evoked an endothelium-dependent hyperpolarization which averaged −16.4 mV starting from a resting membrane potential of −56.8 mV. There was a negative correlation between the amplitude of the hyperpolarization and the absolute values of the resting membrane potential. The acetylcholine-induced endothelium-dependent hyperpolarization was not altered by charybdotoxin (0.1 μM) or iberiotoxin (30 nM). It was partially but significantly reduced by apamin (0.5 μM) to −12.8±1.2 mV (n=10) or the combination of apamin plus iberiotoxin (−14.3±3.4 mV, n=4). However, the combination of charybdotoxin and apamin abolished the hyperpolarization and under these conditions, acetylcholine evoked a depolarization (+7.1±3.7 mV, n=8). 17-ODYA (10 μM) produced a significant hyperpolarization of the resting membrane potential which averaged −59.6 mV and a partial but significant inhibition of the acetylcholine-induced endothelium-dependent hyperpolarization (−10.9 mV). Apamin did not modify the effects of 17-ODYA but in the presence of charybdotoxin or iberiotoxin, 17-ODYA no longer influenced the resting membrane potential or the acetylcholine-induced hyperpolarization. When compared to solvent (ethanol, 1% v/v), epoxyeicosatrienoic acids (EpETrEs) (5,6-, 8,9-, 11,12- and 14,15-EpETrE, 3 μM) did not affect the cell membrane potential and did not relax the guinea-pig isolated internal carotid artery. These results indicate that, in the guinea-pig internal carotid artery, the involvement of metabolites of arachidonic acid through the cytochrome P

Grape juice causes endothelium-dependent relaxation via a redox-sensitive Src- and Akt-dependent activation of eNOS.

PubMed

Anselm, Eric; Chataigneau, Marta; Ndiaye, Mamadou; Chataigneau, Thierry; Schini-Kerth, Valérie B

2007-01-15

An enhanced endothelial formation of nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF), is thought to contribute to the protective effect of moderate consumption of red wine on coronary diseases. The present study has characterized endothelium-dependent relaxations to Concord grape juice (CGJ), a non-alcoholic rich source of grape-derived polyphenols, in the coronary artery. Porcine coronary artery rings were suspended in organ chambers for the measurement of changes in isometric tension in the presence of indomethacin. NO formation was assessed by electron spin resonance spectroscopy, and the phosphorylation of Src, Akt and endothelial NO synthase (eNOS) by Western blot analysis in cultured endothelial cells. Endothelium-dependent relaxations to CGJ were slightly but significantly reduced by L-NA, not affected by charybdotoxin (CTX) plus apamin (APA, two inhibitors of EDHF-mediated responses) whereas the combination of L-NA, CTX plus APA reduced maximal relaxation to about 50%. In the presence of CTX plus APA, relaxations to CGJ were markedly reduced by the membrane permeant mimetic of superoxide dismutase (SOD), MnTMPyP, the membrane permeant analogue of catalase polyethyleneglycol-catalase (PEG-catalase), PP2, an inhibitor of Src kinase, and by wortmannin, an inhibitor of the PI3-kinase. CGJ stimulated the formation of reactive oxygen species and the N(omega)-nitro-L-arginine-, PP2- and wortmannin-sensitive formation of NO in endothelial cells. The formation of NO was associated with a redox-sensitive and time-dependent phosphorylation of Src, Akt and eNOS. CGJ induces endothelium-dependent relaxations of coronary arteries, which involve a NO-mediated component and also, to a minor extent, an EDHF-mediated component. In addition, CGJ-induced NO formation is due to the redox-sensitive activation of Src kinase with the subsequent PI3-kinase/Akt-dependent phosphorylation of eNOS.

Alpha 2-adrenoceptors and endothelium-dependent relaxation in canine large arteries.

PubMed Central

Angus, J. A.; Cocks, T. M.; Satoh, K.

1986-01-01

Ring preparations from the carotid, coronary, renal, mesenteric and femoral arteries of the dog were precontracted with the thromboxane mimetic U46619, after ensuring that the resting conditions were comparable from the Laplace relationship. In the presence of prazosin (1 microM) and propranolol (3 microM), noradrenaline (NA) relaxed the arteries in the order coronary greater than carotid greater than femoral greater than renal = mesenteric. When maximum relaxation to nitroglycerin (10 microM) was taken to be 100% the maximum relaxation to noradrenaline in each artery was: coronary 70%; carotid 34%; femoral 19%; renal 7% and mesenteric 2%. In endothelium-intact arteries UK14304 mimicked the relaxation responses to NA and idazoxan shifted the curves to both agonists to the right, consistent with an alpha 2-adrenoceptor classification. Substance P relaxed the arteries in the same order as for NA but showed higher efficacy i.e.: coronary 100%; carotid 80%; femoral 71% renal 49%; and mesenteric 41%. Removal of the endothelium abolished the relaxation to NA. We conclude that endothelium-dependent relaxation to NA and substance P varies greatly across 5 large arteries of the dog. This may indicate that endothelium-derived relaxing factor (EDRF) release is site-dependent or that the efficacy of EDRF on smooth muscle varies; being greatest in the coronary and weakest in the renal and mesenteric arteries. PMID:2427147

Great heterogeneity of commercial fruit juices to induce endothelium-dependent relaxations in isolated porcine coronary arteries: role of the phenolic content and composition.

PubMed

Auger, Cyril; Pollet, Brigitte; Arnold, Cécile; Marx, Céline; Schini-Kerth, Valérie B

2015-01-01

Since polyphenol-rich products such as red wine, grape juice, and grape extracts have been shown to induce potent endothelium-dependent relaxations, we have evaluated whether commercial fruit juices such as those from berries are also able to induce endothelium-dependent relaxations of isolated coronary arteries and, if so, to determine whether this effect is related to their phenolic content. Among the 51 fruit juices tested, 2/12 grape juices, 3/7 blackcurrant juices, 4/5 cranberry juices, 1/6 apple juices, 0/5 orange juices, 2/6 red fruit and berry juices, 3/6 blends of red fruit juices, and 0/4 non-red fruit juices were able to induce relaxations achieving more than 50% at a volume of 1%. The active fruit juices had phenolic contents ranging from 0.31 to 1.86 g GAE/L, which were similar to those of most of the less active juices with the exception of one active grape juice (2.14 g GAE/L) and one active blend of red fruit juices (3.48 g GAE/L). Altogether, these findings indicate that very few commercial fruit juices have the ability to induce potent endothelium-dependent relaxations, and that this effect is not related to their quantitative phenolic content, but rather to their qualitative phenolic composition.

Cannabinoid CB1 receptor and endothelium-dependent hyperpolarization in guinea-pig carotid, rat mesenteric and porcine coronary arteries

PubMed Central

Chataigneau, T; Félétou, M; Thollon, C; Villeneuve, N; Vilaine, J- P; Duhault, J; Vanhoutte, P M

1998-01-01

charybdotoxin plus apamin (17.3±2.3 mV, n=4).In the guinea-pig carotid artery, acetylcholine (1 μM) evoked endothelium-dependent hyperpolarization (18.8±0.7 mV, n=15). SR 141716 (10 nM to 10 μM), caused a direct, concentration-dependent hyperpolarization (up to 10 mV at 10 μM) and a significant inhibition of the acetylcholine-induced hyperpolarization. Anandamide (0.1 to 3 μM) did not influence the membrane potential. At a concentration of 30 μM, the cannabinoid agonist induced a non-reproducible hyperpolarization (5.6±1.3 mV, n=10) with a slow onset. SR 141716 (1 μM) did not affect the hyperpolarization induced by 30 μM anandamide (5.3±1.5 mV, n=3).In the porcine coronary artery, anandamide up to 30 μM did not hyperpolarize or relax the smooth muscle cells. The endothelium-dependent hyperpolarization and relaxation induced by bradykinin were not influenced by SR 141716 (1 μM).These results indicate that the endothelium-dependent hyperpolarizations, observed in the guinea-pig carotid, rat mesenteric and porcine coronary arteries, are not related to the activation of cannabinoid CB1 receptors. PMID:9535027

Electrophysiological and mechanical effects of substance P and acetylcholine on rabbit aorta.

PubMed Central

Bény, J L; Brunet, P C

1988-01-01

1. The mechanical and electrical properties of smooth muscle cells of the rabbit aorta were recorded simultaneously using respectively a force transducer and a 3 M-KCl-filled glass microelectrode. 2. Acetylcholine had two effects depending on concentration. At low concentration, it caused a persistent endothelium-dependent relaxation and hyperpolarization. At higher concentrations the acetylcholine endothelium-dependent relaxation summed with an endothelium-independent contraction. 3. Substance P caused a transient endothelium-dependent relaxation and hyperpolarization. 4. Acetylcholine and substance P depolarized and contracted de-endothelialized smooth muscle. When the de-endothelialized strip was pre-contracted by noradrenaline, acetylcholine depolarized the muscle but substance P did not. 5. In a 'cascade' experiment, the perfusate from an upstream intact aorta passed over a downstream de-endothelialized strip. Acetylcholine and substance P relaxed the downstream strip showing that they released an endothelial humoral factor which relaxes smooth muscle. 6. The results suggest a constant release of a factor from the endothelial cells which hyperpolarizes the smooth muscle cells in the media. Activation of acetylcholine and substance P receptors on the endothelium accelerates the release of this factor and causes vasodilatation. PMID:2455799

Acute resistance exercise reduces blood pressure and vascular reactivity, and increases endothelium-dependent relaxation in spontaneously hypertensive rats.

PubMed

Faria, Thaís de Oliveira; Targueta, Gabriel Pelegrineti; Angeli, Jhuli Keli; Almeida, Edna Aparecida Silveira; Stefanon, Ivanita; Vassallo, Dalton Valentim; Lizardo, Juliana Hott de Fúcio

2010-09-01

The aim of the present study was to assess the effects of acute dynamic resistance exercise on resting blood pressure (BP) and on endothelial function of vascular bed of spontaneously hypertensive rats. Hemodynamic measurements were performed before and after acute dynamic resistance exercise in conscious animals. After exercise, the tail artery was cannulated for mean perfusion pressure with constant flow measurement and for performing concentration-response curves to acetylcholine (ACh) and sodium nitroprusside (SNP) and dose-response curves to phenylephrine (PHE). PHE protocol was also repeated with damaged endothelium and after L-NAME and indomethacin perfusion on the tail. The maximal response (E(max)) and sensitivity (pD(2)) were evaluated to these drugs. Exercise reduced resting systolic and diastolic BP (Delta -79 +/- 1.8; -23 +/- 2.3 mmHg, respectively; P < 0.05). ACh-induced relaxation increased in the exercise group (pD(2) = 9.8 +/- 0.06, P < 0.05) when compared with control rats (pD(2) = 8.7 +/- 0.1). The E(max) to PHE with intact endothelium decreased following exercise condition (439 +/- 18 mmHg, P < 0.05) when compared with control rats (276 +/- 22 mmHg). This response was abolished after L-NAME and indomethacin administration. After damage of the endothelium, PHE responses were not significantly different between the groups; however, E(max) and pD(2) increased when compared with responses obtained with intact endothelium. The results demonstrated that acute dynamic resistance exercise decreased resting BP and reactivity to PHE and increased endothelium-dependent relaxation. Nitric oxide and vasodilators prostanoids appear to be involved in post-exercise endothelial and pressor responses.

Effect of fatty acids on endothelium-dependent relaxation in the rabbit aorta.

PubMed

Edirisinghe, Indika; McCormick Hallam, Kellie; Kappagoda, C Tissa

2006-08-01

The metabolic syndrome, Type II (non-insulin-dependent) diabetes and obesity are associated with endothelial dysfunction and increased plasma concentrations of NEFAs (non-esterified fatty acids; free fatty acids). The present study was undertaken to define the inhibitory effects of saturated NEFAs on EDR (endothelium-dependent relaxation). Experiments were performed in rings of rabbit aorta to establish (i) dose-response relationships, (ii) the effect of chain length, (iii) the effect of the presence of double bonds, (iv) reversibility and time course of inhibition, and (v) the effect on nitric oxide production. Aortic rings were incubated (1 h) with NEFA-albumin complexes derived from lauric (C(12:0)), myristic (C(14:0)), palmitic (C(16:0)), stearic (C(18:0)) and linolenic (C(18:3)) acids. EDR induced by acetylcholine (0.1-10 mumol/l) was measured after pre-contraction with noradrenaline. Inhibition of EDR was dose-dependent (0.5-2 mmol/l NEFA), and the greatest inhibition (51%) was observed with stearic acid (2 mmol/l). Lauric acid had the smallest inhibitory effect. The inhibitory effects were always reversible and were evident after 15 min of incubation. Linolenic acid caused a significantly lower inhibition of EDR than stearic acid. SOD (superoxide dismutase) restored the inhibitory effect caused by NEFAs, suggesting the involvement of ROS (reactive oxygen species) in removing nitric oxide. The nitric oxide concentration measured after exposure of the rings to acetylcholine was lower after incubation with NEFAs than with Krebs buffer alone. This finding is consistent with removal of nitric oxide by ROS. This claim was supported by the demonstration of increased concentrations of nitrated tyrosine in the rings incubated with NEFAs.

Dietary soy modulates endothelium-dependent relaxation in aged male rats: Increased agonist-induced endothelium-derived hyperpolarising factor and basal nitric oxide activity

PubMed Central

Knock, Greg A.; Mahn, Katharina; Mann, Giovanni E.; Ward, Jeremy P.T.; Aaronson, Philip I.

2018-01-01

We examined the effects of dietary soy on the contributions of endothelium-derived hyperpolarising factor (EDHF), nitric oxide (NO), and oxidative stress to vascular tone in isolated aortic rings and small mesenteric and pulmonary arteries in vitro. Male Wistar rats were either continuously fed a soy-deficient diet (SD) or switched from a soy-deficient diet to a soy-rich one for 6 months (SW). Contractile responses were generally smaller in arteries from SW rats. In mesenteric arteries, this difference was blunted by L-NAME, but not by charybdotoxin and apamin. Preconstricted SW mesenteric arteries were more sensitive to acetylcholine (ACh) than SD ones. This difference was unaffected by L-NAME but was abolished by charybdotoxin and apamin. Exogenous superoxide dismutase (SOD) and catalase induced powerful relaxations in aortic rings, which were smaller in those from SW rats. In mesenteric and pulmonary arteries, however, they partially inhibited ACh-mediated relaxation, and enhanced PGF2α–mediated contraction, respectively. Our results suggest that feeding aging male rats a soy-rich diet results in improved agonist-mediated EDHF production and a generalized reduction in contractile force, which is partly due to elevated basal NO. Our data also suggest a prorelaxant role for endogenous H2O2 in small arteries, which is modulated by a soy diet. PMID:16895793

Lipid Emulsions Containing Medium Chain Triacylglycerols Blunt Bradykinin-Induced Endothelium-Dependent Relaxation in Porcine Coronary Artery Rings.

PubMed

Amissi, Said; Boisramé-Helms, Julie; Burban, Mélanie; Rashid, Sherzad K; León-González, Antonio J; Auger, Cyril; Toti, Florence; Meziani, Ferhat; Schini-Kerth, Valérie B

2017-03-01

Lipid emulsions for parenteral nutrition are used to provide calories and essential fatty acids for patients. They have been associated with hypertriglyceridemia, hypercholesterolemia, and metabolic stress, which may promote the development of endothelial dysfunction in patients. The aim of the present study was to determine whether five different industrial lipid emulsions may affect the endothelial function of coronary arteries. Porcine coronary artery rings were incubated with lipid emulsions 0.5, 1, or 2% (v/v) for 30 min before the determination of vascular reactivity in organ chambers and the level of oxidative stress using electron paramagnetic resonance. Incubation of coronary artery rings with either Lipidem ® , Medialipid ® containing long- and medium-chain triacylglycerols (LCT/MCT), or SMOFlipid ® containing LCT, MCT, omega-9, and -3, significantly reduced the bradykinin-induced endothelium-dependent relaxation, affecting both the nitric oxide (NO) and endothelium-dependent hyperpolarization (EDH) components, whereas, Intralipid ® containing LCT (soybean oil) and ClinOleic ® containing LCT (soybean and olive oil) did not have such an effect. The endothelial dysfunction induced by Lipidem ® was significantly improved by indomethacin, a cyclooxygenase (COX) inhibitor, inhibitors of oxidative stress (N-acetylcysteine, superoxide dismutase, catalase) and transition metal chelating agents (neocuproine, tetrathiomolybdate, deferoxamine and L-histidine). Lipidem ® significantly increased the arterial level of oxidative stress. The present findings indicate that lipid emulsions containing LCT/MCT induce endothelial dysfunction in coronary artery rings by blunting both NO- and EDH-mediated relaxations. The Lipidem ® -induced endothelial dysfunction is associated with increased vascular oxidative stress and the formation of COX-derived vasoconstrictor prostanoids.

A-FABP and oxidative stress underlie the impairment of endothelium-dependent relaxations to serotonin and the intima-medial thickening in the porcine coronary artery with regenerated endothelium.

PubMed

Chan, Calvin K; Zhao, Yingzi; Liao, Song Yan; Zhang, Yue Lin; Lee, Mary Y K; Xu, Aimin; Tse, Hung Fat; Vanhoutte, Paul M

2013-01-16

Experiments were designed to determine the cause of the selective dysfunction of G(i) proteins, characterized by a reduced endothelium-dependent relaxation to serotonin (5-hydroxytryptamine), in coronary arteries lined with regenerated endothelial cells. Part of the endothelium of the left anterior descending coronary artery of female pigs was removed in vivo to induce regeneration. The animals were treated chronically with vehicle (control), apocynin (antioxidant), or BMS309403 (A-FABP inhibitor) for 28 days before functional examination and histological analysis of segments of coronary arteries with native or regenerated endothelium of the same hearts. Isometric tension was recorded in organ chambers and cumulative concentration-relaxation curves obtained in response to endothelium-dependent [serotonin (G(i) protein mediated activation of eNOS) and bradykinin (G(q) protein mediated activation of eNOS)] and independent [detaNONOate (cGMP-mediated), isoproterenol (cAMP-mediated)] vasodilators. The two inhibitors tested did not acutely affect relaxations of preparations with either native or regenerated endothelium. In the chronically treated groups, however, both apocynin and BMS309403 abolished the reduction in relaxation to serotonin in segments covered with regenerated endothelium and prevented the intima-medial thickening caused by endothelial regeneration, without affecting responses to bradykinin or endothelium-independent agonists (detaNONOate and isoproterenol). Thus, inhibition of either oxidative stress or A-FABP likely prevents both the selective dysfunction of G(i) protein mediated relaxation to serotonin and the neointimal thickening resulting from endothelial regeneration.

Developmental changes in endothelium-dependent pulmonary vasodilatation in pigs.

PubMed Central

Liu, S. F.; Hislop, A. A.; Haworth, S. G.; Barnes, P. J.

1992-01-01

1. We compared in vitro endothelium-dependent vasorelaxant responses to acetylcholine (ACh) and the endothelium-independent vasodilator response to sodium nitroprusside (SNP) in prostaglandin F2 alpha (PGF2 alpha)-precontracted muscular pulmonary arteries (PA) from pigs aged 5 min to 2 h (neonatal), 3-10 days, 3-8 weeks and adults. 2. In the pulmonary artery (PA) rings from neonatal animals, the vasodilator response to ACh was negligible. However, responses to ACh were present in all PA rings from older animals, being greatest at 3-10 days and then decreasing with age (P less than 0.001, ANOVA). ACh (30 microM) induced a 1 +/- 1%, 92 +/- 9%, 62 +/- 5% and 51 +/- 6% reduction of the PGF2 alpha-generated tension in neonatal, 3-10 days, 3-8 weeks and adult groups, respectively. 3. The relaxant response to SNP was present in the PA rings from all age groups and increased with age (P less than 0.001, ANOVA). SNP (1 microM)-induced relaxation was 55 +/- 9%, 73 +/- 7%, 97 +/- 5% and 93 +/- 6% in neonatal, 3-10 days, 3-8 week and adult groups, respectively. 4. Removal of the vascular endothelium abolished the relaxant response to ACh but had no effect on the response to SNP in any groups. 5. NG-monomethyl-L-arginine (30 microM), a nitric oxide synthesis inhibitor, inhibited the response to ACh but not to SNP. The lipoxygenase inhibitor, nordihydroguaiaretic acid, had no significant effect on responses to ACh or SNP in any group.(ABSTRACT TRUNCATED AT 250 WORDS) Images Figure 1 PMID:1393265

Regional heterogeneity of substance P-induced endothelium-dependent contraction, relaxation, and -independent contraction in rabbit pulmonary arteries.

PubMed

Miike, Tomohiro; Shirahase, Hiroaki; Kanda, Mamoru; Kunishiro, Kazuyoshi; Kurahashi, Kazuyoshi

2008-12-05

The present study examined whether substance P (SP)-induced endothelium-dependent TXA(2)-mediated contraction (EDC), nitric oxide (NO)-mediated relaxation (EDR), and endothelium-independent contraction (EIC) are different between the rabbit proximal and distal intrapulmonary arteries. The helically cut strips of isolated proximal and distal arteries were fixed vertically between hooks in organ bath, and changes in isometric tension were measured. SP-induced EDC was greater in the distal than proximal arteries, and EDR was greater in the proximal than distal arteries. However, under the complete blockade of NK(2) receptors and NO production, SP (10(-9)-3x10(-7) M)-induced EDC did not differ between proximal and distal arteries. Under the complete blockade of NK(2) receptors and TXA(2) production, SP (3x10(-10)-3x10(-8) M)-induced EDR was greater in the proximal than distal arteries. Neither contraction induced by U-46619, a TXA(2) agonist, nor relaxation by sodium nitroprusside, an NO donor, was different between both portions of the arteries. Both ionomycin (10(-8) M)- and l-arginine (1 mM)-induced EDRs were also significantly greater in the proximal than distal arteries. Under the blockade of NK(1) receptors and NO and TXA(2) production, SP (10(-7) M)-induced EIC was greater in the distal than proximal arteries. In summary, the capacity for NO production is higher in the proximal than distal arteries, resulting in SP-induced higher EDR and lower EDC in the proximal arteries. These regional differences in responses to SP may play important roles in maintaining the homogenous distribution of blood flow in the lung.

Pravastatin and endothelium dependent vasomotion after coronary angioplasty: the PREFACE trial

PubMed Central

Mulder, H; Schalij, M; Kauer, B; Visser, R; van Dijkman, P R M; Jukema, J; Zwinderman, A; Bruschke, A

2001-01-01

OBJECTIVE—To test the hypothesis that the 3-hydroxy-3-methylglutaryl coenzyme-A reductase inhibitor pravastatin ameliorates endothelium mediated responses of dilated coronary segments: the PREFACE (pravastatin related effects following angioplasty on coronary endothelium) trial.
DESIGN—A double blind, randomised, placebo controlled, multicentre study.
SETTING—Four hospitals in the Netherlands.
PATIENTS—63 non-smoking, non-hypercholesterolaemic patients scheduled for elective balloon angioplasty (pravastatin 34, placebo 29).
INTERVENTIONS—The effects of three months of pravastatin treatment (40 mg daily) on endothelium dependent vasomotor function were studied. Balloon angioplasty was undertaken one month after randomisation, and coronary vasomotor function tests using acetylcholine were performed two months after balloon angioplasty. The angiograms were analysed quantitatively.
MAIN OUTCOME MEASURES—The efficacy measure was the acetylcholine induced change in mean arterial diameter, determined in the dilated segment and in an angiographically normal segment of an adjacent non-manipulated coronary artery.
RESULTS—Increasing acetylcholine doses produced vasoconstriction in the dilated segments (p = 0.004) but not in the normal segments. Pravastatin did not affect the vascular response to acetylcholine in either the dilated segments (p = 0.09) or the non-dilated sites. Endothelium dependent vasomotion in normal segments was correlated with that in dilated segments (r = 0.47, p < 0.001). There were fewer procedure related events in the pravastatin group than in the placebo group (p < 0.05).
CONCLUSIONS—Endothelium dependent vasomotion in normal segments is correlated with that in dilated segments. A significant beneficial effect of pravastatin on endothelial function could not be shown, but in the dilated segments there was a trend towards a beneficial treatment effect in the pravastatin group.


Keywords: angioplasty

Vildagliptin Improves Endothelium-Dependent Vasodilatation in Type 2 Diabetes

PubMed Central

van Poppel, Pleun C.M.; Netea, Mihai G.; Smits, Paul; Tack, Cees J.

2011-01-01

OBJECTIVE To investigate whether the dipeptidyl peptidase-4 inhibitor vildagliptin improves endothelium-dependent vasodilatation in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS Sixteen subjects with type 2 diabetes (age 59.8 ± 6.8 years, BMI 29.1 ± 4.8 kg/m2, HbA1c 6.97 ± 0.61) on oral blood glucose–lowering treatment were included. Participants received vildagliptin 50 mg b.i.d. or acarbose 100 mg t.i.d. for four consecutive weeks in a randomized, double-blind, cross-over design. At the end of each treatment period, we measured forearm vasodilator responses to intra-arterially administered acetylcholine (endothelium-dependent vasodilator) and sodium nitroprusside (endothelium-independent vasodilator). RESULTS Infusion of acetylcholine induced a dose-dependent increase in forearm blood flow in the experimental arm, which was higher during vildagliptin (3.1 ± 0.7, 7.9 ± 1.1, and 12.6 ± 1.4 mL ⋅ dL−1 ⋅ min−1 in response to three increasing dosages of acetylcholine) than during acarbose (2.0 ± 0.7, 5.0 ± 1.2, and 11.7 ± 1.6 mL ⋅ dL−1 ⋅ min−1, respectively; P = 0.01 by two-way ANOVA). Treatment with vildagliptin did not significantly change the vascular responses to sodium nitroprusside. CONCLUSIONS Four weeks’ treatment with vildagliptin improves endothelium-dependent vasodilatation in subjects with type 2 diabetes. This observation might have favorable cardiovascular implications. PMID:21788633

Thimerosal blocks stimulated but not basal release of endothelium-derived relaxing factor (EDRF) in dog isolated coronary artery.

PubMed Central

Crack, P.; Cocks, T.

1992-01-01

1. The effect of an acetly-coA lysolecithin acyltransferase inhibitor, thimerosal, on the release of endothelium-derived relaxing factor (EDRF) was examined in the greyhound isolated coronary artery. 2. Thimerosal (1-10 microM) relaxed fully, ring segments of coronary artery which were contracted with the thromboxane A2-mimetic, U46619 (30 nM). The response was endothelium-dependent, slow in both onset and time to reach maximum. The maximum relaxation to the highest concentration of thimerosal (10 microM) was maintained for 10-20 min before the tissue slowly regained active force (1-2 h) to the same or higher level as that prior to the addition of thimerosal. At this time the endothelium-dependent relaxation responses to acetylcholine (ACh), substance P (SP), bradykinin (BK) and the calcium ionophores, ionomycin and A23187 were abolished. The endothelium-dependent contractions to the nitric oxide synthase inhibitors, NG-nitro-L-arginine (L-NNA; 10-100 microM) and NG-monomethyl-L-arginine (L-NMMA: 10-100 microM), however, were unaffected. 3. Thimerosal (10 microM) did not affect the relaxation curve to sodium nitroprusside (SNP) nor the contraction curve to the thromboxane A2-mimetic, U46619. 4. Both the relaxation response to thimerosal and the selective block of the relaxation responses to stimulated EDRF release were unaffected by either indomethacin (10 microM) or superoxide dismutase (150 u ml-1). 5. L-NNA (100 microM) significantly blocked the relaxation curves to thimerosal and A23187 but not that to SNP.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1384915

Acetylcholine protects mesenteric arteries against hypoxia/reoxygenation injury via inhibiting calcium-sensing receptor.

PubMed

Zhao, Ming; He, Xi; Yang, Yong-Hua; Yu, Xiao-Jiang; Bi, Xue-Yuan; Yang, Yang; Xu, Man; Lu, Xing-Zhu; Sun, Qiang; Zang, Wei-Jin

2015-04-01

The Ca(2+)-sensing receptor (CaSR) plays an important role in regulating vascular tone. In the present study, we investigated the positive effects of the vagal neurotransmitter acetylcholine by suppressing CaSR activation in mesenteric arteries exposed to hypoxia/reoxygenation (H/R). The artery rings were exposed to a modified 'ischemia mimetic' solution and an anaerobic environment to simulate an H/R model. Our results showed that acetylcholine (10(-6) mol/L) significantly reduced the contractions induced by KCl and phenylephrine and enhanced the endothelium-dependent relaxation induced by acetylcholine. Additionally, acetylcholine reduced CaSR mRNA expression and activity when the rings were subjected to 4 h of hypoxia and 12 h of reoxygenation. Notably, the CaSR antagonist NPS2143 significantly reduced the contractions but did not improve the endothelium-dependent relaxation. When a contractile response was achieved with extracellular Ca(2+), both acetylcholine and NPS2143 reversed the H/R-induced abnormal vascular vasoconstriction, and acetylcholine reversed the calcimimetic R568-induced abnormal vascular vasoconstriction in the artery rings. In conclusion, this study suggests that acetylcholine ameliorates the dysfunctional vasoconstriction of the arteries after H/R, most likely by decreasing CaSR expression and activity, thereby inhibiting the increase in intracellular calcium concentration. Our findings may be indicative of a novel mechanism underlying ACh-induced vascular protection. Copyright © 2015 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

Endothelium-independent relaxant effect of Rubus coreanus extracts in corpus cavernosum smooth muscle.

PubMed

Lee, Jun Ho; Chae, Mee Ree; Sung, Hyun Hwan; Ko, Mikyeong; Kang, Su Jeong; Lee, Sung Won

2013-07-01

Rubus coreanus is a perennial shrub native to the southern part of the Korean peninsula. Although it is known that R. coreanus has a dose-dependent relaxation effect on rabbit corpus cavernosum (CC), the exact mechanism of action by which R. coreanus work is not fully known. To elucidate the direct effects of unripe R. coreanus extract (RCE) on CC smooth muscle cells. Dried unripe R. coreanus fruits were pulverized and extracted with 95% ethanol. Isolated rabbit CC strips were mounted in an organ-bath system, and the effects of RCE were evaluated. To estimate [Ca(2+)]i , we used a Fura-2 fluorescent technique. The effects of unripe RCE on ion channels and the intracellular Ca(2+) concentration ([Ca(2+)]i ) of CC. RCE effectively relaxed phenylephrine (PE)-induced tone in rabbit CC, and removal of the endothelium did not completely abolish the relaxation effect of RCE. Tetraethylammonium (1 mM) did not inhibit RCE-induced relaxation in strips precontracted by PE in the organ bath. However, CaCl2 -induced constriction of CC strips, bathed in Ca(2+)-free buffer and primed with PE, was abolished by RCE. In addition, RCE decreased basal [Ca(2+)]i in corporal smooth muscle cells. The increases of [Ca(2+)]i evoked by 60 mM K(+)-containing solution in A7r5 cells were suppressed by RCE, and RCE relaxed KCl-induced tone in endothelium-free CC, which indicated that RCE blocked the voltage-dependent Ca(2+) channels (VDCCs). RCE decreased basal [Ca(2+)]i and the [Arg8]-vasopressin-induced [Ca(2+)]i increases in A7r5 cells, and RCE inhibited the contraction of endothelium-free CC induced by PE in Ca(2+)-free solution, which suggested that RCE might act as a modulator of corporal smooth muscle cell tone by inhibiting Ca(2+) release from sarcoplasmic reticulum. RCE acts through endothelium-independent and endothelium-dependent pathways to relax CC. RCE may inhibit VDCCs and Ca(2+) release from sarcoplasmic reticulum. © 2013 International Society for Sexual Medicine.

Pravastatin and endothelium dependent vasomotion after coronary angioplasty: the PREFACE trial.

PubMed

Mulder, H J; Schalij, M J; Kauer, B; Visser, R F; van Dijkman, P R; Jukema, J W; Zwinderman, A H; Bruschke, A V

2001-11-01

To test the hypothesis that the 3-hydroxy-3-methylglutaryl coenzyme-A reductase inhibitor pravastatin ameliorates endothelium mediated responses of dilated coronary segments: the PREFACE (pravastatin related effects following angioplasty on coronary endothelium) trial. A double blind, randomised, placebo controlled, multicentre study. Four hospitals in the Netherlands. 63 non-smoking, non-hypercholesterolaemic patients scheduled for elective balloon angioplasty (pravastatin 34, placebo 29). The effects of three months of pravastatin treatment (40 mg daily) on endothelium dependent vasomotor function were studied. Balloon angioplasty was undertaken one month after randomisation, and coronary vasomotor function tests using acetylcholine were performed two months after balloon angioplasty. The angiograms were analysed quantitatively. The efficacy measure was the acetylcholine induced change in mean arterial diameter, determined in the dilated segment and in an angiographically normal segment of an adjacent non-manipulated coronary artery. Increasing acetylcholine doses produced vasoconstriction in the dilated segments (p = 0.004) but not in the normal segments. Pravastatin did not affect the vascular response to acetylcholine in either the dilated segments (p = 0.09) or the non-dilated sites. Endothelium dependent vasomotion in normal segments was correlated with that in dilated segments (r = 0.47, p < 0.001). There were fewer procedure related events in the pravastatin group than in the placebo group (p < 0.05). Endothelium dependent vasomotion in normal segments is correlated with that in dilated segments. A significant beneficial effect of pravastatin on endothelial function could not be shown, but in the dilated segments there was a trend towards a beneficial treatment effect in the pravastatin group.

Effects of Chronic Nitric Oxide Synthase Inhibition on Endothelium-Dependent and -Independent Relaxation in Arteries that Perfuse Skeletal Muscle of Swine

PubMed Central

Newcomer, S.C.; Taylor, J.C.; McAllister, R.M.; Laughlin, M.H.

2012-01-01

The purpose of this investigation was to test the hypothesis that chronic L-NAME treatment produces differential effects on conduit artery and resistance arteriole relaxation responses to endothelium-dependent and –independent vasodilators in arteries that perfuse skeletal muscle of swine. To test this hypothesis conduit skeletal muscle arteries and second order skeletal muscle arterioles were harvested from 14 Yucatan swine that were chronically administered L-NAME and 16 controls. In vitro assessments of vasorelaxation to increasing doses of acetylcholine (ACH), bradykinin (BK), and sodium nitroprusside (SNP) were performed in both conduit and 2A arterioles. L-NAME treatment produced a significant reduction in both BK and ACH relaxation responses in the conduit arteries. In contrast, the relaxation response and/or sensitivity to SNP were significantly greater in the intact, but not denuded, conduit arterial rings from chronically L-NAME treated swine. There were no significant effects of chronic L-NAME treatment on vasodilation of skeletal muscle arterioles. These findings suggest: (1) that unlike arterioles, skeletal muscle conduit arteries do not functionally compensate for a lack of NO through the upregulation of alternative vasodilator pathways. (2) that the greater relaxation response in conduit arteries of chronically L-NAME treated swine to SNP can be explained by alterations to the endothelium. PMID:18568942

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.

Long-lasting endothelium-dependent relaxation of isolated arteries caused by an extract from the bark of Combretum leprosum

PubMed Central

Alves, Francisco das Chagas; Cavalcanti, Paulo Marques da Silva; Passaglia, Rita de Cassia Aleixo Tostes; Ballejo, Gustavo

2015-01-01

Objective To describe and to characterize the relaxing effect of an extract of the bark of Combretum leprosum on isolated arterial rings from different animals. Methods Rings (3 to 4mm) from rabbit, rat, or porcine arteries rings were suspended in an organ bath (Krebs, 37°C, 95%O2/5%CO2) to record isometric contractions. After the stabilization period (2 to 3 hours) contractions were induced by the addition of phenylephrine (0.1 to 0.3µM) or U46619 (10 to 100nM), and Combretum leprosum extract was added on the plateau of the contractions. Experiments were performed to determine the potency, duration, reversibility, and to get insights on the potential mechanism involved in extract-induced relaxations. Results In all rings tested, Combretumleprosum extract (1.5μg/mL) was able to cause relaxations, which were strictly endothelium-dependent. In rabbit or rat thoracic aorta rings, the relaxations were reversed by vitamin B12a or L-NG-nitroarginine. In porcine right coronary arteries and rabbit abdominal aorta, extract caused both L-NG-nitroarginine-sensitive and L-NG-nitroarginine-resistant relaxations. In rabbit thoracic aorta, the extract was relatively potent (EC50=0.20µg/mL) and caused relaxations; intriguingly the endothelium continued to produce relaxing factors for a long period after removing the extract. The magnitude of extract-induced relaxations was significantly reduced in the absence of extracellular Ca2+; in addition, the TRPs channels blocker ruthenium red (10µM) was able to revert extract-induced relaxations. Phytochemical analyses indicated that the extract was rich in polyphenol-like reacting substances. Conclusions Combretum leprosum extract contains bioactive compounds capable of promoting Ca2+-dependent stimulation of endothelial cells which results in a prolonged production of relaxing factors. PMID:26466063

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.

Endothelium-Dependent and -Independent Vasodilator Effects of Dimethyl Sulfoxide in Rat Aorta.

PubMed

Kaneda, Takeharu; Sasaki, Noriyasu; Urakawa, Norimoto; Shimizu, Kazumasa

2016-01-01

This study examined the mechanism of vasorelaxation induced by dimethyl sulfoxide (DMSO) in endothelium-intact and -denuded rat aorta. DMSO (0.1-3%) inhibited phenylephrine (PE, 1 μmol/l)-induced contraction in a dose-dependent manner. However, this relaxation was lower in the absence of the endothelium. Increase in DMSO-induced relaxation in the presence of the endothelium was attenuated by preincubation in L-NG-nitroarginine methyl ester (L-NAME, 100 μmol/l) and by the removal of the endothelium. In the aorta with endothelium, DMSO (3%) and CCh (3 μmol/l) increased cGMP contents, significantly and L-NAME (100 μmol/l) inhibited the DMSO-induced increases of cGMP. In fura 2-loaded endothelium-denuded aorta, cumulative application of DMSO (1-3%) inhibited PE-induced muscle tension; however, this application did not affect the [Ca2+]i level. In PE-precontracted endothelium-denuded aorta, relaxation responses to fasudil were significantly less in the presence of DMSO compared to the control. These results suggest that DMSO causes relaxation by increasing the cGMP content in correlation with the release of NO from endothelial cells and by decreasing the Ca2+ sensitivity of contractile elements partly via inhibiting Rho-kinase in rat aorta. © 2016 S. Karger AG, Basel.

Endothelium-dependent and independent vasorelaxant effects of aqueous extract of Tridax procumbens Lin. leaf in rat aortic rings.

PubMed

Salahdeen, Hussein M; Idowu, Gbolahan O; Murtala, Babatunde A

2012-12-01

Tridax procumbens leaf extract induced aortic relaxation in a concentration-dependent manner, for both phenylephrine (PE) and KCl- induced contractions in isolated rat aortic rings. The relaxation effect of the extract on PE-induced contraction was 57% greater than that on KCl- induced contraction. The extract caused dose-dependent relaxations in precontracted isolated rat aorta with phenylephrine; the relaxation was attenuated by the removal of endothelium. However, the relaxation responses to sodium nitroprusside were not significantly abolished by the removal of endothelium. The vasorelaxatory effect of the extract was completely abolished in presence of L-NAME. The results indicate that the vasorelaxant effect of T. procumbens extract is probably mediated by both endothelium-dependent and-independent mechanisms.

Dietary cod-liver oil improves endothelium-dependent responses in hypercholesterolemic and atherosclerotic porcine coronary arteries.

PubMed

Shimokawa, H; Vanhoutte, P M

1988-12-01

This study examined the effects of dietary supplementation with cod-liver oil on impaired endothelium-dependent relaxations in hypercholesterolemia and in atherosclerosis in porcine coronary arteries. Sixteen male Yorkshire pigs underwent balloon endothelium removal of the left coronary arteries and were fed a 2% high-cholesterol diet for 10 weeks, with or without dietary supplementation of cod-liver oil (30 ml/day) (oil-fed and cholesterol-fed groups, respectively). This model allowed the simultaneous examination of the effects of dietary cod-liver oil on vascular reactivity in hypercholesterolemia alone (right coronary artery) and in atherosclerosis (left coronary artery). After 10 weeks of feeding, the dietary treatment with cod-liver oil caused an increase in plasma levels of eicosapentaenoic acid and a decrease in the plasma levels of arachidonic acid, whereas the treatment had no significant effect on the increases in plasma lipid levels induced by the high-cholesterol feeding. Morphometric analysis showed significant inhibition of coronary atherosclerosis by the treatment. Endothelium-dependent responses were examined in vitro in ring preparations and in bioassay experiments. Endothelium-dependent relaxations to bradykinin, serotonin, and adenosine 5'-diphosphate were larger in both right and left coronary arteries from oil-fed than from cholesterol-fed animals. Aggregating platelets from cholesterol-fed and oil-fed pigs induced comparable, larger endothelium-dependent relaxations in rings from oil-fed than from cholesterol-fed pigs. The contractions induced by serotonin or aggregating platelets were significantly inhibited in rings with endothelium from oil-fed pigs, whereas they were comparable in rings without endothelium in both groups. Relaxations to sodium nitroprusside and contractions to potassium chloride or serotonin were comparable in rings without endothelium in both groups. The bioassay experiments revealed that the release of endothelium

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.

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.

Effect of prolonged incubation with copper on endothelium-dependent relaxation in rat isolated aorta

PubMed Central

Chiarugi, Alberto; Pitari, Giovanni Mario; Costa, Rosa; Ferrante, Margherita; Villari, Loredana; Amico-Roxas, Matilde; Godfraind, Théophile; Bianchi, Alfredo; Salomone, Salvatore

2002-01-01

We investigated the effects of prolonged exposure to copper (Cu2+) on vascular functioning of isolated rat aorta. Aortic rings were exposed to CuSO4 (3–24 h) in Dulbecco's modified Eagle medium with or without 10% foetal bovine serum (FBS) and then challenged with vasoconstrictors or vasodilators in the absence of Cu2+. Exposure to 2 μM Cu2+ in the absence of FBS did not modify the response to phenylephrine (PE) or acetylcholine (ACh) in aortic rings incubated for 24 h. Identical exposure in the presence of FBS increased the contractile response to 1 μM PE by 30% (P<0.05) and impaired the relaxant response to 3 μM ACh or 1 μM A23187 (ACh, from 65.7±7.1 to 6.2±1.1%, n=8; A23187, from 74.6±8.2 to 12.0±0.8%, n=6; P<0.01 for both). Cu2+ exposure did not affect the relaxant response to NO-donors. Impairment of vasorelaxation appeared 3 h after incubation with 2 μM Cu2+ and required 12 h to attain a steady state. Vasorelaxation to ACh was partially restored by 1 mM tiron (intracellular scavenger of superoxide ions; maximum relaxation 34.2±6.4%, n=10, P<0.01 vs Cu2+ alone), whereas catalase, superoxide dismutase or cycloheximide were ineffective. Twenty-four hour-exposure to 2 μM Cu2+ did not affect endothelium integrity or eNOS expression, and increased the Cu content in arterial rings from 6.8±1.1 to 18.9±2.9 ng mg−1 wet weight, n=8; P<0.01. Our results show that, in the presence of FBS, prolonged exposure to submicromolar concentrations of Cu2+ impaired endothelium-dependent vasorelaxation in aortic rings, probably through an intracellular generation of superoxide ions. PMID:12163352

Aronia melanocarpa juice, a rich source of polyphenols, induces endothelium-dependent relaxations in porcine coronary arteries via the redox-sensitive activation of endothelial nitric oxide synthase.

PubMed

Kim, Jong Hun; Auger, Cyril; Kurita, Ikuko; Anselm, Eric; Rivoarilala, Lalainasoa Odile; Lee, Hyong Joo; Lee, Ki Won; Schini-Kerth, Valérie B

2013-11-30

This study examined the ability of Aronia melanocarpa (chokeberry) juice, a rich source of polyphenols, to cause NO-mediated endothelium-dependent relaxations of isolated coronary arteries and, if so, to determine the underlying mechanism and the active polyphenols. A. melanocarpa juice caused potent endothelium-dependent relaxations in porcine coronary artery rings. Relaxations to A. melanocarpa juice were minimally affected by inhibition of the formation of vasoactive prostanoids and endothelium-derived hyperpolarizing factor-mediated responses, and markedly reduced by N(ω)-nitro-l-arginine (endothelial NO synthase (eNOS) inhibitor), membrane permeant analogs of superoxide dismutase and catalase, PP2 (Src kinase inhibitor), and wortmannin (PI3-kinase inhibitor). In cultured endothelial cells, A. melanocarpa juice increased the formation of NO as assessed by electron paramagnetic resonance spectroscopy using the spin trap iron(II)diethyldithiocarbamate, and reactive oxygen species using dihydroethidium. These responses were associated with the redox-sensitive phosphorylation of Src, Akt and eNOS. A. melanocarpa juice-derived fractions containing conjugated cyanidins and chlorogenic acids induced the phosphorylation of Akt and eNOS. The present findings indicate that A. melanocarpa juice is a potent stimulator of the endothelial formation of NO in coronary arteries; this effect involves the phosphorylation of eNOS via the redox-sensitive activation of the Src/PI3-kinase/Akt pathway mostly by conjugated cyanidins and chlorogenic acids. Copyright © 2013. Published by Elsevier Inc.

Crataegus special extract WS 1442 causes endothelium-dependent relaxation via a redox-sensitive Src- and Akt-dependent activation of endothelial NO synthase but not via activation of estrogen receptors.

PubMed

Anselm, Eric; Socorro, Vanesca Frota Madeira; Dal-Ros, Stéphanie; Schott, Christa; Bronner, Christian; Schini-Kerth, Valérie B

2009-03-01

This study determined whether the Crataegus (Hawthorn species) special extract WS 1442 stimulates the endothelial formation of nitric oxide (NO), a vasoprotective factor, and characterized the underlying mechanism. Vascular reactivity was assessed in porcine coronary artery rings, reactive oxygen species (ROS) formation in artery sections by microscopy, and phosphorylation of Akt and endothelial NO synthase (eNOS) in endothelial cells by Western blot analysis. WS 1442 caused endothelium-dependent relaxations in coronary artery rings, which were reduced by N-nitro-L-arginine (a competitive inhibitor of NO synthase) and by charybdotoxin plus apamin (two inhibitors of endothelium-derived hyperpolarizing factor-mediated responses). Relaxations to WS 1442 were inhibited by intracellular ROS scavengers and inhibitors of Src and PI3-kinase, but not by an estrogen receptor antagonist. WS 1442 stimulated the endothelial formation of ROS in artery sections, and a redox-sensitive phosphorylation of Akt and eNOS in endothelial cells. WS 1442 induced endothelium-dependent NO-mediated relaxations of coronary artery rings through the redox-sensitive Src/PI3-kinase/Akt-dependent phosphorylation of eNOS.

Poly(ADP-ribose) polymerase-1 protects from oxidative stress induced endothelial dysfunction

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

Gebhard, Catherine; Staehli, Barbara E.; Zurich Center for Integrative Human Physiology

2011-11-04

Highlights: Black-Right-Pointing-Pointer The nuclear enzyme PARP-1 is a downstream effector of oxidative stress. Black-Right-Pointing-Pointer PARP-1 protects from oxidative stress induced endothelial dysfunction. Black-Right-Pointing-Pointer This effect is mediated through inhibition of vasoconstrictor prostanoid production. Black-Right-Pointing-Pointer Thus, PARP-1 may play a protective role as antioxidant defense mechanism. -- Abstract: Background: Generation of reactive oxygen species (ROS) is a key feature of vascular disease. Activation of the nuclear enzyme poly (adenosine diphosphate [ADP]-ribose) polymerase-1 (PARP-1) is a downstream effector of oxidative stress. Methods: PARP-1(-/-) and PARP-1(+/+) mice were injected with paraquat (PQ; 10 mg/kg i.p.) to induce intracellular oxidative stress. Aortic rings weremore » suspended in organ chambers for isometric tension recording to analyze vascular function. Results: PQ treatment markedly impaired endothelium-dependent relaxations to acetylcholine in PARP-1(-/-), but not PARP-1(+/+) mice (p < 0.0001). Maximal relaxation was 45% in PQ treated PARP-1(-/-) mice compared to 79% in PARP-1(+/+) mice. In contrast, endothelium-independent relaxations to sodium nitroprusside (SNP) were not altered. After PQ treatment, L-NAME enhanced contractions to norepinephrine by 2.0-fold in PARP-1(-/-) mice, and those to acetylcholine by 3.3-fold, respectively, as compared to PARP-1(+/+) mice. PEG-superoxide dismutase (SOD) and PEG-catalase prevented the effect of PQ on endothelium-dependent relaxations to acetylcholine in PARP-1(-/-) mice (p < 0.001 vs. PQ treated PARP-1(+/+) mice. Indomethacin restored endothelium-dependent relaxations to acetylcholine in PQ treated PARP-1(-/-) mice (p < 0.05 vs. PQ treated PARP-1(+/+). Conclusion: PARP-1 protects from acute intracellular oxidative stress induced endothelial dysfunction by inhibiting ROS induced production of vasoconstrictor prostanoids.« less

Arginase up-regulation and eNOS uncoupling contribute to impaired endothelium-dependent vasodilation in a rat model of intrauterine growth restriction.

PubMed

Grandvuillemin, Isabelle; Buffat, Christophe; Boubred, Farid; Lamy, Edouard; Fromonot, Julien; Charpiot, Philippe; Simoncini, Stephanie; Sabatier, Florence; Dignat-George, Françoise; Peyter, Anne-Christine; Simeoni, Umberto; Yzydorczyk, Catherine

2018-05-09

Individuals born after intrauterine growth restriction (IUGR) are at increased risk of developing cardiovascular diseases in adulthood, notably hypertension (HTN). Alterations in the vascular system, particularly impaired endothelium-dependent vasodilation, may play an important role in long-term effects of IUGR. Whether such vascular dysfunction precedes HTN has not been fully established in individuals born after IUGR. Moreover, the intimate mechanisms of altered endothelium-dependent vasodilation remain incompletely elucidated. We therefore investigated, using a rat model of IUGR, whether impaired endothelium-dependent relaxation precedes the development of HTN and whether key components of the L-Arginine-nitric oxide (NO) pathway are involved in its pathogenesis. Pregnant rats were fed with a control (CTRL, 23% casein) or low-protein diet (LP, 9% casein) to induce IUGR. Systolic blood pressure (SBP) was measured by tail-cuff plethysmography in 5- and 8-week-old male offspring. Aortic rings were isolated to investigate relaxation to acetylcholine, NO production, eNOS protein content, arginase activity, and superoxide anion production. SBP was not different at 5 weeks, but significantly increased in 8-week-old LP vs. CRTL offspring. In 5-week-old LP vs. CRTL males, endothelium-dependent vasorelaxation was significantly impaired, but restored by pre-incubation with L-Arginine or the arginase inhibitor BEC; NO production was significantly reduced, but restored by L-Arginine pretreatment; total eNOS protein, dimer/monomer ratio, and arginase activity were significantly increased; superoxide anion production was significantly enhanced, but normalized by pretreatment with the NOS inhibitor L-NNA. In this model, IUGR leads to early-impaired endothelium-dependent vasorelaxation, resulting from arginase up-regulation and eNOS uncoupling, which precedes the development of HTN.

K(Ca)3.1 channel downregulation and impaired endothelium-derived hyperpolarization-type relaxation in pulmonary arteries from chronically hypoxic rats.

PubMed

Kroigaard, Christel; Kudryavtseva, Olga; Dalsgaard, Thomas; Wandall-Frostholm, Christine; Olesen, Søren-Peter; Simonsen, Ulf

2013-04-01

Calcium-activated potassium channels of small (K(Ca)2, SK) and intermediate (K(Ca)3.1, IK) conductance are involved in endothelium-dependent relaxation of pulmonary arteries. We hypothesized that the function and expression of K(Ca)2 and K(Ca)3.1 increase as a compensatory mechanism to counteract hypoxia-induced pulmonary hypertension in rats. For functional studies, pulmonary arteries were mounted in microvascular myographs for isometric tension recordings. The K(Ca) channel expression was evaluated by immunoblotting and quantitative PCR. Although ACh induced similar relaxations, the ACh-induced relaxations were abolished by the combined inhibition of nitric oxide synthase (by L-nitro-arginine, L-NOARG), cyclo-oxygenase (by indomethacin) and soluble guanylate cyclase (by ODQ) in pulmonary arteries from hypoxic rats, whereas 20 ± 6% (n = 8) maximal relaxation in response to ACh persisted in arteries from normoxic rats. Inhibiting Na(+),K(+)-ATPase with ouabain or blocking K(Ca)2 and K(Ca)3.1 channels reduced the persisting ACh-induced relaxation. In the presence of L-NOARG and indomethacin, a novel K(Ca)2 and K(Ca)3.1 channel activator, NS4591, induced concentration- and endothelium-dependent relaxations, which were markedly reduced in arteries from chronically hypoxic rats compared with arteries from normoxic rats. The mRNA levels of K(Ca)2.3 and K(Ca)3.1 were unaltered, whereas K(Ca)2.3 protein expression was upregulated and K(Ca)3.1 protein expression downregulated in pulmonary arteries from rats exposed to hypoxia. In conclusion, endothelium-dependent relaxation was conserved in pulmonary arteries from chronically hypoxic rats, while endothelium-derived hyperpolarization (EDH)-type relaxation was impaired in chronically hypoxic pulmonary small arteries despite upregulation of K(Ca)2.3 channels. Since impaired EDH-type relaxation was accompanied by K(Ca)3.1 channel protein downregulation, these findings suggest that K(Ca)3.1 channels are important for the

Effects of 7-ketocholesterol on the activity of endothelial poly(ADP-ribose) polymerase and on endothelium-dependent relaxant function.

PubMed

Kiss, Levente; Chen, Min; Gero, Domokos; Módis, Katalin; Lacza, Zsombor; Szabó, Csaba

2006-12-01

Oxidative and nitrosative stress play an important role in the development of endothelial vascular dysfunction during early atherosclerosis. Oxidative stress activates the nuclear enzyme poly(ADP-ribose) polymerase (PARP) in endothelial cells. In patients with atherosclerosis the level of oxidized LDL in the plasma is elevated. In oxidized LDL various oxysterols have been identified, such as 7-ketocholesterol (7K). 7K has been shown to induce PARP activation in microglial cells. The aim of the current study was to clarify the effects of 7K on the activity of endothelial PARP and on the endothelium-dependent relaxant function of blood vessels. We treated human umbilical vein endothelial (HUVEC) cells with 2-16 microg/ml 7K as well as vascular rings harvested from BALB/c mouse thoracic aorta with 90 microg/ml 7K for 2 h. A group of mice was treated with 7K subcutaneously for 1 week (10 mg/kg/day). We also conducted in vitro and in vivo experiments using pretreatment with buthionine sulphoximine (BSO), a glutathione-lowering agent. The activity of PARP was calculated by measurement of tritiated NAD incorporation. The activity of PARP increased significantly in 7K-treated HUVEC cells. After BSO pretreatment, this increase was higher. Isolated vascular rings demonstrated no change in endothelium-dependent relaxant function after 2 h of incubation with 7K, even after BSO pretreatment. In vivo treatment with 7K for 1 week had no effect on the relaxant function. Our experimental results suggest that although 7-ketocholesterol can activate PARP enzyme in endothelial cells, it is not sufficient on its own to cause impairment in the endothelium-dependent vascular reactivity.

Folic acid consumption reduces resistin level and restores blunted acetylcholine-induced aortic relaxation in obese/diabetic mice.

PubMed

Seto, Sai Wang; Lam, Tsz Yan; Or, Penelope Mei Yu; Lee, Wayne Yuk Wai; Au, Alice Lai Shan; Poon, Christina Chui Wa; Li, Rachel Wai Sum; Chan, Shun Wan; Yeung, John Hok Keung; Leung, George Pak Heng; Lee, Simon Ming Yuen; Ngai, Sai Ming; Kwan, Yiu Wa

2010-09-01

Folic acid supplementation provides beneficial effects on endothelial functions in patients with hyperhomocysteinemia. However, its effects on vascular functions under diabetic conditions are largely unknown. Therefore, the effect(s) of folic acid (5.7 and 71 microg/kg/day for 4 weeks) on aortic relaxation was investigated using obese/diabetic (+db/+db) mice and lean littermate (+db/+m) mice. Acetylcholine-induced relaxation in +db/+db mice was less than that observed in +db/+m mice. The reduced relaxation in +db/+db mice was restored by consumption of 71 microg/kg folic acid. Acetylcholine-induced relaxation (with and without folic acid treatment) was sensitive to N(G)-nitro-L-arginine methyl ester, 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one, geldanamycin and triciribine. In addition, acetylcholine-induced relaxation was attenuated by resistin. The plasma level of resistin in +db/+db mice was sevenfold higher than that measured in +db/+m mice, and the elevated plasma level of resistin in +db/+db mice was reduced by 25% after treatment with 71 microg/kg folic acid. Folic acid slightly increased the ratio of reduced glutathione to oxidized glutathione in +db/+db mice. Moreover, folic acid caused a reduction in PTEN (phosphatase and tensin homolog deleted on chromosome 10) expression, an increase in the phosphorylation of endothelial nitric oxide synthase (eNOS(Ser1177)) and Akt(Ser473), and an enhanced interaction of heat shock protein 90 (HSP90) with eNOS in both strains, with greater magnitude observed in +db/+db mice. In conclusion, folic acid consumption improved blunted acetylcholine-induced relaxation in +db/+db mice. The mechanism may be, at least partly, attributed to enhancement of PI3K/HSP90/eNOS/Akt cascade, reduction in plasma resistin level, down-regulation of PTEN and slight modification of oxidative state. Copyright 2010 Elsevier Inc. All rights reserved.

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.

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.

Calycosin and Formononetin Induce Endothelium-Dependent Vasodilation by the Activation of Large-Conductance Ca2+-Activated K+ Channels (BKCa)

PubMed Central

Tseng, Hisa Hui Ling; Vong, Chi Teng; Leung, George Pak-Heng; Seto, Sai Wang; Lee, Simon Ming-Yuen

2016-01-01

Calycosin and formononetin are two structurally similar isoflavonoids that have been shown to induce vasodilation in aorta and conduit arteries, but study of their actions on endothelial functions is lacking. Here, we demonstrated that both isoflavonoids relaxed rat mesenteric resistance arteries in a concentration-dependent manner, which was reduced by endothelial disruption and nitric oxide synthase (NOS) inhibition, indicating the involvement of both endothelium and vascular smooth muscle. In addition, the endothelium-dependent vasodilation, but not the endothelium-independent vasodilation, was blocked by BKCa inhibitor iberiotoxin (IbTX). Using human umbilical vein endothelial cells (HUVECs) as a model, we showed calycosin and formononetin induced dose-dependent outwardly rectifying K+ currents using whole cell patch clamp. These currents were blocked by tetraethylammonium chloride (TEACl), charybdotoxin (ChTX), or IbTX, but not apamin. We further demonstrated that both isoflavonoids significantly increased nitric oxide (NO) production and upregulated the activities and expressions of endothelial NOS (eNOS) and neuronal NOS (nNOS). These results suggested that calycosin and formononetin act as endothelial BKCa activators for mediating endothelium-dependent vasodilation through enhancing endothelium hyperpolarization and NO production. Since activation of BKCa plays a role in improving behavioral and cognitive disorders, we suggested that these two isoflavonoids could provide beneficial effects to cognitive disorders through vascular regulation. PMID:27994632

N-acetylcysteine potentiates platelet inhibition by endothelium-derived relaxing factor.

PubMed

Stamler, J; Mendelsohn, M E; Amarante, P; Smick, D; Andon, N; Davies, P F; Cooke, J P; Loscalzo, J

1989-09-01

Recent evidence suggests that endothelium-derived relaxing factor exhibits properties of nitric oxide. Like nitric oxide, it inhibits platelet function and mediates its effects by elevating intracellular cyclic GMP. In this study we have investigated the role of reduced thiol in the mechanism of action of endothelium-derived relaxing factor on platelets. Bovine aortic endothelial cells were grown on microcarrier beads and pretreated with aspirin before use. Endothelial cells stimulated with bradykinin or exposed to stirred medium expressed a dose-dependent inhibition of platelet aggregation that was potentiated by the reduced thiol, N-acetylcysteine. Endothelial cell-mediated platelet inhibition was attenuated by methylene blue. Inhibition of platelet aggregation by endothelial cells was associated with a rise in platelet intracellular cyclic GMP, an effect that was enhanced by N-acetylcysteine. These data show that 1) the reduced thiol N-acetylcysteine potentiates platelet inhibition by endothelium-derived relaxing factor and 2) this effect is associated with increasing intracellular platelet cyclic GMP levels.

Calycosin and Formononetin Induce Endothelium-Dependent Vasodilation by the Activation of Large-Conductance Ca2+-Activated K+ Channels (BKCa).

PubMed

Tseng, Hisa Hui Ling; Vong, Chi Teng; Leung, George Pak-Heng; Seto, Sai Wang; Kwan, Yiu Wa; Lee, Simon Ming-Yuen; Hoi, Maggie Pui Man

2016-01-01

Calycosin and formononetin are two structurally similar isoflavonoids that have been shown to induce vasodilation in aorta and conduit arteries, but study of their actions on endothelial functions is lacking. Here, we demonstrated that both isoflavonoids relaxed rat mesenteric resistance arteries in a concentration-dependent manner, which was reduced by endothelial disruption and nitric oxide synthase (NOS) inhibition, indicating the involvement of both endothelium and vascular smooth muscle. In addition, the endothelium-dependent vasodilation, but not the endothelium-independent vasodilation, was blocked by BK Ca inhibitor iberiotoxin (IbTX). Using human umbilical vein endothelial cells (HUVECs) as a model, we showed calycosin and formononetin induced dose-dependent outwardly rectifying K + currents using whole cell patch clamp. These currents were blocked by tetraethylammonium chloride (TEACl), charybdotoxin (ChTX), or IbTX, but not apamin. We further demonstrated that both isoflavonoids significantly increased nitric oxide (NO) production and upregulated the activities and expressions of endothelial NOS (eNOS) and neuronal NOS (nNOS). These results suggested that calycosin and formononetin act as endothelial BK Ca activators for mediating endothelium-dependent vasodilation through enhancing endothelium hyperpolarization and NO production. Since activation of BK Ca plays a role in improving behavioral and cognitive disorders, we suggested that these two isoflavonoids could provide beneficial effects to cognitive disorders through vascular regulation.

The progestin levonorgestrel induces endothelium-independent relaxation of rabbit jugular vein via inhibition of calcium entry and protein kinase C: role of cyclic AMP

PubMed Central

Herkert, Olaf; Kuhl, Herbert; Busse, Rudi; Schini-Kerth, Valérie B

2000-01-01

The progestin and oestrogen component of oral contraceptives have been involved in the development of venous thromboembolic events in women. In the present study we determined the vasoactive effects of sex steroids used in oral contraceptives in isolated preconstricted rabbit jugular veins in the presence of diclofenac and examined the underlying mechanisms.The natural hormone progesterone, the synthetic progestins levonorgestrel, 3-keto-desogestrel, gestodene and chlormadinone acetate, and the synthetic estrogen 17 α-ethinyloestradiol induced concentration-dependent relaxations of endothelium-intact veins constricted with U46619. Levonorgestrel also inhibited constrictions evoked by either a high potassium (K+) solution or phorbol myristate acetate (PMA) in the absence and presence of extracellular calcium (Ca2+). In addition, levonorgestrel depressed contractions evoked by Ca2+ and reduced 45Ca2+ influx in depolarized veins.Relaxations to levonorgestrel in U46619-constricted veins were neither affected by the presence of the endothelium nor by the inhibitor of soluble guanylyl cyclase, NS2028, but were significantly improved either by the selective cyclic AMP phosphodiesterase inhibitor rolipram or in the absence of diclofenac, and decreased by the protein kinase A inhibitor, Rp-8-CPT-cAMPS. Rolipram also potentiated relaxations to levonorgestrel in PMA-constricted veins in the presence, but not in the absence of extracellular Ca2+. Levonorgestrel increased levels of cyclic AMP and inhibited PMA-induced activation of protein kinase C in veins.These findings indicate that levonorgestrel caused endothelium-independent relaxations of jugular veins via inhibition of Ca2+ entry and of protein kinase C activation. In addition, the cyclic AMP effector pathway contributes to the levonorgestrel-induced relaxation possibly by depressing Ca2+ entry. PMID:10952682

Endothelium-dependent relaxation evoked by ATP and UTP in the aorta of P2Y2-deficient mice

PubMed Central

Guns, Pieter-Jan D F; Van Assche, Tim; Fransen, Paul; Robaye, Bernard; Boeynaems, Jean-Marie; Bult, Hidde

2006-01-01

Based on pharmacological criteria, we previously suggested that in the mouse aorta, endothelium-dependent relaxation by nucleotides is mediated by P2Y1 (adenosine diphosphate (ADP)), P2Y2 (adenosine triphosphate (ATP)) and P2Y6 (uridine diphosphate (UDP)) receptors. For UTP, it was unclear whether P2Y2, P2Y6 or yet another subtype was involved. Therefore, in view of the lack of selective purinergic agonists and antagonists, we used P2Y2-deficient mice to clarify the action of UTP. Thoracic aorta segments (width 2 mm) of P2Y2-deficient and wild-type (WT) mice were mounted in organ baths to measure isometric force development and intracellular calcium signalling. Relaxations evoked by ADP, UDP and acetylcholine were identical in knockout and WT mice, indicating that the receptors for these agonists function normally. P2Y2-deficient mice showed impaired ATP- and adenosine 5′[γ-thio] triphosphate (ATPγS)-evoked relaxation, suggesting that in WT mice, ATP and ATPγS activate predominantly the P2Y2 subtype. The ATP/ATPγS-evoked relaxation and calcium signals in the knockout mice were partially rescued by P2Y1, as they were sensitive to 2′-deoxy-N6-methyladenosine 3′,5′-bisphosphate (MRS2179), a P2Y1-selective antagonist. In contrast to ATP, the UTP-evoked relaxation was not different between knockout and WT mice. Moreover, the action of UTP was not sensitive to MRS2179. Therefore, the action of UTP is probably mediated mainly by a P2Y6(like) receptor subtype. In conclusion, we demonstrated that ATP-evoked relaxation of the murine aorta is mainly mediated by P2Y2. But this P2Y2 receptor has apparently no major role in UTP-evoked relaxation. The vasodilator effect of UTP is probably mediated mainly by a P2Y6(like) receptor. PMID:16415908

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

Ethanol extract of seeds of Oenothera odorata induces vasorelaxation via endothelium-dependent NO-cGMP signaling through activation of Akt-eNOS-sGC pathway.

PubMed

Kim, Hye Yoom; Oh, Hyuncheol; Li, Xiang; Cho, Kyung Woo; Kang, Dae Gill; Lee, Ho Sub

2011-01-27

The vasorelaxant effect of ethanol extract of seeds of Oenothera odorata (Onagraceae) (one species of evening primroses) (ESOO) and its mechanisms involved were defined. Changes in vascular tension, guanosine 3',5'-cyclic monophosphate (cGMP) levels, and Akt expression were measured in carotid arterial rings from rats. Seeds of Oenothera odorata were extracted with ethanol (94%) and the extract was filtered, concentrated and stored at -70°C. ESOO relaxed endothelium-intact, but not endothelium-denuded, carotid arterial rings in a concentration-dependent manner. Similarly, ESOO increased cGMP levels of the carotid arterial rings. Pretreatment of endothelium-intact arterial rings with L-NAME, an inhibitor of nitric oxide synthase (NOS), or ODQ, an inhibitor of soluble guanylyl cyclase (sGC), blocked the ESOO-induced vasorelaxation and increase in cGMP levels. Nominally Ca(2+)-free but not L-typed Ca(2+) channel inhibition attenuated the ESOO-induced vasorelaxation. Thapsigargin, Gd(3+), and 2-aminoethyl diphenylborinate, modulators of store-operated Ca(2+) entry (SOCE), significantly attenuated the ESOO-induced vasorelaxation and increase in cGMP levels. Further, wortmannin, an inhibitor of Akt, attenuated the ESOO-induced vasorelaxation and increases in cGMP levels and phosphorylated Akt2 expression. K(+) channel blockade with TEA, 4-aminopyridine, and glibenclamide attenuated the ESOO-induced vascular relaxation. Taken together, the present study demonstrates that ESOO relaxes vascular smooth muscle via endothelium-dependent NO-cGMP signaling through activation of the Akt-eNOS-sGC pathway. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Sex-specific effects of cardiovascular risk factors on endothelium-dependent dilation and endothelin activity in middle-aged women and men.

PubMed

Brar, Vijaywant; Gill, Sartaj; Cardillo, Carmine; Tesauro, Manfredi; Panza, Julio A; Campia, Umberto

2015-01-01

Healthy middle-aged postmenopausal women have higher endothelium-dependent dilation and lower vasoconstrictor activity of endothelin-1 than men. Whether these sex-specific differences extend to patients with cardiovascular risk factors has not been investigated. The current study aimed to determine whether, in patients with cardiovascular risk factors, sex-specific differences exist in endothelium-dependent dilation and endothelin-1 activity. Forearm blood flow responses were measured by strain-gauge plethysmography during the intra-arterial infusion of acetylcholine, sodium nitroprusside, and the selective endothelin type A receptor blocker BQ-123 in 50 women and 64 men with cardiovascular risk factors. Acetylcholine and sodium nitroprusside induced a significant vasodilation in women and men alike (p < 0.01 for both). Also BQ-123 caused a significant vasodilation (p < 0.001) in both groups. The vasodilator response to acetylcholine was greater in women compared to men; however there were no differences in the response to sodium nitroprusside and BQ-123 (p = NS for both) between the two sex groups. Middle-aged women with cardiovascular risk factors have significantly higher endothelium-dependent dilation than middle-aged men; however, vascular endothelin 1 activity is similar in the two groups. These findings suggest that the presence of cardiovascular risk factors is associated with sex-specific effects on endothelium-dependent dilation but not on endothelin 1 activity. Further study is needed to confirm our findings and to characterize the mechanisms underlying this sex-specific regulation of endothelial function.

Decreased contraction induced by endothelium-derived contracting factor in prolonged treatment of rat renal artery with endoplasmic reticulum stress inducer.

PubMed

Ando, Makoto; Matsumoto, Takayuki; Taguchi, Kumiko; Kobayashi, Tsuneo

2018-05-04

Recent evidence suggests that endoplasmic reticulum (ER) stress is involved in the regulation of various physiological functions, including those of the vascular system. However, the relationship between ER stress and vascular function is poorly understood. The endothelial cells control the vascular tone by releasing endothelium-derived relaxing factors and contracting factors (EDCFs). We hypothesized that tunicamycin, an inducer of ER stress, modifies endothelium-dependent contraction and prostaglandins (PGs), a major class of EDCFs, induced contractions in the rat renal artery in rats. An organ-culture technique was used to purely investigate the effects of ER stress on the vascular tissue. We observed that tunicamycin treatment (20 μg/mL for 23 ± 1 h) did not affect acetylcholine (ACh)-induced relaxation and decreased EDCF-mediated contractions under nitric oxide synthase (NOS) inhibition induced by ACh, ATP, or A23187 (a calcium ionophore) in the renal arteries. Under NOS inhibition, U46619 (a thromboxane A 2 mimetic)- and beraprost (a prostacyclin analog)-induced contractions were also decreased in the renal arteries of the tunicamycin-treated group (vs. vehicle), while PGE 2 - and PGF 2α -induced contractions were similar between the groups. Tunicamycin treatment slightly enhanced the contractions induced by phenylephrine, an α 1 adrenoceptor ligand. Isotonic high-K + -induced contractions were similar between the vehicle- and tunicamycin-treated groups. Another ER stress inducer, thapsigargin (4 μmol/L for 23 ± 1 h), also caused substantial reduction of ACh-induced EDCF-mediated contraction (vs. vehicle-treated group). In the cultured renal arteries, tunicamycin and thapsigargin increased the expression of binding immunoglobulin protein (BiP), an ER stress marker. In conclusion, ER stress induction directly affects renal arterial function, especially in reducing EDCF-mediated contractions.

N-acetylcysteine does not influence the activity of endothelium-derived relaxing factor in vivo.

PubMed

Creager, M A; Roddy, M A; Boles, K; Stamler, J S

1997-02-01

Nitric oxide forms complexes with an array of biomolecular carriers that retain biological activity. This reactivity of nitric oxide in physiological systems has led to some dispute as to whether endothelium-derived relaxing factors nitric oxide or a closely related adduct thereof, such as a nitrosothiol. In vitro bioassays used to address this question are limited by the exclusion of biological thiols that are requisite for nitrosothiol formation. Thus, the purpose of this study was to obtain insight into the identity of endothelium-derived relaxing factor in vivo. We reasoned that if endothelium-derived relaxing factor in nitric oxide, infusion of physiological concentrations of thiol would potentiate its bioactivity by analogy with effects seen in vitro, whereas nitrosothiol would be resistant to such modulation. We used venous-occlusion plethysmography to study forearm blood flow in normal subjects. Methacholine (0.3 to 10 micrograms/min) and nitroglycerin (1 to 30 micrograms/min) were infused via the brachial artery to elicit endothelium-dependent and endothelium-independent vasodilation, respectively. Dose-response determinations were made for each drug before and after an intra-arterial infusion of the reduced thiol, N-acetylcysteine, at rates estimated to achieve a physiological concentration of 1 mmol/L. Methacholine increased forearm blood flow in a dose-dependent manner. Infusion of N-acetylcysteine did not change the sensitivity (ED50, 1.7 versus 1.7 micrograms/min, P = NS) or maximal response to methacholine. In contrast, thiol increased the sensitivity to nitroglycerin (ED50, 4.7 versus 2.8 micrograms/min, P < .01). Thus, conflicting with reports in vitro, thiol does not modulate endothelium-derived relaxing factor responses in vivo. These data indicate that sulfhydryl groups are not a limiting factor for endothelium-derived relaxing factor responses in forearm resistance vessels in normal humans and are in keeping with reports that nitrosothiol

[Changes in endothelium-dependent dilation and α1-adrenoreactivity of rat aorta caused by inducible NO-synthase inhibition after motor activity restrictions].

PubMed

Solodkov, A P; Iatskovskaia, N M

2013-07-01

The aim of work was to study the influence of the highly selective blocker of the inducible NO-synthase (iNOS) of S-methylthiourea on the alteration of the endothelium-dependent vasodilation and α1-adrenoreactivity of the isolated rat aortic rings which underwent a short-term restriction of physical activity. The experiments were carried out on rat aortic rings preparations from female-rats bathed in Krebs-Henseleit solution, bubbled with 95% O2 and 5% CO2 and contracting in isometric mode. Endothelium-dependent dilation was caused by cumulative addition of acetylcholine (10-(10)-10(-4) M) after phenylephrine precontraction(10(-6) M). Adrenoreactivity was assessed through the response to increasing concentrations of α1-adrenergic receptor agonist. The 60-minute immobilization stress, characterized by the increase of the relative weight of the adrenal glands by 19.5%, the concentration of glucocorticoids (twice as much), of NO2/NO3 (stable NO degradation products) by 35%, the reduction in the level of thyroxine (by 16%), triiodothyronine (by 10%) and the increase in thyrotropic hormone by 45%, interleukin-1b (twice as much) and the appearance of tumour necrosis factor alpha in the blood serum, was accompanied by the two types of reaction of isolated aortic rings to acetylcholine and phenylephrine. The first one was expressed in the enhancing of acetylcholine-induced dilation of isolated aortic rings and the reduction of its response to α1-adrenergic stimulant phenylephrine. The second one showed a decrease in the response of isolated aortic rings to acetylcholine and enhancing the response to phenylephrine. But both of these reaction types were eliminated by using highly selective inducible NO-synthase inhibitor with S-methylisothiourea. However, it was differently directed with a different type of reaction. Taken together, these results suggest that the iNOS is formed in the cells of rat aorta under short-term stress. In some cases it can be a source of a large

Relaxation effect of abacavir on rat basilar arteries.

PubMed

Li, Rachel Wai Sum; Yang, Cui; Chan, Shun Wan; Hoi, Maggie Pui Man; Lee, Simon Ming Yuen; Kwan, Yiu Wa; Leung, George Pak Heng

2015-01-01

The use of abacavir has been linked with increased cardiovascular risk in patients with human immunodeficiency virus infection; however, the mechanism involved remains unclear. We hypothesize that abacavir may impair endothelial function. In addition, based on the structural similarity between abacavir and adenosine, we propose that abacavir may affect vascular contractility through endogenous adenosine release or adenosine receptors in blood vessels. The relaxation effect of abacavir on rat basilar arteries was studied using the myograph technique. Cyclic GMP and AMP levels were measured by immunoassay. The effects of abacavir on nucleoside transporters were studied using radiolabeled nucleoside uptake experiments. Ecto-5' nucleotidase activity was determined by measuring the generation of inorganic phosphate using adenosine monophosphate as the substrate. Abacavir induced the relaxation of rat basilar arteries in a concentration-dependent manner. This relaxation was abolished when endothelium was removed. In addition, the relaxation was diminished by the nitric oxide synthase inhibitor, L-NAME, the guanylyl cyclase inhibitor, ODQ, and the protein kinase G inhibitor, KT5820. Abacavir also increased the cGMP level in rat basilar arteries. Abacavir-induced relaxation was also abolished by adenosine A2 receptor blockers. However, abacavir had no effect on ecto-5' nucleotidase and nucleoside transporters. Short-term and long-term treatment of abacavir did not affect acetylcholine-induced relaxation in rat basilar arteries. Abacavir induces acute endothelium-dependent relaxation of rat basilar arteries, probably through the activation of adenosine A2 receptors in endothelial cells, which subsequently leads to the release of nitric oxide, resulting in activation of the cyclic guanosine monophosphate/protein kinase G-dependent pathway in vascular smooth muscle cells. It is speculated that abacavir-induced cardiovascular risk may not be related to endothelial dysfunction

Oral administration of the antioxidant, N-acetylcysteine, abrogates diabetes-induced endothelial dysfunction.

PubMed

Pieper, G M; Siebeneich, W

1998-07-01

Oxidative stress is believed to play an important role in the development of vascular complications associated with diabetes mellitus. In this study, we examined the efficacy of long-term treatment with the antioxidant, N-acetylcysteine, in preventing the development of defective endothelium-dependent relaxation in streptozotocin-induced, Sprague-Dawley diabetic rats. At 48 h after injection of streptozotocin, a portion of diabetic rats received 250 mg/L N-acetylcysteine in drinking water for a total duration of 8 weeks. Oral administration did not alter the increase in blood glucose or the reduction in serum insulin but did modestly reduce total glycosylated hemoglobin. In precontracted thoracic aortic rings suspended in isolated tissue baths, endothelium-dependent relaxation to acetylcholine was impaired in diabetic rings compared with control rings. Endothelium-independent relaxation to nitroglycerin was unaltered. Long-term oral administration of N-acetylcysteine did not alter responses to nitroglycerin but completely prevented the defective relaxation to acetylcholine. These studies indicate a dissociation between glycemic control and correction of endothelial dysfunction and suggest that long-term exposure to reactive oxygen subsequent to diabetes rather than hyperglycemia per se is responsible for the development of endothelial dysfunction in diabetes mellitus.

Endothelium-derived contracting factors mediate the Ang II-induced endothelial dysfunction in the rat aorta: preventive effect of red wine polyphenols.

PubMed

Kane, Modou O; Etienne-Selloum, Nelly; Madeira, Soccoro V F; Sarr, Mamadou; Walter, Allison; Dal-Ros, Stéphanie; Schott, Christa; Chataigneau, Thierry; Schini-Kerth, Valérie B

2010-04-01

Angiotensin II (Ang II)-induced hypertension is associated with vascular oxidative stress and an endothelial dysfunction. This study examined the role of reactive oxygen species (ROS) and endothelium-derived contracting factors in Ang II-induced endothelial dysfunction and whether these effects are prevented by red wine polyphenols (RWPs), a rich source of natural antioxidants. Rats were infused with Ang II for 14 days. RWPs were administered in the drinking water 1 week before and during the Ang II infusion. Arterial pressure was measured in conscious rats. Vascular reactivity was assessed in organ chambers and cyclooxygenase-1 (COX-1) and COX-2 expression by Western blot and immunofluorescence analyses. Ang II-induced hypertension was associated with blunted endothelium-dependent relaxations and induction of endothelium-dependent contractions in the presence of nitro-L-arginine in response to acetylcholine (Ach). These effects were not affected by the combination of membrane permeant analogs of superoxide dismutase and catalase but were abolished by the thromboxane A(2) (TP) receptor antagonist GR32191B and the COX-2 inhibitor NS-398. The COX-1 inhibitor SC-560 also prevented contractile responses to Ach. Ang II increased the expression of COX-1 and COX-2 in the aortic wall. RWPs prevented Ang II-induced hypertension, endothelial dysfunction, and upregulation of COX-1 and COX-2. Thus, Ang II-induced endothelial dysfunction cannot be explained by an acute formation of ROS reducing the bioavailability of nitric oxide but rather by COX-dependent formation of contracting factors acting on TP receptors. RWPs are able to prevent the Ang II-induced endothelial dysfunction mostly due to their antioxidant properties.

Nanoparticle inhalation impairs endothelium-dependent vasodilation in subepicardial arterioles

PubMed Central

LeBlanc, AJ; Cumpston, JL; Chen, BT; Frazer, D; Castranova, V; Nurkiewicz, TR

2009-01-01

Exposure to fine particulate matter (PM, mean aerodynamic diameter ≤ 2.5 μm) has been shown to be a risk factor for cardiovascular disease mortality and may contribute to acute coronary events such as myocardial infarction (MI). There is sufficient reason to believe that smaller particles, such as nanoparticles, might be even more detrimental than larger-sized particles due to their increased surface area and higher pulmonary deposition. Our lab showed that nanoparticle inhalation impairs endothelium-dependent arteriolar vasodilation in skeletal muscle. However, it is not known if coronary microvascular endothelial function is affected in a similar manner. Rats were exposed to filtered air (control) or TiO2 nanoparticles (primary particle diameter, ~21 nm) via inhalation at concentrations that produced measured depositions (10 μg) relevant to ambient air pollution. Subepicardial arterioles (~150 μm in diameter) were isolated and responses to transmural pressure, flow-induced dilation (FID), acetylcholine, the Ca2+ ionophore A23187, and sodium nitroprusside (SNP) assessed. Myogenic responsiveness was preserved between groups. In addition, there was no difference in the vasodilation to SNP, signifying that smooth muscle sensitivity to nitric oxide (NO) is unaffected by nano-TiO2 exposure. However, inhalation of nano-TiO2 produced an increase in spontaneous tone in coronary arterioles and also impaired endothelium-dependent FID. In addition, ACh- and A23187-induced vasodilation was also blunted in arterioles after inhalation of nano-TiO2. Data showed that nanoparticle exposure significantly impairs endothelium-dependent vasodilation in subepicardial arterioles. Such disturbances in coronary microvascular function are consistent with the cardiac events associated with particle pollution exposure. PMID:20077232

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.

Responsiveness of Coronary Arteries to Nitroglycerin under Hypoxia: The Importance of the Endothelium.

PubMed

Tawa, Masashi; Shimosato, Takashi; Sakonjo, Hiroshi; Okamura, Tomio

2017-01-01

Nitroglycerin is widely used as a coronary vasodilator in the treatment of ischemic heart diseases. This study investigated the influence of hypoxia on nitroglycerin-induced relaxation in endothelium-intact and -denuded rabbit, monkey, and porcine coronary arteries. Helically cut strips of coronary arteries were suspended in organ chambers, and isometric tension was recorded. Nitroglycerin concentration dependently relaxed endothelium-intact rabbit coronary arteries, which were not different under normoxic and hypoxic conditions. On the other hand, nitroglycerin-induced relaxation of endothelium-denuded arteries was significantly attenuated by hypoxia. Similarly, the relaxant response of endothelium-intact monkey coronary arteries to nitroglycerin was not affected by hypoxia, whereas that of endothelium-denuded arteries was impaired. As is the case with rabbit and monkey coronary arteries, exposure to hypoxia resulted in impaired relaxation by nitroglycerin in endothelium-denuded but not endothelium-intact porcine coronary arteries. These findings suggest that coronary endothelium plays a pivotal role in preventing the hypoxia-induced impairment of nitroglycerin responsiveness, regardless of the animal species. © 2017 S. Karger AG, Basel.

Dissimilarities between methylene blue and cyanide on relaxation and cyclic GMP formation in endothelium-intact intrapulmonary artery caused by nitrogen oxide-containing vasodilators and acetylcholine

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

Ignarro, L.J.; Harbison, R.G.; Wood, K.S.

1986-01-01

The objective of the present study was to ascertain whether cyanide shares the properties of methylene blue as a selective inhibitor of vascular smooth muscle relaxation elicited by agents that stimulate the formation of cyclic GMP. Experiments were performed with endothelium-intact rings prepared from bovine intrapulmonary artery. Methylene blue, a good inhibitor of soluble guanylate cyclase, antagonized both arterial relaxation and cyclic GMP accumulation in response to sodium nitroprusside, glyceryl trinitrate, S-nitroso-N-acetylpenicillamine and acetylcholine. In contrast, cyanide inhibited only the responses to sodium nitroprusside. Increasing concentrations of methylene blue depressed resting arterial levels of cyclic GMP and caused slowly developingmore » but marked contractions whereas cyanide was without effect. Contractile responses to phenylephrine, potassium and U46619 were potentiated by methylene blue but not by cyanide. Preincubation of dilute solutions of cyanide containing sodium nitroprusside in oxygenated Krebs' buffer at 37 degrees C for 15 min before addition to bath chambers depressed relaxation and cyclic GMP accumulation caused by sodium nitroprusside markedly. Similar treatment of glyceryl trinitrate, however, failed to alter its effects in arterial rings. A chemical inactivation of sodium nitroprusside by cyanide appears to account for the specific inhibitory action of cyanide on arterial responses to sodium nitroprusside. This study indicates clearly that cyanide does not share the properties of methylene blue as an inhibitor of arterial relaxation elicited by vasodilators that stimulate cyclic GMP formation.« less

Relaxation Effect of Abacavir on Rat Basilar Arteries

PubMed Central

Li, Rachel Wai Sum; Yang, Cui; Chan, Shun Wan; Hoi, Maggie Pui Man; Lee, Simon Ming Yuen; Kwan, Yiu Wa; Leung, George Pak Heng

2015-01-01

Background The use of abacavir has been linked with increased cardiovascular risk in patients with human immunodeficiency virus infection; however, the mechanism involved remains unclear. We hypothesize that abacavir may impair endothelial function. In addition, based on the structural similarity between abacavir and adenosine, we propose that abacavir may affect vascular contractility through endogenous adenosine release or adenosine receptors in blood vessels. Methods The relaxation effect of abacavir on rat basilar arteries was studied using the myograph technique. Cyclic GMP and AMP levels were measured by immunoassay. The effects of abacavir on nucleoside transporters were studied using radiolabeled nucleoside uptake experiments. Ecto-5′ nucleotidase activity was determined by measuring the generation of inorganic phosphate using adenosine monophosphate as the substrate. Results Abacavir induced the relaxation of rat basilar arteries in a concentration-dependent manner. This relaxation was abolished when endothelium was removed. In addition, the relaxation was diminished by the nitric oxide synthase inhibitor, L-NAME, the guanylyl cyclase inhibitor, ODQ, and the protein kinase G inhibitor, KT5820. Abacavir also increased the cGMP level in rat basilar arteries. Abacavir-induced relaxation was also abolished by adenosine A2 receptor blockers. However, abacavir had no effect on ecto-5’ nucleotidase and nucleoside transporters. Short-term and long-term treatment of abacavir did not affect acetylcholine-induced relaxation in rat basilar arteries. Conclusion Abacavir induces acute endothelium-dependent relaxation of rat basilar arteries, probably through the activation of adenosine A2 receptors in endothelial cells, which subsequently leads to the release of nitric oxide, resulting in activation of the cyclic guanosine monophosphate/protein kinase G-dependent pathway in vascular smooth muscle cells. It is speculated that abacavir-induced cardiovascular risk may

Vasorelaxant and antihypertensive effects of formononetin through endothelium-dependent and -independent mechanisms.

PubMed

Sun, Tao; Liu, Rui; Cao, Yong-xiao

2011-08-01

To investigate the mechanisms underlying the vasorelaxant effect of formononetin, an O-methylated isoflavone, in isolated arteries, and its antihypertensive activity in vivo. Arterial rings of superior mesenteric arteries, renal arteries, cerebral basilar arteries, coronary arteries and abdominal aortas were prepared from SD rats. Isometric tension of the arterial rings was recorded using a myograph system. Arterial pressure was measured using tail-cuff method in spontaneously hypertensive rats. Formononetin (1-300 μmol/L) elicited relaxation in arteries of the five regions that were pre-contracted by KCl (60 mmol/L), U46619 (1 μmol/L) or phenylephrine (10 μmol/L). The formononetin-induced relaxation was reduced by removal of endothelium or by pretreatment with L-NAME (100 μmol/L). Under conditions of endothelium denudation, formononetin (10, 30, and 100 μmol/L) inhibited the contraction induced by KCl and that induced by CaCl(2) in Ca(2+)-free depolarized medium. In the absence of extracellular Ca(2+), formononetin (10, 30, and 100 μmol/L) depressed the constriction caused by phenylephrine (10 μmol/L), but did not inhibit the tonic contraction in response to the addition of CaCl(2) (2 mmol/L). The contraction caused by caffeine (30 mmol/L) was not inhibited by formononetin (100 μmol/L). Formononetin (10 and 100 μmol/L) reduced the change rate of Ca(2+)-fluorescence intensity in response to KCl (50 mmol/L). In spontaneously hypertensive rats, formononetin (5, 10, and 20 mg/kg) slowly lowered the systolic, diastolic and mean arterial pressure. Formononetin causes vasodilatation via two pathways: (1) endothelium-independent pathway, probably due to inhibition of voltage-dependent Ca(2+) channels and intracellular Ca(2+) release; and (2) endothelium-dependent pathway by releasing NO. Both the pathways may contribute to its antihypertensive effect.

Vasorelaxant and antihypertensive effects of formononetin through endothelium-dependent and -independent mechanisms

PubMed Central

SUN, Tao; LIU, Rui; CAO, Yong-xiao

2011-01-01

Aim: To investigate the mechanisms underlying the vasorelaxant effect of formononetin, an O-methylated isoflavone, in isolated arteries, and its antihypertensive activity in vivo. Methods: Arterial rings of superior mesenteric arteries, renal arteries, cerebral basilar arteries, coronary arteries and abdominal aortas were prepared from SD rats. Isometric tension of the arterial rings was recorded using a myograph system. Arterial pressure was measured using tail-cuff method in spontaneously hypertensive rats. Results: Formononetin (1–300 μmol/L) elicited relaxation in arteries of the five regions that were pre-contracted by KCl (60 mmol/L), U46619 (1 μmol/L) or phenylephrine (10 μmol/L). The formononetin-induced relaxation was reduced by removal of endothelium or by pretreatment with L-NAME (100 μmol/L). Under conditions of endothelium denudation, formononetin (10, 30, and 100 μmol/L) inhibited the contraction induced by KCl and that induced by CaCl2 in Ca2+-free depolarized medium. In the absence of extracellular Ca2+, formononetin (10, 30, and 100 μmol/L) depressed the constriction caused by phenylephrine (10 μmol/L), but did not inhibit the tonic contraction in response to the addition of CaCl2 (2 mmol/L). The contraction caused by caffeine (30 mmol/L) was not inhibited by formononetin (100 μmol/L). Formononetin (10 and 100 μmol/L) reduced the change rate of Ca2+-fluorescence intensity in response to KCl (50 mmol/L). In spontaneously hypertensive rats, formononetin (5, 10, and 20 mg/kg) slowly lowered the systolic, diastolic and mean arterial pressure. Conclusion: Formononetin causes vasodilatation via two pathways: (1) endothelium-independent pathway, probably due to inhibition of voltage-dependent Ca2+ channels and intracellular Ca2+ release; and (2) endothelium-dependent pathway by releasing NO. Both the pathways may contribute to its antihypertensive effect. PMID:21818108

Formononetin upregulates nitric oxide synthase in arterial endothelium through estrogen receptors and MAPK pathways.

PubMed

Sun, Tao; Cao, Lei; Ping, Na-Na; Wu, Yue; Liu, Dong-Zheng; Cao, Yong-Xiao

2016-03-01

Formononetin, a phytoestrogen, can improve arterial endothelial cell function by upregulating endothelial nitric oxide synthase (eNOS). The estrogen receptor plays an important role in the regulation of eNOS. This study investigated the hypothesis that formononetin upregulates eNOS through estrogen receptors and MAPK pathways. The rat superior mesenteric arteries were cultured with formononetin or formononetin plus inhibitors for 24 h. The isometric tension of the arteries was measured using a myograph system. The mRNA and protein expression levels of eNOS were determined by real-time PCR and immunohistochemistry, respectively. Acetylcholine (ACh) relaxed the mesenteric arteries precontracted with 5-hydroxytryptamine. This relaxation could be enhanced by formononetin. The removal of endothelium or incubation with l-NAME (a NOS inhibitor) completely abolished the formononetin-enhanced relaxation induced by ACh, suggesting that the formononetin-enhanced vasodilatation is dependent on endothelium and NO pathway. The estrogen receptor inhibitor ICI 182780 attenuated the formononetin-enhanced vasodilatation induced by ACh, suggesting that the formononetin-enhanced arterial relaxation is mediated by the estrogen receptor. Formononetin increased the mRNA and protein expression levels of eNOS. ICI 182780, U0126 (an ERK1/2 inhibitor) and SP600125 (a JNK inhibitor) prevented the increases in arterial relaxation and eNOS levels. Formononetin upregulates eNOS expression in mesenteric arteries via estrogen receptors, ERK1/2 and JNK pathways. © 2016 Royal Pharmaceutical Society, Journal of Pharmacy and Pharmacology.

Testosterone-induced relaxation of coronary arteries: activation of BKCa channels via the cGMP-dependent protein kinase

PubMed Central

Deenadayalu, Viju; Puttabyatappa, Yashoda; Liu, Alexander T.; Stallone, John N.

2012-01-01

Androgens are reported to have both beneficial and detrimental effects on human cardiovascular health. The aim of this study was to characterize nongenomic signaling mechanisms in coronary artery smooth muscle (CASM) and define the ionic basis of testosterone (TES) action. TES-induced relaxation of endothelium-denuded porcine coronary arteries was nearly abolished by 20 nM iberiotoxin, a highly specific inhibitor of large-conductance, calcium-activated potassium (BKCa) channels. Molecular patch-clamp studies confirmed that nanomolar concentrations of TES stimulated BKCa channel activity by ∼100-fold and that inhibition of nitric oxide synthase (NOS) activity by NG-monomethyl-l-arginine nearly abolished this effect. Inhibition of nitric oxide (NO) synthesis or guanylyl cyclase activity also attenuated TES-induced coronary artery relaxation but did not alter relaxation due to 8-bromo-cGMP. Furthermore, we detected TES-stimulated NO production in porcine coronary arteries and in human CASM cells via stimulation of the type 1 neuronal NOS isoform. Inhibition of the cGMP-dependent protein kinase (PKG) attenuated TES-stimulated BKCa channel activity, and direct assay determined that TES increased activity of PKG in a concentration-dependent fashion. Last, the stimulatory effect of TES on BKCa channel activity was mimicked by addition of purified PKG to the cytoplasmic surface of a cell-free membrane patch from CASM myocytes (∼100-fold increase). These findings indicate that TES-induced relaxation of endothelium-denuded coronary arteries is mediated, at least in part, by enhanced NO production, leading to cGMP synthesis and PKG activation, which, in turn, opens BKCa channels. These findings provide a molecular mechanism that could help explain why androgens have been reported to relax coronary arteries and relieve angina pectoris. PMID:22081702

Long-term effects of prenatal hypoxia on endothelium-dependent relaxation responses in pulmonary arteries of adult sheep.

PubMed

Liu, Jie; Gao, Yuansheng; Negash, Sewite; Longo, Lawrence D; Raj, J Usha

2009-03-01

Chronic hypoxia during the course of pregnancy is a common insult to the fetus. However, its long-term effect on the pulmonary vasculature in adulthood has not been described. In this study, the vasorelaxation responses of conduit pulmonary arteries in adult female sheep that were chronically hypoxic as fetuses and raised postnatally at sea level were investigated. Vessel tension studies revealed that endothelium-dependent relaxation responses were attenuated in pulmonary arteries from adult sheep that experienced prenatal hypoxia. Endothelial nitric oxide synthase (eNOS) protein expression was unchanged, but eNOS activity was significantly decreased in pulmonary arteries from prenatally hypoxic sheep. Protein expression of eNOS partners, caveolin-1, calmodulin, and heat shock protein 90 (Hsp90) did not change following prenatal hypoxia. However, the association between eNOS and caveolin-1, its inhibitory binding partner, was significantly increased, whereas association between eNOS and its stimulatory partners calmodulin and Hsp90 was greatly decreased. Furthermore, phosphorylation of Ser(1177) in eNOS decreased, whereas phosphorylation of Thr(495) increased, in the prenatally hypoxic pulmonary arteries, events that are related to eNOS activity. These data demonstrate that prenatal hypoxia results in persistent abnormalities in endothelium-dependent relaxation responses of pulmonary arteries in adult sheep due to decreased eNOS activity resulting from altered posttranslational regulation.

Long-term effects of prenatal hypoxia on endothelium-dependent relaxation responses in pulmonary arteries of adult sheep

PubMed Central

Liu, Jie; Gao, Yuansheng; Negash, Sewite; Longo, Lawrence D.; Raj, J. Usha

2009-01-01

Chronic hypoxia during the course of pregnancy is a common insult to the fetus. However, its long-term effect on the pulmonary vasculature in adulthood has not been described. In this study, the vasorelaxation responses of conduit pulmonary arteries in adult female sheep that were chronically hypoxic as fetuses and raised postnatally at sea level were investigated. Vessel tension studies revealed that endothelium-dependent relaxation responses were attenuated in pulmonary arteries from adult sheep that experienced prenatal hypoxia. Endothelial nitric oxide synthase (eNOS) protein expression was unchanged, but eNOS activity was significantly decreased in pulmonary arteries from prenatally hypoxic sheep. Protein expression of eNOS partners, caveolin-1, calmodulin, and heat shock protein 90 (Hsp90) did not change following prenatal hypoxia. However, the association between eNOS and caveolin-1, its inhibitory binding partner, was significantly increased, whereas association between eNOS and its stimulatory partners calmodulin and Hsp90 was greatly decreased. Furthermore, phosphorylation of Ser1177 in eNOS decreased, whereas phosphorylation of Thr495 increased, in the prenatally hypoxic pulmonary arteries, events that are related to eNOS activity. These data demonstrate that prenatal hypoxia results in persistent abnormalities in endothelium-dependent relaxation responses of pulmonary arteries in adult sheep due to decreased eNOS activity resulting from altered posttranslational regulation. PMID:19136582

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.

β-adrenergic Receptor Blocker ICI 118,551 Selectively Increases Intermediate-Conductance Calcium-Activated Potassium Channel (IKCa )-Mediated Relaxations in Rat Main Mesenteric Artery.

PubMed

Ozkan, Melike Hacer; Uma, Serdar

2018-06-01

Endothelial IK C a and/or SK C a channels play an important role in the control of vascular tone by participating in endothelium-dependent relaxation. Whether β-AR antagonists, mainly used in hypertension, affect endothelial K C a channel function is unknown. In this study, we examined the effect of the β2-AR antagonist and inverse agonist ICI 118,551 on the IK C a /SK C a channel activity by assessing functional relaxation responses to several agonists that stimulate these channels. Mesenteric arterial rings isolated from male Sprague Dawley mounted to organ baths. Acetylcholine elicited IK C a - and SK C a -mediated relaxations that were abolished by TRAM-34 and apamin, respectively. ICI 118,551, which did not dilate the arteries per se, increased the IK C a -mediated relaxations, whereas SK C a -mediated relaxations remained unaltered. Same potentiating effect was also detected on the IK C a -mediated relaxations to carbachol and A23187, but not to NS309. Neither acetylcholine-induced nitric oxide-mediated relaxations nor SNP relaxations changed with ICI 118,551. The PKA inhibitor KT-5720, the selective β2-AR agonist salbutamol, the selective β2-AR antagonist butoxamine, the non-selective β-AR antagonist propranolol, and the inverse agonists carvedilol or nadolol failed to affect the IK C a -mediated relaxations. ICI 118,551-induced increase was not reversed by salbutamol or propranolol as well. Besides, low potassium-induced relaxations in endothelium-removed arteries remained the same in the presence of ICI 118,551. These data demonstrate a previously unrecognized action of ICI 118,551, the ability to potentiate endothelial IK C a channel-mediated vasodilation, through a mechanism independent of β2-AR antagonistic or inverse agonistic action. Instead, the enhancement of acetylcholine relaxation seems likely to occur by a mechanism secondary to endothelial calcium increase. © 2017 Nordic Association for the Publication of BCPT (former Nordic

High-fat feeding reduces endothelium-dependent vasodilation in rats: differential mechanisms for saturated and unsaturated fatty acids?

PubMed

Song, Guang-Yao; Gao, Yu; Di, Yu-Wei; Pan, Li-Li; Zhou, Yu; Ye, Ji-Ming

2006-08-01

1. Chronic feeding with a high-fat diet can cause metabolic syndrome in rodents similar to humans, but the role of saturated versus unsaturated fats in vascular tension remains unclear. 2. The present study shows that rats on a diet rich in either saturated or unsaturated fat had higher blood pressure compared with chow-fed rats (approximately 130 vs 100 mmHg, respectively), along with hyperlipidaemia and insulin resistance. Compared with responses of phenylephrine-preconstricted artery segments from chow-fed rats, vasorelaxation of isolated renal arteries from high-fat fed rats was reduced substantially (> 50%) in response to acetylcholine (0.01-10 micromol/L) and moderately to nitroprusside (>or=1 micromol/L) at low concentrations. Acetylcholine-induced vasorelaxation of arteries from high-fat fed rats was also more sensitive to inhibition by the nitric oxide (NO) synthase inhibitors NG-nitro-L-arginine and methylene blue. 3. In human umbilical vein endothelial cells, the production of NO and endothelin-1 was significantly inhibited by unsaturated fatty acids. In comparison, saturated fatty acids stimulated endothelin-1 production without altering NO production. 4. The data indicate that both saturated and unsaturated high-fat feeding may result in an increase in blood pressure owing to reduced endothelium-dependent vasorelaxation in the arterial system. The impaired endothelium-dependent vasorelaxation induced by saturated and unsaturated fatty acids may involve different mechanisms.

In vivo evidence for an endothelium-dependent mechanism in radiation-induced normal tissue injury

PubMed Central

Rannou, Emilie; François, Agnès; Toullec, Aurore; Guipaud, Olivier; Buard, Valérie; Tarlet, Georges; Mintet, Elodie; Jaillet, Cyprien; Iruela-Arispe, Maria Luisa; Benderitter, Marc; Sabourin, Jean-Christophe; Milliat, Fabien

2015-01-01

The pathophysiological mechanism involved in side effects of radiation therapy, and especially the role of the endothelium remains unclear. Previous results showed that plasminogen activator inhibitor-type 1 (PAI-1) contributes to radiation-induced intestinal injury and suggested that this role could be driven by an endothelium-dependent mechanism. We investigated whether endothelial-specific PAI-1 deletion could affect radiation-induced intestinal injury. We created a mouse model with a specific deletion of PAI-1 in the endothelium (PAI-1KOendo) by a Cre-LoxP system. In a model of radiation enteropathy, survival and intestinal radiation injury were followed as well as intestinal gene transcriptional profile and inflammatory cells intestinal infiltration. Irradiated PAI-1KOendo mice exhibited increased survival, reduced acute enteritis severity and attenuated late fibrosis compared with irradiated PAI-1flx/flx mice. Double E-cadherin/TUNEL labeling confirmed a reduced epithelial cell apoptosis in irradiated PAI-1KOendo. High-throughput gene expression combined with bioinformatic analyses revealed a putative involvement of macrophages. We observed a decrease in CD68+cells in irradiated intestinal tissues from PAI-1KOendo mice as well as modifications associated with M1/M2 polarization. This work shows that PAI-1 plays a role in radiation-induced intestinal injury by an endothelium-dependent mechanism and demonstrates in vivo that the endothelium is directly involved in the progression of radiation-induced enteritis. PMID:26510580

Bradykinin-induced relaxation of coronary microarteries: S-nitrosothiols as EDHF?

PubMed Central

Batenburg, Wendy W; Popp, Rüdiger; Fleming, Ingrid; Vries, René de; Garrelds, Ingrid M; Saxena, Pramod R; Danser, A H Jan

2004-01-01

To investigate whether S-nitrosothiols, in addition to NO, mediate bradykinin-induced vasorelaxation, porcine coronary microarteries (PCMAs) were mounted in myographs. Following preconstriction, concentration–response curves (CRCs) were constructed to bradykinin, the NO donors S-nitroso-N-penicillamine (SNAP) and diethylamine NONOate (DEA-NONOate) and the S-nitrosothiols L-S-nitrosocysteine (L-SNC) and D-SNC. All agonists relaxed PCMAs. L-SNC was ≈5-fold more potent than D-SNC. The guanylyl cyclase inhibitor ODQ and the NO scavenger hydroxocobalamin induced a larger shift of the bradykinin CRC than the NO synthase inhibitor L-NAME, although all three inhibitors equally suppressed bradykinin-induced cGMP responses. Complete blockade of bradykinin-induced relaxation was obtained with L-NAME in the presence of the large- and intermediate-conductance Ca2+-activated K+-channel (BKCa, IKCa) blocker charybdotoxin and the small-conductance Ca2+-activated K+-channel (SKCa) channel blocker apamin, but not in the presence of L-NAME, apamin and the BKCa channel blocker iberiotoxin. Inhibitors of cytochrome P450 epoxygenase, cyclooxygenase, voltage-dependent K+ channels and ATP-sensitive K+ channels did not affect bradykinin-induced relaxation. SNAP-, DEA-NONOate- and D-SNC-induced relaxations were mediated entirely by the NO-guanylyl cyclase pathway. L-SNC-induced relaxations were partially blocked by charybdotoxin+apamin, but not by iberiotoxin+apamin, and this blockade was abolished following endothelium removal. ODQ, but not hydroxocobalamin, prevented L-SNC-induced increases in cGMP, and both drugs shifted the L-SNC CRC 5–10-fold to the right. L-SNC hyperpolarized intact and endothelium-denuded coronary arteries. Our results support the concept that bradykinin-induced relaxation is mediated via de novo synthesized NO and a non-NO, endothelium-derived hyperpolarizing factor (EDHF). S-nitrosothiols, via stereoselective activation of endothelial IKCa and SKCa channels

[The role of N-acetylcysteine against the injury of pulmonary artery induced by LPS].

PubMed

Huang, Xin-li; Ling, Yi-ling; Zhu, Tie-nian

2002-11-01

To investigate the alleviating effect of N-acetylcysteine (NAC) on lung injury induced by lipopolysaccharides (LPS) and its mechanism. The effects of NAC on changes of the pulmonary arterial reactivity and the ultrastructure of pulmonary arterial endothelium induced by LPS were observed with the isolated artery ring technique and scanning electron microscope (SEM). Malondialdehyde (MDA), nitric oxide (NO) contents and superoxide dismutase (SOD) activity of pulmonary artery tissues were detected. The exposure of pulmonary artery to LPS (4 microg/ml, 7 h) led to reduction of endothelium-dependent relaxation response to acetylcholine (ACh), which was reversed by the concomitant exposure to NAC (0.5 mmol/L, 7 h), whereas NAC itself had no effect on the response. Significant structural injury were observed under SEM in LPS group and alleviated the changes in LPS + NAC group. The MDA, NO contents increased but SOD activity decreased in LPS group, which were reversed by the concomitant exposure to NAC. NAC protects pulmonary artery endothelium and enhances endothelium-dependent relaxation response of pulmonary artery by antioxidation effect, which may be one of the mechanisms of its reversing pulmonary artery hypertension and following lung injury induced by LPS.

Insufficient sleep is associated with impaired nitric oxide-mediated endothelium-dependent vasodilation.

PubMed

Bain, Anthony R; Weil, Brian R; Diehl, Kyle J; Greiner, Jared J; Stauffer, Brian L; DeSouza, Christopher A

2017-10-01

Habitual short nightly sleep duration is associated with increased atherosclerotic cardiovascular disease risk and morbidity. Vascular endothelial dysfunction represents an important mechanism that may underlie this heightened cardiovascular risk. Impaired endothelium-dependent vasodilation, particularly NO-mediated vasodilation, contributes to the development and progression of atherosclerotic vascular disease and acute vascular events. We tested the hypothesis that chronic insufficient sleep is associated with impaired NO-mediated endothelium-dependent vasodilation in middle-aged adults. Thirty adult men were studied: 15 with normal nightly sleep duration (age: 58 ± 2 y; sleep duration: 7.7 ± 0.2 h/night) and 15 with short nightly sleep duration (55 ± 2 y; 6.1 ± 0.2 h/night). Forearm blood flow (FBF) responses to intra-arterial infusion of acetylcholine, in the absence and presence of the endothelial NO synthase inhibitor N G -monomethyl-L-arginine (L-NMMA), as well as responses to sodium nitroprusside, were determined by strain-gauge venous occlusion plethysmography. The FBF response to acetylcholine was lower (∼20%; p<0.05) in the short sleep duration group (from 4.6 ± 0.3 to 11.7 ± 1.0 ml/100 ml tissue/min) compared with normal sleep duration group (from 4.4 ± 0.3 to 14.5 ± 0.5 ml/100 ml tissue/min). L-NMMA significantly reduced the FBF response to acetylcholine in the normal sleep duration group (∼40%), but not the short sleep duration group. There were no group differences in the vasodilator response to sodium nitroprusside. These data indicate that short nightly sleep duration is associated with endothelial-dependent vasodilator dysfunction due, in part, to diminished NO bioavailability. Impaired NO-mediated endothelium-dependent vasodilation may contribute to the increased cardiovascular risk with insufficient sleep. Copyright © 2017 Elsevier B.V. All rights reserved.

Ca2+ mobilization in the aortic endothelium in streptozotocin-induced diabetic and cholesterol-fed mice.

PubMed

Kamata, K; Nakajima, M

1998-04-01

1. Experiments were performed to compare Ca2+ mobilization in the aortic endothelium in streptozotocin (STZ)-induced diabetic and cholesterol-fed mice with that in age-matched controls. 2. The intracellular free Ca2+ ([Ca2+]i) in the fura PE-3 loaded endothelium of aortic rings was dose-dependently increased by cumulative administration of acetylcholine (ACh). ACh caused a transient rise in [Ca2+]i in Ca2+-free medium. The ACh-induced increase in [Ca2+]i in normal or Ca2+-free medium was significantly weaker in both STZ-induced diabetic and cholesterol-fed mice. 3. The weaker [Ca2+]i response in Ca2+-containing medium in STZ-induced diabetic and cholesterol-fed mice was normalized by chronic administration of cholestyramine. 4. The increased low density lipoprotein (LDL) levels seen in both STZ-induced diabetic and cholesterol-fed mice were normalized by the same chronic administration of cholestyramine (300 mg kg(-1), p.o. daily for 10 weeks). Chronic administration of cholestyramine had no effect on the plasma glucose level. 5. Lysophosphatidylcholine (LPC) decreased the [Ca2+]i responses to ACh in the aortic endothelium from normal mice. 6. These results suggest that ACh increases both Ca2+ influx and Ca2+ release from storage in the aortic endothelium. The weaker [Ca2+]i influx seen in the endothelium of aortae from both STZ-induced diabetic and cholesterol-fed mice was improved by the chronic administration of cholestyramine, and we suggest that this improvement is due, at least in part, to a lowering of the plasma LDL level. It is further suggested that LPC may have an important influence over Ca2+ mobilization in the endothelium.

Endothelium-dependent vasorelaxant effect of procyanidin B2 on human internal mammary artery.

PubMed

Novakovic, Aleksandra; Marinko, Marija; Jankovic, Goran; Stojanovic, Ivan; Milojevic, Predrag; Nenezic, Dragoslav; Kanjuh, Vladimir; Yang, Qin; He, Guo-Wei

2017-07-15

The aim of the present study was to investigate and characterize vasorelaxant effect of procyanidin B2 on human internal mammary artery (HIMA) as one of the mechanisms of its protective effect against vascular risk. Procyanidin B2 induced strong concentration-dependent relaxation of HIMA rings pre-contracted by phenylephrine. Pretreatment with L-NAME, a NO synthase inhibitor, hydroxocobalamin, a NO scavenger, and ODQ, an inhibitor of soluble guanylate cyclase, significantly inhibited procyanidin B2-induced relaxation of HIMA, while indomethacin, a cyclooxygenase inhibitor, considerably reduced effects of low concentrations. Among K + channel blockers, iberiotoxin, a selective blocker of large conductance Ca 2+ -activated K + channels (BK Ca ), abolished procyanidin B2-induced relaxation, glibenclamide, a selective ATP-sensitive K + (K ATP ) channels blocker, induced partial inhibition, while 4-aminopyridine, a blocker of voltage-gated K + (K V ) channels, and TRAM-34, an inhibitor of intermediate-conductance Ca 2+ -activated K + (IK Ca ) channels, slightly reduced maximal relaxation of HIMA. Further, procyanidin B2 relaxed contraction induced by phenylephrine in Ca 2+ -free Krebs solution, but had no effect on contraction induced by caffeine. Finally, thapsigargin, a sarcoplasmic reticulum Ca 2+ -ATPase inhibitor, significantly reduced relaxation of HIMA produced by procyanidin B2. These results demonstrate that procyanidin B2 produces endothelium-dependent relaxation of HIMA pre-contracted by phenylephrine. This effect is primarily the result of an increased NO synthesis and secretion by endothelial cells and partially of prostacyclin, although it involves activation of BK Ca and K ATP , as well as K V and IK Ca channels in high concentrations of procyanidin B2. Copyright © 2017 Elsevier B.V. All rights reserved.

The inhibitory effect of 3-amino-1,2,4-triazole on relaxation induced by hydroxylamine and sodium azide but not hydrogen peroxide or glyceryl trinitrate in rat aorta.

PubMed Central

Mian, K. B.; Martin, W.

1995-01-01

1. In this study we investigated the role of catalase in relaxation induced by hydroxylamine, sodium azide, glyceryl trinitrate and hydrogen peroxide in isolated rings of rat aorta. 2. Hydrogen peroxide (1 microM-1 mM)-induced concentration-dependent relaxation of phenylephrine (PE)-induced tone in endothelium-containing rings. In endothelium-denuded rings, however, higher concentrations (30 microM-1 mM) of hydrogen peroxide were required to produce relaxation. The endothelium-dependent component of hydrogen peroxide-induced relaxation was abolished following pretreatment with N(O)-nitro-L-arginine methyl ester (L-NAME, 30 microM). L-NAME (30 microM) had no effect, however, on hydrogen peroxide-induced relaxation in endothelium-denuded rings. 3. Pretreatment of endothelium-denuded rings with catalase (1000 u ml-1) blocked relaxation induced by hydrogen peroxide (10 microM-1 mM). The ability of catalase to inhibit hydrogen peroxide-induced relaxation was partially blocked following incubation with 3-amino-1,2, 4-triazole (AT, 50 mM) for 30 min and completely blocked at 90 min. 4. Pretreatment of endothelium-denuded rings with methylene blue (MeB, 30 microM) inhibited relaxation induced by hydrogen peroxide (10 microM-1 mM), sodium azide (1-300 nM), hydroxylamine (1-300 nM) and glyceryl trinitrate (1-100 nM) suggesting that each acted by stimulation of soluble guanylate cyclase. 5. Pretreatment of endothelium-denuded rings with AT (1-50 mM, 90 min) to inhibit endogenous catalase blocked relaxation induced by sodium azide (1-300 nM) and hydroxylamine (1-300 nM) but had no effect on relaxation induced by hydrogen peroxide (10 microM-1 mM) or glyceryl trinitrate (1-100 nM). 6. In a cell-free system, incubation of sodium azide (10 microM-3 mM) and hydroxylamine (10 microM-30 mM) but not glyceryl trinitrate (10 microM-1 mM) with catalase (1000 u ml-1) in the presence of hydrogen peroxide (1 mM) led to production of nitrite, a major breakdown product of nitric oxide. AT (1

Enhancement effects of nicotine on neurogenic relaxation responses in the corpus cavernosum in rabbits: the role of nicotinic acetylcholine receptor subtypes.

PubMed

Ozturk Fincan, Gokce Sevim; Vural, Ismail Mert; Ercan, Zeynep Sevim; Sarioglu, Yusuf

2010-02-10

Nicotine acts as an agonist of nicotinic acetylcholine receptors, which belong to a superfamily of neurotransmitter-gated ion channels. We previously demonstrated that nicotine increases the electrical field stimulation (EFS)-evoked nitrergic relaxation responses via activation of nicotinic acetylcholine receptors. The aim of the present study is to investigate the subtypes of nicotinic acetylcholine receptors in rabbit corpus cavernosum. EFS-evoked relaxation responses were recorded from corpus cavernosum strips obtained from rabbits with an isometric force displacement transducers. Effects of nicotine on EFS-evoked relaxations were examined in pre-contracted tissues. Then the effect of nicotine on the EFS-evoked relaxations was examined in the presence of hexamethonium, dihydro-beta-erythroidine, mecamylamine or alpha-bungarotoxin. In our study, nicotine (3 x 10(-5), 10(-4)) transiently increased nitrergic relaxations induced by EFS in the rabbit isolated corpus cavernosum. While hexamethonium and mecamylamine near totally inhibited or abolished the neurorelaxation response to nicotine (3 x 10(-5)) on EFS, dihydro-beta-erythroidine and alpha-bungarotoxin partially inhibited these responses. These findings demonstrated that the alpha3-beta4, alpha4-beta2 and alpha7 subunits of nicotinic acetylcholine receptors play role on the nicotine-induced augmentation in EFS-evoked relaxation responses in rabbit corpus cavernosum. Copyright (c) 2009 Elsevier B.V. All rights reserved.

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.

Endothelium-Dependent Vasorelaxant Effect of Butanolic Fraction from Caryocar brasiliense Camb. Leaves in Rat Thoracic Aorta

PubMed Central

de Oliveira, Lais Moraes; Rodrigues, Aline Gabriela; da Silva, Elaine Fernanda; Cerqueira, Letícia Bonancio; Castro, Carlos Henrique; Pedrino, Gustavo Rodrigues; de Carvalho, Maria Helena Catelli; Pontarolo, Roberto; Costa, Elson Alves; Campos, Francinete Ramos; Filgueira, Fernando Paranaiba; Ghedini, Paulo César

2012-01-01

Caryocar brasiliense Camb. “pequi” is a native plant from the Cerrado region of Brazil that contains bioactive components reported to be antioxidant agents. Previous work has demonstrated that dietary supplementation with pequi decreased the arterial pressure of volunteer athletes. We found that the crude hydroalcoholic extract (CHE) of C. brasiliense leaves relaxed, in a concentration-dependent manner, rat aortic rings precontracted with phenylephrine, and that the butanolic fraction (BF) produced an effect similar to that of the CHE. Aortic relaxation induced by BF was abolished by endothelium removal, by incubation of the nitric oxide synthase inhibitor L-NAME, or the soluble guanylatecyclase inhibitor ODQ. However, incubation with atropine and pyrilamine had no effect on the BF-induced vasorelaxation. Moreover, this effect was not inhibited by indomethacin and tetraethylammonium. The concentration-response curve to calcium in denuded-endothelium rings was not modified after incubation with BF, and the vasorelaxation by BF in endothelium-intact rings precontracted with KCl was abolished after incubation with L-NAME. In addition, administration of BF in anesthetized rats resulted in a reversible hypotension. The results reveal that C. brasiliense possesses both in vivo and in vitro activities and that the vascular effect of BF involves stimulation of the nitric oxide/cyclic GMP pathway. PMID:22927883

Endothelium-derived relaxing factor produced and released from artery and vein is nitric oxide

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

Ignarro, L.J.; Buga, G.M.; Wood, K.S.

1987-12-01

The objective of this study was to determine whether nitric oxide (NO) is responsible for the vascular smooth muscle relaxation elicited by endothelium-derived relaxing factor (EDRF). EDRF is an unstable humoral substance released from artery and vein that mediates the action of endothelium-dependent vasodilators. NO is and unstable endothelium-independent vasodilator that is released from vasodilator drugs such as nitroprusside and glyceryl trinitrate. The authors have repeatedly observed that the actions of NO on vascular smooth muscle closely resemble those of EDRF. In the present study the vascular effects of EDRF released from perfused bovine intrapulmonary artery and vein were comparedmore » with the effects of NO delivered by superfusion over endothelium-denuded arterial and venous strips arranged in a cascade. EDRF was indistinguishable from NO in that both were labile inactivated by pyrogallol or superoxide anion, stabilized by superoxide dismutase, and inhibited by oxyhemoglobin or potassium. Both EDRF and NO produced comparable increases in cyclic GMP accumulation in artery and vein, and this cyclic GMP accumulation was inhibited by pyrogallol, oxyhemoglobin, potassium, and methylene blue. EDRF was identified chemically as NO, or a labile nitroso species, by two procedures. Thus, EDRF released from artery and vein possesses identical and biological and chemical properties as NO.« less

Activated Rho Kinase Mediates Diabetes-Induced Elevation of Vascular Arginase Activation and Contributes to Impaired Corpora Cavernosa Relaxation: Possible Involvement of p38 MAPK Activation

PubMed Central

Nunes, Kenia P.; Yao, Lin; Liao, James K.; Webb, R. Clinton; Caldwell, Ruth B.; Caldwell, R. William

2013-01-01

Introduction Activated RhoA/Rho kinase (ROCK) has been implicated in diabetes-induced erectile dysfunction. Earlier studies have demonstrated involvement of ROCK pathway in the activation of arginase in endothelial cells. However, signaling pathways activated by ROCK in the penis remain unclear. Aim We tested whether ROCK and p38 MAPK are involved in the elevation of arginase activity and subsequent impairment of corpora cavernosal (CC) relaxation in diabetes. Methods Eight weeks after streptozotocin-induced diabetes, vascular functional studies, arginase activity assay, and protein expression of RhoA, ROCK, phospho-p38 MAPK, p38 MAPK, phospho-MYPT-1Thr850, MYPT-1 and arginase levels were assessed in CC tissues from nondiabetic wild type (WT), diabetic (D) WT (WT + D), partial ROCK 2+/− knockout (KO), and ROCK 2+/− KO + D mice. Main Outcome Measures The expression of RhoA, ROCK 1 and 2, phosphorylation of MYPT-1Thr850 and p38 MAPK, arginase activity/expression, endothelial- and nitrergic-dependent relaxation of CC was assayed. Results Diabetes significantly reduced maximum relaxation (Emax) to both endothelium-dependent acetylcholine (WT + D: Emax; 61 ± 4% vs. WT: Emax; 75 ± 2%) and nitrergic nerve stimulation. These effects were associated with increased expression of active RhoA, ROCK 2, phospho-MYPT-1Thr850, phospho-p38 MAPK, arginase II, and activity of corporal arginase (1.6-fold) in WT diabetic CC. However, this impairment in CC of WT + D mice was absent in heterozygous ROCK 2+/− KO + D mice for acetylcholine (Emax: 80 ± 5%) and attenuated for nitrergic nerve-induced relaxation. CC of ROCK 2+/− KO + D mice showed much less ROCK activity, did not exhibit p38 MAPK activation, and had reduced arginase activity and arginase II expression. These findings indicate that ROCK 2 mediates diabetes-induced elevation of arginase activity. Additionally, pretreatment of WT diabetic CC with inhibitors of arginase (ABH) or p38 MAPK (SB203580) partially prevented

Acyl Chain-Dependent Effect of Lysophosphatidylcholine on Endothelium-Dependent Vasorelaxation

PubMed Central

Rao, Shailaja P.; Riederer, Monika; Lechleitner, Margarete; Hermansson, Martin; Desoye, Gernot; Hallström, Seth; Graier, Wolfgang F.; Frank, Saša

2013-01-01

Previously we identified palmitoyl-, oleoyl-, linoleoyl-, and arachidonoyl-lysophosphatidylcholine (LPC 16:0, 18:1, 18:2 and 20:4) as the most prominent LPC species generated by endothelial lipase (EL). In the present study, we examined the impact of those LPC on acetylcholine (ACh)- induced vascular relaxation. All tested LPC attenuated ACh-induced relaxation, measured ex vivo, using mouse aortic rings and wire myography. The rank order of potency was as follows: 18:2>20:4>16:0>18:1. The attenuating effect of LPC 16:0 on relaxation was augmented by indomethacin-mediated cyclooxygenase (COX)-inhibition and CAY10441, a prostacyclin (PGI2)- receptor (IP) antagonist. Relaxation attenuated by LPC 20:4 and 18:2 was improved by indomethacin and SQ29548, a thromboxane A2 (TXA2)- receptor antagonist. The effect of LPC 20:4 could also be improved by TXA2- and PGI2-synthase inhibitors. As determined by EIA assays, the tested LPC promoted secretion of PGI2, TXA2, PGF2α, and PGE2, however, with markedly different potencies. LPC 16:0 was the most potent inducer of superoxide anion production by mouse aortic rings, followed by LPC 18:2, 20:4 and 18:1, respectively. The strong antioxidant tempol recovered relaxation impairment caused by LPC 18:2, 18:1 and 20:4, but not by LPC 16:0. The tested LPC attenuate ACh-induced relaxation through induction of proconstricting prostanoids and superoxide anions. The potency of attenuating relaxation and the relative contribution of underlying mechanisms are strongly related to LPC acyl-chain length and degree of saturation. PMID:23741477

The induction of nitric oxide-mediated relaxation of human isolated pulmonary arteries by PACAP

PubMed Central

Cardell, Lars Olaf; Hjert, Ola; Uddman, Rolf

1997-01-01

The effects of pituitary adenylate cyclase-activating peptide (PACAP) and vasoactive intestinal peptide (VIP) were analysed in human isolated circular segments of pulmonary arteries. Guinea-pig pulmonary arteries were used for comparison. The responses obtained were analysed in relation to the vascular endothelium and the nitric oxide (NO) synthase inhibitor NG-monomethyl L-arginine (L-NMMA).PACAP and VIP induced concentration-dependent relaxations of precontracted pulmonary arteries. The maximal dilator response (Imax,%) and the potency (pEC50 value) were the same for both peptides, and there were no differences in the effects obtained on human and guinea-pig segments. PACAP and VIP were both more potent that acetylcholine (ACh).Removal of the vascular endothelium abolished the PACAP induced dilator response in pulmonary arteries from both species. The VIP induced dilatation was unaffected, whereas the response to ACh was abolished. L-NMMA given before PACAP inhibited the dilatation. Furthermore, L-NMMA also reversed the dilatation already induced by PACAP and excess concentrations of L-arginine restored the dilator response of the L-NMMA treated arteries.PACAP is a potent dilator of human pulmonary arteries. Although the dilator effect seems to be similar in amplitude to the one induced by VIP, the present results suggest differences in the underlying mechanisms of action (endothelium-dependency) between the two peptides. PMID:9134222

Improvement of Acetylcholine-Induced Vasodilation by Acute Exercise in Ovariectomized Hypertensive Rats.

PubMed

Cheng, Tsung-Lin; Lin, Yi-Yuan; Su, Chia-Ting; Hu, Chun-Che; Yang, Ai-Lun

2016-06-30

Postmenopause is associated with the development of cardiovascular disease, such as hypertension. However, limited information is available regarding effects of exercise on cardiovascular responses and its underlying mechanisms in the simultaneous postmenopausal and hypertensive status. We aimed to investigate whether acute exercise could enhance vasodilation mediated by acetylcholine (ACh) and sodium nitroprusside (SNP) in ovariectomized hypertensive rats. The fifteen-week-old female spontaneously hypertensive rats (SHR) were bilaterally ovariectomized, at the age of twenty-four weeks, and randomly divided into sedentary (SHR-O) and acute exercise (SHR-OE) groups. Age-matched WKY rats were used as the normotensive control group. The SHR-OE group ran on a motor-driven treadmill at a speed of 24 m/min for one hour in a moderate-intensity program. Following a single bout of exercise, rat aortas were isolated for the evaluation of the endothelium-dependent (ACh-induced) and endothelium-independent (SNP-induced) vasodilation by the organ bath system. Also, the serum levels of oxidative stress and antioxidant activities, including malondialdehyde (MDA), superoxide dismutase (SOD), and catalase, were measured after acute exercise among the three groups. We found that acute exercise significantly enhanced the ACh-induced vasodilation, but not the SNP-induced vasodilation, in ovariectomized hypertensive rats. This increased vasodilation was eliminated after the inhibition of nitric oxide synthase (NOS). Also, the activities of SOD and catalase were significantly increased after acute exercise, whereas the level of MDA was comparable among the three groups. These results indicated that acute exercise improved the endothelium-dependent vasodilating response to ACh through the NOS-related pathway in ovariectomized hypertensive rats, which might be associated with increased serum antioxidant activities.

Chronic social isolation in the prairie vole induces endothelial dysfunction: implications for depression and cardiovascular disease

PubMed Central

Peuler, Jacob D.; Scotti, Melissa-Ann L.; Phelps, Laura E.; McNeal, Neal; Grippo, Angela J.

2012-01-01

Humans with depression show impaired endothelium-dependent vasodilation, one recent demonstration of which was in the form of a reduced acetylcholine (ACh)-induced relaxation of adrenergically-precontracted small arteries biopsied from older depressed patients. Results from such uses of ACh in general have been validated as the most predictive marker of endothelium-related cardiovascular diseases. Accordingly, we examined vascular reactivity to ACh in the socially isolated prairie vole, a new animal model relevant to human depression and cardiovascular disease. Thoracic aortas were carefully dissected from female prairie voles after one month of social isolation (versus pairing with a sibling). Only aortas that contracted to the adrenergic agent phenylephrine (PE) and then relaxed to ACh were evaluated. Among those, ACh-induced relaxations were significantly reduced by social isolation (p<0.05), with maximum relaxation reaching only 30% (of PE-induced precontraction) compared to 47% in aortas from paired (control) animals. Experimental removal of the endothelium from an additional set of aortic tissues abolished all ACh relaxations including that difference. In these same tissues, maximally-effective concentrations of the nitric oxide-donor nitroprusside still completely relaxed all PE-induced precontraction of the endothelial-free smooth muscle, and to the same degree in tissues from isolated versus paired animals. Finally, in the absence of PE-induced precontraction ACh did not relax but rather contracted aortic tissues, and to a significantly greater extent in tissues from socially isolated animals if the endothelium was intact (p<0.05). Thus, social isolation in the prairie vole may 1) impair normal release of protective anti-atherosclerotic factors like nitric oxide from the vascular endothelium (without altering the inherent responsiveness of the vascular smooth muscle to such factors) and 2) cause the endothelium to release contracting factors. To our

Altered potassium ATP channel signaling in mesenteric arteries of old high salt-fed rats

PubMed Central

Whidden, Melissa A.; Basgut, Bilgen; Kirichenko, Nataliya; Erdos, Benedek; Tümer, Nihal

2016-01-01

[Purpose] Both aging and the consumption of a high salt diet are associated with clear changes in the vascular system that can lead to the development of cardiovascular disease; however the mechanisms are not clearly understood. Therefore, we examined whether aging and the consumption of excess salt alters the function of potassium ATP-dependent channel signaling in mesenteric arteries [Methods] Young (7 months) and old (29 months) Fischer 344 x Brown Norway rats were fed a control or a high salt diet (8% NaCl) for 12 days and mesenteric arteries were utilized for vascular reactivity measurements. [Results] Acetylcholine-induced endothelium relaxation was significantly reduced in old arteries (81 ± 4%) when compared with young arteries (92 ± 2%). Pretreatment with the potassium-ATP channel blocker glibenclamide reduced relaxation to acetylcholine in young arteries but did not alter dilation in old arteries. On a high salt diet, endothelium dilation to acetylcholine was significantly reduced in old salt arteries (60 ± 3%) when compared with old control arteries (81 ± 4%). Glibenclamide reduced acetylcholine-induced dilation in young salt arteries but had no effect on old salt arteries. Dilation to cromakalim, a potassium-ATP channel opener, was reduced in old salt arteries when compared with old control arteries. [Conclusion] These findings demonstrate that aging impairs endothelium-dependent relaxation in mesenteric arteries. Furthermore, a high salt diet alters the function of potassium-ATP-dependent channel signaling in old isolated mesenteric arteries and affects the mediation of relaxation stimuli. PMID:27508155

Vascular protective actions of a nitric oxide aspirin analog in both in vitro and in vivo models of diabetes mellitus.

PubMed

Pieper, Galen M; Siebeneich, Wolfgang; Olds, Cara L; Felix, Christopher C; Del Soldato, Piero

2002-06-01

Defective endothelium-dependent relaxation is observed in experimental and human diabetes mellitus. The nature of this defect is not fully understood but may involve decreased nitric oxide (NO) bioactivity due to enhanced production of reactive oxygen species (ROS). In this paper, we examine the benefits and actions of a novel NO-donating, antioxidant called 2-acetoxybenzoic acid 2-(2-nitrooxymethyl) phenyl ester, and denoted as NCX4016, on NO-mediated endothelium-dependent relaxation in normal arteries exposed to acute elevations in glucose or in arteries derived from chronic diabetic animals. Intrinsic free radical scavenging by NO-NSAIDs in solution were evaluated using electron paramagnetic resonance (EPR) spectroscopy and spin trapping with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). In acute studies, normal rat aortas were exposed in tissue culture for 18 h to 5.5 mM or 40 mM in the presence or absence of NCX4016, a NO-donating NSAID unrelated to aspirin (NCX2216) or aspirin. Vascular reactivity of thoracic aortic rings to endothelium-dependent relaxation to acetylcholine in vitro was determined. For chronic hyperglycemia, diabetes was induced in rats by intravenous injection with streptozotocin. Vascular reactivity of thoracic aortic rings to endothelium-dependent relaxation to acetylcholine in vitro was determined after 8 wks in untreated animals or animals chronically-treated with NCX4016. Antioxidant efficacy in vivo was determined by measurement of plasma isoprostanes and by nuclear binding activity of NF-kappaB in nuclear fractions of aortae. Incubation with NCX4016 and NCX2216 produced a concentration-dependent inhibition of DMPO-OH formation indicating scavenging of hydroxyl radicals (HO(*)). In contrast, little efficacy to scavenge superoxide anion radicals was noted. Acute incubation of normal arteries with elevated glucose concentration caused inhibition of normal relaxation to acetylcholine. This impairment was prevented by co-incubation with NCX4106

Ruthenium Complex Improves the Endothelial Function in Aortic Rings From Hypertensive Rats

PubMed Central

Vatanabe, Izabela Pereira; Rodrigues, Carla Nascimento dos Santos; Buzinari, Tereza Cristina; de Moraes, Thiago Francisco; da Silva, Roberto Santana; Rodrigues, Gerson Jhonatan

2017-01-01

Background The endothelium is a monolayer of cells that extends on the vascular inner surface, responsible for the modulation of vascular tone. By means of the release of nitric oxide (NO), the endothelium has an important protective function against cardiovascular diseases. Objective Verify if cis- [Ru(bpy)2(NO2)(NO)](PF6)2 (BPY) improves endothelial function and the sensibility of conductance (aorta) and resistance (coronary) to vascular relaxation induced by BPY. Methods Normotensive (2K) and hypertensive (2K-1C) Wistar rats were used. For vascular reactivity study, thoracic aortas were isolated, rings with intact endothelium were incubated with: BPY(0.01 to10 µM) and concentration effect curves to acetylcholine were performed. In addition, cumulative concentration curves were performed to BPY (1.0 nM to 0.1 µM) in aortic and coronary rings, with intact and denuded endothelium. Results In aorta from 2K-1C animals, the treatment with BPY 0.1µM increased the potency of acetylcholine-induced relaxation and it was able to revert the endothelial dysfunction. The presence of the endothelium did not modify the effect of BPY in inducing the relaxation in aortas from 2K and 2K-1C rats. In coronary, the endothelium potentiated the vasodilator effect of BPY in vessels from 2K and 2K-1C rats. Conclusion Our results suggest that 0.1 µM of BPY is able to normalize the relaxation endothelium dependent in hypertensive rats, and the compound BPY induces relaxation in aortic from normotensive and hypertensive rats with the same potency. The endothelium potentiate the relaxation effect induced by BPY in coronary from normotensive and hypertensive rats, with lower effect on coronary from hypertensive rats. PMID:28678930

A new experimental approach in endothelium-dependent pharmacological investigations on isolated porcine coronary arteries mounted for impedance planimetry

PubMed Central

Tankó, László B; Mikkelsen, Erich O; Simonsen, Ulf

1999-01-01

The aim of this study was to investigate whether the balloon-based impedance planimetry technique could be a useful tool in endothelium-dependent investigations. Porcine large coronary arteries contracted with prostaglandin F2α (PGF2α, 10 μM) did not relax to bradykinin (0.1 nM–0.1 μM), but did relax to sodium nitroprusside (SNP, 10 μM). However, after eversion of the segments, bradykinin induced relaxations with pD2 values and maximal responses of 8.78±0.09 and 75±2% (n=6), respectively. Incubation with captopril (1 μM) did not reveal a relaxation to bradykinin in the normal vessel configuration and had no influence on the concentration-relaxation relationship in everted segments. Lowering the luminal pressure in contracted segments from 131±5 mmHg (isometric, n=5) to 60 mmHg (isobaric, n=5) did not facilitate the action of bradykinin. Eversion of segments did not influence the concentration-response relationship for K+ (4.7–125 mM), PGF2α (0.3–30 μM), and SNP (30 nM–30 μM), although the time-courses of responses were faster when the agents were added from the intimal compared to the adventitial side of the preparation. In the same everted segment contracted with PGF2α, the concentration-response relationship for bradykinin was not different under isometric and isobaric conditions. These results indicate that, (1) reduced endothelium-dependent relaxations to adventitially administered substances can be ascribed to a diffusion barrier in the vessel wall, while enzymatic degradation, luminal pressure and precontractile responses seem not to play a role, (2) impedance planimetry applied to everted cylindrical segments could be a useful experimental approach in pharmacological studies of endothelium-dependent responses under isobaric and isometric conditions. PMID:10498848

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

Blood transfusions may impair endothelium-dependent vasodilatation during coronary artery bypass surgery.

PubMed

Rungatscher, Alessio; Milani, Elisabetta; Covajes, Cecilia; Hallström, Seth; Gottin, Leonardo; Guidi, Gian Cesare; Luciani, Giovanni Battista; Faggian, Giuseppe

2017-07-01

The hemolytic product free-hemoglobin (fHb) reduces nitric oxide (NO) bioavailability. The present study aims to establish whether administration of different blood transfusions result in increased circulating fHb levels and NO consumption with effects on arterial NO-dependent blood flow in patients undergoing CABG surgery. Ninety-five consecutive patients undergoing elective CABG surgery were prospectively divided in four groups based on blood transfusion requirements during surgery: stored blood cells (SBC, n. 21), intraoperative autologous salvaged blood (ASB, n. 25), SBC and ASB (n.22), no transfusion (control, n. 27). Blood samples were collected before and after intervention to analyse plasma levels of fHb and NO consumption. Endothelium-dependent relaxation was assessed in left internal mammary artery (LIMA) rings harvested before chest closure. Peripheral artery tonometry was assessed after intervention. Transfusions with SBC increased plasma fHb (p<0.05). Transfusions of ASB resulted in higher plasma fHb compared to SBC (p<0.01). fHb concentrations directly correlated with NO consumption (r=0.65, p<0.001). Maximal endothelium-dependent relaxation in LIMA was significantly attenuated in SBC and ASB patients compared to control (15.2±3.1% vs 21.1±2.5% vs 43±5.0% respectively; p<0.01). Significant correlations were identified between the aortic pressure wave velocity, plasma fHb concentration and NO consumption (p<0.01). Intraoperative blood transfusions and particularly autologous salvaged blood impair endothelium-dependent relaxation through NO scavenging by fHb. These findings obtained in vitro and in vivo provide new insights into the adverse relation between blood transfusions and patient outcome. Copyright © 2017 Elsevier Inc. All rights reserved.

Properties of acetylcholine-induced relaxation of smooth muscle isolated from the proximal colon of the guinea-pig.

PubMed

Kodama, Youhei; Iino, Satoshi; Shigemasa, Yuhsuke; Suzuki, Hikaru

2010-01-01

The properties of mechanical responses elicited by stimulation with acetylcholine (ACh) were investigated in circular smooth muscle preparations isolated from the proximal colon of guinea-pig. Application of ACh (10(-8)-10(-6) M) for 3-5 min produced a biphasic response, with an initial contraction followed by a relaxation. Atropine inhibited the initial contraction, while N(ω)-nitro-L-arginine (L-NA) inhibited the relaxation, suggesting that the former was produced by activation of muscarinic receptors while the latter was produced by an elevated production of nitric oxide (NO). In the presence of atropine, the ACh-relaxation was attenuated by removal of the mucosa and abolished by removal of both submucosal and mucosal layers. The ACh-induced relaxation was also attenuated by either tetrodotoxin (TTX, 3 × 10(-7) M) or hexamethonium (10(-6) M). In the presence of atropine, transmural nerve stimulation (TNS) elicited a biphasic response, with an initial phasic contraction followed by a relaxation. The amplitude of TNS-induced relaxation was significantly reduced by hexamethonium or L-NA and was abolished by TTX. Both ACh and TNS produced relaxation in preparations isolated from the proximal colon, but not in those from the middle part of colon. Immunohistochemistry for neuronal nitric oxide synthase revealed no difference in the distribution of nitrergic nerves between the proximal and middle part of the colon, with nitrergic nerves in both the mucosal and submucosal layers as well as in the smooth muscle and myenteric layers. These results suggest that ACh induces NO production by excitation of postganglionic nerves distributed mainly in the mucosal and submucosal layers. In circular smooth muscle preparations isolated from the middle part of colon, ACh or TNS produced contractile responses alone, with no associated relaxation, suggesting that the ACh-activated postganglionic nitrergic nerves are distributed in the mucosal and submucosal layers of the proximal

Inward rectifier potassium (Kir2.1) channels as end-stage boosters of endothelium-dependent vasodilators.

PubMed

Sonkusare, Swapnil K; Dalsgaard, Thomas; Bonev, Adrian D; Nelson, Mark T

2016-06-15

Increase in endothelial cell (EC) calcium activates calcium-sensitive intermediate and small conductance potassium (IK and SK) channels, thereby causing hyperpolarization and endothelium-dependent vasodilatation. Endothelial cells express inward rectifier potassium (Kir) channels, but their role in endothelium-dependent vasodilatation is not clear. In the mesenteric arteries, only ECs, but not smooth muscle cells, displayed Kir currents that were predominantly mediated by the Kir2.1 isoform. Endothelium-dependent vasodilatations in response to muscarinic receptor, TRPV4 (transient receptor potential vanilloid 4) channel and IK/SK channel agonists were highly attenuated by Kir channel inhibitors and by Kir2.1 channel knockdown. These results point to EC Kir channels as amplifiers of vasodilatation in response to increases in EC calcium and IK/SK channel activation and suggest that EC Kir channels could be targeted to treat endothelial dysfunction, which is a hallmark of vascular disorders. Endothelium-dependent vasodilators, such as acetylcholine, increase intracellular Ca(2+) through activation of transient receptor potential vanilloid 4 (TRPV4) channels in the plasma membrane and inositol trisphosphate receptors in the endoplasmic reticulum, leading to stimulation of Ca(2+) -sensitive intermediate and small conductance K(+) (IK and SK, respectively) channels. Although strong inward rectifier K(+) (Kir) channels have been reported in the native endothelial cells (ECs) their role in EC-dependent vasodilatation is not clear. Here, we test the idea that Kir channels boost the EC-dependent vasodilatation of resistance-sized arteries. We show that ECs, but not smooth muscle cells, of small mesenteric arteries have Kir currents, which are substantially reduced in EC-specific Kir2.1 knockdown (EC-Kir2.1(-/-) ) mice. Elevation of extracellular K(+) to 14 mm caused vasodilatation of pressurized arteries, which was prevented by endothelial denudation and Kir channel

Angiotensin II infusion alters vascular function in mouse resistance vessels: roles of O and endothelium.

PubMed

Wang, Dan; Chabrashvili, Tina; Borrego, Lillian; Aslam, Shakil; Umans, Jason G

2006-01-01

We hypothesized that prolonged angiotensin II (AngII) infusion would alter vascular reactivity by enhancing superoxide anion (O-.2) generation. Male C57BL/6 mice were infused with AngII at 400 ng/kg/min (n=16, AngII mice) or vehicle (n=16, sham mice) for 2 weeks via subcutaneous osmotic minipumps. Contraction and relaxation of mesenteric resistance vessels (MRVs) were assessed using a Mulvany-Halpern myograph. AngII infusion increased systolic blood pressure, MRV NADPH oxidase activity and expression of p22phox mRNA. Contraction to norepinephrine was unchanged, but AngII infusion increased contractile responses to AngII (41+/-5 vs. 10+/-4%, p<0.001) and endothelin-1 (ET-1; 95+/-10 vs. 70+/-9%, p<0.05), which was normalized by tempol (10(-4) M, a stable membrane-permeable superoxide dismutase mimetic) and ebselen [10(-5) M, a peroxynitrite (ONOO-) scavenger]. Endothelium removal enhanced MRV contraction to AngII and ET-1 in sham mice but blunted these contractile responses in AngII mice. Relaxation to ACh was impaired in AngII mice (60.1+/-8.8 vs. 83.2+/-3.5%, p<0.01), which normalized by tempol, whereas relaxation to sodium nitroprusside was similar in both groups. N-nitro-L-arginine (NNLA, a nitric oxide synthase inhibitor), partially inhibited acetylcholine relaxation of vessels from sham mice but not from AngII mice. The residual endothelium-dependent hyperpolarizing-factor-like relaxation was not different between groups. In conclusion,the AngII slow pressor response in mouse MRVs consisted of specific contractile hyperresponsiveness and impairment in the NO-mediated component of endothelium-dependent relaxation, which was mediated by O-.2 and ONOO- in the vascular smooth muscle cell. Copyright (c) 2006 S. Karger AG, Basel.

Vascular influences of calcium supplementation and vitamin D-induced hypercalcemia in NaCl-hypertensive rats.

PubMed

Kähönen, Mika; Näppi, Satu; Jolma, Pasi; Hutri-Kähönen, Nina; Tolvanen, Jari-Petteri; Saha, Heikki; Koivisto, Pasi; Krogerus, Leena; Kalliovalkama, Jarkko; Pörsti, Ilkka

2003-09-01

This 8-week study investigated the effects of increasing dietary Ca2+ content from 1.0% to 3.0% and hypercalcemia induced by oral 1alpha-OH vitamin D3 (1OH-D3, 1.2 microg/kg), on arterial tone in NaCl-hypertensive rats. The high-Ca2+ diet completely prevented the increase in blood pressure induced by the 6.0% NaCl chow, while plasma total Ca2+ and body weight were not different from controls. The 1OH-D3 treatment moderately elevated plasma total Ca2+ and attenuated the NaCl-induced rise in blood pressure, but also impaired weight gain. The tone of isolated mesenteric arterial rings was examined at the end of study. The endothelium-independent relaxations to nitroprusside, isoproterenol, and cromakalim were impaired in NaCl-hypertension. Experiments with NG-nitro-l-arginine methyl ester and tetraethylammonium in vitro suggested that both the nitric oxide- and hyperpolarization-mediated components of endothelium-dependent relaxation to acetylcholine were reduced in NaCl-hypertensive rats. All of the impaired relaxations in NaCl hypertension were normalized by concomitant Ca2+ supplementation. The 1OH-D3 treatment did not affect vascular relaxation, but it attenuated maximal contractile responses induced by norepinephrine and KCl by more than 50%. The reduced vasoconstrictor responses could not be explained by increased apoptosis in the vessel wall, but calcification may have played a role, since moderate signs of medial or adventitial calcification were observed in the aortic preparations after the 1OH-D3 treatment. In conclusion, a high-Ca2+ diet, which did not cause hypercalcemia, normalized blood pressure and endothelium-dependent and endothelium-independent vasorelaxation in NaCl-hypertensive rats. In contrast, chronic hypercalcemia induced by 1OH-D3 was associated with moderately lowered blood pressure, possibly because of reduced vasoconstrictor responses in arterial smooth muscle.

Effect of exercise training and food restriction on endothelium-dependent relaxation in the Otsuka Long-Evans Tokushima Fatty rat, a model of spontaneous NIDDM.

PubMed

Sakamoto, S; Minami, K; Niwa, Y; Ohnaka, M; Nakaya, Y; Mizuno, A; Kuwajima, M; Shima, K

1998-01-01

We investigated whether endothelial function may be impaired in the Otsuka Long-Evans Tokushima Fatty (OLETF) rat, a model of spontaneous NIDDM. The effect of exercise training and food restriction on endothelial function was also studied. OLETF rats were divided into three groups at age 16 weeks: sedentary, exercise trained, and food restricted (70% of the food intake of sedentary rats). Otsuka Long-Evans Tokushima rats were used as the age-matched nondiabetic controls. Endothelium-dependent relaxation of the thoracic aorta induced by histamine was significantly attenuated in the sedentary or food-restricted rats, and exercise training improved endothelial function. Relaxation induced by sodium nitroprusside, a donor of nitric oxide, did not differ significantly among groups. Both exercise training and food restriction significantly suppressed plasma levels of glucose and insulin and serum levels of triacylglycerol and cholesterol and reduced the accumulation of abdominal fat. Insulin sensitivity, as measured by the hyperinsulinemic-euglycemic clamp technique, was significantly decreased in sedentary rats but was enhanced in exercise-trained and food-restricted rats. The urinary excretion of nitrite was significantly decreased in sedentary and food-restricted rats compared with nondiabetic rats and was significantly increased in exercise-trained rats. These results indicate that exercise training, but not food restriction, prevents endothelial dysfunction in NIDDM rats, presumably due to the exercise-induced increase in the production of nitric oxide.

Hypoxia and alkalinization inhibit endothelium-derived nitric oxide but not endothelium-derived hyperpolarizing factor responses in porcine coronary artery.

PubMed

Shimizu, S; Paul, R J

1999-10-01

We investigated the mechanisms by which hypoxia and alkalinization inhibit the endothelium-dependent relaxation to Substance P (SP) in porcine coronary artery. In a KCl contracture, the major component of the SP response is endothelium-derived nitric oxide (EDNO), whereas with receptor-mediated 9,11-dideoxy-llalpha, 9alpha-epoxymethanoprostaglandin F(2alpha) (U46619) stimulation, the SP response is dependent on both EDNO and endothelium-derived hyperpolarization factor. Intracellular alkalinization by NH(4)Cl reduced the peak of SP responses when arteries were contracted with KCl, whereas with U46619 stimulation, the peak was little effected but the duration was shortened. In endothelial cell-denuded arteries, alkalinization with NH(4)Cl shifted the sodium nitroprusside concentration-relaxation relations rightward. The effects of NH(4)Cl in SP- and sodium nitroprusside-induced relaxations were attenuated by decreasing extracellular pH (pH(o)) from 7.4 to 7.2, which normalized intracellular pH (pH(i)) to control levels. In contrast, in U46619 contractures, the SP response in the presence of a NO synthase inhibitor was unaffected by NH(4)Cl. Moreover, hypoxia blunted but did not abolish the responses to SP for U46619 contractures; addition of KCl, however, abolished the SP response under hypoxia. Endothelial [Ca(2+)](i) was measured with fura-2 differentially loaded only into endothelial cells on intact arteries. Despite the attenuation of the SP response in KCl contractures by NH(4)Cl or hypoxia, endothelial [Ca(2+)](i) responses were unchanged. Our results suggest that hypoxia and alkalinization inhibit EDNO but not endothelium-derived hyperpolarization factor relaxations through a mechanism(s) not involving endothelial cell [Ca(2+)](i). Inhibition of EDNO relaxation by alkalinization with NH(4)Cl is likely to occur at the level of activation of guanylate cyclase and/or at a step downstream in smooth muscle.

Cigarette smoke induces β2-integrin-dependent neutrophil migration across human endothelium

PubMed Central

2011-01-01

Background Cigarette smoking induces peripheral inflammatory responses in all smokers and is the major risk factor for neutrophilic lung disease such as chronic obstructive pulmonary disease. The aim of this study was to investigate the effect of cigarette smoke on neutrophil migration and on β2-integrin activation and function in neutrophilic transmigration through endothelium. Methods and results Utilizing freshly isolated human PMNs, the effect of cigarette smoke on migration and β2-integrin activation and function in neutrophilic transmigration was studied. In this report, we demonstrated that cigarette smoke extract (CSE) dose dependently induced migration of neutrophils in vitro. Moreover, CSE promoted neutrophil adherence to fibrinogen. Using functional blocking antibodies against CD11b and CD18, it was demonstrated that Mac-1 (CD11b/CD18) is responsible for the cigarette smoke-induced firm adhesion of neutrophils to fibrinogen. Furthermore, neutrophils transmigrated through endothelium by cigarette smoke due to the activation of β2-integrins, since pre-incubation of neutrophils with functional blocking antibodies against CD11b and CD18 attenuated this transmigration. Conclusion This is the first study to describe that cigarette smoke extract induces a direct migratory effect on neutrophils and that CSE is an activator of β2-integrins on the cell surface. Blocking this activation of β2-integrins might be an important target in cigarette smoke induced neutrophilic diseases. PMID:21651795

Developmental conditioning of endothelium-derived hyperpolarizing factor-mediated vasorelaxation

PubMed Central

Stead, Rebecca; Musa, Moji G.; Bryant, Claire L.; Lanham, Stuart A.; Johnston, David A.; Reynolds, Richard; Torrens, Christopher; Fraser, Paul A.; Clough, Geraldine F.

2016-01-01

Objectives: The endothelium maintains vascular homeostasis through the release of endothelium-derived relaxing factors (EDRF) and endothelium-derived hyperpolarization (EDH). The balance in EDH : EDRF is disturbed in cardiovascular disease and may also be susceptible to developmental conditioning through exposure to an adverse uterine environment to predispose to later risk of hypertension and vascular disease. Methods: Developmentally conditioned changes in EDH : EDRF signalling pathways were investigated in cremaster arterioles (18–32 μm diameter) and third-order mesenteric arteries of adult male mice offspring of dams fed either a fat-rich (high fat, HF, 45% energy from fat) or control (C, 10% energy from fat) diet. After weaning, offspring either continued on high fat or were placed on control diets to give four dietary groups (C/C, HF/C, C/HF, and HF/HF) and studied at 15 weeks of age. Results: EDH via intermediate (IKCa) and small (SKca) conductance calcium-activated potassium channels contributed less than 10% to arteriolar acetylcholine-induced relaxation in in-situ conditioned HF/C offspring compared with ∼60% in C/C (P < 0.01). The conditioned reduction in EDH signalling in HF/C offspring was reversed in offspring exposed to a high-fat diet both before and after weaning (HF/HF, 55%, P < 0.01 vs. HF/C). EDH signalling was unaffected in arterioles from C/HF offspring. The changes in EDH : EDRF were associated with altered endothelial cell expression and localization of IKCa channels. Conclusion: This is the first evidence that EDH-mediated microvascular relaxation is susceptible to an adverse developmental environment through down-regulation of the IKCa signalling pathway. Conditioned offspring exposed to a ‘second hit’ (HF/HF) exhibit adaptive vascular mechanisms to preserve dilator function. PMID:26682783

Developmental conditioning of endothelium-derived hyperpolarizing factor-mediated vasorelaxation.

PubMed

Stead, Rebecca; Musa, Moji G; Bryant, Claire L; Lanham, Stuart A; Johnston, David A; Reynolds, Richard; Torrens, Christopher; Fraser, Paul A; Clough, Geraldine F

2016-03-01

The endothelium maintains vascular homeostasis through the release of endothelium-derived relaxing factors (EDRF) and endothelium-derived hyperpolarization (EDH). The balance in EDH : EDRF is disturbed in cardiovascular disease and may also be susceptible to developmental conditioning through exposure to an adverse uterine environment to predispose to later risk of hypertension and vascular disease. Developmentally conditioned changes in EDH : EDRF signalling pathways were investigated in cremaster arterioles (18-32  μm diameter) and third-order mesenteric arteries of adult male mice offspring of dams fed either a fat-rich (high fat, HF, 45% energy from fat) or control (C, 10% energy from fat) diet. After weaning, offspring either continued on high fat or were placed on control diets to give four dietary groups (C/C, HF/C, C/HF, and HF/HF) and studied at 15 weeks of age. EDH via intermediate (IKCa) and small (SKca) conductance calcium-activated potassium channels contributed less than 10% to arteriolar acetylcholine-induced relaxation in in-situ conditioned HF/C offspring compared with ∼60% in C/C (P < 0.01). The conditioned reduction in EDH signalling in HF/C offspring was reversed in offspring exposed to a high-fat diet both before and after weaning (HF/HF, 55%, P < 0.01 vs. HF/C). EDH signalling was unaffected in arterioles from C/HF offspring. The changes in EDH : EDRF were associated with altered endothelial cell expression and localization of IKCa channels. This is the first evidence that EDH-mediated microvascular relaxation is susceptible to an adverse developmental environment through down-regulation of the IKCa signalling pathway. Conditioned offspring exposed to a 'second hit' (HF/HF) exhibit adaptive vascular mechanisms to preserve dilator function.

Endogenous γ-aminobutyric Acid Modulates Tonic Guinea Pig Airway Tone and Propofol-induced Airway Smooth Muscle Relaxation

PubMed Central

Gallos, George; Gleason, Neil R.; Virag, Laszlo; Zhang, Yi; Mizuta, Kentauro; Whittington, Robert A.; Emala, Charles W.

2009-01-01

Background Emerging evidence indicates that an endogenous autocrine/paracrine system involving γ-aminobutyric acid (GABA) is present in airways. GABAA channels, GABAB receptors and the enzyme that synthesizes GABA have been identified in airway epithelium and smooth muscle. However, the endogenous ligand itself, GABA, has not been measured in airway tissues. We sought to demonstrate that GABA is released in response to contractile agonists and tonically contributes a pro-relaxant component to contracted airway smooth muscle. Methods The amount and cellular localization of GABA in upper guinea pig airways under resting and contracted tone was determined by high pressure liquid chromatography and immunohistochemistry, respectively. The contribution that endogenous GABA imparts on the maintenance of airway smooth muscle acetylcholine-induced contraction was assessed in intact guinea pig airway tracheal rings using selective GABAA antagonism (gabazine) under resting or acetylcholine-contracted conditions. The ability of an allosteric agent (propofol) to relax a substance P-induced relaxation in an endogenous GABA-dependent manner was assessed. Results GABA levels increased and localized to airway smooth muscle following contractile stimuli in guinea pig upper airways. Acetylcholine-contracted guinea pig tracheal rings exhibited an increase in contracted force upon addition of the GABAA antagonist gabazine which was subsequently reversed by the addition of the GABAA agonist muscimol. Propofol dose-dependently relaxed a substance P contraction that was blocked by gabazine. Conclusion These studies demonstrate that GABA is endogenously present and increases following contractile stimuli in guinea pig upper airways and that endogenous GABA contributes a tonic pro-relaxant component in the maintenance of airway smooth muscle tone. PMID:19322939

Antioxidant effect of lidocaine and procaine on reactive oxygen species-induced endothelial dysfunction in the rabbit abdominal aorta

PubMed Central

Lee, Jae Myeong; Jeong, Ji Seon; Cho, Sang Yun; Kim, Dong Won

2010-01-01

Background Reactive oxygen species (ROS) induce lipid peroxidation and tissue damage in the endothelium. We tested the antioxidant effect of lidocaine and procaine on ROS-induced endothelial damage in the rabbit aorta. Methods Aortic rings isolated from rabbits were suspended in an organ bath filled with Krebs-Henseleit (K-H) solution bubbled with 5% CO2 and 95% O2 at 37.5℃. After precontraction with phenylephrine (PE, 10-6 M), changes in tension were recorded following a cumulative administration of acetylcholine (ACh 3 × 10-8 to 10-6 M). Differences were measured as percentages of ACh-induced relaxation of aortic rings before and after exposure to ROS as generated by electrolysis of the K-H solution. The aortic rings were pretreated with lidocaine or procaine (10-5 M to 3 × 10-3 M) to compare their effects, as well as ROS scavengers, catalase, mannitol, sodium salicylate, and deferoxamine, and a catalase inhibitor, 3-amino-1,2,4-triazole (3AT). Results Lidocaine and procaine dose-dependently maintained endothelium-dependent relaxation induced by ACh despite ROS activity (P < 0.05 vs control value). The 3AT pretreated procaine (3 × 10-3 M) group decreased more significantly than the un-pretreated procaine group (P < 0.05). Conclusions These findings suggest that lidocaine and procaine dose-dependently preserve endothelium-dependent vasorelaxation against ROS attack, potentially via hydrogen peroxide scavenging. PMID:20740215

GPER-1 agonist G1 induces vasorelaxation through activation of epidermal growth factor receptor-dependent signalling pathway.

PubMed

Jang, Eun Jin; Seok, Young Mi; Arterburn, Jeffrey B; Olatunji, Lawrence A; Kim, In Kyeom

2013-10-01

The G protein-coupled oestrogen receptor-1 (GPER-1) agonist G1 induces endothelium-dependent relaxation. Activation of the epidermal growth factor (EGF) receptor leads to transduction of signals from the plasma membrane for the release of nitric oxide. We tested the hypothesis that G1 induces endothelium-dependent vasorelaxation through activation of the EGF receptor. Rat aortic rings were mounted in organ baths. After pretreatment with various inhibitors, aortic rings contracted with 11,9-epoxymethano-prostaglandin F2α or KCl were subjected to relaxation by G1. G1 induced endothelium-dependent vasorelaxation, which was attenuated by pretreatment with either L -N(ω) -nitroarginine methyl ester (L -NAME), an inhibitor of nitric oxide synthase, or (3aS,4R,9bR)-4-(6-bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinoline HB-EGF, heparin-binding EGF-like growth factor, a GPER-1 antagonist. Neither a general oestrogen receptor antagonist, ICI 182 780, nor a selective oestrogen receptor-α antagonist, methyl-piperidino-pyrazole dihydrochloride (MPP), had an effect on G1-induced vasorelaxation. However, pretreatment with EGF receptor blockers, AG1478 or DAPH, resulted in attenuated G1-induced vasorelaxation. In addition, pretreatment with Src inhibitor 4-amino-3-(4-chlorophenyl)-1-(t-butyl)-1H-pyrazolo[3,4-d]pyrimidine, 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine or Akt inhibitor VIII also resulted in attenuated vascular relaxation induced by the cumulative addition of G1. However, neither phosphatidylinositol-3 kinase inhibitors LY294002 and wortmannin nor an extracellular signal-regulated kinase inhibitor 1,4-diamino-2,3-dicyano-1,4-bis(o-aminophenylmercapto) butadiene monoethanolate had effect on vascular relaxation induced by the cumulative addition of G1. G1 induces endothelium-dependent vasorelaxation through Src-mediated activation of the EGF receptor and the Akt pathway in rat aorta. © 2013 Royal Pharmaceutical Society.

Chronic social stress increases nitric oxide-dependent vasorelaxation in normotensive rats

PubMed Central

Puzserova, Angelika; Bernatova, Iveta

2010-01-01

The aim of this study was to examine oxidative load and endothelium-dependent vasorelaxation in the serotonin pre-constricted femoral artery (FA) of Wistar-Kyoto (WKY) rats exposed to chronic social stress produced by crowding in the presence or absence of ascorbic acid (AsA) in working solution. Adult male rats were randomly divided into control (living space: 480 cm2/rat) or stressed (living space: 200 cm2/rat) groups for 8 weeks. Blood pressure and heart rate, determined using tail-cuff plethysmography, were not influenced by stress vs. control. Conjugated dienes (CD) and concentrations of thiobarbituric acid-reactive substances (TBARS) were measured in the left ventricle and liver (for assessment of oxidative load) and were found unchanged by chronic crowding. The nitric oxide (NO)-dependent component of endothelium-dependent relaxation was investigated in the FA using a wire myograph. In both the presence and absence of AsA, acetylcholine-induced relaxation of the FA of stressed rats significantly exceeded that of the controls, which was associated with an increase of the NO-dependent component. In conclusion, the data showed that chronic crowding did not produce oxidative stress in the organs investigated and indicate that elevation of NO production during chronic stress is an important way of adaptation, which may prevent normotensive rats from the development of stress-induced hypertension. PMID:21331175

Preliminary Studies of Acute Cadmium Administration Effects on the Calcium-Activated Potassium (SKCa and BKCa) Channels and Na+/K+-ATPase Activity in Isolated Aortic Rings of Rats.

PubMed

Vassallo, Dalton V; Almenara, Camila C P; Broseghini-Filho, Gilson Brás; Teixeira, Ariane Calazans; da Silva, David Chaves F; Angeli, Jhuli K; Padilha, Alessandra S

2018-06-01

Cadmium is an environmental pollutant closely linked with cardiovascular diseases that seems to involve endothelium dysfunction and reduced nitric oxide (NO) bioavailability. Knowing that NO causes dilatation through the activation of potassium channels and Na + /K + -ATPase, we aimed to determine whether acute cadmium administration (10 μM) alters the participation of K + channels, voltage-activated calcium channel, and Na + /K + -ATPase activity in vascular function of isolated aortic rings of rats. Cadmium did not modify the acetylcholine-induced relaxation. After L-NAME addition, the relaxation induced by acetylcholine was abolished in presence or absence of cadmium, suggesting that acutely, this metal did not change NO release. However, tetraethylammonium (a nonselective K + channels blocker) reduced acetylcholine-induced relaxation but this effect was lower in the preparations with cadmium, suggesting a decrease of K + channels function in acetylcholine response after cadmium incubation. Apamin (a selective blocker of small Ca 2+ -activated K + channels-SK Ca ), iberiotoxin (a selective blocker of large-conductance Ca 2+ -activated K + channels-BK Ca ), and verapamil (a blocker of calcium channel) reduced the endothelium-dependent relaxation only in the absence of cadmium. Finally, cadmium decreases Na + /K + -ATPase activity. Our results provide evidence that the cadmium acute incubation unaffected the calcium-activated potassium channels (SK Ca and BK Ca ) and voltage-calcium channels on the acetylcholine vasodilatation. In addition, acute cadmium incubation seems to reduce the Na + /K + -ATPase activity.

[Correction of the endothelial function damaged by gamma-irradiation with free and liposomal quercetin].

PubMed

Kyslova, O V; Sapatyĭ, A L; Kupnovyts'ka, I H; Moĭbenko, O O

2007-01-01

It has been investigation the action of solubil quercetin (corvitin) and quercetin filled liposomes (lipoflavon) on endothelium--dependent r-irradiated isolated rats aortic rings relaxations to acetylcholine. It has been showed, that corvitin addition directly to the buffer solution (0.1 mg/ml) increase endothelium--dependent vascular responses to acetylcholine on 35%, lipoflavon addition--on 25%.

Vascular smooth muscle relaxation mediated by nitric oxide donors: a comparison with acetylcholine, nitric oxide andnitroxyl ion

PubMed Central

Wanstall, Janet C; Jeffery, Trina K; Gambino, Agatha; Lovren, Fina; Triggle, Christopher R

2001-01-01

Vasorelaxant properties of three nitric oxide (NO) donor drugs (glyceryl trinitrate, sodium nitroprusside and spermine NONOate) in mouse aorta (phenylephrine pre-contracted) were compared with those of endothelium-derived NO (generated with acetylcholine), NO free radical (NO·; NO gas solution) and nitroxyl ion (NO−; from Angeli's salt). The soluble guanylate cyclase inhibitor, ODQ (1H-(1,2,4-)oxadiazolo(4,3-a)-quinoxalin-1-one; 0.3, 1 and 10 μM), concentration-dependently inhibited responses to all agents. 10 μM ODQ abolished responses to acetylcholine and glyceryl trinitrate, almost abolished responses to sodium nitroprusside but produced parallel shifts (to a higher concentration range; no depression in maxima) in the concentration-response curves for NO gas solution, Angeli's salt and spermine NONOate. The NO· scavengers, carboxy-PTIO, (2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide; 100 μM) and hydroxocobalamin (100 μM), both inhibited responses to NO gas solution and to the three NO donor drugs, but not Angeli's salt. Hydroxocobalamin, but not carboxy-PTIO, also inhibited responses to acetylcholine. The NO− inhibitor, L-cysteine (3 mM), inhibited responses to Angeli's salt, acetylcholine and the three NO donor drugs, but not NO gas solution. The data suggest that, in mouse aorta, responses to all three NO donors involve (i) activation of soluble guanylate cyclase, but to differing degrees and (ii) generation of both NO· and NO−. Glyceryl trinitrate and sodium nitroprusside, which generate NO following tissue bioactivation, have profiles resembling the profile of endothelium-derived NO more than that of exogenous NO. Spermine NONOate, which generates NO spontaneously outside the tissue, was the drug that most closely resembled (but was not identical to) exogenous NO. PMID:11588100

KCa 3.1 upregulation preserves endothelium-dependent vasorelaxation during aging and oxidative stress.

PubMed

Choi, Shinkyu; Kim, Ji Aee; Li, Hai-Yan; Shin, Kyong-Oh; Oh, Goo Taeg; Lee, Yong-Moon; Oh, Seikwan; Pewzner-Jung, Yael; Futerman, Anthony H; Suh, Suk Hyo

2016-10-01

Endothelial oxidative stress develops with aging and reactive oxygen species impair endothelium-dependent relaxation (EDR) by decreasing nitric oxide (NO) availability. Endothelial KCa 3.1, which contributes to EDR, is upregulated by H2 O2 . We investigated whether KCa 3.1 upregulation compensates for diminished EDR to NO during aging-related oxidative stress. Previous studies identified that the levels of ceramide synthase 5 (CerS5), sphingosine, and sphingosine 1-phosphate were increased in aged wild-type and CerS2 mice. In primary mouse aortic endothelial cells (MAECs) from aged wild-type and CerS2 null mice, superoxide dismutase (SOD) was upregulated, and catalase and glutathione peroxidase 1 (GPX1) were downregulated, when compared to MAECs from young and age-matched wild-type mice. Increased H2 O2 levels induced Fyn and extracellular signal-regulated kinases (ERKs) phosphorylation and KCa 3.1 upregulation. Catalase/GPX1 double knockout (catalase(-/-) /GPX1(-/-) ) upregulated KCa 3.1 in MAECs. NO production was decreased in aged wild-type, CerS2 null, and catalase(-/-) /GPX1(-/-) MAECs. However, KCa 3.1 activation-induced, N(G) -nitro-l-arginine-, and indomethacin-resistant EDR was increased without a change in acetylcholine-induced EDR in aortic rings from aged wild-type, CerS2 null, and catalase(-/-) /GPX1(-/-) mice. CerS5 transfection or exogenous application of sphingosine or sphingosine 1-phosphate induced similar changes in levels of the antioxidant enzymes and upregulated KCa 3.1. Our findings suggest that, during aging-related oxidative stress, SOD upregulation and downregulation of catalase and GPX1, which occur upon altering the sphingolipid composition or acyl chain length, generate H2 O2 and thereby upregulate KCa 3.1 expression and function via a H2 O2 /Fyn-mediated pathway. Altogether, enhanced KCa 3.1 activity may compensate for decreased NO signaling during vascular aging. © 2016 The Authors. Aging Cell published by the Anatomical Society and

Role of endothelium sensitivity to shear stress in noradrenaline-induced constriction of feline femoral arterial bed under constant flow and constant pressure perfusions.

PubMed

Kartamyshev, Sergey P; Balashov, Sergey A; Melkumyants, Arthur M

2007-01-01

The effect of shear stress at the endothelium in the attenuation of the noradrenaline-induced constriction of the femoral vascular bed perfused at a constant blood flow was investigated in 16 anesthetized cats. It is known that the adrenergic vasoconstriction of the femoral vascular bed is considerably greater at a constant pressure perfusion than at a constant blood flow. This difference may depend on the ability of the endothelium to relax smooth muscle in response to an increase in wall shear stress. Since the shear stress is directly related to the blood flow and inversely related to the third power of vessel diameter, vasoconstriction at a constant blood flow increases the wall shear stress that is the stimulus for smooth muscle relaxation opposing constriction. On the other hand, at a constant perfusion pressure, vasoconstriction is accompanied by a decrease in flow rate, which prevents a wall shear stress increase. To reveal the effect of endothelial sensitivity to shear stress, we compared noradrenaline-induced changes in total and proximal arterial resistances during perfusion of the hind limb at a constant blood flow and at a constant pressure in vessels with intact and injured endothelium. We found that in the endothelium-intact bed the same concentration of noradrenaline at a constant flow caused an increase in overall vascular peripheral resistance that was half as large as at a constant perfusion pressure. This difference is mainly confined to the proximal arterial vessels (arteries and large arterioles) whose resistance at a constant flow increased only 0.19 +/- 0.03 times compared to that at a constant pressure. The removal of the endothelium only slightly increased constrictor responses at the perfusion under a constant pressure (noradrenaline-induced increases of both overall and proximal arterial resistance augmented by 12%), while the responses of the proximal vessels at a constant flow became 4.7 +/- 0.4 times greater than in the endothelium

Uridine Adenosine Tetraphosphate-Induced Coronary Relaxation Is Blunted in Swine With Pressure Overload: A Role for Vasoconstrictor Prostanoids

PubMed Central

Zhou, Zhichao; Lankhuizen, Inge M.; van Beusekom, Heleen M.; Cheng, Caroline; Duncker, Dirk J.; Merkus, Daphne

2018-01-01

Plasma levels of the vasoactive substance uridine adenosine tetraphosphate (Up4A) are elevated in hypertensive patients and Up4A-induced vascular contraction is exacerbated in various arteries isolated from hypertensive animals, suggesting a potential role of Up4A in development of hypertension. We previously demonstrated that Up4A produced potent and partially endothelium-dependent relaxation in the porcine coronary microvasculature. Since pressure-overload is accompanied by structural abnormalities in the coronary microvasculature as well as by endothelial dysfunction, we hypothesized that pressure-overload blunts the coronary vasodilator response to Up4A, and that the involvement of purinergic receptors and endothelium-derived factors is altered. The effects of Up4A were investigated using wire-myography in isolated coronary small arteries from Sham-operated swine and swine with prolonged (8 weeks) pressure overload of the left ventricle induced by aortic banding (AoB). Expression of purinergic receptors and endothelium-derived factors was assessed in isolated coronary small arteries using real-time PCR. Up4A (10-9 to 10-5 M) failed to produce contraction in isolated coronary small arteries from either Sham or AoB swine, but produced relaxation in preconstricted arteries, which was significantly blunted in AoB compared to Sham. Blockade of purinergic P1, and P2 receptors attenuated Up4A-induced coronary relaxation more, while the effect of P2X1-blockade was similar and the effects of A2A- and P2Y1-blockade were reduced in AoB as compared to Sham. mRNA expression of neither A1, A2, A3, nor P2X1, P2X7, P2Y1, P2Y2, nor P2Y6-receptors was altered in AoB as compared to Sham, while P2Y12 expression was higher in AoB. eNOS inhibition attenuated Up4A-induced coronary relaxation in both Sham and AoB. Additional blockade of cyclooxygenase enhanced Up4A-induced coronary relaxation in AoB but not Sham swine, suggesting the involvement of vasoconstrictor prostanoids. In

Uridine Adenosine Tetraphosphate-Induced Coronary Relaxation Is Blunted in Swine With Pressure Overload: A Role for Vasoconstrictor Prostanoids.

PubMed

Zhou, Zhichao; Lankhuizen, Inge M; van Beusekom, Heleen M; Cheng, Caroline; Duncker, Dirk J; Merkus, Daphne

2018-01-01

Plasma levels of the vasoactive substance uridine adenosine tetraphosphate (Up 4 A) are elevated in hypertensive patients and Up 4 A-induced vascular contraction is exacerbated in various arteries isolated from hypertensive animals, suggesting a potential role of Up 4 A in development of hypertension. We previously demonstrated that Up 4 A produced potent and partially endothelium-dependent relaxation in the porcine coronary microvasculature. Since pressure-overload is accompanied by structural abnormalities in the coronary microvasculature as well as by endothelial dysfunction, we hypothesized that pressure-overload blunts the coronary vasodilator response to Up 4 A, and that the involvement of purinergic receptors and endothelium-derived factors is altered. The effects of Up 4 A were investigated using wire-myography in isolated coronary small arteries from Sham-operated swine and swine with prolonged (8 weeks) pressure overload of the left ventricle induced by aortic banding (AoB). Expression of purinergic receptors and endothelium-derived factors was assessed in isolated coronary small arteries using real-time PCR. Up 4 A (10 -9 to 10 -5 M) failed to produce contraction in isolated coronary small arteries from either Sham or AoB swine, but produced relaxation in preconstricted arteries, which was significantly blunted in AoB compared to Sham. Blockade of purinergic P1, and P2 receptors attenuated Up 4 A-induced coronary relaxation more, while the effect of P2X 1 -blockade was similar and the effects of A 2A - and P2Y 1 -blockade were reduced in AoB as compared to Sham. mRNA expression of neither A1, A2, A3, nor P2X 1 , P2X 7 , P2Y 1 , P2Y 2 , nor P2Y 6 -receptors was altered in AoB as compared to Sham, while P2Y 12 expression was higher in AoB. eNOS inhibition attenuated Up 4 A-induced coronary relaxation in both Sham and AoB. Additional blockade of cyclooxygenase enhanced Up 4 A-induced coronary relaxation in AoB but not Sham swine, suggesting the involvement

Time-dependent alteration in cromakalim-induced relaxation of corpus cavernosum from streptozocin-induced diabetic rats.

PubMed

Ghasemi, Mehdi; Sadeghipour, Hamed; Asadi, Shahrzad; Dehpour, Ahmad Reza

2007-09-01

The purpose of the present study was to investigate the relaxant responses to the ATP-sensitive potassium (K(ATP)) channel opener cromakalim in corpus cavernosum strips from 1-, 2-, 4-, 6-, and 8-week streptozocin-induced diabetic rats. Cromakalim (1 nM-0.1 mM) produced concentration-dependent relaxation in phenylephrine (7.5 microM)-precontracted isolated rat corporal strips. Compared with age-matched control animals, a significant enhancement in cromakalim-induced relaxation of corpus cavernosum was observed in 2-week diabetic animals, whereas the relaxant responses to cromakalim were decreased in 6-and 8-week diabetic animals. However, the cromakalim-induced relaxation was not altered in either 1-week or 4-week rat corporal strips in comparison with corresponding age-matched non-diabetic groups. Preincubation with the K(ATP) channel blocker glibenclamide (10 microM) significantly inhibited the cromakalim-induced relaxation in both non-diabetic and diabetic rat corpus cavernosum, but neither the voltage-dependent K(+) channel (K(V)) antagonist 4-aminopyridine (1 mM) nor the calcium-activated K(+) channel (K(Ca)) antagonist charybdotoxin (0.1 microM) had significant effect on cromakalim-induced relaxation in both control and diabetic rat corporal strips. Relaxation responses to the nitric oxide donor sodium nitroprusside (1 nM-0.1 mM) in diabetic rat corpus cavernosum were similar to that of age-matched controls. These data demonstrated that the relaxant responses to cromakalim were altered in diabetic cavernosal strips in a time dependent manner, suggesting that the period of diabetes mellitus may play a key role in the K(ATP) channels function in rat corpus cavernosum.

Evaluation of the rat bladder-derived relaxant factor by coaxial bioassay system.

PubMed

Bozkurt, Turgut Emrah; Sahin-Erdemli, Inci

2004-07-14

The release of bladder-derived relaxant factor in a coaxial bioassay system and the effects of reactive oxygen species were studied. After precontraction with phenylephrine (10(-6)-3x10(-6)) or 50 mM K+, acetylcholine (10(-8)-10(-3) M) induced relaxation in rat anococcygeus muscle mounted within rat bladder in a tissue bath. This relaxation was not altered by the removal of the urothelium or incubation with tetrodotoxin (10(-6) M). However, bupivacaine (10(-4) M) and lidocaine (3 x 10(-4) M) inhibited this response after raising the pH of the nutrient solution to 7.8, and oxybuprocaine (10(-4) M) exerted inhibitory effect at both physiological pH (7.4) and at pH 7.8. Exposure to electrolysis-generated reactive oxygen species or incubation with hydrogen peroxide and pyrogallol did not alter the acetylcholine response. Present results indicate that the bladder-derived relaxant factor does not behave like endothelium-derived hyperpolarizing factor, but its release may be associated with tetrodotoxin-resistant Na+ channels, which are probably in the neurons of the bladder rather than in the urothelium or detrusor muscle. Furthermore, reactive oxygen species do not interact with this relaxing factor, the exact nature and the physiological importance of which, however, remains to be established.

Ikarisoside A inhibits acetylcholine-induced catecholamine secretion and synthesis by suppressing nicotinic acetylcholine receptor-ion channels in cultured bovine adrenal medullary cells.

PubMed

Li, Xiaojia; Toyohira, Yumiko; Horisita, Takafumi; Satoh, Noriaki; Takahashi, Keita; Zhang, Han; Iinuma, Munekazu; Yoshinaga, Yukari; Ueno, Susumu; Tsutsui, Masato; Sata, Takeyoshi; Yanagihara, Nobuyuki

2015-12-01

Ikarisoside A is a natural flavonol glycoside derived from plants of the genus Epimedium, which have been used in Traditional Chinese Medicine as tonics, antirheumatics, and aphrodisiacs. Here, we report the effects of ikarisoside A and three other flavonol glycosides on catecholamine secretion and synthesis in cultured bovine adrenal medullary cells. We found that ikarisoside A (1-100 μM), but not icariin, epimedin C, or epimedoside A, concentration-dependently inhibited the secretion of catecholamines induced by acetylcholine, a physiological secretagogue and agonist of nicotinic acetylcholine receptors. Ikarisoside A had little effect on catecholamine secretion induced by veratridine and 56 mM K(+). Ikarisoside A (1-100 μM) also inhibited (22)Na(+) influx and (45)Ca(2+) influx induced by acetylcholine in a concentration-dependent manner similar to that of catecholamine secretion. In Xenopus oocytes expressing α3β4 nicotinic acetylcholine receptors, ikarisoside A (0.1-100 μM) directly inhibited the current evoked by acetylcholine. It also suppressed (14)C-catecholamine synthesis and tyrosine hydroxylase activity induced by acetylcholine at 1-100 μM and 10-100 μM, respectively. The present findings suggest that ikarisoside A inhibits acetylcholine-induced catecholamine secretion and synthesis by suppression of nicotinic acetylcholine receptor-ion channels in bovine adrenal medullary cells.

Endogenous gamma-aminobutyric acid modulates tonic guinea pig airway tone and propofol-induced airway smooth muscle relaxation.

PubMed

Gallos, George; Gleason, Neil R; Virag, Laszlo; Zhang, Yi; Mizuta, Kentaro; Whittington, Robert A; Emala, Charles W

2009-04-01

Emerging evidence indicates that an endogenous autocrine/paracrine system involving gamma-aminobutyric acid (GABA) is present in airways. GABAA channels, GABAB receptors, and the enzyme that synthesizes GABA have been identified in airway epithelium and smooth muscle. However, the endogenous ligand itself, GABA, has not been measured in airway tissues. The authors sought to demonstrate that GABA is released in response to contractile agonists and tonically contributes a prorelaxant component to contracted airway smooth muscle. The amount and cellular localization of GABA in upper guinea pig airways under resting and contracted tone was determined by high pressure liquid chromatography and immunohistochemistry, respectively. The contribution that endogenous GABA imparts on the maintenance of airway smooth muscle acetylcholine-induced contraction was assessed in intact guinea pig airway tracheal rings using selective GABAA antagonism (gabazine) under resting or acetylcholine-contracted conditions. The ability of an allosteric agent (propofol) to relax a substance P-induced relaxation in an endogenous GABA-dependent manner was assessed. GABA levels increased and localized to airway smooth muscle after contractile stimuli in guinea pig upper airways. Acetylcholine-contracted guinea pig tracheal rings exhibited an increase in contracted force upon addition of the GABAA antagonist gabazine that was subsequently reversed by the addition of the GABAA agonist muscimol. Propofol dose-dependently relaxed a substance P contraction that was blocked by gabazine. These studies demonstrate that GABA is endogenously present and increases after contractile stimuli in guinea pig upper airways and that endogenous GABA contributes a tonic prorelaxant component in the maintenance of airway smooth muscle tone.

Rho-kinase inhibitor and nicotinamide adenine dinucleotide phosphate oxidase inhibitor prevent impairment of endothelium-dependent cerebral vasodilation by acute cigarette smoking in rats.

PubMed

Iida, Hiroki; Iida, Mami; Takenaka, Motoyasu; Fukuoka, Naokazu; Dohi, Shuji

2008-06-01

We previously reported that acute cigarette smoking can cause a dysfunction of endothelium-dependent vasodilation in cerebral vessels, and that blocking the angiotensin II (Ang II) type 1 (AT1) receptor with valsartan prevented this impairment. Our aim was to investigate the effects of a Rho-kinase inhibitor (fasudil) and a Nicotinamide Adenine Dinucleotide PHosphate (NADPH) oxidase inhibitor (apocynin) on smoking-induced endothelial dysfunction in cerebral arterioles. In Sprague-Dawley rats, we used a closed cranial window preparation to measure changes in pial vessel diameters following topical acetylcholine (ACh) before smoking. After one-minute smoking, we again examined the arteriolar responses to ACh. Finally, after intravenous fasudil or apocynin pre-treatment we re-examined the vasodilator responses to topical ACh (before and after cigarette smoking). Under control conditions, cerebral arterioles were dose-dependently dilated by topical ACh (10(-6) M and 10(-5) M). One hour after a one-minute smoking (1 mg-nicotine cigarette), 10(-5) M ACh constricted cerebral arterioles. However, one hour after a one-minute smoking, 10(-5) M ACh dilated cerebral pial arteries both in the fasudil pre-treatment and the apocynin pre-treatment groups, responses that were significantly different from those obtained without fasudil or apocynin pre-treatment. Thus, inhibition of Rho-kinase and NADPH oxidase activities may prevent the above smoking-induced impairment of endothelium-dependent vasodilation.

(-)-Epicatechin-induced relaxation of isolated human saphenous vein: Roles of K+ and Ca2+ channels.

PubMed

Marinko, Marija; Jankovic, Goran; Nenezic, Dragoslav; Milojevic, Predrag; Stojanovic, Ivan; Kanjuh, Vladimir; Novakovic, Aleksandra

2018-02-01

In this study, we aimed to investigate relaxant effect of flavanol (-)-epicatechin on the isolated human saphenous vein (HSV), as a part of its cardioprotective action, and to define the mechanisms underlying this vasorelaxation. (-)-Epicatechin induced a concentration-dependent relaxation of HSV pre-contracted by phenylephrine. Among K + channel blockers, 4-aminopyridine, margatoxin, and iberiotoxin significantly inhibited relaxation of HSV, while glibenclamide considerably reduced effects of the high concentrations of (-)-epicatechin. Additionally, (-)-epicatechin relaxed contraction induced by 80 mM K + , whereas in the presence of nifedipine produced partial relaxation of HSV rings pre-contracted by phenylephrine. In Ca 2+ -free solution, (-)-epicatechin relaxed contraction induced by phenylephrine, but had no effect on contraction induced by caffeine. A sarcoplasmic reticulum Ca 2+ -ATPase inhibitor, thapsigargin, significantly reduced relaxation of HSV produced by (-)-epicatechin. These results demonstrate that (-)-epicatechin produces endothelium-independent relaxation of isolated HSV rings. Vasorelaxation to (-)-epicatechin probably involves activation of 4-aminopyridine- and margatoxin-sensitive K V channels, BK Ca channels, and at least partly, K ATP channels. In addition, not only the inhibition of extracellular Ca 2+ influx, but regulation of the intracellular Ca 2+ release, via inositol-trisphosphate receptors and reuptake into sarcoplasmic reticulum, via stimulation of Ca 2+ -ATPase, as well, most likely participate in (-)-epicatechin-induced relaxation of HSV. Copyright © 2017 John Wiley & Sons, Ltd.

Effects of exercise training and detraining on cutaneous microvascular function in man: the regulatory role of endothelium-dependent dilation in skin vasculature.

PubMed

Wang, Jong-Shyan

2005-01-01

This study investigated how exercise training and detraining affect the cutaneous microvascular function and the regulatory role of endothelium-dependent dilation in skin vasculature. Ten healthy sedentary subjects cycled on an ergometer at 50% of maximal oxygen uptake (VO(2max)) for 30 min daily, 5 days a week, for 8 weeks, and then detrained for 8 weeks. Plasma nitric oxide (NO) metabolites (nitrite plus nitrate) were measured by a microplate fluorometer. The cutaneous microvascular perfusion responses to six graded levels of iontophoretically applied 1% acetylcholine (ACh) and 1% sodium nitroprusside (SNP) in the forearm skin were determined by laser Doppler. After training, (1) resting heart rate and blood pressure were reduced, whereas VO(2max), skin blood flow and cutaneous vascular conductance to acute exercise were enhanced; (2) plasma NO metabolite levels and ACh-induced cutaneous perfusion were increased; (3) skin vascular responses to SNP did not change significantly. However, detraining reversed these effects on cutaneous microvascular function and plasma NO metabolite levels. The results suggest that endothelium-dependent dilation in skin vasculature is enhanced by moderate exercise training and reversed to the pretraining state with detraining.

Nicotine impairs cyclooxygenase-2-dependent kinin-receptor-mediated murine airway relaxations

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

Xu, Yuan, E-mail: yuan.xu@ki.se; Cardell, Lars-Olaf

Introduction: Cigarette smoke induces local inflammation and airway hyperreactivity. In asthmatics, it worsens the symptoms and increases the risk for exacerbation. The present study investigates the effects of nicotine on airway relaxations in isolated murine tracheal segments. Methods: Segments were cultured for 24 h in the presence of vehicle, nicotine (10 μM) and/or dexamethasone (1 μM). Airway relaxations were assessed in myographs after pre-contraction with carbachol (1 μM). Kinin receptors, cyclooxygenase (COX) and inflammatory mediator expressions were assessed by real-time PCR and confocal-microscopy-based immunohistochemistry. Results: The organ culture procedure markedly increased bradykinin- (selective B{sub 2} receptor agonist) and des-Arg{sup 9}-bradykinin-more » (selective B{sub 1} receptor agonist) induced relaxations, and slightly increased relaxation induced by isoprenaline, but not that induced by PGE{sub 2}. The kinin receptor mediated relaxations were epithelium-, COX-2- and EP2-receptor-dependent and accompanied by drastically enhanced mRNA levels of kinin receptors, as well as inflammatory mediators MCP-1 and iNOS. Increase in COX-2 and mPGES-1 was verified both at mRNA and protein levels. Nicotine selectively suppressed the organ-culture-enhanced relaxations induced by des-Arg{sup 9}-bradykinin and bradykinin, at the same time reducing mPGES-1 mRNA and protein expressions. α7-nicotinic acetylcholine receptor inhibitors α-bungarotoxin and MG624 both blocked the nicotine effects on kinin B{sub 2} receptors, but not those on B{sub 1}. Dexamethasone completely abolished kinin-induced relaxations. Conclusion: It is tempting to conclude that a local inflammatory process per se could have a bronchoprotective component by increasing COX-2 mediated airway relaxations and that nicotine could impede this safety mechanism. Dexamethasone further reduced airway inflammation together with relaxations. This might contribute to the steroid resistance

Mechanisms of the palmitoylcarnitine-induced response in vascular endothelial cells.

PubMed

Taki, H; Muraki, K; Imaizumi, Y; Watanabe, M

1999-09-01

The mechanisms of Ca2+ mobilization induced by palmitoylcarnitine (Palcar) in rabbit aortic endothelial cells (ETCs) were examined using electrophysiological techniques. The results obtained were compared with those induced by acetylcholine (ACh). When a rabbit aortic muscle preparation with an intact endothelium was treated with 10 microM Palcar, the ACh-induced relaxation was markedly attenuated, whereas endothelium-independent relaxation caused by sodium nitroprusside was not affected. Under perforated-patch whole-cell-clamp conditions, the application of Palcar over the concentration range 0.3 and 10 microM elicited a slowly activating outward current (IPalcar-out), whereas ACh induced a rapidly activating outward current (IACh). A potassium channel blocker, 4-aminopyridine, significantly inhibited both IPalcar-out and IACh. Removal of external Ca2+ almost abolished IPalcar-out. Under the same conditions, however, IACh remained transient. Addition of cation channel blockers SK&F96365 and La3+ inhibited IPalcar-out more effectively than IACh. Application of staurosporine, an inhibitor of protein kinase C, affected neither IACh nor IPalcar-out. In contrast, treatment of ETCs with pertussis toxin (PTX) reduced IACh and almost abolished IPalcar-out. These findings demonstrate that, in ETCs, Palcar induces Ca2+ influx via the activation of PTX-sensitive GTP-binding protein, leading to the activation of Ca(2+)-dependent K+ current and hyperpolarization of the cell.

Oxidative stress augments secretion of endothelium-derived relaxing peptides, C-type natriuretic peptide and adrenomedullin.

PubMed

Chun, T H; Itoh, H; Saito, T; Yamahara, K; Doi, K; Mori, Y; Ogawa, Y; Yamashita, J; Tanaka, T; Inoue, M; Masatsugu, K; Sawada, N; Fukunaga, Y; Nakao, K

2000-05-01

Excess oxidative stress is one of the major metabolic abnormalities on vascular walls in hypertension and atherosclerosis. In order to further elucidate the endothelial function under oxidative stress, the effect of hydrogen peroxide (H2O2) on expression of two novel endothelium-derived vasorelaxing peptides, C-type natriuretic peptide (CNP) and adrenomedullin (AM) from bovine carotid artery endothelial cells (BCAECs) was examined. BCAECs were treated with H2O2 (0.1-1.0 mmol/ l) and/or an antioxidant, N-acetylcysteine (NAC) (5-10 mmol/l), and incubated for 48 h. The concentrations of CNP and AM were measured with the specific radioimmuno assays that we originally developed. CNP and AM mRNA expressions were also examined by reverse transcription-polymerase chain reaction (RT-PCR). Treatment of BCAECs with 0.5 and 1 mmol/l H2O2 induced 9-and 10-fold increases of CNP concentration in the media. Addition of 10 mmol/l NAC significantly suppressed the effect of H2O2 by 52%. RT-PCR analysis showed that CNP mRNA expression in BCAECs was also rapidly augmented within 1 h with H2O2 (1 mmol/l) treatment, and reached a peak at 3 h to show a 10-fold increase. AM secretion from BCAECs also increased to two-fold with exposure to 0.5 mmol/l H2O2, accompanied with the augmented level of AM mRNA. NAC 10 mmol/l completely suppressed the effect of H2O2 on AM secretion. In this study, it has been demonstrated that H2O2 augments endothelial secretion of the two endothelium-derived relaxing peptides, CNP and AM. Our findings suggest the increased secretion of CNP and AM from endothelium under oxidative stress may function to compensate the impaired nitric oxide-dependent vasorelaxation in hypertension and atherosclerosis.

N-acetylcysteine enhances endothelium-dependent vasorelaxation in the isolated rat mesenteric artery.

PubMed

Lopez, B L; Snyder, J W; Birenbaum, D S; Ma, X I

1998-10-01

Previous studies have suggested that N-acetylcysteine (NAC) may confer additional protection in acetaminophen (APAP) overdose by improving hepatic microcirculation. We hypothesize that NAC enhances release of nitric oxide (NO) from the vasculature. Sprague-Dawley rat superior mesenteric artery rings were suspended in oxygenated Krebs-Henseleit tissue baths and contracted with U-46619 (a thromboxane A2-mimetic). In part 1, the effect of NAC on endothelial cell (EC) release of NO was assessed by measurement of vasorelaxation induced by acetylcholine (ACh, an EC-dependent vasorelaxor) in the presence and absence of NAC. In part 2, the effect of glutathione (a major component of NAC hepatoprotection) was examined by measuring ACh-induced vasorelaxation in rings from rats treated with L-buthionine sulfoxamine (BSO, a glutathione synthesis inhibitor). Data were analyzed by repeated-measures ANOVA. Addition of 15 to 30 mmol/L NAC after ring contraction had no direct vasodilatory effect. By contrast, pretreatment of rings with NAC (15 mmol/L) enhanced vasorelaxation induced by ACh (95.0% +/- 7.9% versus 62.3% +/- 7.6% for control; ACh dose, 1 mumol/L; P < .001) or by A23187, a receptor-independent, NO-mediated vasodilator (91.6% +/- 9.6% versus 68.3% +/- 12.1% for control; A23187 dose, 1 mumol/L; P < .001). In rings from BSO-treated rats, NAC also enhanced vasorelaxation (76.5% +/- 7.1%; P < .001 versus control), but to a lesser degree than in nontreated rats. NAC enhances endothelium-dependent vasodilation in an isolated rat mesenteric artery ring preparation. In addition to its antioxidant effects, NAC may decrease APAP hepatotoxicity by stimulating NO production and improving microvascular circulation.

Jabuticaba-Induced Endothelium-Independent Vasodilating Effect on Isolated Arteries.

PubMed

Andrade, Daniela Medeiros Lobo de; Borges, Leonardo Luis; Torres, Ieda Maria Sapateiro; Conceição, Edemilson Cardoso da; Rocha, Matheus Lavorenti

2016-09-01

Despite the important biological effects of jabuticaba, its actions on the cardiovascular system have not been clarified. To determine the effects of jabuticaba hydroalcoholic extract (JHE) on vascular smooth muscle (VSM) of isolated arteries. Endothelium-denuded aortic rings of rats were mounted in isolated organ bath to record isometric tension. The relaxant effect of JHE and the influence of K+ channels and Ca2+ intra- and extracellular sources on JHE-stimulated response were assessed. Arteries pre-contracted with phenylephrine showed concentration-dependent relaxation (0.380 to 1.92 mg/mL). Treatment with K+ channel blockers (tetraethyl-ammonium, glibenclamide, 4-aminopyridine) hindered relaxation due to JHE. In addition, phenylephrine-stimulated contraction was hindered by previous treatment with JHE. Inhibition of sarcoplasmic reticulum Ca2+ ATPase did not change relaxation due to JHE. In addition, JHE inhibited the contraction caused by Ca2+ influx stimulated by phenylephrine and KCl (75 mM). JHE induces endothelium-independent vasodilation. Activation of K+ channels and inhibition of Ca2+ influx through the membrane are involved in the JHE relaxant effect. Embora a jabuticaba apresente importantes efeitos biológicos, suas ações sobre o sistema cardiovascular ainda não foram esclarecidas. Determinar os efeitos do extrato de jabuticaba (EHJ) sobre o músculo liso vascular (MLV) em artérias isoladas. Aortas (sem endotélio) de ratos foram montadas em banho de órgãos isolados para registro de tensão isométrica. Foram verificados o efeito relaxante, a influência dos canais de K+ e das fontes de Ca2+ intra- e extracelular sob a resposta estimulada pelo EHJ. Artérias pré-contraídas com fenilefrina apresentaram relaxamento concentração-dependente (0,380 a 1,92 mg/mL). O tratamento com bloqueadores de canais de K+ (tetraetilamônio, glibenclamida, 4-aminopiridina) prejudicaram o relaxamento pelo EHJ. A contração estimulada com fenilefrina tamb

Thiopental inhibits nitric oxide production in rat aorta.

PubMed

Castillo, C; Asbun, J; Escalante, B; Villalón, C M; López, P; Castillo, E F

1999-12-01

We studied whether thiopental affects endothelial nitric oxide dependent vasodilator responses and nitrite production (an indicator of nitric oxide production) elicited by acetylcholine, histamine, and A23187 in rat aorta (artery in which nitric oxide is the main endothelial relaxant factor). In addition, we evaluated the barbiturate effect on nitric oxide synthase (NOS) activity in both rat aorta and kidney homogenates. Thiopental (10-100 microg/mL) reversibly inhibited the endothelium-dependent relaxation elicited by acetylcholine, histamine, and A23187. On the contrary, this anesthetic did not modify the endothelium-independent but cGMP-dependent relaxation elicited by sodium nitroprusside (1 nM - 1 microM) and nitroglycerin (1 nM - 1 microM), thus excluding an effect of thiopental on guanylate cyclase of vascular smooth muscle. Thiopental (100 microg/mL) inhibited both basal (87.8+/-14.3%) and acetylcholine- or A23187-stimulated (78.6+/-3.9 and 39.7+/-5.6%, respectively) production of nitrites in aortic rings. In addition the barbiturate inhibited (100 microg/mL) the NOS (45+/-4 and 42.8+/-9%) in aortic and kidney homogenates, respectively (measured as 14C-labeled citrulline production). In conclusion, thiopental inhibition of endothelium-dependent relaxation and nitrite production in aortic rings strongly suggests an inhibitory effect on NOS. Thiopental inhibition of the NOS provides further support to this contention.

Pomegranate Extract Enhances Endothelium-Dependent Coronary Relaxation in Isolated Perfused Hearts from Spontaneously Hypertensive Ovariectomized Rats

PubMed Central

Delgado, Nathalie T. B.; Rouver, Wender do N.; Freitas-Lima, Leandro C.; de Paula, Tiago D.-C.; Duarte, Andressa; Silva, Josiane F.; Lemos, Virgínia S.; Santos, Alexandre M. C.; Mauad, Helder; Santos, Roger L.; Moysés, Margareth R.

2017-01-01

prevented the decreasing in plasmatic nitrite. We observed a reduction in total cholesterol and LDL in the Sham-PHE group. The treatment with PHE enhances the endothelium-dependent coronary relaxation and improves cardiovascular parameters, which suggests a therapeutic role of PHE. PMID:28101057

Endothelium-derived relaxing factor (nitric oxide) has protective actions in the stomach

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

MacNaughton, W.K.; Wallace, J.L.; Cirino, G.

1989-01-01

The role that nitric oxide, an endothelium-derived relaxing factor, may play in the regulation of gastric mucosal defense was investigated by assessing the potential protective actions of this factor against the damage caused by ethanol in an ex vivo chamber preparation of the rat stomach. Topical application of glyceryl trinitrate and sodium nitroprusside, which have been shown to release nitric oxide, markedly reduced the area of 70% ethanol-induced hemorrhagic damage. Topical application of a 0.01% solution of authentic nitric oxide also significantly reduced the severity of mucosal damage. Pretreatment with indomethacin precluded the involvement of endogenous prostaglandins in the protectivemore » effects of these agents. The protective effects of NO were transient, since a delay of 5 minutes between NO administration and ethanal administration resulted in a complete loss of the protective activity. The protection against ethanol afforded by 10 ug/ml nitroprusside could be completely reversed by intravenous infusion of either 1% methylene blue or 1 mM hemoglobin, both of which inhibit vasodilation induced by nitric oxide. Intravenous infusion of 1% methylene blue significantly increased the susceptibility of the mucosa to damage induced by topical 20% ethanol.« less

Endothelium-dependent vasodilatory signalling modulates α1 -adrenergic vasoconstriction in contracting skeletal muscle of humans.

PubMed

Hearon, Christopher M; Kirby, Brett S; Luckasen, Gary J; Larson, Dennis G; Dinenno, Frank A

2016-12-15

'Functional sympatholysis' describes the ability of contracting skeletal muscle to attenuate sympathetic vasoconstriction, and is critical to ensure proper blood flow and oxygen delivery to metabolically active skeletal muscle. The signalling mechanism responsible for sympatholysis in healthy humans is unknown. Evidence from animal models has identified endothelium-derived hyperpolarization (EDH) as a potential mechanism capable of attenuating sympathetic vasoconstriction. In this study, increasing endothelium-dependent signalling during exercise significantly enhanced the ability of contracting skeletal muscle to attenuate sympathetic vasoconstriction in humans. This is the first study in humans to identify endothelium-dependent regulation of sympathetic vasoconstriction in contracting skeletal muscle, and specifically supports a role for EDH-like vasodilatory signalling. Impaired functional sympatholysis is a common feature of cardiovascular ageing, hypertension and heart failure, and thus identifying fundamental mechanisms responsible for sympatholysis is clinically relevant. Stimulation of α-adrenoceptors elicits vasoconstriction in resting skeletal muscle that is blunted during exercise in an intensity-dependent manner. In humans, the underlying mechanisms remain unclear. We tested the hypothesis that stimulating endothelium-dependent vasodilatory signalling will enhance the ability of contracting skeletal muscle to blunt α 1 -adrenergic vasoconstriction. Changes in forearm vascular conductance (FVC; Doppler ultrasound, brachial intra-arterial pressure via catheter) to local intra-arterial infusion of phenylephrine (PE; α 1 -adrenoceptor agonist) were calculated during (1) infusion of the endothelium-dependent vasodilators acetylcholine (ACh) and adenosine triphosphate (ATP), the endothelium-independent vasodilator (sodium nitroprusside, SNP), or potassium chloride (KCl) at rest; (2) mild or moderate intensity handgrip exercise; and (3) combined mild

Acute but not chronic metabolic acidosis potentiates the acetylcholine-induced reduction in blood pressure: an endothelium-dependent effect

PubMed Central

Celotto, A.C.; Ferreira, L.G.; Capellini, V.K.; Albuquerque, A.A.S.; Rodrigues, A.J.; Evora, P.R.B.

2015-01-01

Metabolic acidosis has profound effects on vascular tone. This study investigated the in vivo effects of acute metabolic acidosis (AMA) and chronic metabolic acidosis (CMA) on hemodynamic parameters and endothelial function. CMA was induced by ad libitum intake of 1% NH4Cl for 7 days, and AMA was induced by a 3-h infusion of 6 M NH4Cl (1 mL/kg, diluted 1:10). Phenylephrine (Phe) and acetylcholine (Ach) dose-response curves were performed by venous infusion with simultaneous venous and arterial blood pressure monitoring. Plasma nitrite/nitrate (NOx) was measured by chemiluminescence. The CMA group had a blood pH of 7.15±0.03, which was associated with reduced bicarbonate (13.8±0.98 mmol/L) and no change in the partial pressure of arterial carbon dioxide (PaCO2). The AMA group had a pH of 7.20±0.01, which was associated with decreases in bicarbonate (10.8±0.54 mmol/L) and PaCO2 (47.8±2.54 to 23.2±0.74 mmHg) and accompanied by hyperventilation. Phe or ACh infusion did not affect arterial or venous blood pressure in the CMA group. However, the ACh infusion decreased the arterial blood pressure (ΔBP: -28.0±2.35 mm Hg [AMA] to -4.5±2.89 mmHg [control]) in the AMA group. Plasma NOx was normal after CMA but increased after AMA (25.3±0.88 to 31.3±0.54 μM). These results indicate that AMA, but not CMA, potentiated the Ach-induced decrease in blood pressure and led to an increase in plasma NOx, reinforcing the effect of pH imbalance on vascular tone and blood pressure control. PMID:26648089

Regular exercise enhances blood pressure lowering effect of acetylcholine by increased contribution of nitric oxide.

PubMed

Dörnyei, G; Monos, E; Kaley, G; Koller, A

2000-01-01

This study is aimed to test the hypothesis, that short-term daily bouts of exercise alter the endothelial regulation of peripheral vascular resistance by nitric oxide. Rats ran on a treadmill once a day, 5 days a week, for an average of three weeks with gradually increasing intensity (EX), while a control group remained sedentary (SED). Dose dependent reductions in mean arterial blood pressure (resting MABP; SED: 120.0 +/- 3.4 and EX: 127.8 +/- 4.0 mm Hg) of pentobarbital anesthetized rats to intravenous endothelium independent dilator sodium nitropmsside (SNP; 0.6-3.0 microg/kg) were not different in EX and SED animals. In contrast, dose dependent reductions in MABP to endothelium dependent dilator acetylcholine (ACh) were significantly enhanced in EX compared to those in SED rats (at 0.5 and 1.0 microg/kg ACh: 60.3 +/- 2.4 and 66.5 +/- 1.8 vs 52.8 +/- 2.0 and 59.8 +/- 1.7 mmHg, respectively, p<0.01). There was no significant difference in the heart rate (HR) response to ACh and SNP in the two groups of rats. Intravenous administration of 20 mg/kg Nomega-nitro-L-arginine (L-NNA, a nitric oxide synthase inhibitor) elicited a similar increase (approximately 30%) in the MABP in the two groups and eliminated the difference between ACh-induced blood pressure lowering responses in EX and SED rats (at 0.5 and 1.0 microg/kg ACh: 44.6 +/- 4.7 and 56.3 +/- 4.4 vs 50.9 +/- 4.5 and 59.4 +/- 3.6 mm Hg, respectively). Thus, we suggest that the enhanced acetylcholine-induced decrease in systemic blood pressure following regular daily exercise is primarily due to the augmented synthesis of nitric oxide in the endothelium of peripheral vasculature. This change in the function of endothelium could be important in the adaptation of circulation to exercise training.

The time-dependence of exchange-induced relaxation during modulated radio frequency pulses.

PubMed

Sorce, Dennis J; Michaeli, Shalom; Garwood, Michael

2006-03-01

The problem of the relaxation of identical spins 1/2 induced by chemical exchange between spins with different chemical shifts in the presence of time-dependent RF irradiation (in the first rotating frame) is considered for the fast exchange regime. The solution for the time evolution under the chemical exchange Hamiltonian in the tilted doubly rotating frame (TDRF) is presented. Detailed derivation is specified to the case of a two-site chemical exchange system with complete randomization between jumps of the exchanging spins. The derived theory can be applied to describe the modulation of the chemical exchange relaxation rate constants when using a train of adiabatic pulses, such as the hyperbolic secant pulse. Theory presented is valid for quantification of the exchange-induced time-dependent rotating frame longitudinal T1rho,ex and transverse T2rho,ex relaxations in the fast chemical exchange regime.

Chronic administration of imipramine but not agomelatine and moclobemide affects the nitrergic relaxation of rabbit corpus cavernosum smooth muscle.

PubMed

Gocmez, Semil Selcen; Utkan, Tijen; Gacar, Nejat

2013-08-15

Sexual dysfunction is a common and underestimated effect of antidepressants. However, the mechanism by which these drugs cause erectile dysfunction is unclear. We investigated the reactivity of the corpus cavernosum of rabbits that were treated with either chronic imipramine, which is a tricyclic agent; agomelatine, which is a melatonergic agonist and serotonin 5HT(2c) antagonist; or moclobemide, which is a reversible inhibitor of monoamine-oxidase A. Twenty rabbits were randomly divided into four groups: the control group (n=5), the imipramine-treated group (n=5), which received i.p. injections of 10 mg/kg/day of imipramine, the moclobemide-treated group (n=5), which received i.p. injections of 20 mg/kg/day of moclobemide, and the agomelatine-treated group (n=5), which was orally administered 10 mg/kg/day of agomelatine. The reactivities of corpus cavernosum tissue obtained from the antidepressant-treated and the control groups were studied in organ chambers after the animals were subjected to 21 days of drug administration. The acetylcholine-induced endothelium-dependent and the electrical field stimulation (EFS)-induced neurogenic relaxation of the corpus cavernosum of the imipramine-treated group was significantly decreased compared with the control group. However, neither the acetylcholine- nor EFS-induced relaxation was changed in the moclobemide- or agomelatine-treated groups. There were no change in the relaxant response to the nitric oxide (NO) donor sodium nitroprusside and contractile response to KCl between the groups. This study suggests that chronic imipramine treatment but not agomelatine and moclobemide treatments causes significant functional changes in the penile erectile tissue of rabbits and that these changes may contribute to the development of impotence. © 2013 Elsevier B.V. All rights reserved.

Effect of L-arginine on the relaxation caused by sodium nitroprusside on isolated rat renal artery.

PubMed

Orescanin, Z; Milovanović, S R

2006-12-01

In the present study we investigated the mechanism of nitric oxide induced relaxation of renal arteries, with or without endothelium, taken from normotensive and spontaneously hypertensive (SH) rats. With this purpose in mind, the effects of the nitric oxide donor, sodium nitroprusside (SNP), with and without L-arg in the medium, on isolated rat renal artery relaxation were studied. Relaxing effect of SNP was higher in normotensive (10(-5) M of SNP caused 220% of relaxation in the cases with endothelium and 240% without endothelium), in comparison with SH rats (100% of relaxation with endothelium and 150% without). L-arg antagonized the relaxing effect of SNP in the examined renal arteries, more in normotensive (100-160% with endothelium and 110-195% without) than in hypertensive ones (0-10% with endothelium and 35-75% without) at SNP concentrations 10(-7) - 10(-5) M, respectively (*P < 0.05; **P < 0.001). L-arg did not significantly change relaxing effect of SNP in the isolated renal arteries with endothelium taken from SH rats, which show that L-arg, by modifying the chemical versatility of NO into redox active forms -nitrosonium (NO+) and -nitroxyl (NO-), produces different relaxing effects in normotensive and hypertensive isolated arteries of rats, with or without endothelium, potentiating the role of nitroxyl induced relaxation in SH rats.

Involvement of thromboxane A2 in the endothelium-dependent contractions induced by myricetin in rat isolated aorta

PubMed Central

Jiménez, Rosario; Andriambeloson, Emile; Duarte, Juan; Andriantsitohaina, Ramaroson; Jiménez, José; Pérez-Vizcaino, Francisco; Zarzuelo, Antonio; Tamargo, Juan

1999-01-01

The present study was undertaken to analyse the mechanism of the contractile response induced by the bioflavonoid myricetin in isolated rat aortic rings.Myricetin induced endothelium-dependent contractile responses (maximal value=21±2% of the response induced by 80 mM KCl and pD2=5.12±0.03). This effect developed slowly, reached a peak within 6 min and then declined progressively.Myricetin-induced contractions were almost abolished by the phospholipase A2 (PLA2) inhibitor, quinacrine (10 μM), the cyclo-oxygenase inhibitor, indomethacin (10 μM), the thromboxane synthase inhibitor, dazoxiben (100 μM), the putative thromboxane A2 (TXA2)/prostaglandin endoperoxide receptor antagonist, ifetroban (3 μM). These contractions were abolished in Ca2+-free medium but were not affected by the Ca2+ channel blocker verapamil (10 μM).In cultured bovine endothelial cells (BAEC), myricetin (50 μM) produced an increase in cytosolic free calcium ([Ca2+]i) which peaked within 1 min and remained sustained for 6 min, as determined by the fluorescent probe fura 2. This rise in [Ca2+]i was abolished after removal of extracellular Ca2+ in the medium.Myricetin (50 μM) significantly increased TXB2 production both in aortic rings with and without endothelium and in BAEC. These increases were abolished both by Ca2+-free media and by indomethacin.Taken together, these results suggests that myricetin stimulates Ca2+ influx and subsequently triggers the activation of the PLA2 and cyclo-oxygenase pathways releasing TXA2 from the endothelium to contract rat aortic rings. The latter response occurs via the activation of Tp receptors on vascular smooth muscle cells. PMID:10455307

Endothelium-dependent vasodilatation and exercise hyperaemia in ageing humans: impact of acute ascorbic acid administration

PubMed Central

Kirby, Brett S; Voyles, Wyatt F; Simpson, Carrie B; Carlson, Rick E; Schrage, William G; Dinenno, Frank A

2009-01-01

Age-related increases in oxidative stress impair endothelium-dependent vasodilatation in humans, leading to the speculation that endothelial dysfunction contributes to impaired muscle blood flow and vascular control during exercise in older adults. We directly tested this hypothesis in 14 young (22 ± 1 years) and 14 healthy older men and women (65 ± 2 years). We measured forearm blood flow (FBF; Doppler ultrasound) and calculated vascular conductance (FVC) responses to single muscle contractions at 10, 20 and 40% maximum voluntary contraction (MVC) before and during ascorbic acid (AA) infusion, and we also determined the effects of AA on muscle blood flow during mild (10% MVC) continuous rhythmic handgrip exercise. For single contractions, the peak rapid hyperaemic responses to all contraction intensities were impaired ∼45% in the older adults (all P < 0.05), and AA infusion did not impact the responses in either age group. For the rhythmic exercise trial, FBF (∼28%) and FVC (∼31%) were lower (P= 0.06 and 0.05) in older versus young adults after 5 min of steady-state exercise with saline. Subsequently, AA was infused via brachial artery catheter for 10 min during continued exercise. AA administration did not significantly influence FBF or FVC in young adults (1–3%; P= 0.24–0.59), whereas FBF increased 34 ± 7% in older adults at end-exercise, and this was due to an increase in FVC (32 ± 7%; both P < 0.05). This increase in FBF and FVC during exercise in older adults was associated with improvements in vasodilator responses to acetylcholine (ACh; endothelium dependent) but not sodium nitroprusside (SNP; endothelium independent). AA had no effect on ACh or SNP responses in the young. We conclude that acute AA administration does not impact the observed age-related impairment in the rapid hyperaemic response to brief muscle contractions in humans; however, it does significantly increase muscle blood flow during continuous dynamic exercise in older adults

Effects of asymmetric dimethylarginine on renal arteries in portal hypertension and cirrhosis.

PubMed

Segarra, Gloria; Cortina, Belén; Mauricio, María Dolores; Novella, Susana; Lluch, Paloma; Navarrete-Navarro, Javier; Noguera, Inmaculada; Medina, Pascual

2016-12-28

To evaluate the effects of asymmetric dimethylarginine (ADMA) in renal arteries from portal hypertensive and cirrhotic rats. Rat renal arteries from Sham ( n = 15), pre-hepatic portal hypertension (PPVL; n = 15) and bile duct ligation and excision-induced cirrhosis (BDL; n = 15) were precontracted with norepinephrine, and additional contractions were induced with ADMA (10 -6 -10 -3 mol/L), an endogenous inhibitor of nitric oxide (NO) synthase. Concentration-response curves to acetylcholine (1 × 10 -9 -3 × 10 -6 mol/L) were determined in precontracted renal artery segments with norepinephrine in the absence and in the presence of ADMA. Kidneys were collected to determine the protein expression and activity of dimethylarginine dimethylaminohydrolase (DDAH), an enzyme that catabolizes ADMA. In renal arteries precontracted with norepinephrine, ADMA caused endothelium-dependent contractions. The pD 2 values to ADMA were similar in the Sham and PPVL groups (4.20 ± 0.08 and 4.11 ± 0.09, P > 0.05, respectively), but were lower than those of the BDL group (4.79 ± 0.16, P < 0.05). Acetylcholine-induced endothelium-dependent relaxation that did not differ, in terms of pD 2 and maximal relaxation, among the 3 groups studied. Treatment with ADMA (3 × 10 -4 mol/L) inhibited acetylcholine-induced relaxation in the 3 groups, but the inhibition was higher ( P < 0.05) in the BDL group compared with that for the Sham and PPVL groups. The mRNA and protein expression of DDAH-1 were similar in kidneys from the three groups. Conversely, DDAH-2 expression was increased ( P < 0.05) in PPVL and further enhanced ( P < 0.05) in the BDL group. However, renal DDAH activity was significantly decreased in the BDL group. Cirrhosis increased the inhibitory effect of ADMA on basal- and induced-release of NO in renal arteries, and decreased DDAH activity in the kidney.

Acetylcholine released by endothelial cells facilitates flow‐mediated dilatation

PubMed Central

Wilson, Calum; Lee, Matthew D.

2016-01-01

Key points The endothelium plays a pivotal role in the vascular response to chemical and mechanical stimuli.The endothelium is exquisitely sensitive to ACh, although the physiological significance of ACh‐induced activation of the endothelium is unknown.In the present study, we investigated the mechanisms of flow‐mediated endothelial calcium signalling.Our data establish that flow‐mediated endothelial calcium responses arise from the autocrine action of non‐neuronal ACh released by the endothelium. Abstract Circulating blood generates frictional forces (shear stress) on the walls of blood vessels. These frictional forces critically regulate vascular function. The endothelium senses these frictional forces and, in response, releases various vasodilators that relax smooth muscle cells in a process termed flow‐mediated dilatation. Although some elements of the signalling mechanisms have been identified, precisely how flow is sensed and transduced to cause the release of relaxing factors is poorly understood. By imaging signalling in large areas of the endothelium of intact arteries, we show that the endothelium responds to flow by releasing ACh. Once liberated, ACh acts to trigger calcium release from the internal store in endothelial cells, nitric oxide production and artery relaxation. Flow‐activated release of ACh from the endothelium is non‐vesicular and occurs via organic cation transporters. ACh is generated following mitochondrial production of acetylCoA. Thus, we show ACh is an autocrine signalling molecule released from endothelial cells, and identify a new role for the classical neurotransmitter in endothelial mechanotransduction. PMID:27730645

Lactobacillus Fermentum Improves Tacrolimus-Induced Hypertension by Restoring Vascular Redox State and Improving eNOS Coupling.

PubMed

Toral, Marta; Romero, Miguel; Rodríguez-Nogales, Alba; Jiménez, Rosario; Robles-Vera, Iñaki; Algieri, Francesca; Chueca-Porcuna, Natalia; Sánchez, Manuel; de la Visitación, Néstor; Olivares, Mónica; García, Federico; Pérez-Vizcaíno, Francisco; Gálvez, Julio; Duarte, Juan

2018-05-30

Our aim was to analyse whether the probiotic Lactobacillus fermentum CECT5716 (LC40) could prevent endothelial dysfunction and hypertension induced by tacrolimus in mice. Tacrolimus increased systolic blood pressure (SBP) and impaired endothelium-dependent relaxation to acetylcholine and these effects were partially prevented by LC40. Endothelial dysfunction induced by tacrolimus was related to both increased NADPH oxidase (NOX2) and uncoupled eNOS driven-superoxide production and Rho-kinase mediated eNOS inhibition. LC40 treatment prevented all the aortic changes induced by tacrolimus. LC40 restored the imbalance between T-helper 17 (Th17)/ regulatory T (Treg) cells induced by tacrolimus in mesenteric lymph nodes and spleen. Tacrolimus induced gut dysbiosis, i.e. it decreased microbial diversity, increased Firmicutes/Bacteroidetes ratio and decreased acetate- and butyrate-producing bacteria and these effects were prevented by LC40. Fecal microbiota transplantation from LC40 treated mice to control mice prevented the increase in SBP and the impaired relaxation to acetylcholine induced by tacrolimus. LC40 treatment prevented hypertension and endothelial dysfunction induced by tacrolimus by inhibiting gut dysbiosis. These effects were associated with a reduction in vascular oxidative stress, mainly through NOX2 down-regulation and prevention of eNOS-uncoupling, and inflammation possibly because of decreased Th17 and increased Treg cells polarization in mesenteric lymph nodes. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Effect of melatonin on vascular responses in aortic rings of aging rats.

PubMed

Reyes-Toso, Carlos F; Obaya-Naredo, Daniel; Ricci, Conrado R; Planells, Fernando M; Pinto, Jorge E; Linares, Laura M; Cardinali, Daniel P

2007-04-01

In old animals a marked reduction in endothelium-dependent relaxation occurs. Since there is evidence that the endothelial dysfunction associated with aging may be partly related to the local formation of reactive oxygen species, the purpose of this study was to examine the effect of the natural antioxidant melatonin (10(-5)mol/l) on in vitro contractility of aged aortic rings under conditions of increased oxidative stress (40 m mol/l glucose concentration in medium). Experiments were carried out in 18-20 months old, Wistar male rats, using adult (6-7 months old) animals as controls. A higher plasma lipid peroxidation was found in aged rats as compared to the younger ones. In a first experiment, dose-response curves for acetylcholine-induced relaxation of aortic rings were conducted. Analyzed as a main factor in a factorial ANOVA, age decreased and melatonin augmented the relaxing response to acetylcholine. melatonin's restoring effect on aortic ring relaxation was found in aged aortic rings only and was more pronounced in the presence of a high glucose medium. In a second experiment, the effect of melatonin on the contractility response to phenylephrine of intact or endothelium-denuded aortic rings obtained from aged or control rats was examined in normal or high glucose medium. A main factor analysis in the factorial ANOVA indicated that age and operation augmented, and melatonin decreased, aortic ring contractility response to phenylephrine. Melatonin's restoring effect on aortic contractility was seen in aged aortic rings. The effect of age or a high glucose medium on phenylephrine-induced contractility was more pronounced in the absence of an intact endothelium. Aging did not affect the relaxant response of intact or endothelium-denuded rings to sodium nitroprusside. The results support the improvement by melatonin of vascular response in aging rats, presumably via its antioxidant activity.

A new NO donor failed to release NO and to induce relaxation in the rat basilar artery.

PubMed

Paulo, Michele; Rodrigues, Gerson J; da Silva, Roberto S; Bendhack, Lusiane M

2012-02-14

Nitric oxide (NO)-donors are pharmacologically active substances that in vivo or in vitro release NO. Their most common side effect is headache caused by cerebral vasodilatation. We previously demonstrated that the new NO-donor Ru(terpy)(bdq)NO](3+) (Terpy), synthesized in our laboratory, induces relaxation of rat aorta. This study aimed to verify the effect of Terpy and sodium nitroprusside (SNP) in basilar artery. We conducted vascular reactivity experiments on endothelium-denuded basilar rings. The concentrations of iron (Fe) and ruthenium (Ru) complex were analyzed in basilar artery lysates after incubation with NO donors by mass spectrometry. We also evaluated the NO released from SNP and Terpy by using confocal microscopy. Interestingly, Terpy did not induce relaxation of the basilar artery. SNP induced relaxation in a concentration-dependent way. NO donors cross the membrane of vascular smooth muscle and entered the cell. In spite of its permeability, Terpy did not release NO in the basilar artery. Otherwise, SNP released NO in the basilar artery cells cytoplasm. Taken together, our results demonstrate that the new NO donor (Terpy) failed to release NO and to induce relaxation in the basilar artery. The NO donor SNP induces vascular relaxation due to NO release in the vascular smooth muscle cells. Copyright © 2011 Elsevier B.V. All rights reserved.

In Vivo Cannabidiol Treatment Improves Endothelium-Dependent Vasorelaxation in Mesenteric Arteries of Zucker Diabetic Fatty Rats

PubMed Central

Wheal, Amanda J.; Jadoon, Khalid; Randall, Michael D.; O’Sullivan, Saoirse E.

2017-01-01

Background and purpose: We have shown that in vitro treatment with cannabidiol (CBD, 2 h) enhances endothelial function in arteries from Zucker diabetic fatty (ZDF) rats, partly due to a cyclooxygenase (COX)-mediated mechanism. The aim of the present study was to determine whether treatment with CBD in vivo would also enhance endothelial function. Experimental approach: Male ZDF rats, or ZDF Lean rats, were treated for 7 days (daily i.p. injection) with either 10mg/kg CBD or vehicle (n = 6 per group). Sections of mesenteric resistance arteries, femoral arteries and thoracic aortae were mounted on a wire myograph, and cumulative concentration-response curves to endothelium-dependent (acetylcholine, ACh, 1 nM–100 μM) or endothelium-independent (sodium nitroprusside, SNP, 1 nM–100 μM) agents were constructed. Multiplex analysis was used to measure serum metabolic and cardiovascular biomarkers. Key results: Vasorelaxation to ACh was significantly enhanced in mesenteric arteries from CBD-treated ZDF rats, but not ZDF Lean rats. The enhanced vasorelaxation in ZDF mesenteric arteries was no longer observed after COX inhibition using indomethacin or nitric oxide (NO) inhibition using L-NAME. Increased levels of serum c-peptide, insulin and intracellular adhesion molecule-1 observed in the ZDF compared to ZDF Lean rats were no longer significant after 7 days CBD treatment. Conclusion and implications: Short-term in vivo treatment with CBD improves ex vivo endothelium-dependent vasorelaxation in mesenteric arteries from ZDF rats due to COX- or NO-mediated mechanisms, and leads to improvements in serum biomarkers. PMID:28572770

Crataegus special extract WS(®)1442 prevents aging-related endothelial dysfunction.

PubMed

Idris-Khodja, N; Auger, C; Koch, E; Schini-Kerth, V B

2012-06-15

Aging is associated with a markedly increased incidence of cardiovascular diseases due, in part, to the development of vascular endothelial dysfunction. The present study has evaluated whether the Crataegus special extract WS(®)1442 prevents the development of aging-related endothelial dysfunction in rats, and, if so, to determine the underlying mechanisms. Wistar rats received either a control diet or the same diet containing 100 or 300 mg/kg/day of WS(®)1442 from week 25 until week 65. Vascular reactivity was assessed in mesenteric artery rings using organ chambers, oxidative stress by dihydroethidine staining and cyclooxygenase-1 (COX-1) and -2 (COX-2) expression by immunohistochemistry. Acetylcholine-induced endothelium-dependent relaxations in mesenteric artery rings were blunted in 65-week-old rats compared to 16-week-old rats. This effect was associated with a marked reduction of the endothelium-derived hyperpolarizing factor (EDHF) component whereas the nitric oxide (NO) component was not affected. Aging was also associated with the induction of endothelium-dependent contractile responses to acetylcholine. Both aging-related impairment of endothelium-dependent relaxations and the induction of endothelium-dependent contractile responses were improved by the Crataegus treatment and by COX inhibitors. An excessive vascular oxidative stress and an upregulation of COX-1 and COX-2 were observed in the mesenteric artery of old rats compared to young rats, and these effects were improved by the Crataegus treatment. In conclusion, chronic intake of Crataegus prevented aging-related endothelial dysfunction by reducing the prostanoid-mediated contractile responses, most likely by improving the increased oxidative stress and the overexpression of COX-1 and COX-2. Copyright © 2012 Elsevier GmbH. All rights reserved.

Effect of hypothyroidism on the nitrergic relaxant responses of corpus cavernosal smooth muscle in rabbits.

PubMed

Sarac, Bulent; Yildirim, Mustafa K; Bagcivan, Ihsan; Kaya, Kemal; Kilicarslan, Hakan; Yildirim, Sahin

2006-01-01

The incidence of hormonal dysfunction as a cause of impotence remains controversial. However, several recent studies have reported evidence of hormonal abnormalities in 25-35% of impotent men. Hypothyroidism has been reported to occur in 6% of impotent men. In the present study, we examined nitrergic responses in hypothyroidism in rabbit corpus cavernosum and compared them with controls. Carbachol-induced relaxation responses and electrical field stimulation (EFS)-induced frequency-dependent relaxations decreased significantly in hypothyroid rabbits. Papaverine and sodium nitroprusside (SNP)-induced relaxation responses did not change significantly in hypothyroid rabbits. The contraction responses of phenylephrine and EFS-induced frequency-dependent contractions were significantly decreased in the hypothyroid group. We can speculate that the reduction of relaxant responses to EFS and carbachol in hypothyroid rabbits can depend on a decreased release of nitric oxide (NO) from nitrergic nerves and endothelium or a reduction of muscarinic receptor density. Also, decreases in contraction responses may depend on diminished adrenoceptor density.

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 influence of DOCA-salt hypertension and chronic administration of the FAAH inhibitor URB597 on KCa2.3/KCa3.1-EDH-type relaxation in rat small mesenteric arteries.

PubMed

Kloza, Monika; Baranowska-Kuczko, Marta; Malinowska, Barbara; Karpińska, Olga; Harasim-Symbor, Ewa; Kasacka, Irena; Kozłowska, Hanna

2017-12-01

The aim of this study was to examine the influence of deoxycorticosterone acetate-salt (DOCA-salt) hypertension and chronic treatment with the fatty acid amide hydrolase inhibitor, URB597, on small and intermediate conductance calcium-activated potassium channels and endothelium-dependent hyperpolarization (K Ca 2.3/K Ca 3.1-EDH) in rat small mesenteric arteries (sMAs). The EDH-type response was investigated, in endothelium-intact sMAs using a wire myograph, by examining acetylcholine-evoked vasorelaxation in the presence of N ω -nitro-L-arginine methyl ester and indomethacin (inhibitors of nitric oxide synthase and cyclooxygenase, respectively). In normo- and hypertension the efficacy of EDH-type relaxation was similar and inhibition of K Ca 2.3 and K Ca 3.1 by UCL1684 and TRAM-34, respectively, given alone or in combination, attenuated EDH-mediated vasorelaxation. K Ca 3.1 expression and NS309 (K Ca 2.3/K Ca 3.1 activator)-induced relaxation was reduced in sMAs of DOCA-salt rats. Endothelium denudation and incubation with UCL1684 and TRAM-34 attenuated the maximal NS309-evoked vasorelaxation in both groups. URB597 had no effect in functional studies, but increased the expression of K Ca 3.1 in the sMAs. K Ca 2.3/K Ca 3.1-EDH-mediated relaxation was maintained in the sMAs of DOCA-salt rats despite endothelial dysfunction and down-regulation of K Ca 3.1. Furthermore, K Ca 3.1 played a key role in the EDH-type dilator response of sMAs in normo- and hypertension. The hypotensive effect of URB597 is independent of K Ca 2.3/K Ca 3.1-EDH-type relaxation. Copyright © 2017 Elsevier Inc. All rights reserved.

Mechanisms of the anti-hypertensive effect of Hibiscus sabdariffa L. calyces.

PubMed

Ajay, M; Chai, H J; Mustafa, A M; Gilani, A H; Mustafa, M R

2007-02-12

Previous studies have demonstrated the anti-hypertensive effects of Hibiscus sabdariffa L. (HS) in both humans and experimental animals. To explore the mechanisms of the anti-hypertensive effect of the HS, we examined the effects of a crude methanolic extract of the calyces of HS (HSE) on vascular reactivity in isolated aortas from spontaneously hypertensive rats. HSE relaxed, concentration-dependently, KCl (high K(+), 80 mM)- and phenylephrine (PE, 1 microM)-pre-contracted aortic rings, with a greater potency against the alpha(1)-adrenergic receptor agonist. The relaxant effect of HSE was partly dependent on the presence of a functional endothelium as the action was significantly reduced in endothelium-denuded aortic rings. Pretreatment with atropine (1 microM), L-NAME (10 microM) or methylene blue (10 microM), but not indomethacin (10 microM), significantly blocked the relaxant effects of HSE. Endothelium-dependent and -independent relaxations induced by acetylcholine and sodium nitroprusside, respectively, were significantly enhanced in aortic rings pretreated with HSE when compared to those observed in control aortic rings. The present results demonstrated that HSE has a vasodilator effect in the isolated aortic rings of hypertensive rats. These effects are probably mediated through the endothelium-derived nitric oxide-cGMP-relaxant pathway and inhibition of calcium (Ca(2+))-influx into vascular smooth muscle cells. The present data further supports previous in vivo findings and the traditional use of HS as an anti-hypertensive agent.

EPA:DHA 6:1 prevents angiotensin II-induced hypertension and endothelial dysfunction in rats: role of NADPH oxidase- and COX-derived oxidative stress.

PubMed

Niazi, Zahid Rasul; Silva, Grazielle C; Ribeiro, Thais Porto; León-González, Antonio J; Kassem, Mohamad; Mirajkar, Abdur; Alvi, Azhar; Abbas, Malak; Zgheel, Faraj; Schini-Kerth, Valérie B; Auger, Cyril

2017-12-01

Eicosapentaenoic acid:docosahexaenoic acid (EPA:DHA) 6:1, an omega-3 polyunsaturated fatty acid formulation, has been shown to induce a sustained formation of endothelial nitric oxide (NO) synthase-derived NO, a major vasoprotective factor. This study examined whether chronic intake of EPA:DHA 6:1 prevents hypertension and endothelial dysfunction induced by angiotensin II (Ang II) in rats. Male Wister rats received orally corn oil or EPA:DHA 6:1 (500 mg kg -1 per day) before chronic infusion of Ang II (0.4 mg kg -1 per day). Systolic blood pressure was determined by tail cuff sphingomanometry, vascular reactivity using a myograph, oxidative stress using dihydroethidium and protein expression by immunofluorescence and western blot analysis. Ang II-induced hypertension was associated with reduced acetylcholine-induced relaxations of secondary branch mesenteric artery rings affecting the endothelium-dependent hyperpolarization (EDH)- and the NO-mediated relaxations, both of which were improved by the NADPH oxidase inhibitor VAS-2870. The Ang II treatment induced also endothelium-dependent contractile responses (EDCFs), which were abolished by the cyclooxygenase (COX) inhibitor indomethacin. An increased level of vascular oxidative stress and expression of NADPH oxidase subunits (p47 phox and p22 phox ), COX-1 and COX-2, endothelial NO synthase and Ang II type 1 receptors were observed in the Ang II group, whereas SK Ca and connexin 37 were downregulated. Intake of EPA:DHA 6:1 prevented the Ang II-induced hypertension and endothelial dysfunction by improving both the NO- and EDH-mediated relaxations, and by reducing EDCFs and the expression of target proteins. The present findings indicate that chronic intake of EPA:DHA 6:1 prevented the Ang II-induced hypertension and endothelial dysfunction in rats, most likely by preventing NADPH oxidase- and COX-derived oxidative stress.

The inhibition of inducible nitric oxide synthase and oxidative stress by agmatine attenuates vascular dysfunction in rat acute endotoxemic model.

PubMed

El-Awady, Mohammed S; Nader, Manar A; Sharawy, Maha H

2017-10-01

Vascular dysfunction leading to hypotension is a major complication in patients with septic shock. Inducible nitric oxide synthase (iNOS) together with oxidative stress play an important role in development of vascular dysfunction in sepsis. Searching for an endogenous, safe and yet effective remedy was the chief goal for this study. The current study investigated the effect of agmatine (AGM), an endogenous metabolite of l-arginine, on sepsis-induced vascular dysfunction induced by lipopolysaccharides (LPS) in rats. AGM pretreatment (10mg/kg, i.v.) 1h before LPS (5mg/kg, i.v.) prevented the LPS-induced mortality and elevations in serum creatine kinase-MB isoenzyme (CK-MB) activity, lactate dehydrogenase (LDH) activity, C-reactive protein (CRP) level and total nitrite/nitrate (NOx) level after 24h from LPS injection. The elevation in aortic lipid peroxidation illustrated by increased malondialdehyde (MDA) content and the decrease in aortic glutathione (GSH) and superoxide dismutase (SOD) were also ameliorated by AGM. Additionally, AGM prevented LPS-induced elevation in mRNA expression of iNOS, while endothelial NOS (eNOS) mRNA was not affected. Furthermore AGM prevented the impaired aortic contraction to KCl and phenylephrine (PE) and endothelium-dependent relaxation to acetylcholine (ACh) without affecting endothelium-independent relaxation to sodium nitroprusside (SNP). AGM may represent a potential endogenous therapeutic candidate for sepsis-induced vascular dysfunction through its inhibiting effect on iNOS expression and oxidative stress. Copyright © 2017 Elsevier B.V. All rights reserved.

Acetylcholine-induced current in perfused rat myoballs

PubMed Central

1980-01-01

Spherical "myoballs" were grown under tissue culture conditions from striated muscle of neonatal rat thighs. The myoballs were examined electrophysiologically with a suction pipette which was used to pass current and perfuse internally. A microelectrode was used to record membrane potential. Experiments were performed with approximately symmetrical (intracellular and extracellular) sodium aspartate solutions. The resting potential, acetylcholine (ACh) reversal potential, and sodium channel reversal potential were all approximately 0 mV. ACh-induced currents were examined by use of both voltage jumps and voltage ramps in the presence of iontophoretically applied agonist. The voltage-jump relaxations had a single exponential time-course. The time constant, tau, was exponentially related to membrane potential, increasing e-fold for 81 mV hyperpolarization. The equilibrium current- voltage relationship was also approximately exponential, from -120 to +81 mV, increasing e-fold for 104 mV hyperpolarization. The data are consistent with a first-order gating process in which the channel opening rate constant is slightly voltage dependent. The instantaneous current-voltage relationship was sublinear in the hyperpolarizing direction. Several models are discussed which can account for the nonlinearity. Evidence is presented that the "selectivity filter" for the ACh channel is located near the intracellular membrane surface. PMID:7381423

Modulation of the vasodepressor actions of acetylcholine, bradykinin, substance P and endothelin in the rat by a specific inhibitor of nitric oxide formation.

PubMed Central

Whittle, B. J.; Lopez-Belmonte, J.; Rees, D. D.

1989-01-01

1. The effects of the specific inhibitor of nitric oxide (NO) formation, NG-monomethyl-L-arginine (L-NMMA), on resting systemic arterial blood pressure (BP) and on the actions of both endothelium-dependent and endothelium-independent vasodilators were investigated in the anaesthetized, normotensive rat. 2. Intravenous administration of L-NMMA (12.5-50 mg kg-1; 47-188 mumol kg-1) but not its enantiomer, D-NMMA, induced a dose-related increase in BP, which was reversed by the intravenous administration of L-arginine (150-600 mumol kg-1), but not D-arginine. 3. The vasodepressor responses to intravenous administration of the endothelium-dependent vasodilators, acetylcholine, bradykinin and substance P were significantly inhibited by L-NMMA (94 and 188 mumol kg-1 i.v.), but not by D-NMMA. 4. The inhibition by L-NMMA of these vasodepressor responses was reversed by administration of L-arginine, but not D-arginine. 5. Endothelin (ET-1) induced dose-related vasodepressor responses following bolus intravenous administration, which were significantly inhibited by L-NMMA but not by D-NMMA. This inhibition was reversed by administration of L-arginine. 6. The vasodepressor effects of the endothelium-independent vasodilators, glyceryl trinitrate or prostacyclin, were not significantly inhibited by L-NMMA. 7. These findings with L-NMMA suggest that resting blood pressure in the rat is modulated by endogenous NO biosynthesis and that endothelium-dependent vasodilators act through the formation of endogenous NO to exert their actions in vivo. PMID:2479442

Participation of reactive oxygen species in diabetes-induced endothelial dysfunction.

PubMed

Zúrová-Nedelcevová, Jana; Navarová, Jana; Drábiková, Katarína; Jancinová, Viera; Petríková, Margita; Bernátová, Iveta; Kristová, Viera; Snirc, Vladimír; Nosál'ová, Viera; Sotníková, Ruzena

2006-12-01

In the present study, the relationship between diabetes-induced hyperglycemia, reactive oxygen species production and endothelium-mediated arterial function was examined. The effect of antioxidant on the reactive oxygen species induced damage was tested. Diabetes was induced by streptozotocin (STZ), 3 x 30 mg/kg i.p., administered on three consecutive days. After 10 weeks of diabetes, the functional state of the endothelium of the aorta was tested, endothelemia evaluation was performed and systolic blood pressure was measured. Reactive oxygen species (ROS) formation in blood and the aorta was measured using luminol-enhanced chemiluminescence (CL). Levels of reduced glutathione (GSH) were determined in the aorta, kidney, and plasma. To study the involvement of hyperglycemia in functional impairment of the endothelium, aortal rings incubated in solution with high glucose concentration were tested in in vitro experiments. After 10 weeks of diabetes, endothelial injury was observed, exhibited by diminished endothelium-dependent relaxation of the aorta, increased endothelemia and by elevated systolic blood pressure. Using luminol-enhanced CL, a significant increase of ROS production was found in arterial tissue and blood. GSH levels were significantly increased in the kidney, while there were no GSH changes in plasma and the aorta. Incubation of aortic rings in solution with high glucose concentration led to impairment of endothelium-dependent relaxation. The synthetic antioxidant SMe1EC2 was able to restore reduced endothelium-mediated relaxation. Our results suggest an important role of hyperglycemia-induced ROS production in mediating endothelial dysfunction in experimental diabetes, confirmed by CL and the protective effect of the antioxidant SMe1EC2.

Endothelial dysfunction and metabolic control in streptozotocin-induced diabetic rats

PubMed Central

Rodríguez-Mañas, Leocadio; Angulo, Javier; Peiró, Concepción; Llergo, José L; Sánchez-Ferrer, Alberto; López-Dóriga, Pedro; Sánchez-Ferrer, Carlos F

1998-01-01

The aim of this work was to study the influence of the metabolic control, estimated by the levels of glycosylated haemoglobin in total blood samples (HbA1c), in developing vascular endothelial dysfunction in streptozotocin-induced diabetic rats. Four groups of animals with different levels of insulin treatment were established, by determining HbA1c values in 5.5 to 7.4%, 7.5 to 9.4%, 9.5 to 12% and >12%, respectively.The parameters analysed were: (1) the endothelium-dependent relaxations to acetylcholine (ACh) in isolated aorta and mesenteric microvessels; (2) the vasodilator responses to exogenous nitric oxide (NO) in aorta; and (3) the existence of oxidative stress by studying the influence of the free radical scavenger superoxide dismutase (SOD) on the vasodilator responses to both ACh and NO.In both isolated aortic segments and mesenteric microvessels, the endothelium-mediated concentration-dependent relaxant responses elicited by ACh were significantly decreased when the vessels were obtained from diabetic animals but only with HbA1c values higher than 7.5%. There was a high correlation between HbA1c levels and the impairment of ACh-induced relaxations, measured by pD2 values.The concentration-dependent vasorelaxant responses to NO in endothelium-denuded aortic segments were significantly reduced only in vessels from diabetic animals with HbA1c values higher than 7.5%. Again, a very high correlation was found between the HbA1c values and pD2 for NO-evoked responses.In the presence of SOD, the responses to ACh or NO were only increased in the segments from diabetic rats with HbA1c levels higher than 7.5%, but not in those from non-diabetic or diabetic rats with a good metabolic control (HbA1c levels <7.5%).These results suggest the existence of: (1) a close relation between the degree of endothelial dysfunction and the metabolic control of diabetes, estimated by the levels of HbA1c; and (2) an increased production of superoxide anions in the vascular wall of

The role of endothelium in the vasorelaxant effects of the essential oil of Ocimum gratissimum in aorta and mesenteric vascular bed of rats.

PubMed

Pires, Alana F; Madeira, Socorro V Frota; Soares, Pedro M G; Montenegro, Claudia M; Souza, Emmanuel P; Resende, Angela C; Soares de Moura, Roberto; Assreuy, Ana M S; Criddle, David N

2012-10-01

This study investigated the endothelium-dependent vasorelaxant effects of the essential oil of Ocimum gratissimum (EOOG) in aortas and mesenteric vascular beds isolated from rats. EOOG (3-300 µg/mL) relaxed the tonic contractions induced by phenylephrine (0.1 µmol/L) in isolated aortas in a concentration-dependent manner in both endothelium-containing and endothelium-denuded preparations. This effect was partially reversed by L-NAME (100 µmol/L) but not by indomethacin (10 µmol/L) or TEA (5 mmol/L). In mesenteric vascular beds, bolus injections of EOOG (30, 50, 100, and 300 ng) decreased the perfusion pressure induced by noradrenaline (6 µmol/L) in endothelium-intact preparations but not in those treated with deoxycholate. L-NAME (300 µmol/L) but not TEA (1 mmol/L) or indomethacin (3 µmol/L) significantly reduced the vasodilatory response to EOOG at all of the doses tested. Our data showed that EOOG exerts a dose-dependent vasodilatory response in the resistance blood vessels of rat mesenteric vascular beds and in the capacitance blood vessel, the rat aorta. This action is completely dependent on endothelial nitric oxide (NO) release in the mesenteric vascular beds but only partially dependent on NO in the aorta. These novel effects of EOOG highlight interesting differences between resistance and capacitance blood vessels.

Nitric oxide-dependent vasorelaxation induced by extractive solutions and fractions of Maytenus ilicifolia Mart ex Reissek (Celastraceae) leaves.

PubMed

Rattmann, Yanna D; Cipriani, Thales R; Sassaki, Guilherme L; Iacomini, Marcello; Rieck, Lia; Marques, Maria C A; da Silva-Santos, José E

2006-04-06

This study reveals that an ethanolic supernatant obtained from an aqueous extractive solution prepared from residues of methanolic extracts of ground leaves of Maytenus ilicifolia is able to cause a concentration- and endothelium-dependent relaxation in pre-contract rat aorta rings, with EC(50) of 199.7 (190-210) microg/ml. The non-selective nitric oxide synthase inhibitors l-NAME and l-NMMA abolished this effect, while superoxide dismutase and MnTBAP (a non-enzymatic superoxide dismutase mimetic) enhanced it. Further, relaxation induced by this ethanolic supernatant have been strongly inhibited by the guanylate cyclase inhibitors methylene blue and ODQ, as well as by the potassium channel blockers 4-aminopyridine and tetraethylammonium, but was unchanged by the cyclooxygenase inhibitor indomethacin and the membrane receptor antagonists atropine, HOE-140 and pirilamine. Partition of the ethanolic supernatant between H(2)O and EtOAc generated a fraction several times more potent, able to fully relax endothelium-intact aorta rings with an EC(50) of 4.3 (3.9-4.8) microg/ml. (13)C NMR spectrum of this fraction showed signals typical of catechin. This study reveals that the leaves of M. ilicifolia possess one or more potent substances able to relax endothelium-intact rat aorta rings, an event that appears to involve nitric oxide production, guanylate cyclase activation and potassium channel opening.

pH-dependent hydrolysis of acetylcholine: Consequences for non-neuronal acetylcholine.

PubMed

Wessler, Ignaz; Michel-Schmidt, Rosmarie; Kirkpatrick, Charles James

2015-11-01

Acetylcholine is inactivated by acetylcholinesterase and butyrylcholinesterase and thereby its cellular signalling is stopped. One distinguishing difference between the neuronal and non-neuronal cholinergic system is the high expression level of the esterase activity within the former and a considerably lower level within the latter system. Thus, any situation which limits the activity of both esterases will affect the non-neuronal cholinergic system to a much greater extent than the neuronal one. Both esterases are pH-dependent with an optimum at pH above 7, whereas at pH values below 6 particularly the specific acetylcholinesterase is more or less inactive. Thus, acetylcholine is prevented from hydrolysis at such low pH values. The pH of the surface of the human skin is around 5 and therefore non-neuronal acetylcholine released from keratinocytes can be detected in a non-invasive manner. Several clinical conditions like metabolic acidosis, inflammation, fracture-related haematomas, cardiac ischemia and malignant tumours are associated with local or systemic pH values below 7. Thus, the present article describes some consequences of an impaired inactivation of extracellular non-neuronal acetylcholine. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of asymmetric dimethylarginine on renal arteries in portal hypertension and cirrhosis

PubMed Central

Segarra, Gloria; Cortina, Belén; Mauricio, María Dolores; Novella, Susana; Lluch, Paloma; Navarrete-Navarro, Javier; Noguera, Inmaculada; Medina, Pascual

2016-01-01

AIM To evaluate the effects of asymmetric dimethylarginine (ADMA) in renal arteries from portal hypertensive and cirrhotic rats. METHODS Rat renal arteries from Sham (n = 15), pre-hepatic portal hypertension (PPVL; n = 15) and bile duct ligation and excision-induced cirrhosis (BDL; n = 15) were precontracted with norepinephrine, and additional contractions were induced with ADMA (10-6-10-3 mol/L), an endogenous inhibitor of nitric oxide (NO) synthase. Concentration-response curves to acetylcholine (1 × 10-9-3 × 10-6 mol/L) were determined in precontracted renal artery segments with norepinephrine in the absence and in the presence of ADMA. Kidneys were collected to determine the protein expression and activity of dimethylarginine dimethylaminohydrolase (DDAH), an enzyme that catabolizes ADMA. RESULTS In renal arteries precontracted with norepinephrine, ADMA caused endothelium-dependent contractions. The pD2 values to ADMA were similar in the Sham and PPVL groups (4.20 ± 0.08 and 4.11 ± 0.09, P > 0.05, respectively), but were lower than those of the BDL group (4.79 ± 0.16, P < 0.05). Acetylcholine-induced endothelium-dependent relaxation that did not differ, in terms of pD2 and maximal relaxation, among the 3 groups studied. Treatment with ADMA (3 × 10-4 mol/L) inhibited acetylcholine-induced relaxation in the 3 groups, but the inhibition was higher (P < 0.05) in the BDL group compared with that for the Sham and PPVL groups. The mRNA and protein expression of DDAH-1 were similar in kidneys from the three groups. Conversely, DDAH-2 expression was increased (P < 0.05) in PPVL and further enhanced (P < 0.05) in the BDL group. However, renal DDAH activity was significantly decreased in the BDL group. CONCLUSION Cirrhosis increased the inhibitory effect of ADMA on basal- and induced-release of NO in renal arteries, and decreased DDAH activity in the kidney. PMID:28082806

[Role of acetylcholine in gelsenicine-induced death in mice].

PubMed

Lai, Zhou-Yi; Wang, Hai-Bo; Lv, Rui-Ling; Tan, Qiu-Chan; Deng, Zhi-Qin; Wang, Yuan; Sun, Xiao-Xue; Wu, Jia-Bao; Zhu, Lin-Yan; Wang, Lei; Chen, Li-Xin; Ye, Wen-Cai; Wang, Li-Wei

2016-06-25

The aim of this study was to investigate the relationship between the acetylcholine concentration in the blood and gelsenicine-induced death in mice. Kunming mice were given intraperitoneal injections of normal saline, gelsenicine or different doses of acetylcholine chloride. Atropine was given to the mice which received gelsenicine or medium dose acetylcholine chloride injection. The blood was sampled immediately when the mice died or survived for 20 min after injection. The acetylcholine concentration and acetylcholinesterase activity in the blood were measured by the testing kits, and the mortality was calculated and analyzed. The results showed that half lethal dose of gelsenicine (0.15 mg/kg) reduced the acetylcholinesterase activity and increased the blood acetylcholine concentration. The blood acetylcholine concentration of the dead mice in the gelsenicine group was increased to 43.0 μg/mL (from 31.1 μg/mL in the control), which was lower than that (53.9 μg/mL) of the dead mice in the medium dose acetylcholine chloride group, but almost equal to that (42.7 μg/mL) of the survival mice in the medium dose acetylcholine chloride group. Atropine could successfully rescue the mice from acetylcholine poisoning, but its efficiency of rescuing the mice from gelsenicine intoxication was weak. These results suggest that gelsenicine can inhibit acetylcholinesterase activity and increase blood acetylcholine concentration, but the accumulation of acetylcholine may not be the only or main cause of the death induced by gelsenicine in mice.

Role of GTP-protein and endothelium in contraction induced by ethanol in pig coronary artery.

PubMed Central

Kuroiwa, M; Aoki, H; Kobayashi, S; Nishimura, J; Kanaide, H

1993-01-01

1. We examined the effects of ethanol on the contractility of strips of porcine coronary artery, with and without endothelium, and following permeabilization with alpha-toxin, and of aortic valvular endothelial cells, in situ. Changes in cytosolic Ca2+ concentration ([Ca2+]i) of the coronary artery smooth muscle cells and of the valvular endothelial cells were monitored using front-surface fluorometry of the calcium indicator dye, fura-2. In permeabilized preparations, [Ca2+]i was clamped using 10 mM ethyleneglycol-bis-(beta-aminoethylether)-N,N,N',N'-tetra ace tic acid (EGTA) and 10 microM A23187 (a calcium ionophore). 2. The strips without endothelium were placed in normal physiological salt solution (normal PSS) in the presence of ethanol (100-1000 mM). There were dose-dependent increases in [Ca2+]i and a rapid sustained rise in tension. In Ca(2+)-free PSS, ethanol increased [Ca2+]i and tension, similar to, but much smaller than, findings with normal PSS. 3. For a given change in [Ca2+]i induced by ethanol, the developed tension was greater than that observed during contractions induced by high [K+]o. Thus, the [Ca2+]-tension curve for ethanol was shifted to the left of that for high [K+]o. The [Ca2+]-tension curve for the contraction induced by ethanol in the absence of extracellular Ca2+ was shifted further to the left from that obtained in the presence of [Ca2+]o. 4. The mechanisms involved in this Ca(2+)-sensitizing effect of ethanol were investigated using alpha-toxin-permeabilized coronary medial strips. Ethanol increased the tension development, in a concentration-dependent manner, at a fixed concentration of Ca2+ (pCa = 6.3) in the presence of guanosine-5'-triphosphate (GTP), an effect antagonized by guanosine-5'-O-(beta-thiodiphosphate) (GDP beta S), a non-hydrolysable GDP analogue. 5. With intact endothelium, the ethanol-induced tension development was markedly reduced, although inhibition in the increase in [Ca2+]i was slight. The [Ca2+]-tension

Quercetin acutely relaxes airway smooth muscle and potentiates β-agonist-induced relaxation via dual phosphodiesterase inhibition of PLCβ and PDE4

PubMed Central

Emala, Charles W.

2013-01-01

Asthma is a disease of the airways with symptoms including exaggerated airway narrowing and airway inflammation. Early asthma therapies used methylxanthines to relieve symptoms, in part, by inhibiting cyclic nucleotide phosphodiesterases (PDEs), the enzyme responsible for degrading cAMP. The classification of tissue-specific PDE subtypes and the clinical introduction of PDE-selective inhibitors for chronic obstructive pulmonary disease (i.e., roflumilast) have reopened the possibility of using PDE inhibition in the treatment of asthma. Quercetin is a naturally derived PDE4-selective inhibitor found in fruits, vegetables, and tea. We hypothesized that quercetin relaxes airway smooth muscle via cAMP-mediated pathways and augments β-agonist relaxation. Tracheal rings from male A/J mice were mounted in myographs and contracted with acetylcholine (ACh). Addition of quercetin (100 nM-1 mM) acutely and concentration-dependently relaxed airway rings precontracted with ACh. In separate studies, pretreatment with quercetin (100 μM) prevented force generation upon exposure to ACh. In additional studies, quercetin (50 μM) significantly potentiated isoproterenol-induced relaxations. In in vitro assays, quercetin directly attenuated phospholipase C activity, decreased inositol phosphate synthesis, and decreased intracellular calcium responses to Gq-coupled agonists (histamine or bradykinin). Finally, nebulization of quercetin (100 μM) in an in vivo model of airway responsiveness significantly attenuated methacholine-induced increases in airway resistance. These novel data show that the natural PDE4-selective inhibitor quercetin may provide therapeutic relief of asthma symptoms and decrease reliance on short-acting β-agonists. PMID:23873842

[Changes of vascular reactivity and reactive oxygen species in conditions of varying duration of permanent stay in the alienation zone in mice].

PubMed

Tkachenko, M M; Kotsiuruba, A V; Baziliuk, O V; Horot', I V; Sahach, V F

2010-01-01

Peculiarities of changes in the vascular reactivity and in the content of reactive forms of oxygen and stable metabolites of nitric oxide (NO) were studied in the aorta preparations of C57BL/6 and BALB/c mice of the two age groups (6 and 18 mo.), which were born and permanently kept in the Chernobyl alienation zone. The results obtained showed a disturbance of acetylcholine-induced endothelium-dependent reactions of relaxation of smooth muscles of the thoracic aorta. A lower level of NO synthesis and lower level of oxidative arginase metabolism of arginine corresponded to a higher degree of damage of endothelium-dependent reactions of relaxation of the thoracic aorta smooth muscles. A decrease of NO synthesis in conditions of permanent effects of low doses of radiation was conditioned by an increase of generation of reactive forms of oxygen, namely, superoxide and hydroxyl radicals, which might be formed in mitochondria. In conditions of permanent effects of low doses of radiation a lesser level of protein nitrosothilation, same as lesser one of generation of OH-radical, corresponded to a higher level of damage of endothelium-dependent reactions.

Monoamine oxidases are mediators of endothelial dysfunction in the mouse aorta.

PubMed

Sturza, Adrian; Leisegang, Matthias S; Babelova, Andrea; Schröder, Katrin; Benkhoff, Sebastian; Loot, Annemarieke E; Fleming, Ingrid; Schulz, Rainer; Muntean, Danina M; Brandes, Ralf P

2013-07-01

Monoamine oxidases (MAOs) generate H(2)O(2) as a by-product of their catalytic cycle. Whether MAOs are mediators of endothelial dysfunction is unknown and was determined here in the angiotensin II and lipopolysaccharide-models of vascular dysfunction in mice. Quantitative real-time polymerase chain reaction revealed that mouse aortas contain enzymes involved in catecholamine generation and MAO-A and MAO-B mRNA. MAO-A and -B proteins could be detected by Western blot not only in mouse aortas but also in human umbilical vein endothelial cells. Ex vivo incubation of mouse aorta with recombinant MAO-A increased H(2)O(2) formation and induced endothelial dysfunction that was attenuated by polyethylene glycol-catalase and MAO inhibitors. In vivo lipopolysaccharide (8 mg/kg IP overnight) or angiotensin II (1 mg/kg per day, 2 weeks, minipump) treatment induced vascular MAO-A and -B expressions and resulted in attenuated endothelium-dependent relaxation of the aorta in response to acetylcholine. MAO inhibitors reduced the lipopolysaccharide- and angiotensin II-induced aortic reactive oxygen species formation by 50% (ferrous oxidation xylenol orange assay) and partially normalized endothelium-dependent relaxation. MAO-A and MAO-B inhibitors had an additive effect; combined application completely restored endothelium-dependent relaxation. To determine how MAO-dependent H(2)O(2) formation induces endothelial dysfunction, cyclic GMP was measured. Histamine stimulation of human umbilical vein endothelial cells to activate endothelial NO synthase resulted in an increase in cyclic GMP, which was almost abrogated by MAO-A exposure. MAO inhibition prevented this effect, suggesting that MAO-induced H(2)O(2) formation is sufficient to attenuate endothelial NO release. Thus, MAO-A and MAO-B are both expressed in the mouse aorta, induced by in vivo lipopolysaccharide and angiotensin II treatment and contribute via the generation of H(2)O(2) to endothelial dysfunction in vascular disease

Triiodothyronine Potentiates Vasorelaxation via PKG/VASP Signaling in Vascular Smooth Muscle Cells.

PubMed

Samuel, Sherin; Zhang, Kuo; Tang, Yi-Da; Gerdes, A Martin; Carrillo-Sepulveda, Maria Alicia

2017-01-01

Vascular relaxation caused by Triiodothyronine (T3) involves direct activation of endothelial cells (EC) and vascular smooth muscle cells (VSMC). Activation of protein kinase G (PKG) has risen as a novel contributor to the vasorelaxation mechanism triggered by numerous stimuli. We hypothesize that T3-induced vasorelaxation involves PKG/vasodilator-stimulated phosphoprotein (VASP) signaling pathway in VSMC. Human aortic endothelial cells (HAEC) and VSMC were treated with T3 for short (2 to 60 minutes) and long term (24 hours). Nitric oxide (NO) production was measured using DAF-FM. Expression of protein targets was determined using western blot. For functional studies, rat aortas were isolated and treated with T3 for 20 minutes and mounted in a wire myograph. Relaxation was measured by a concentration-dependent response to acetylcholine (ACh) and sodium nitroprusside (SNP). Aortas stimulated with T3 exhibited augmented sensitivity to ACh and SNP-induced relaxation, endothelium-dependent and endothelium-independent responses, respectively. T3 directly increased vasorelaxation, which was abolished in the presence of a PKG inhibitor. T3 markedly induced phosphorylation of Akt, eNOS and consequently increased NO production in EC. Likewise, T3 induced phosphorylation of VASP at serine 239 via the PKG pathway in VSMC. Our findings have uncovered a PKG/VASP signaling pathway in VSMC as a key molecular mechanism underlying T3-induced vascular relaxation. © 2017 The Author(s)Published by S. Karger AG, Basel.

Ca2+ influx in the endothelial cells is required for the bradykinin-induced endothelium-dependent contraction in the porcine interlobar renal artery

PubMed Central

Ihara, Eikichi; Derkach, Dmitry N; Hirano, Katsuya; Nishimura, Junji; Nawata, Hajime; Kanaide, Hideo

2001-01-01

To determine the mechanism of bradykinin-induced production of endothelium-derived contracting factors, we monitored the changes in cytosolic Ca2+ concentration ([Ca2+]i) in in situ endothelial cells in porcine aortic valvular strips and the changes in [Ca2+]i of smooth muscle cells and force in porcine interlobar renal arterial strips using front-surface fluorometry of fura-2. In the presence of Nω-nitro-l-arginine methyl ester, bradykinin caused an endothelium-dependent transient elevation of [Ca2+]i and contraction in smooth muscle in the interlobar renal artery. This contraction was completely inhibited by a prostaglandin H2/thromboxane A2 receptor antagonist. In the absence of extracellular Ca2+, bradykinin failed to induce contraction. However, replenishing extracellular Ca2+ to 0.75 mm and higher induced an instantaneous contraction. However, replenishing Ca2+per se did not induce any contraction in the absence of bradykinin. Pretreatment with either 10−5m 1-(β-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenethyl)-1H-imidazole hydrochloride (SKF96365) or 0.2 mm Ni2+ abolished the contraction induced by bradykinin in the presence of extracellular Ca2+. Treatment with 10−5m indomethacin completely inhibited the contractile response induced by Ca2+ replenishment, regardless of the timing of its application, before or after the application of bradykinin. In endothelial cells in the valvular strips, bradykinin caused a transient [Ca2+]i elevation in the presence of 1.25 mm extracellular Ca2+, but [Ca2+]i returned to the resting level within 10 min. Neither 10−5m SKF96365 nor 0.2 mm Ni2+ had any effect on the peak [Ca2+]i elevation, but decreased [Ca2+]i in the declining phase. In the absence of extracellular Ca2+, bradykinin induced a transient [Ca2+]i elevation to a level similar to that seen in the presence of 1.25 mm extracellular Ca2+. However, [Ca2+]i then rapidly returned to the prestimulation level within 5 min. Subsequent Ca2+ replenishment to 0.75 mm

Role of inducible nitric oxide synthase in endothelium‐independent relaxation to raloxifene in rat aorta

PubMed Central

Au, Chak Leung; Tsang, Suk Ying; Lau, Chi Wai; Yao, Xiaoqiang; Cai, Zongwei

2017-01-01

Background and Purpose Raloxifene can induce both endothelium‐dependent and ‐independent relaxation in different arteries. However, the underlying mechanisms by which raloxifene triggers endothelium‐independent relaxation are still incompletely understood. The purpose of present study was to examine the roles of NOSs and Ca2+ channels in the relaxant response to raloxifene in the rat isolated, endothelium‐denuded aorta. Experimental Approach Changes in isometric tension, cGMP, nitrite, inducible NOS protein expression and distribution in response to raloxifene in endothelium‐denuded aortic rings were studied by organ baths, radioimmunoassay, Griess reaction, western blot and immunohistochemistry respectively. Key Results Raloxifene reduced the contraction to CaCl2 in a Ca2+‐free, high K+‐containing solution in intact aortic rings. Raloxifene also acutely relaxed the aorta primarily through an endothelium‐independent mechanism involving NO, mostly from inducible NOS (iNOS) in vascular smooth muscle layers. This effect of raloxifene involved the generation of cGMP and nitrite. Also, it was genomic in nature, as it was inhibited by a classical oestrogen receptor antagonist and inhibitors of RNA and protein synthesis. Raloxifene‐induced stimulation of iNOS gene expression was partly mediated through activation of the NF‐κB pathway. Raloxifene was more potent than 17β‐estradiol or tamoxifen at relaxing endothelium‐denuded aortic rings by stimulation of iNOS. Conclusions and Implications Raloxifene‐mediated vasorelaxation in rat aorta is independent of a functional endothelium and is mediated by oestrogen receptors and NF‐κB. This effect is mainly mediated through an enhanced production of NO, cGMP and nitrite, via the induction of iNOS and inhibition of calcium influx through Ca2+ channels in rat aortic smooth muscle. PMID:28138957

Tissue Vibration Induces Carotid Artery Endothelial Dysfunction: A Mechanism Linking Snoring and Carotid Atherosclerosis?

PubMed Central

Cho, Jin-Gun; Witting, Paul K.; Verma, Manisha; Wu, Ben J.; Shanu, Anu; Kairaitis, Kristina; Amis, Terence C.; Wheatley, John R.

2011-01-01

Study Objectives: We have previously identified heavy snoring as an independent risk factor for carotid atherosclerosis. In order to explore the hypothesis that snoring-associated vibration of the carotid artery induces endothelial dysfunction (an established atherogenic precursor), we utilized an animal model to examine direct effects of peri-carotid tissue vibration on carotid artery endothelial function and structure. Design: In supine anesthetized, ventilated rabbits, the right carotid artery (RCA) was directly exposed to vibrations for 6 h (peak frequency 60 Hz, energy matched to that of induced snoring in rabbits). Similarly instrumented unvibrated rabbits served as controls. Features of OSA such as hypoxemia, large intra-pleural swings and blood pressure volatility were prevented. Carotid endothelial function was then examined: (1) biochemically by measurement of tissue cyclic guanosine monophosphate (cGMP) to acetylcholine (ACh) and sodium nitroprusside (SNP); and (2) functionally by monitoring vessel relaxation with acetylcholine in a myobath. Measurement and Results: Vessel cGMP after stimulation with ACh was reduced in vibrated RCA compared with unvibrated (control) arteries in a vibration energy dose-dependent manner. Vibrated RCA also showed decreased vasorelaxation to ACh compared with control arteries. Notably, after addition of SNP (nitric oxide donor), cGMP levels did not differ between vibrated and control arteries, thereby isolating vibration-induced dysfunction to the endothelium alone. This dysfunction occurred in the presence of a morphologically intact endothelium without increased apoptosis. Conclusions: Carotid arteries subjected to 6 h of continuous peri-carotid tissue vibration displayed endothelial dysfunction, suggesting a direct plausible mechanism linking heavy snoring to the development of carotid atherosclerosis. Citation: Cho JG; Witting PK; Verma M; Wu BJ; Shanu A; Kairaitis K; Amis TC; Wheatley JR. Tissue vibration induces

N,N-diacetyl-L-cystine improves endothelial function in atherosclerotic Watanabe heritable hyperlipidaemic rabbits.

PubMed

Pettersson, Knut S; Eliasson, Ulla Brandt; Abrahamsson, Tommy; Wågberg, Maria; Carrier, Martin; Kengatharan, Ken M

2007-01-01

N,N-diacetyl-L-cystine (DiNAC), a novel immunomodulator, stimulates contact sensitivity/delayed type hypersensitivity reactions in mice induced by oxazolone and reduces atherosclerosis in Watanabe heritable hyperlipidaemic (WHHL) rabbits. Forty-week-old WHHL rabbits were given DiNAC (3 micromol/kg per day) for 8 weeks, and endothelium-mediated dilatation was investigated in vivo using pulse wave analysis. A significant improvement in endothelial function was found after 3 weeks of treatment, which was further improved after 8 weeks. For experiments on isolated blood vessels, 40-week-old rabbits were treated for 3 weeks. Treatment did not affect plasma lipid levels. At termination, aortic rings from the thoracic and abdominal aorta were contracted with phenylephrine in vitro. Concentration-effect curves to acetylcholine and the calcium ionophore A 23187 were used to measure endothelium-mediated vasodilatation, and nitroprusside to elicit endothelium-independent relaxations. Abdominal aorta relaxations were generally larger than in thoracic aorta. DiNAC improved endothelium-dependent relaxations in the abdominal but not in the thoracic aorta. This effect was independent of the degree of atherosclerosis. It is concluded that DiNAC improved endothelial function in atherosclerotic rabbit arteries in vivo and in vitro, and may represent a new treatment modality for atherosclerosis-related diseases.

Hydrogen sulfide replacement therapy protects the vascular endothelium in hyperglycemia by preserving mitochondrial function.

PubMed

Suzuki, Kunihiro; Olah, Gabor; Modis, Katalin; Coletta, Ciro; Kulp, Gabriella; Gerö, Domokos; Szoleczky, Petra; Chang, Tuanjie; Zhou, Zongmin; Wu, Lingyun; Wang, Rui; Papapetropoulos, Andreas; Szabo, Csaba

2011-08-16

The goal of the present studies was to investigate the role of changes in hydrogen sulfide (H(2)S) homeostasis in the pathogenesis of hyperglycemic endothelial dysfunction. Exposure of bEnd3 microvascular endothelial cells to elevated extracellular glucose (in vitro "hyperglycemia") induced the mitochondrial formation of reactive oxygen species (ROS), which resulted in an increased consumption of endogenous and exogenous H(2)S. Replacement of H(2)S or overexpression of the H(2)S-producing enzyme cystathionine-γ-lyase (CSE) attenuated the hyperglycemia-induced enhancement of ROS formation, attenuated nuclear DNA injury, reduced the activation of the nuclear enzyme poly(ADP-ribose) polymerase, and improved cellular viability. In vitro hyperglycemia resulted in a switch from oxidative phosphorylation to glycolysis, an effect that was partially corrected by H(2)S supplementation. Exposure of isolated vascular rings to high glucose in vitro induced an impairment of endothelium-dependent relaxations, which was prevented by CSE overexpression or H(2)S supplementation. siRNA silencing of CSE exacerbated ROS production in hyperglycemic endothelial cells. Vascular rings from CSE(-/-) mice exhibited an accelerated impairment of endothelium-dependent relaxations in response to in vitro hyperglycemia, compared with wild-type controls. Streptozotocin-induced diabetes in rats resulted in a decrease in the circulating level of H(2)S; replacement of H(2)S protected from the development of endothelial dysfunction ex vivo. In conclusion, endogenously produced H(2)S protects against the development of hyperglycemia-induced endothelial dysfunction. We hypothesize that, in hyperglycemic endothelial cells, mitochondrial ROS production and increased H(2)S catabolism form a positive feed-forward cycle. H(2)S replacement protects against these alterations, resulting in reduced ROS formation, improved endothelial metabolic state, and maintenance of normal endothelial function.

Effect of atherosclerosis on endothelium-dependent inhibition of platelet activation in humans.

PubMed

Diodati, J G; Dakak, N; Gilligan, D M; Quyyumi, A A

1998-07-07

We investigated whether luminal release of nitric oxide (NO) contributes to inhibition of platelet activation and whether these effects are reduced in patients with atherosclerosis. Femoral blood flow velocity and ex vivo whole blood platelet aggregation by impedance aggregometry were measured in femoral venous blood during femoral arterial infusion of acetylcholine (ACh; 30 microg/min) in 30 patients, 19 of whom had angiographic atherosclerosis. Measurements were repeated with sodium nitroprusside (40 microg/min), L-arginine (160 micromol/min), and N(G)-monomethyl-L-arginine (L-NMMA; 16 micromol/min). There was significant inhibition of collagen-induced platelet aggregation with ACh (45+/-9.5% lower, P<0.001), and this inhibition was greater in patients without atherosclerosis (68.7+/-10.4% reduction) than in those with atherosclerosis (32.5+/-8.1%, P=0.04). The magnitude of inhibition correlated with vasodilation with ACh, indicating an association between the smooth muscle and antiplatelet effects of endothelium-dependent stimulation. Neither L-NMMA nor sodium nitroprusside altered platelet aggregation. L-Arginine inhibited platelet aggregation equally in vitro (34+/-8% reduction, P<0.01) and in vivo (37+/-13% reduction, P<0.01). Stimulation of NO release into the vascular lumen with ACh inhibits platelet aggregation, an effect that is attenuated in patients with atherosclerosis and endothelial dysfunction. Basal NO release does not appear to contribute to platelet passivation in vivo. L-Arginine inhibited platelet aggregation by its direct action on platelets. These findings provide a pathophysiological basis for the observed increase in thrombotic events in atherosclerosis. Use of L-arginine and other strategies to improve endothelial NO activity may impact favorably on thrombotic events in atherosclerosis.

Tocotrienol Rich Palm Oil Extract Is More Effective Than Pure Tocotrienols at Improving Endothelium-Dependent Relaxation in the Presence of Oxidative Stress.

PubMed

Ali, Saher F; Woodman, Owen L

2015-01-01

Oxidative endothelial dysfunction is a critical initiator of vascular disease. Vitamin E is an effective antioxidant but attempts to use it to treat vascular disorders have been disappointing. This study investigated whether tocotrienols, the less abundant components of vitamin E compared to tocopherols, might be more effective at preserving endothelial function. Superoxide generated by hypoxanthine/xanthine oxidase or rat aorta was measured using lucigenin-enhanced chemiluminescence. The effect of α-tocopherol, α-, δ-, and γ-tocotrienols and a tocotrienol rich palm oil extract (tocomin) on levels of superoxide was assessed. Endothelial function in rat aorta was assessed in the presence of the auto-oxidant pyrogallol. Whilst all of the compounds displayed antioxidant activity, the tocotrienols were more effective when superoxide was produced by hypoxanthine/xanthine oxidase whereas tocomin and α-tocopherol were more effective in the isolated aorta. Tocomin and α-tocopherol restored endothelial function in the presence of oxidant stress but α-, δ-, and γ-tocotrienols were ineffective. The protective effect of tocomin was replicated when the tocotrienols were present with, but not without, α-tocopherol. Tocotrienol rich tocomin is more effective than α-tocopherol at reducing oxidative stress and restoring endothelium-dependent relaxation in rat aortae and although α-, δ-, and γ-tocotrienols effectively scavenged superoxide, they did not improve endothelial function.

Endothelial cell-dependent relaxation and contraction induced by histamine in the isolated guinea-pig pulmonary artery.

PubMed

Satoh, H; Inui, J

1984-01-27

Histamine (10(-8)-10(-6) M) relaxed in a concentration-dependent manner the guinea-pig pulmonary artery which had been contracted by noradrenaline (5 X 10(-7) M). After the removal of endothelial cells (ETCs) histamine at the same concentrations did not cause relaxation but induced additional contraction. Both responses to histamine were antagonized by chlorpheniramine (3 X 10(-7) M). These results suggest that in the pulmonary artery histamine simultaneously stimulates H1-receptors located on both ETCs and smooth muscle cells. This results in two opposite effects, relaxation mediated by ETCs, and contraction.

Endothelium as a transducing surface.

PubMed

Ryan, U S

1989-02-01

Endothelial cells responses to a variety of agonists include release of endothelium dependent vasodilators, such as endothelium dependent relaxing factor (EDRF) and prostacyclin (PGI2). These substances act on vascular smooth muscle to cause relaxation and also have potent anti-aggregatory effects on platelets. A study of the mechanisms of signal transduction involved in these processes was undertaken. An investigation of intracellular calcium using FURA-2 and INDO-1 loaded endothelial cells shows transient elevation in response to vasodilator agonists. The calcium content of endothelial cells calculated using 45Ca flux techniques is increased in response to bradykinin and thrombin. Receptor activation leads to increased phosphoinositide turnover in endothelial cells and activates protein kinase C, the latter may be involved in feedback regulation. Patch clamp studies have demonstrated receptor-operated ionic channels in the endothelial cell membrane. Thus, intracellular calcium concentration is elevated in response to receptor activation, both as a result of liberation of calcium from intracellular stores and calcium entry from extracellular sources. Endothelial cells also respond to particulate stimuli. They can selectively bind and phagocytize bacteria. Phagocytosis leads to generation of superoxide aionin, a process which also seems to be controlled by elevation of intracellular calcium and activation of protein kinase C. In addition phagocytosis activates endothelial cells resulting in increased migration, division and further phagocytosis. All in all, the plethora of different endothelial responses to a variety of stimuli suggests a complex and multipotent cell type.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum alkaline phosphatase negatively affects endothelium-dependent vasodilation in naïve hypertensive patients.

PubMed

Perticone, Francesco; Perticone, Maria; Maio, Raffaele; Sciacqua, Angela; Andreucci, Michele; Tripepi, Giovanni; Corrao, Salvatore; Mallamaci, Francesca; Sesti, Giorgio; Zoccali, Carmine

2015-10-01

Tissue nonspecific alkaline phosphatase, promoting arterial calcification in experimental models, is a powerful predictor of total and cardiovascular mortality in general population and in patients with renal or cardiovascular diseases. For this study, to evaluate a possible correlation between serum alkaline phosphatase levels and endothelial function, assessed by strain gauge plethysmography, we enrolled 500 naïve hypertensives divided into increasing tertiles of alkaline phosphatase. The maximal response to acetylcholine was inversely related to alkaline phosphatase (r=−0.55; P<0.001), and this association was independent (r=−0.61; P<0.001) of demographic and classical risk factors, body mass index, estimated glomerular filtration rate, serum phosphorus and calcium, C-reactive protein, and albuminuria. At multiple logistic regression analysis, the risk of endothelial dysfunction was ≈3-fold higher in patients in the third tertile than that of patients in the first tertile. We also tested the combined role of alkaline phosphatase and serum phosphorus on endothelial function. The steepness of the alkaline phosphatase/vasodilating response to acetylcholine relationship was substantially attenuated (P<0.001) in patients with serum phosphorus above the median value when compared with patients with serum phosphorus below the median (−5.0% versus −10.2% per alkaline phosphatase unit, respectively), and this interaction remained highly significant (P<0.001) after adjustment of all the previously mentioned risk factors. Our data support a strong and significant inverse relationship between alkaline phosphatase and endothelium-dependent vasodilation, which was attenuated by relatively higher serum phosphorus levels.

Rabbit aortic endothelial dysfunction by low-density lipoprotein is attenuated by L-arginine, L-ascorbate and pyridoxine

PubMed Central

Ji, Yong; Han, Yi; Diao, Jianxin; Huang, Yan; Chen, Qi; Ferro, Albert

2003-01-01

We investigated the relative effectiveness of L-arginine, L-ascorbate and pyridoxine in preventing the impairment of endothelium-mediated vasorelaxation induced by native low-density lipoprotein (nLDL) from healthy subjects, oxidised LDL (oxLDL, formed by oxidation of nLDL) or nLDL from type II diabetic patients (dLDL). Rabbit aortic rings were exposed to nLDL, dLDL or oxLDL (50–200 mg protein l−1), or corresponding vehicle, following which they were constricted with noradrenaline 10−6 M; concentration–relaxation curves were determined to acetylcholine (ACh), A23187, or sodium nitroprusside (NP), in the absence or presence of L-arginine (10−5–10−3 M), L-ascorbate (10−5–10−3 M) and pyridoxine (0.5–2.0 mM). nLDL, dLDL and oxLDL all inhibited relaxant responses to ACh and A23187, but not to NP, in a concentration-dependent manner (oxLDL>dLDL>nLDL). In the presence of all LDL preparations, L-arginine, L-ascorbate or pyridoxine each improved ACh and A23187 responses, although none completely normalised endothelium-dependent relaxations. The maximal effect of L-arginine occurred at 10−4 M. The combination of L-arginine 10−4 M, L-ascorbate 10−5 M and pyridoxine 2.0 mM was equally effective as L-arginine 10−4 M alone. Our results confirm that nLDL, dLDL and oxLDL exert inhibitory effects on endothelium dependent, but not endothelium independent, relaxation of rabbit aorta. ACh and A23187 responses in the presence of any LDL species can be ameliorated by supplementation with L-arginine, L-ascorbate or pyridoxine, either singly or in combination, with no agent or combination proving superior to L-arginine alone. Nevertheless, ACh and A23187 responses are not completely normalised with such supplements, suggesting that there also exists a component of LDL-induced inhibition of endothelium-mediated vasorelaxation that is independent of the nitric oxide system. PMID:14597596

Activation of endogenous GABAA channels on airway smooth muscle potentiates isoproterenol-mediated relaxation.

PubMed

Gallos, George; Gleason, Neil R; Zhang, Yi; Pak, Sang-Woo; Sonett, J R; Yang, Jay; Emala, Charles W

2008-12-01

Reactive airway disease predisposes patients to episodes of acute smooth muscle mediated bronchoconstriction. We have for the first time recently demonstrated the expression and function of endogenous ionotropic GABA(A) channels on airway smooth muscle cells. We questioned whether endogenous GABA(A) channels on airway smooth muscle could augment beta-agonist-mediated relaxation. Guinea pig tracheal rings or human bronchial airway smooth muscles were equilibrated in organ baths with continuous digital tension recordings. After pretreatment with or without the selective GABA(A) antagonist gabazine (100 muM), airway muscle was contracted with acetylcholine or beta-ala neurokinin A, followed by relaxation induced by cumulatively increasing concentrations of isoproterenol (1 nM to 1 muM) in the absence or presence of the selective GABA(A) agonist muscimol (10-100 muM). In separate experiments, guinea pig tracheal rings were pretreated with the large conductance K(Ca) channel blocker iberiotoxin (100 nM) after an EC(50) contraction with acetylcholine but before cumulatively increasing concentrations of isoproterenol (1 nM to 1 uM) in the absence or presence of muscimol (100 uM). GABA(A) activation potentiated the relaxant effects of isoproterenol after an acetylcholine or tachykinin-induced contraction in guinea pig tracheal rings or an acetylcholine-induced contraction in human endobronchial smooth muscle. This muscimol-induced potentiation of relaxation was abolished by gabazine pretreatment but persisted after blockade of the maxi K(Ca) channel. Selective activation of endogenous GABA(A) receptors significantly augments beta-agonist-mediated relaxation of guinea pig and human airway smooth muscle, which may have important therapeutic implications for patients in severe bronchospasm.

Antioxidant Effect of Captopril and Enalapril on Reactive Oxygen Species-Induced Endothelial Dysfunction in the Rabbit Abdominal Aorta

PubMed Central

Kim, Ji Hoon; Kim, Young Hak; Chung, Won-Sang; Suh, Jung Kook; Kim, Sung Jin

2013-01-01

Background Reactive oxygen species (ROS) are known to be related to cardiovascular diseases. Many studies have demonstrated that angiotensin-converting enzyme inhibitors have beneficial effects against ROS. We investigated the antioxidant effect of captopril and enalapril in nitric oxide mediated vascular endothelium-dependent relaxations. Materials and Methods Isolated rabbit abdominal aorta ring segments were exposed to ROS by electrolysis of the organ bath medium (Krebs-Henseleit solution) after pretreatment with various concentrations (range, 10-5 to 3×10-4 M) of captopril and enalapril. Before and after electrolysis, the endothelial function was measured by preconstricting the vessels with norepinephrine (10-6 M) followed by the cumulative addition of acetylcholine (range, 3×10-8 to 10-6 M). The relevance of the superoxide anion and hydrogen peroxide scavenging effect of captopril and enalapril was investigated using additional pretreatments of diethyldithiocarbamate (DETCA, 0.5 mM), an inhibitor of Cu/Zn superoxide dismutase, and 3-amino-1,2,4-triazole (3AT, 50 mM), an inhibitor of catalase. Results Both captopril and enalapril preserved vascular endothelium-dependent relaxation after exposure to ROS in a dose-dependent manner (p<0.0001). Pretreatment with DETCA attenuated the antioxidant effect of captopril and enalapril (p<0.0001), but pretreatment with 3AT did not have an effect. Conclusion Both captopril and enalapril protect endothelium against ROS in a dose-dependent fashion in isolated rabbit abdominal aortas. This protective effect is related to superoxide anion scavenging. PMID:23422724

Novel Roles for Kv7 Channels in Shaping Histamine-Induced Contractions and Bradykinin-Dependent Relaxations in Pig Coronary Arteries

PubMed Central

Chen, Xingjuan; Li, Wennan; Hiett, S. Christopher; Obukhov, Alexander G.

2016-01-01

-contracted CAs. We propose that in CAs, a decreased expression or a loss of function of Kv7 channels may lead to sustained histamine-induced contractions and reduced endothelium-dependent relaxation, both risk factors for coronary spasm. PMID:26844882

Effects of long-term high-saturated and unsaturated fatty acid diets on relaxation and contraction of renal arteries in insulin resistant rats.

PubMed

Gao, Yu; Song, Guang-Yao; Ma, Hui-Juan; Zhang, Wen-Jie; Zhou, Yu

2007-06-25

The present study was designed to investigate the effects of high-saturated and high-unsaturated fatty acid diets on relaxation and contraction of the renal arteries in insulin resistance (IR) rats. Wistar rats were fed normal chow diet (control), high-saturated fatty acid diet or high-unsaturated fatty acid diet for 6 months (n=14 in each group). IR was evaluated by glucose infusion rate (GIR) of hyperinsulinemic euglycemic clamp. Blood pressure was measured via the tail-cuff method. Body weight (BW), plasma total triglyceride (TG), free fatty acid (FFA), insulin, fasting blood glucose (FBG) and nitric oxide metabolite (NO2(-)/NO3(-)) were compared among the three groups. The rats were sacrificed and the renal arterial rings were placed in the physiological tissue baths for measurement of vascular response to various agents. After the arterial rings were constricted with 3 mmol/L noradrenaline (NA), endothelium-dependent vasorelaxation to acetylcholine (ACh) and endothelium-independent vasorelaxation to sodium nitroprusside (NTP) were measured. Endothelium-dependent vasorelaxation to ACh was also observed in renal arterial rings incubated with L-arginine (L-Arg), N(omega)-nitro-L-arginine (L-NNA) and methylene blue (MB), respectively. Arterial contractility was evaluated from concentration-response curves to 10 nmol/L-100 micromol/L NA. Saturated or unsaturated fatty acids led to moderate rises in blood pressure (P<0.05). It was associated with higher levels of plasma lipids and lower whole body insulin sensitivity (P<0.01). There were no significant differences in BW, FBG, TG, insulin and FFA between saturated and unsaturated fatty acid-fed rats. A decrease in endothelium-dependent vasorelaxation of the renal arteries in saturated and unsaturated fatty acid-fed rats was observed (P<0.01), but there was no marked difference between the two high-fatty acid diet groups. Endothelium-dependent vasorelaxation was increased when the arteries were incubated with L

Tocotrienol Rich Palm Oil Extract Is More Effective Than Pure Tocotrienols at Improving Endothelium-Dependent Relaxation in the Presence of Oxidative Stress

PubMed Central

Ali, Saher F.; Woodman, Owen L.

2015-01-01

Oxidative endothelial dysfunction is a critical initiator of vascular disease. Vitamin E is an effective antioxidant but attempts to use it to treat vascular disorders have been disappointing. This study investigated whether tocotrienols, the less abundant components of vitamin E compared to tocopherols, might be more effective at preserving endothelial function. Superoxide generated by hypoxanthine/xanthine oxidase or rat aorta was measured using lucigenin-enhanced chemiluminescence. The effect of α-tocopherol, α-, δ-, and γ-tocotrienols and a tocotrienol rich palm oil extract (tocomin) on levels of superoxide was assessed. Endothelial function in rat aorta was assessed in the presence of the auto-oxidant pyrogallol. Whilst all of the compounds displayed antioxidant activity, the tocotrienols were more effective when superoxide was produced by hypoxanthine/xanthine oxidase whereas tocomin and α-tocopherol were more effective in the isolated aorta. Tocomin and α-tocopherol restored endothelial function in the presence of oxidant stress but α-, δ-, and γ-tocotrienols were ineffective. The protective effect of tocomin was replicated when the tocotrienols were present with, but not without, α-tocopherol. Tocotrienol rich tocomin is more effective than α-tocopherol at reducing oxidative stress and restoring endothelium-dependent relaxation in rat aortae and although α-, δ-, and γ-tocotrienols effectively scavenged superoxide, they did not improve endothelial function. PMID:26075031

Modulatory effect of neuropeptide Y on acetylcholine-induced oedema and vasoconstriction in isolated perfused lungs of rabbit.

PubMed Central

Delaunois, A; Gustin, P; Dessy-Doize, C; Ansay, M

1994-01-01

1. The modulatory role of neuropeptide Y (NPY) on pulmonary oedema induced by acetylcholine and capsaicin was investigated. The effects of NPY on the haemodynamic response to acetylcholine, phenylephrine and substance P were also investigated. 2. Isolated, ventilated, exsanguinated lungs of the rabbit were perfused with a constant flow of recirculating blood-free perfusate. The double/arterial/venous occlusion method was used to partition the total pressure gradient (delta Pt) into four components: the arterial gradient (delta Pa), the pre- and post-capillary gradients (respectively delta Pa' and delta Pv') and the venous pressure gradient (delta Pv). Endothelial permeability was evaluated by measuring the capillary filtration coefficient (Kf,c). 3. Acetylcholine (10(-8) M to 10(-4) M) and substance P (SP, 10(-10) M to 10(-6) M) induced a concentration-dependent increase in the Kf,c. Capsaicin (10(-4) M) and 5-hydroxytryptamine (5-HT) (10(-4) M) also increased this parameter. NPY (10(-8) M) completely inhibited the effects of acetylcholine and capsaicin on the Kf,c, without preventing the effects of substance P and 5-HT. 4. Acetylcholine induced concentration-dependent vasoconstriction in the precapillary segment. The effect was inhibited by NPY and aspirin, an inhibitor of cyclo-oxygenase, while ketanserin, a 5-HT2 receptor antagonist, and SR140333, a new NK1 antagonist, had no protective effect. Phenylephrine increased delta Pa at high concentration, an effect also inhibited by NPY and aspirin. Substance P had no significant haemodynamic effect. When injected together with NPY, substance P (10(-6) M) induced a significant increase in the total pressure gradient.(ABSTRACT TRUNCATED AT 250 WORDS) Images Figure 2 Figure 3 PMID:7532083

Tramadol state-dependent memory: involvement of dorsal hippocampal muscarinic acetylcholine receptors.

PubMed

Jafari-Sabet, Majid; Jafari-Sabet, Ali-Reza; Dizaji-Ghadim, Ali

2016-08-01

The effects on tramadol state-dependent memory of bilateral intradorsal hippocampal (intra-CA1) injections of physostigmine, an acetylcholinesterase inhibitor, and atropine, a muscarinic acetylcholine receptor antagonist, were examined in adult male NMRI mice. A single-trial step-down passive avoidance task was used for the assessment of memory retention. Post-training intra-CA1 administration of an atypical μ-opioid receptor agonist, tramadol (0.5 and 1 μg/mouse), dose dependently impaired memory retention. Pretest injection of tramadol (0.5 and 1 μg/mouse, intra-CA1) induced state-dependent retrieval of the memory acquired under the influence of post-training tramadol (1 μg/mouse, intra-CA1). A pretest intra-CA1 injection of physostigmine (1 μg/mouse) reversed the memory impairment induced by post-training administration of tramadol (1 μg/mouse, intra-CA1). Moreover, pretest administration of physostigmine (0.5 and 1 μg/mouse, intra-CA1) with an ineffective dose of tramadol (0.25 μg/mouse, intra-CA1) also significantly restored retrieval. Pretest administration of physostigmine (0.25, 0.5, and 1 μg/mouse, intra-CA1) by itself did not affect memory retention. A pretest intra-CA1 injection of the atropine (1 and 2 μg/mouse) 5 min before the administration of tramadol (1 μg/mouse, intra-CA1) dose dependently inhibited tramadol state-dependent memory. Pretest administration of atropine (0.5, 1, and 2 μg/mouse, intra-CA1) by itself did not affect memory retention. It can be concluded that dorsal hippocampal muscarinic acetylcholine receptor mechanisms play an important role in the modulation of tramadol state-dependent memory.

Investigation of terpinen-4-ol effects on vascular smooth muscle relaxation.

PubMed

Maia-Joca, Rebeca Peres Moreno; Joca, Humberto Cavalcante; Ribeiro, Francisca Jéssica Penha; do Nascimento, Renata Vieira; Silva-Alves, Kerly Shamyra; Cruz, Jader S; Coelho-de-Souza, Andrelina Noronha; Leal-Cardoso, José Henrique

2014-10-12

This study investigated the mechanisms underlying the vascular effects of terpinen-4-ol in isolated rat aortic ring preparations. The thoracic aortae of healthy rats were submitted to isometric tension recording. Membrane resting potential and input membrane resistance were measured by conventional microelectrode technique. Terpinen-4-ol reversibly relaxed endothelium-containing preparations pre-contracted with high K(+) and phenylephrine with IC50 values of 421.43 μM and 802.50 μM, respectively. These effects were significantly reduced by vascular endothelium removal. In Ca(2+)-free and high K(+) (80 mM) medium, the contractions produced by Ba(2+) were reduced by terpinen-4-ol (100-1000 μM) in a concentration-dependent manner. In aortic rings maintained under Ca(2+)-free conditions, terpinen-4-ol significantly reduced the contractions induced by either phenylephrine (1 μM) or phorbol 12,13-dibutyrate (1 μM). Terpinen-4-ol (10-1000 μM) also relaxed the contractions evoked by BAYK-8644 (3 μM) with an IC50 of 454.23 μM. Neither membrane resting potential nor input resistance of smooth muscle cells was altered by terpinen-4-ol exposure. The present results suggest that terpinen-4-ol induced vascular smooth muscle relaxation that was preferentially due to the inhibition of electromechanical pathways related to calcium influx through voltage-operated calcium channels. Copyright © 2014 Elsevier Inc. All rights reserved.

Serelaxin treatment reverses vascular dysfunction and left ventricular hypertrophy in a mouse model of Type 1 diabetes

PubMed Central

Ng, Hooi Hooi; Leo, Chen Huei; Prakoso, Darnel; Qin, Chengxue; Ritchie, Rebecca H.; Parry, Laura J.

2017-01-01

Serelaxin prevents endothelial dysfunction in the mouse aorta ex vivo and inhibits apoptosis in cardiomyocytes under acute hyperglycaemia. Less is known about the effects of serelaxin in an in vivo mouse model of diabetes. Therefore, we tested the hypothesis in streptozotocin (STZ)-treated mice that serelaxin is able to reverse diabetes-induced vascular dysfunction and cardiac remodelling. Mice were divided into citrate buffer + placebo, STZ + placebo and STZ + serelaxin (0.5 mg/kg/d, 2 weeks) groups. After 12 weeks of diabetes, sensitivity to the endothelium-dependent agonist acetylcholine (ACh) was reduced in the mesenteric artery. This was accompanied by an enhanced vasoconstrictor prostanoid contribution and a decrease in endothelium-derived hyperpolarisation (EDH)-mediated relaxation. Serelaxin restored endothelial function by increasing nitric oxide (NO)-mediated relaxation but not EDH. It also normalised the contribution of vasoconstrictor prostanoids to endothelial dysfunction and suppressed diabetes-induced hyper-responsiveness of the mesenteric artery to angiotensin II. Similarly, diabetes reduced ACh-evoked NO-mediated relaxation in the aorta which was reversed by serelaxin. In the left ventricle, diabetes promoted apoptosis, hypertrophy and fibrosis; serelaxin treatment reversed this ventricular apoptosis and hypertrophy, but had no effect on fibrosis. In summary, serelaxin reversed diabetes-induced endothelial dysfunction by enhancing NO-mediated relaxation in the mouse vasculature and attenuating left ventricular hypertrophy and apoptosis. PMID:28067255

Acute retinal ischemia inhibits endothelium-dependent nitric oxide-mediated dilation of retinal arterioles via enhanced superoxide production.

PubMed

Hein, Travis W; Ren, Yi; Potts, Luke B; Yuan, Zhaoxu; Kuo, Enoch; Rosa, Robert H; Kuo, Lih

2012-01-03

Because retinal vascular disease is associated with ischemia and increased oxidative stress, the vasodilator function of retinal arterioles was examined after retinal ischemia induced by elevated intraocular pressure (IOP). The role of superoxide anions in the development of vascular dysfunction was assessed. IOP was increased and maintained at 80 to 90 mm Hg for 30, 60, or 90 minutes by infusing saline into the anterior chamber of a porcine eye. The fellow eye with normal IOP (10-20 mm Hg) served as control. In some pigs, superoxide dismutase mimetic TEMPOL (1 mM) or vehicle (saline) was injected intravitreally before IOP elevation. After enucleation, retinal arterioles were isolated and pressurized without flow for functional analysis by recording diameter changes using videomicroscopic techniques. Dihydroethidium (DHE) was used to detect superoxide production in isolated retinal arterioles. Isolated retinal arterioles developed stable basal tone and the vasodilations to endothelium-dependent nitric oxide (NO)-mediated agonists bradykinin and L-lactate were significantly reduced only by 90 minutes of ischemia. However, vasodilation to endothelium-independent NO donor sodium nitroprusside was unaffected after all time periods of ischemia. DHE staining showed that 90 minutes of ischemia significantly increased superoxide levels in retinal arterioles. Intravitreal injection of membrane-permeable radical scavenger but not vehicle before ischemia prevented elevation of vascular superoxide and preserved bradykinin-induced dilation. Endothelium-dependent NO-mediated dilation of retinal arterioles is impaired by 90 minutes of ischemia induced by elevated IOP. The inhibitory effect appears to be mediated by the alteration of NO signaling via vascular superoxide.

Comparison of captopril and enalapril to study the role of the sulfhydryl-group in improvement of endothelial dysfunction with ACE inhibitors in high dieted methionine mice.

PubMed

Liu, Yu-Hui; Liu, Li-Ying; Wu, Jin-Xiang; Chen, Shuang-Xiu; Sun, Yin-Xue

2006-01-01

To examine the role of sulfhydryl (-SH) group in improvement of endothelial dysfunction with angiotensin-converting enzyme (ACE) inhibitors in experimental high dose of methionine dieted rats. We compared the effects of Captopril (an ACE inhibitor with -SH group), enalapril (an ACE-inhibitor without -SH group), N-acetylcysteine (only -SH group not ACE inhibitor) on endothelial dysfunction injured by methionine-induced hyperhomocysteinemia (HHcy) in rats. Male Sprague-Dawley rats were divided randomly into seven groups: control group, L-methionine group, low dose Captopril (15 mg/kg), middle dose Captopril (30 mg/kg), high dose Captopril (45 mg/kg), enalapril (20 mg/kg), N-acetylcysteine (200 mg/kg); control group were intragastric gavaged by water and others groups were intragastric gavaged by L-methionine and drugs in water one time every day. Acetylcholine (ACh)-induced endothelium-dependent relaxation (EDR), sodium nitroprusside (SNP)-induced endothelium-independent relaxation of aortic rings were examined. Paraoxonase1 (PON1) and ACE activity, malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD) in serum were analyzed. It was found that a single intragastric gavage by L-methionine resulted in inhibition of endothelium-dependent relaxation, markedly increased the serum level of malondialdehyde and decreased the activity of PON1 and SOD, similarly decreased the level of NO in the serum; but had no effects on endothelium-independent relaxation and angiotensin-converting enzyme activity compared with the control group. Given the treatment with three doses of Captopril (15 approximately 45 mg/kg) markedly attenuated inhibition of vasodilator responses to ACh, and eliminated the increased level of malondialdehyde, the decreased level of NO, activity of PON1 and SOD in serum by single intragastric gavaged L-methionine. However, there were some significant differences among Captopril (30 mg/kg or 45 mg/kg), enalapril (20 mg/kg), and N

Exercise training-enhanced, endothelium-dependent dilation mediated by altered regulation of BKCa channels in collateral-dependent porcine coronary arterioles

PubMed Central

Xie, Wei; Parker, Janet L.; Heaps, Cristine L.

2012-01-01

Objective Test the hypothesis that exercise training increases the contribution of large-conductance, Ca2+-dependent K+ (BKCa) channels to endothelium-mediated dilation in coronary arterioles from collateral-dependent myocardial regions of chronically occluded pig hearts and may function downstream of H2O2. Methods An ameroid constrictor was placed around the proximal left circumflex coronary artery to induce gradual occlusion in Yucatan miniature swine. Eight weeks postoperatively, pigs were randomly assigned to sedentary or exercise training (treadmill; 14 wk) regimens. Results Exercise training significantly enhanced bradykinin-mediated dilation in collateral-dependent arterioles (~125 μm diameter) compared with sedentary pigs. The BKCa-channel blocker, iberiotoxin alone or in combination with the H2O2 scavenger, polyethylene glycol catalase, reversed exercise training-enhanced dilation in collateral-dependent arterioles. Iberiotoxin-sensitive whole-cell K+ currents (i.e., BKCa-channel currents) were not different between smooth muscle cells of nonoccluded and collateral-dependent arterioles of sedentary and exercise trained groups. Conclusions These data provide evidence that BKCa-channel activity contributes to exercise training-enhanced endothelium-dependent dilation in collateral-dependent coronary arterioles despite no change in smooth muscle BKCa-channel current. Taken together, our findings suggest that a component of the bradykinin signaling pathway, which stimulates BKCa channels, is enhanced by exercise training in collateral-dependent arterioles and suggest a potential role for H2O2 as the mediator. PMID:23002811

Inhibitory effects of pine nodule extract and its component, SJ-2, on acetylcholine-induced catecholamine secretion and synthesis in bovine adrenal medullary cells.

PubMed

Li, Xiaojia; Horishita, Takafumi; Toyohira, Yumiko; Shao, Hui; Bai, Jie; Bo, Haixia; Song, Xinbo; Ishikane, Shin; Yoshinaga, Yukari; Satoh, Noriaki; Tsutsui, Masato; Yanagihara, Nobuyuki

2017-04-01

Extract of pine nodules (matsufushi) formed by bark proliferation on the surface of trees of Pinus tabulaeformis or Pinus massoniana has been used as an analgesic for joint pain, rheumatism, neuralgia, dysmenorrhea and other complaints in Chinese traditional medicine. Here we report the effects of matsufushi extract and its components on catecholamine secretion and synthesis in cultured bovine adrenal medullary cells. We found that matsufushi extract (0.0003-0.005%) and its component, SJ-2 (5-hydroxy-3-methoxy-trans-stilbene) (0.3-100 μM), but not the other three, concentration-dependently inhibited catecholamine secretion induced by acetylcholine, a physiological secretagogue. Matsufushi extract (0.0003-0.005%) and SJ-2 (0.3-100 μM) also inhibited 45 Ca 2+ influx induced by acetylcholine in a concentration-dependent manner, similar to its effect on catecholamine secretion. They also suppressed 14 C-catecholamine synthesis and tyrosine hydroxylase activity induced by acetylcholine. In Xenopus oocytes expressing α3β4 nicotinic acetylcholine receptors, matsufushi extract (0.00003-0.001%) and SJ-2 (1-100 μM) directly inhibited the current evoked by acetylcholine. The present findings suggest that SJ-2, as well as matsufushi extract, inhibits acetylcholine-induced catecholamine secretion and synthesis by suppression of nicotinic acetylcholine receptor-ion channels in bovine adrenal medullary cells. Copyright © 2017 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

The relaxant effect induced by Allium sativum L. bulb aqueous extract on rat isolated trachea

PubMed Central

Fehri, Badreddine; Ahmed, Mueen K.K.; Aiache, Jean-Marc

2011-01-01

Background: Garlic plays an important role in complementary and alternative medicine. Most people believe in and use herbal products even when they have not been as thoroughly researched as garlic. Garlic is also known for its beneficial effects on the cardiovascular system. Materials and Methods: The relaxant effect of Allium sativum L. bulb aqueous extract (ASBAE) containing 0.06%-0.10% of allicin was studied on isolated smooth muscle of trachea of rats precontracted using acetylcholine (10−5 M). Results: It was found that ASBAE induced a dose-dependent relaxation with recorded EC 50 values of 71.87 ± 5.90 µg/mL (n = 7). Pretreatments with mepyramine (10−7 M), methysergide (10−7 M), caffeine (10−6 M), theophylline (10−6 M), nifedipine (10−6 M), and dipyridamole (10−6 M) did not alter ASBAE concentration-response curves. In turn, concentration-response curves to ASBAE were significantly shifted toward right in the presence of aspirin (3.10−3 M), indomethacin (10−6 M), prazosin (10−6 M), and propranolol (10−7 M). Conclusion: It is suggested that the recorded relaxation results are due to the release of prostaglandins E 1 and E 2 consecutively to α- and β-adrenoreceptor stimulation. PMID:21472073

Hypothermia Inhibits Endothelium-Independent Vascular Contractility via Rho-kinase Inhibition

PubMed Central

Chung, Yoon Hee; Oh, Keon Woong; Kim, Sung Tae; Park, Eon Sub; Je, Hyun Dong; Yoon, Hyuk-Jun; Sohn, Uy Dong; Jeong, Ji Hoon; La, Hyen-Oh

2018-01-01

The present study was undertaken to investigate the influence of hypothermia on endothelium-independent vascular smooth muscle contractility and to determine the mechanism underlying the relaxation. Denuded aortic rings from male rats were used and isometric contractions were recorded and combined with molecular experiments. Hypothermia significantly inhibited fluoride-, thromboxane A2-, phenylephrine-, and phorbol ester-induced vascular contractions regardless of endothelial nitric oxide synthesis, suggesting that another pathway had a direct effect on vascular smooth muscle. Hypothermia significantly inhibited the fluoride-induced increase in pMYPT1 level and phorbol ester-induced increase in pERK1/2 level, suggesting inhibition of Rho-kinase and MEK activity and subsequent phosphorylation of MYPT1 and ERK1/2. These results suggest that the relaxing effect of moderate hypothermia on agonist-induced vascular contraction regardless of endothelial function involves inhibition of Rho-kinase and MEK activities. PMID:28208012

Beneficial effects of calcitriol on hypertension, glucose intolerance, impairment of endothelium-dependent vascular relaxation, and visceral adiposity in fructose-fed hypertensive rats.

PubMed

Chou, Chu-Lin; Pang, Cheng-Yoong; Lee, Tony J F; Fang, Te-Chao

2015-01-01

Besides regulating calcium homeostasis, the effects of vitamin D on vascular tone and metabolic disturbances remain scarce in the literature despite an increase intake with high-fructose corn syrup worldwide. We investigated the effects of calcitriol, an active form of vitamin D, on vascular relaxation, glucose tolerance, and visceral fat pads in fructose-fed rats. Male Wistar-Kyoto rats were divided into 4 groups (n = 6 per group). Group Con: standard chow diet for 8 weeks; Group Fru: high-fructose diet (60% fructose) for 8 weeks; Group Fru-HVD: high-fructose diet as Group Fru, high-dose calcitriol treatment (20 ng / 100 g body weight per day) 4 weeks after the beginning of fructose feeding; and Group Fru-LVD: high-fructose diet as Group Fru, low-dose calcitriol treatment (10 ng / 100 g body weight per day) 4 weeks after the beginning of fructose feeding. Systolic blood pressure was measured twice a week by the tail-cuff method. Blood was examined for serum ionized calcium, phosphate, creatinine, glucose, triglycerides, and total cholesterol. Intra-peritoneal glucose intolerance test, aortic vascular reactivity, the weight of visceral fat pads, adipose size, and adipose angiotensin II levels were analyzed at the end of the study. The results showed that the fructose-fed rats significantly developed hypertension, impaired glucose tolerance, heavier weight and larger adipose size of visceral fat pads, and raised adipose angiotensin II expressions compared with the control rats. High- and low-dose calcitriol reduced modestly systolic blood pressure, increased endothelium-dependent aortic relaxation, ameliorated glucose intolerance, reduced the weight and adipose size of visceral fat pads, and lowered adipose angiotensin II expressions in the fructose-fed rats. However, high-dose calcitriol treatment mildly increased serum ionized calcium levels (1.44 ± 0.05 mmol/L). These results suggest a protective role of calcitriol treatment on endothelial function, glucose

Nicotinic Acetylcholine Receptor (nAChR) Dependent Chorda Tympani Taste Nerve Responses to Nicotine, Ethanol and Acetylcholine.

PubMed

Ren, Zuo Jun; Mummalaneni, Shobha; Qian, Jie; Baumgarten, Clive M; DeSimone, John A; Lyall, Vijay

2015-01-01

Nicotine elicits bitter taste by activating TRPM5-dependent and TRPM5-independent but neuronal nAChR-dependent pathways. The nAChRs represent common targets at which acetylcholine, nicotine and ethanol functionally interact in the central nervous system. Here, we investigated if the nAChRs also represent a common pathway through which the bitter taste of nicotine, ethanol and acetylcholine is transduced. To this end, chorda tympani (CT) taste nerve responses were monitored in rats, wild-type mice and TRPM5 knockout (KO) mice following lingual stimulation with nicotine free base, ethanol, and acetylcholine, in the absence and presence of nAChR agonists and antagonists. The nAChR modulators: mecamylamine, dihydro-β-erythroidine, and CP-601932 (a partial agonist of the α3β4* nAChR), inhibited CT responses to nicotine, ethanol, and acetylcholine. CT responses to nicotine and ethanol were also inhibited by topical lingual application of 8-chlorophenylthio (CPT)-cAMP and loading taste cells with [Ca2+]i by topical lingual application of ionomycin + CaCl2. In contrast, CT responses to nicotine were enhanced when TRC [Ca2+]i was reduced by topical lingual application of BAPTA-AM. In patch-clamp experiments, only a subset of isolated rat fungiform taste cells exposed to nicotine responded with an increase in mecamylamine-sensitive inward currents. We conclude that nAChRs expressed in a subset of taste cells serve as common receptors for the detection of the TRPM5-independent bitter taste of nicotine, acetylcholine and ethanol.

Nicotinic Acetylcholine Receptor (nAChR) Dependent Chorda Tympani Taste Nerve Responses to Nicotine, Ethanol and Acetylcholine

PubMed Central

Ren, Zuo Jun; Mummalaneni, Shobha; Qian, Jie; Baumgarten, Clive M.; DeSimone, John A.; Lyall, Vijay

2015-01-01

Nicotine elicits bitter taste by activating TRPM5-dependent and TRPM5-independent but neuronal nAChR-dependent pathways. The nAChRs represent common targets at which acetylcholine, nicotine and ethanol functionally interact in the central nervous system. Here, we investigated if the nAChRs also represent a common pathway through which the bitter taste of nicotine, ethanol and acetylcholine is transduced. To this end, chorda tympani (CT) taste nerve responses were monitored in rats, wild-type mice and TRPM5 knockout (KO) mice following lingual stimulation with nicotine free base, ethanol, and acetylcholine, in the absence and presence of nAChR agonists and antagonists. The nAChR modulators: mecamylamine, dihydro-β-erythroidine, and CP-601932 (a partial agonist of the α3β4* nAChR), inhibited CT responses to nicotine, ethanol, and acetylcholine. CT responses to nicotine and ethanol were also inhibited by topical lingual application of 8-chlorophenylthio (CPT)-cAMP and loading taste cells with [Ca2+]i by topical lingual application of ionomycin + CaCl2. In contrast, CT responses to nicotine were enhanced when TRC [Ca2+]i was reduced by topical lingual application of BAPTA-AM. In patch-clamp experiments, only a subset of isolated rat fungiform taste cells exposed to nicotine responded with an increase in mecamylamine-sensitive inward currents. We conclude that nAChRs expressed in a subset of taste cells serve as common receptors for the detection of the TRPM5-independent bitter taste of nicotine, acetylcholine and ethanol. PMID:26039516

The Sophora flavescens flavonoid compound trifolirhizin inhibits acetylcholine induced airway smooth muscle contraction.

PubMed

Yang, Nan; Liang, Banghao; Srivastava, Kamal; Zeng, Jia; Zhan, Jixun; Brown, LaVerne; Sampson, Hugh; Goldfarb, Joseph; Emala, Charles; Li, Xiu-Min

2013-11-01

Asthma is a serious health problem worldwide, particularly in industrialized countries. Despite a better understanding of the pathophysiology of asthma, there are still considerable gaps in knowledge as well as a need for classes of drugs. ASHMI™ (Anti-asthma Herbal Medicine Intervention) is an aqueous extract of Ganoderma lucidum (Fr.) P. Karst (Ling Zhi), Sophora flavescens Aiton (Ku Shen) and Glycyrrhiza uralensis Fisch. ex DC (Gan Cao). It prevents allergic asthma airway hyper-reactivity in mice and inhibits acetylcholine (ACh) induced airway smooth muscle (ASM) contraction in tracheal rings from allergic asthmatic mice. The purpose of this research was to identify individual herb(s) and their active compound(s) that inhibit ASM contraction. It was found that S. flavescens, but not G. lucidum or G. uralensis aqueous extracts, inhibited ASM contraction in tracheal rings from asthmatic mice. Bioassay-guided isolation and identification of flavonoid fractions/compound(s) via methylene chloride extraction, preparative HPLC fractionation, and LC-MS and NMR spectroscopic analyses showed that trifolirhizin is an active constituent that inhibits acetylcholine mediated ASM contraction or directly relaxes pre-contracted ASM independent of β2-adrenoceptors. Copyright © 2013 Elsevier Ltd. All rights reserved.

The Sophora Flavescens flavonoid compound trifolirhizin inhibits acetylcholine induced airway smooth muscle contraction

PubMed Central

Zeng, Jia; Zhan, Jixun; Brown, LaVerne; Sampson, Hugh; Goldfarb, Joseph; Emala, Charles; Li, Xiu-Min

2014-01-01

Asthma is a serious health problem worldwide, particularly in industrialized countries. Despite a better understanding of the pathophysiology of asthma, there are still considerable gaps in knowledge as well as a need for new classes of drugs. ASHMI™ (Anti-asthma Herbal Medicine Intervention) is an aqueous extract of Ganoderma lucidum (Fr.) P. Karst (Ling Zhi), Sophora flavescens Aiton (Ku Shen) and Glycyrrhiza uralensis Fisch. ex DC (Gan Cao). It prevents allergic asthma airway hyper-reactivity in mice and inhibits acetylcholine (ACh) induced airway smooth muscle (ASM) contraction in tracheal rings from allergic asthmatic mice. The purpose of this research was to identify individual herb(s) and their active compound(s) that inhibit ASM contraction. It was found that Sophora flavescens (S. flavescens), but not Ganoderma lucidum (G. lucidum) or Glycyrrhiza uralensis (G. uralensis) aqueous extracts, inhibited ASM contraction in tracheal rings from asthmatic mice. Bioassay-guided isolation and identification of flavonoid fractions/compound(s) via methylene chloride extraction, preparative HPLC fractionation, and LC-MS and NMR spectroscopic analyses showed that trifolirhizin is an active constituent that inhibits acetylcholine mediated ASM contraction or directly relaxes pre-contracted ASM independent of β2-adrenoceptors. PMID:23993294

Protective effect of N-acetylcysteine against oxygen radical-mediated coronary artery injury.

PubMed

Rodrigues, A J; Evora, P R B; Schaff, H V

2004-08-01

The present study investigated the protective effect of N-acetylcysteine (NAC) against oxygen radical-mediated coronary artery injury. Vascular contraction and relaxation were determined in canine coronary arteries immersed in Kreb's solution (95% O2-5% CO2), incubated or not with NAC (10 mM), and exposed to free radicals (FR) generated by xanthine oxidase (100 mU/ml) plus xanthine (0.1 mM). Rings not exposed to FR or NAC were used as controls. The arteries were contracted with 2.5 microM prostaglandin F2alpha. Subsequently, concentration-response curves for acetylcholine, calcium ionophore and sodium fluoride were obtained in the presence of 20 microM indomethacin. Concentration-response curves for bradykinin, calcium ionophore, sodium nitroprusside, and pinacidil were obtained in the presence of indomethacin plus Nomega-nitro-L-arginine (0.2 mM). The oxidative stress reduced the vascular contraction of arteries not exposed to NAC (3.93 +/- 3.42 g), compared to control (8.56 +/- 3.16 g) and to NAC group (9.07 +/- 4.0 g). Additionally, in arteries not exposed to NAC the endothelium-dependent nitric oxide (NO)-dependent relaxation promoted by acetylcholine (1 nM to 10 microM) was also reduced (maximal relaxation of 52.1 +/- 43.2%), compared to control (100%) and NAC group (97.0 +/- 4.3%), as well as the NO/cyclooxygenase-independent receptor-dependent relaxation provoked by bradykinin (1 nM to 10 microM; maximal relaxation of 20.0 +/- 21.2%), compared to control (100%) and NAC group (70.8 +/- 20.0%). The endothelium-independent relaxation elicited by sodium nitroprusside (1 nM to 1 microM) and pinacidil (1 nM to 10 microM) was not affected. In conclusion, the vascular dysfunction caused by the oxidative stress, expressed as reduction of the endothelium-dependent relaxation and of the vascular smooth muscle contraction, was prevented by NAC.

Endothelium-derived hyperpolarizing factor and protein kinase G Iα activation: H2O2 versus S-nitrosothiols.

PubMed

Bautista-Niño, Paula K; van der Stel, Marien; Batenburg, Wendy W; de Vries, René; Roks, Anton J M; Danser, A H Jan

2018-05-15

Protein kinase G (PKG) Iα mediates the cyclic guanosine monophosphate-mediated vasodilatory effects induced by NO. Endothelium-derived hyperpolarizing factors (EDHFs), like H 2 O 2 can activate PKGIα in a cyclic guanosine monophosphate-independent manner, but whether this is true for all EDHFs (e.g., S-nitrosothiols) is unknown. Here, we investigated the contribution of PKGIα to bradykinin-, H 2 O 2 -, L-S-nitrosocysteine-, and light-induced relaxation in porcine coronary arteries, making use of the fact that thioredoxin reductase inhibition with auranofin or 1-chloro-2,4-dinitrobenzene potentiates PKGIα. Thioredoxin reductase inhibition potentiated bradykinin and H 2 O 2 , but not L-S-nitrosocysteine or light. The relaxations by the latter 2 and bradykinin, but not those by H 2 O 2 , were prevented by the soluble guanylyl cyclase (sGC) inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one. Yet, after S-nitrosothiol depletion with ethacrynic acid, thioredoxin reductase inhibition also potentiated light-induced relaxation, and this was prevented by the Na + -K + ATPase inhibitor ouabain. This indicates that photorelaxation depends on sGC activation by S-nitrosothiols, while only after S-nitrosothiol depletion oxidized PKGIα comes into play, and acts via Na + -K + ATPase. In conclusion, both bradykinin- and light-induced relaxation of porcine coronary arteries depend, at least partially, on oxidized PKGIα, and this does not involve sGC. H 2 O 2 also acts via oxidized PKGIα in an sGC-independent manner. Yet, S-nitrosothiol-induced relaxation is PKGIα-independent. Clearly, PKG activation does not contribute universally to all EDHF responses, and targeting PKGIα may only mimick EDHF under certain conditions. It is therefore unlikely that PKGIα activators will be universal vasodilators. Copyright © 2018 Elsevier B.V. All rights reserved.

Factors, fiction and endothelium-derived hyperpolarizing factor.

PubMed

Sandow, Shaun L

2004-09-01

1. The principal mediators of vascular tone are neural, endothelial and physical stimuli that result in the initiation of dilator and constrictor responses to facilitate the control of blood pressure. Two primary vasodilatory stimuli produced by the endothelium are nitric oxide (NO) and prostaglandins. An additional endothelium-dependent vasodilatory mechanism is characterized as the hyperpolarization-mediated relaxation that remains after the inhibition of the synthesis of NO and prostaglandins. This mechanism is due to the action of a so-called endothelium-derived hyperpolarizing factor (EDHF) and is dependent on either the release of diffusible factor(s) and/or to a direct contact-mediated mechanism. 2. Most evidence supports the concept that 'EDHF' activity is dependent on contact-mediated mechanisms. This involves the transfer of an endothelium-derived electrical current, as an endothelium-derived hyperpolarization (EDH), through direct heterocellular coupling of endothelial cells and smooth muscle cells via myoendothelial gap junctions (MEGJ). However, there is a lack of consensus with regard to the nature and mechanism of action of EDHF/EDH (EDH(F)), which has been shown to vary within and between vascular beds, as well as among species, strains, sex and during development, ageing and disease. 3. In addition to actual heterogeneity in EDH(F), further heterogeneity has resulted from the less-than-optimal design, analysis and interpretation of data in some key papers in the EDHF literature; with such views being perpetuated in the subsequent literature. 4. The focus of the present brief review is to examine what factors are proposed as EDH(F) and highlight the correlative structural and functional studies from our laboratory that demonstrate an integral role for MEGJ in the conduction of EDH, which account for the heterogeneity in EDH(F), while incorporating the reported diffusible mechanisms in the regulation of this activity. Furthermore, in addition to the

Losartan reverses COX-2-dependent vascular dysfunction in offspring of hyperglycaemic rats.

PubMed

de Queiroz, Diego Barbosa; Ramos-Alves, Fernanda Elizabethe; Santos-Rocha, Juliana; Duarte, Gloria Pinto; Xavier, Fabiano Elias

2017-09-01

This study examined whether chronic treatment with losartan, an angiotensin II type 1 receptor (AT 1 R) antagonist, might reverse COX-2-mediated vascular dysfunction in mesenteric resistance arteries (MRA) from offspring of hyperglycaemic rats. Male 12-month-old offspring of hyperglycaemic (O-DR) and normoglycaemic (O-CR) rats were treated with losartan (15mg·kg·day -1 ) during 2months. Third order MRA of untreated and losartan-treated O-DR and O-CR were mounted in wire myograph for isometric tension measurements. COX-2 expression was analyzed by Western blot; TxA 2 , PGE 2 and PGF 2α release was measured using commercial kits. O-DR showed increased blood pressure, impaired acetylcholine-induced vasodilation and increased noradrenaline-induced vasoconstriction than O-CR. All these parameters were normalized by losartan in O-DR. Pre-incubation of MRA with indomethacin (COX-1/2 inhibitor), NS-398 (COX-2 inhibitor) or tempol (superoxide dismutase mimetic) increased relaxation to acetylcholine and reduced contraction to noradrenaline only in O-DR. COX-2 expression, TxA 2 , PGE 2 and PGF 2α release were increased in O-DR. In losartan-treated O-DR, NS-398, indomethacin or tempol failed to produce any effect on acetylcholine or noradrenaline responses. Losartan treatment reduced COX-2 expression, TxA 2 , PGE 2 and PGF 2α release in O-DR. The present results reveal that chronic losartan administration in O-DR normalizes endothelial function in MRA by correcting the existing COX-2 overexpression and the imbalance between endothelium-derived relaxing and contracting factors. These findings not only support the beneficial effects of AT 1 receptor antagonist in O-DR, but also suggest the implication of angiotensin II as a putative mediator of hyperglycemia-programmed vascular dysfunction in rats. Copyright © 2017 Elsevier Inc. All rights reserved.

Impaired endothelium-dependent vasodilatation in women with previous gestational diabetes.

PubMed

Anastasiou, E; Lekakis, J P; Alevizaki, M; Papamichael, C M; Megas, J; Souvatzoglou, A; Stamatelopoulos, S F

1998-12-01

To assess whether otherwise healthy women with a history of gestational diabetes mellitus (GDM) may have abnormalities in endothelial function at a very early stage, before glucose intolerance occurs. A total of 33 women with previous GDM (17 nonobese [BMI < 27] and 16 obese [BMI > or = 27]) and 19 healthy nonobese women were examined. A 75-g oral glucose tolerance test was performed, and insulin levels and biochemical parameters were also measured. Using high-resolution ultrasound, we measured vasodilatory responses of the brachial artery during reactive hyperemia (endothelium-dependent vasodilatation), and after nitroglycerin administration, an endothelium-independent vasodilator. Flow-mediated dilatation (FMD) was significantly and equally decreased in both groups of women with previous GDM, compared with control subjects (1.6 +/- 3.7% in the nonobese GDM group and 1.6 +/- 2.5% in the obese GDM group vs. 10.3 +/- 4.4% in control subjects, P < 0.001). FMD correlated inversely with serum uric acid levels, BMI, serum total cholesterol, and basal insulin resistance (homeostasis model assessment). Nitrate-induced dilatation was significantly decreased only in the obese GDM group compared with control subjects, (21.4 +/- 5.1 vs. 27.9 +/- 9.5, P < 0.05). Endothelial dysfunction, which is considered as a very early index of atherogenesis, is already present in both obese and nonobese women with a history of GDM, even when they have normal glucose tolerance.

Open channel noise. I. Noise in acetylcholine receptor currents suggests conformational fluctuations.

PubMed

Sigworth, F J

1985-05-01

The random passage of ions through an open channel is expected to result in shot noise fluctuations in the channel current. The patch-clamp technique now allows fluctuations of this size to be observed in single-channel currents. In the experiments reported here the acetylcholine-induced currents in cultured rat muscle cells were analyzed; fluctuations were found that were considerably larger than expected for shot noise. A low-frequency component, which was fitted with a Lorentzian, was examined in detail; it appears to arise from fluctuations in channel conductance of approximately 3% on a time scale of 1 ms. The characteristic relaxation time is voltage dependent and temperature dependent (Q10 approximately equal to 3) suggesting that the fluctuations arise from conformational fluctuations in the channel protein.

Relaxation-Induced Anxiety: Paradoxical Anxiety Enhancement Due to Relaxation Training.

ERIC Educational Resources Information Center

Heide, Frederick J.; Borkovec, T. D.

1983-01-01

Documented relaxation-induced anxiety in 14 subjects suffering from tension who were given training in progressive relaxation and mantra meditation. Four of the subjects displayed clinical evidence of an anxiety reaction during a preliminary practice period. Progressive relaxation produced less evidence of relaxation-induced anxiety. (Author/JAC)

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.

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.

Agmatine ameliorates atherosclerosis progression and endothelial dysfunction in high cholesterol-fed rabbits.

PubMed

El-Awady, Mohammed S; Suddek, Ghada M

2014-06-01

The aim of this work was to explore possible effects of agmatine, an endogenous inhibitor of inducible nitric oxide synthase (iNOS), against hypercholesterolemia-induced lipid profile changes and endothelial dysfunction. Hypercholesterolemia was induced by feeding rabbits with a high-cholesterol diet (HCD, 0.5%) for 8 weeks. Another HCD-fed group was orally administered agmatine (10 mg/kg/day) during weeks 5 through 8. Serum lipid profile, malondialdehyde (MDA), nitric oxide (NO) and lactate dehydrogenase (LDH) were determined. Aorta was isolated to analyse vascular reactivity, atherosclerotic lesions and intima/media (I/M) ratio. HCD induced a significant increase in serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), triglycerides and high-density lipoprotein cholesterol (HDL-C). Agmatine administration significantly decreased HCD-induced elevations in serum TC and LDL-C, MDA, LDH and NO while significantly increased HDL-C levels. Additionally, agmatine significantly protected against HCD-induced attenuation of rabbit aortic endothelium-dependent relaxation to acetylcholine. HCD and agmatine did not significantly influence aortic endothelium-independent relaxation to sodium nitroprusside. Moreover, agmatine significantly reduced the elevation in aortic atherosclerotic lesion area and I/M ratio. This study is the first to reveal that agmatine has the ability to ameliorate hypercholesterolemia-induced lipemic-oxidative and endothelial function injuries possibly by its antioxidant potential and/or iNOS inhibition. © 2014 Royal Pharmaceutical Society.

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

N-acetylcysteine does not improve the endothelial and smooth muscle function in the human saphenous vein.

PubMed

Sharif, Muhammad Anees; Bayraktutan, Ulvi; Young, Ian Stuart; Soong, Chee Voon

2007-01-01

Oxidative stress can lead to vein graft dysfunction in the saphenous vein. This ex vivo study is aimed to compare the effects of increasing concentrations of the antioxidant N-acetylcysteine (NAC) with heparinized saline (HS) on endothelial and smooth muscle function in the human saphenous vein. Long saphenous vein segment obtained during infrainguinal bypass surgery was divided into 7 rings; 1 immersed in HS and the remaining 6 in increasing NAC concentrations (0.0025%, 0.005%, 0.01%, 0.02%, 0.03%, and 0.04%). Rings were mounted in an organ bath, and relaxant responses to acetylcholine and sodium nitroprusside were assessed through isometric tension studies. Endothelium-dependent relaxations were observed in 77 vein segments from 11 patients. No significant difference was seen in veins treated with either lower NAC concentrations (0.0025%, 0.005%, 0.01%, 0.02%, and 0.03%) or HS. However, HS-treated veins showed significantly better relaxation compared to those treated with maximum (0.04%) NAC (P < .05). Endothelium-independent relaxations were observed in 91 segments from 13 patients. No difference in relaxation was observed between veins treated with HS or any of the NAC concentrations. In conclusion, lower NAC concentrations do not offer better endothelial protection than HS, whereas the highest NAC concentration has a detrimental effect on endothelium-dependent relaxation. Moreover, NAC did not show beneficial effect on direct smooth muscle relaxation.

Mechanism of resveratrol-induced relaxation of the guinea pig fundus.

PubMed

Tsai, Ching-Chung; Tey, Shu-Leei; Lee, Ming-Che; Liu, Ching-Wen; Su, Yu-Tsun; Huang, Shih-Che

2018-04-01

Resveratrol is a polyphenolic compound that can be isolated from plants and also is a constituent of red wine. Resveratrol induces relaxation of vascular smooth muscle and may prevent cardiovascular diseases. Impaired gastric accommodation plays an important role in functional dyspepsia and fundic relaxation and is a therapeutic target of functional dyspepsia. Although drugs for fundic relaxation have been developed, these types of drugs are still rare. The purpose of this study was to investigate the relaxant effects of resveratrol in the guinea pig fundus. We studied the relaxant effects of resveratrol in the guinea pig fundus. In addition, we investigated the mechanism of resveratrol-induced relaxation on the guinea pig fundus by using tetraethylammonium (a non-selective potassium channel blocker), apamine (a selective inhibitor of the small conductance calcium-activated potassium channel), iberiotoxin (an inhibitor of large conductance calcium-activated potassium channels), glibenclamide (an ATP-sensitive potassium channel blocker), KT 5720 (a cAMP-dependent protein kinase A inhibitor), KT 5823 (a cGMP-dependent protein kinase G inhibitor), NG-nitro-L-arginine (a competitive inhibitor of nitric oxide synthase), tetrodotoxin (a selective neuronal Na + channel blocker), ω-conotoxin GVIA (a selective neuronal Ca 2+ channel blocker) and G-15 (a G-protein coupled estrogen receptor antagonist). The results of this study showed that resveratrol has potent and dose-dependent relaxant effects on the guinea pig fundic muscle. In addition, the results showed that resveratrol-induced relaxation of the guinea pig fundus occurs through nitric oxide and ATP-sensitive potassium channels. This study provides the first evidence concerning the relaxant effects of resveratrol in the guinea pig fundic muscle strips. Furthermore, resveratrol may be a potential drug to relieve gastrointestinal dyspepsia. Copyright © 2018 Elsevier GmbH. All rights reserved.

Activation of muscarinic receptors by a hydroalcoholic extract of Dicksonia sellowiana Presl. HooK (Dicksoniaceae) induces vascular relaxation and hypotension in rats.

PubMed

Rattmann, Yanna D; Crestani, Sandra; Lapa, Fernanda R; Miguel, Obdúlio G; Marques, Maria C A; da Silva-Santos, J Eduardo; Santos, Adair R S

2009-01-01

Dicksonia sellowiana (Presl.) Hook is a native plant from the Central and South Americas that contain high levels of polyphenols, antioxidant compounds involved in protection against inflammation, cancer and cardiovascular risk. A phytomedicinal preparation obtained from aerial parts of D. sellowiana is currently under clinical evaluation in Brazil against asthma, and has been associated with several other beneficial effects. This study demonstrates that a hydroalcoholic extract obtained from D. sellowiana leaves (HEDS) fully relax, in a concentration-dependent manner, rat aortic rings precontracted with phenylephrine. Moreover, administration of HEDS (10, 20 and 40 mg/kg, i.v.) in anaesthetized rats resulted in a strong but reversible hypotension. Aortic relaxation induced by HEDS was abolished by endothelium removal, by incubation of the nitric oxide synthase inhibitor L-NAME, or the soluble guanylate cyclase inhibitor ODQ. In addition, this effect was partially inhibited by indomethacin (a cyclooxygenase inhibitor) and KT 5730 (a PKA inhibitor). The potassium channels blockade by either tetraethylammonium or charybdotoxin also resulted in a potent inhibition of HEDS-induced aortic relaxation, whereas apamine only slightly reduced it. In addition HEDS-induced relaxation was unchanged by 4-amynopiridine and glibenclamide. The selective muscarinic receptor antagonist atropine counteracted both aortic relaxation and blood pressure reduction generated by HEDS. Experiments using HPLC revealed the presence of high amounts of phenolic compounds in this extract. Taken together, our results reveal that the D. sellowiana possess substances with both in vivo and in vitro activities and that the vascular effect of HEDS involves activation of muscarinic receptors, stimulation of the nitric oxide pathway and opening of calcium-activated potassium channels.

Chloride channel blockade relaxes airway smooth muscle and potentiates relaxation by β-agonists

PubMed Central

Yim, Peter; Rinderspacher, Alison; Fu, Xiao Wen; Zhang, Yi; Landry, Donald W.; Emala, Charles W.

2014-01-01

Severe bronchospasm refractory to β-agonists continues to cause significant morbidity and mortality in asthmatic patients. We questioned whether chloride channels/transporters are novel targets for the relaxation of airway smooth muscle (ASM). We have screened a library of compounds, derivatives of anthranilic and indanyloxyacetic acid, that were originally developed to antagonize chloride channels in the kidney. We hypothesized that members of this library would be novel calcium-activated chloride channel blockers for the airway. The initial screen of this compound library identified 4 of 20 compounds that relaxed a tetraethylammonium chloride-induced contraction in guinea pig tracheal rings. The two most effective compounds, compounds 1 and 13, were further studied for their potential to either prevent the initiation of or relax the maintenance phase of an acetylcholine (ACh)-induced contraction or to potentiate β-agonist-mediated relaxation. Both relaxed an established ACh-induced contraction in human and guinea pig ex vivo ASM. In contrast, the prevention of an ACh-induced contraction required copretreatment with the sodium-potassium-chloride cotransporter blocker bumetanide. The combination of compound 13 and bumetanide also potentiated relaxation by the β-agonist isoproterenol in guinea pig tracheal rings. Compounds 1 and 13 hyperpolarized the plasma cell membrane of human ASM cells and blocked spontaneous transient inward currents, a measure of chloride currents in these cells. These functional and electrophysiological data suggest that modulating ASM chloride flux is a novel therapeutic target in asthma and other bronchoconstrictive diseases. PMID:24879056

Slow relaxation of cascade-induced defects in Fe

DOE PAGES

Béland, Laurent Karim; Osetsky, Yuri N.; Stoller, Roger E.; ...

2015-02-17

On-the-fly kinetic Monte Carlo (KMC) simulations are performed to investigate slow relaxation of non-equilibrium systems. Point defects induced by 25 keV cascades in α -Fe are shown to lead to a characteristic time-evolution, described by the replenish and relax mechanism. Then, we produce an atomistically-based assessment of models proposed to explain the slow structural relaxation by focusing on the aggregation of 50 vacancies and 25 self-interstital atoms (SIA) in 10-lattice-parameter α-Fe boxes, two processes that are closely related to cascade annealing and exhibit similar time signature. Four atomistic effects explain the timescales involved in the evolution: defect concentration heterogeneities, concentration-enhancedmore » mobility, cluster-size dependent bond energies and defect-induced pressure. In conclusion, these findings suggest that the two main classes of models to explain slow structural relaxation, the Eyring model and the Gibbs model, both play a role to limit the rate of relaxation of these simple point-defect systems.« less

Load dependence of left ventricular contraction and relaxation. Effects of caffeine.

PubMed

Leite-Moreira, A F; Correia-Pinto, J; Gillebert, T C

1999-08-01

Load dependence of left ventricular (LV) contraction and relaxation was investigated at baseline and after alteration of intracellular calcium handling by caffeine. Afterload was increased by aortic clamp occlusions (n = 281) in anesthetized open-chest dogs (n = 7). Control and first heartbeat after the intervention were considered for analysis. Caffeine (50 mg/kg, iv) had no inotropic effect. The systolic LV pressure (LVP), developed in response to aortic occlusion, decreased as ejection proceeded and this pressure generating capacity was not affected by caffeine. Late-systolic aortic occlusions induced premature onset and accelerated rate of initial LVP fall at baseline and similarly after caffeine. Graded diastolic aortic occlusions induced systolic LVP elevations of various magnitudes. Smaller LVP elevations prolonged ejection and accelerated LVP fall, while larger elevations had opposite effects. The transition from acceleration to deceleration was observed at 83.1 +/- 1.1% of peak isovolumetric LVP at baseline and at lower loads, at 77.6 +/- 1.2%, after caffeine (p < 0.01). Isovolumetric heartbeats prolonged the time constant tau by 238 +/- 70% at baseline and only by 155 +/- 44% after caffeine (p < 0.01). The relaxation-systolic pressure relation, which describes afterload dependence of relaxation, was also modified by caffeine. Caffeine affected LV relaxation without altering contractility. As a consequence contraction-relaxation coupling was modified by caffeine. These results might help to understand load dependence of relaxation in conditions where intracellular calcium handling is altered.

Relaxant effect of the ethanol extract of Helichrysum plicatum (Asteraceae) on isolated rat ileum contractions.

PubMed

Bigovic, Dubravka; Brankovic, Suzana; Kitic, Dusanka; Radenkovic, Mirjana; Jankovic, Teodora; Savikin, Katarina; Zivanovic, Slavoljub

2010-05-10

Helichrysum plicatum (Turkish Helichrysum) has been used in folk medicine for the treatment of gastric and hepatic disorders. The aim of the present study was to examine the relaxant activity of an extract of H. plicatum flowers on isolated rat ileum. Segments of ileum of rats were suspended in an organ bath. Cumulative concentrations of H. plicatum ethanol extract induced a relaxant effect on spontaneous rat ileum contractions. H. plicatum extract caused a mean contractile response of 81.68 +/- 6.17% (at a dose of 0.01 mg/mL) and 30.08 +/- 9.07% (at a dose of 1 mg/mL). A similar effect was observed with papaverine (0.01-3 microg/mL). H. plicatum extract (0.01-1 mg/mL) relaxed high K+ (80 mM) precontractions, an effect similar to that caused by papaverine (0.01-3 microg/mL). The plant extract (0.03-0.3 mg/mL) also induced a significant depression of the cumulative concentration response curve for acetylcholine (5-1500 nM) (p < 0.01). Atropine (140 nM) abolished the acetylcholine effect. The extract (0.03-0.3 mg/mL) reduced the histamine (1-300 nM) and BaCl2 (3-900 microM) induced contractions (p < 0.01). Our results showed the relaxant effect of the ethanol extract of Helichrysum plicatum flowers on the isolated rat intestine Extract of H. plicatum can inhibit the spontaneous ileum contractions and contractions induced by acetylcholine, histamine, barium and potassium ions.

Long-term treatment with Nandrolone Decanoate impairs mesenteric vascular relaxation in both sedentary and exercised female rats.

PubMed

Caliman, Izabela F; Bernabe, Cristian S; de Melo, Antônio F; Brasil, Girlândia A; do Nascimento, Andrews M; de Lima, Ewelyne M; Figueiredo, Suely G; de Andrade, Tadeu U; Bissoli, Nazaré S

2017-04-01

Nandrolone Decanoate (ND) is an Anabolic Androgenic Steroid (AAS) that under abusive regimen can lead to multiple physiological adverse effects. Studies of AAS-mediated cardiovascular (CV) alterations were mostly taken from male subjects, even though women are also susceptible to the effects of AAS and gender-specific differences in susceptibility to vascular diseases exist. Here we investigate ND-induced vascular reactivity alterations in both sedentary and exercised female rats and whether these alterations depend on endothelium-derived factors. We show that chronic exposure of female Wistar rats to ND (20mg/Kg/week for 4weeks) impaired the vascular mesenteric bed (MVB) reactivity to vasodilator (acetylcholine) agonist. The endothelium-dependent Nitric Oxide (NO) component was reduced in ND-treated rats, whereas neither the endothelium-derived hyperpolarizing factor (EDHF) component nor prostanoids were altered in the MVBs. Endothelial dysfunction observed in ND-treated rats was associated with decreased eNOS (Ser 1177 ) and Akt (Ser 473 ) phosphorylation sites and upregulation of iNOS and NADPH oxidase expression. Exercise training by weight lifting in water did not improve the vascular alterations induced by ND treatment. ND treatment also significantly reduced the serum levels of estradiol in females, overriding its CV protective effect. These results help uncover the role of ND modulating endothelial function in the setting of CV disease caused by the abuse of AAS in females. If this translates to humans, young women abusing AAS can potentially lose the cardio protective effect rendered by estrogen and be more susceptible to CV alterations. Copyright © 2017 Elsevier Inc. All rights reserved.

Sivelestat relaxes vascular smooth muscle contraction in human gastric arteries.

PubMed

Amemori, Hiroko; Maeda, Yoshinori; Torikai, Arisu; Nakashima, Mikio

2011-12-01

Sivelestat sodium hydrate (sivelestat) is a novel synthetic drug and specific inhibitor of neutrophil elastase that has been approved in Japan as a treatment for acute lung injury associated with systemic inflammatory response syndrome. It is important to determine how sivelestat affects hemodynamics and the regulatory mechanisms of vascular smooth muscle (VSM). We recently found that sivelestat relaxes porcine coronary artery VSM via selective inhibition of Ca(2+) sensitization induced by a receptor agonist without affecting the normal Ca(2+)-induced contraction. Although sivelestat relaxes porcine artery, its effects on human artery are unknown; therefore, the purpose of the present study was to assess the effects of sivelestat on human artery. In the present study, sivelestat induced concentration-dependent (1 × 10(-6) to 3 × 10(-4) M) vasorelaxation in U46619 (1 nM) and sphingosylphosphorylcholine (SPC) (30 mM)-precontracted human gastric artery with or without endothelium, but sivelestat did not induce vasorelaxation in conditions of high K(+) (40 mM) depolarization. Sivelestat inhibited VSM contraction by an agonist and SPC, and it did not affect Ca(2+)-induced normal physiologic contraction.

Endothelium-dependent desensitization to angiotensin II in rabbit aorta: the mechanisms involved.

PubMed

Jerez, S; de Bruno, M P; Coviello, A

2001-06-01

The aim of this study was to characterize the role of the endothelium in angiotensin II-desensitization and its mechanisms of action. Rabbit aortic rings were exposed to increasing doses of angiotensin II (Ang II, 10(-9) to 2.5 x 10(-6)) to generate two cumulative dose-response curves (CDRC I and II). A 50-min interval separated CDRC I and II. Desensitization was observed at all doses in unrubbed aortic tissue and at lower doses in rubbed aortic tissue. Tachyphylaxis was greater in arteries with endothelium. Treatment of intact rings with L-N(G)-nitroarginine methyl ester (L-NAME, 10(-4) M) did not prevent this phenomenon. However, indomethacin (10(-5) M) and miconazol (10(-6) M) attenuated Ang II-desensitization. Treatment of unrubbed rings with nifedipine (10(-6) M) and cromakalim (10(-6) M) inhibited the effect of indomethacin. To confirm the involvement of K+ channels, unrubbed and rubbed aortic rings were treated with the K(Ca2+) blockers apamin (10(-7) M), tetraethylammonium (TEA, 10(-3) M), and iberiotoxin (10(-8) M), and the K(ATP) blocker glibenclamide (10(-5) M). In both arteries apamin, TEA, and glibenclamide abolished the tachyphylaxis without changes in the maximal response. Iberiotoxin diminished Ang II-desensitization in rubbed but not unrubbed arteries. Results from this study suggest that Ang II-desensitization involves endothelium-dependent and -independent mechanisms. Endothelium-dependent desensitization could be mediated by a cyclooxygenase-cytochrome P450 product, which could act by increasing K(Ca2+) channel activity.

Selective endothelin ETA and dual ET(A)/ET(B) receptor blockade improve endothelium-dependent vasodilatation in patients with type 2 diabetes and coronary artery disease.

PubMed

Rafnsson, Arnar; Shemyakin, Alexey; Pernow, John

2014-11-24

Endothelin-1 contributes to endothelial dysfunction in patients with atherosclerosis and type 2 diabetes. In healthy arteries the ETA receptor mediates the main part of the vasoconstriction induced by endothelin-1 whilst the ETB receptor mediates vasodilatation. The ETB receptor expression is upregulated on vascular smooth muscle cells in atherosclerosis and may contribute to the increased vasoconstrictor tone and endothelial dysfunction observed in this condition. Due to these opposing effects of the ETB receptor it remains unclear whether ETB blockade together with ETA blockade may be detrimental or beneficial. The aim was therefore to compare the effects of selective ETA and dual ETA/ETB blockade on endothelial function in patients with type 2 diabetes and coronary artery disease. Forearm endothelium-dependent and endothelium-independent vasodilatation was assessed by venous occlusion plethysmography in 12 patients before and after selective ETA or dual ETA/ETB receptor blockade. Dual ETA/ETB receptor blockade increased baseline forearm blood flow by 30±14% (P<0.01) whereas selective ETA blockade did not (14±8%). Both selective ETA blockade and dual ETA/ETB blockade significantly improved endothelium-dependent vasodilatation. The improvement did not differ between the two treatments. There was also an increase in endothelium-independent vasodilatation with both treatments. Dual ETA/ETB blockade did not significantly increase microvascular flow but improved transcutaneous pO2. Both selective ETA and dual ETA/ETB improve endothelium-dependent vasodilatation in patients with type 2 diabetes and coronary artery disease. ETB blockade increases basal blood flow but does not additionally improve endothelium-dependent vasodilatation. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Crucial roles of Nox2-derived oxidative stress in deteriorating the function of insulin receptors and endothelium in dietary obesity of middle-aged mice.

PubMed

Du, Junjie; Fan, Lampson M; Mai, Anna; Li, Jian-Mei

2013-11-01

Systemic oxidative stress associated with dietary calorie overload plays an important role in the deterioration of vascular function in middle-aged patients suffering from obesity and insulin resistance. However, effective therapy is still lacking. In this study, we used a mouse model of middle-aged obesity to investigate the therapeutic potential of pharmaceutical inhibition (apocynin, 5 mM supplied in the drinking water) or knockout of Nox2, an enzyme generating reactive oxygen species (ROS), in high-fat diet (HFD)-induced obesity, oxidative stress, insulin resistance and endothelial dysfunction. Littermates of C57BL/6J wild-type (WT) and Nox2 knockout (KO) mice (7 months old) were fed with a HFD (45% kcal fat) or normal chow diet (NCD, 12% kcal fat) for 16 weeks and used at 11 months of age. Compared to NCD WT mice, HFD WT mice developed obesity, insulin resistance, dyslipidaemia and hypertension. Aortic vessels from these mice showed significantly increased Nox2 expression and ROS production, accompanied by significantly increased ERK1/2 activation, reduced insulin receptor expression, decreased Akt and eNOS phosphorylation and impaired endothelium-dependent vessel relaxation to acetylcholine. All these HFD-induced abnormalities (except the hyperinsulinaemia) were absent in apocynin-treated WT or Nox2 KO mice given the same HFD. In conclusion, Nox2-derived ROS played a key role in damaging insulin receptor and endothelial function in dietary obesity after middle-age. Targeting Nox2 could represent a valuable therapeutic strategy in the metabolic syndrome. © 2013 The British Pharmacological Society.

Nanosensors for the Chemical Imaging of Acetylcholine Using Magnetic Resonance Imaging.

PubMed

Luo, Yi; Kim, Eric H; Flask, Chris A; Clark, Heather A

2018-06-06

A suite of imaging tools for detecting specific chemicals in the central nervous system could accelerate the understanding of neural signaling events critical to brain function and disease. Here, we introduce a class of nanoparticle sensors for the highly specific detection of acetylcholine in the living brain using magnetic resonance imaging. The nanosensor is composed of acetylcholine-catalyzing enzymes and pH-sensitive gadolinium contrast agents co-localized onto the surface of polymer nanoparticles, which leads to changes in T 1 relaxation rate (1/ T 1 ). The mechanism of the sensor involves the enzymatic hydrolysis of acetylcholine leading to a localized decrease in pH which is detected by the pH-sensitive gadolinium chelate. The concomitant change in 1/ T 1 in vitro measured a 20% increase from 0 to 10 μM acetylcholine concentration. The applicability of the nanosensors in vivo was demonstrated in the rat medial prefrontal cortex showing distinct changes in 1/ T 1 induced by pharmacological stimuli. The highly specific acetylcholine nanosensor we present here offers a promising strategy for detection of cholinergic neurotransmission and will facilitate our understanding of brain function through chemical imaging.

Withaferin A protects against palmitic acid-induced endothelial insulin resistance and dysfunction through suppression of oxidative stress and inflammation

PubMed Central

Batumalaie, Kalaivani; Amin, Muhammad Arif; Murugan, Dharmani Devi; Sattar, Munavvar Zubaid Abdul; Abdullah, Nor Azizan

2016-01-01

Activation of inflammatory pathways via reactive oxygen species (ROS) by free fatty acids (FFA) in obesity gives rise to insulin resistance and endothelial dysfunction. Withaferin A (WA), possesses both antioxidant and anti-inflammatory properties and therefore would be a good strategy to suppress palmitic acid (PA)-induced oxidative stress and inflammation and hence, insulin resistance and dysfunction in the endothelium. Effect of WA on PA-induced insulin resistance in human umbilical vein endothelial cells (HUVECs) was determined by evaluating insulin signaling mechanisms whilst effect of this drug on PA-induced endothelial dysfunction was determined in acetylcholine-mediated relaxation in isolated rat aortic preparations. WA significantly inhibited ROS production and inflammation induced by PA. Furthermore, WA significantly decreased TNF-α and IL-6 production in endothelial cells by specifically suppressing IKKβ/NF-κβ phosphorylation. WA inhibited inflammation-stimulated IRS-1 serine phosphorylation and improved the impaired insulin PI3-K signaling, and restored the decreased nitric oxide (NO) production triggered by PA. WA also decreased endothelin-1 and plasminogen activator inhibitor type-1 levels, and restored the impaired endothelium-mediated vasodilation in isolated aortic preparations. These findings suggest that WA inhibited both ROS production and inflammation to restore impaired insulin resistance in cultured endothelial cells and improve endothelial dysfunction in rat aortic rings. PMID:27250532

Rhynchophylline Ameliorates Endothelial Dysfunction via Src-PI3K/Akt-eNOS Cascade in the Cultured Intrarenal Arteries of Spontaneous Hypertensive Rats

PubMed Central

Hao, Hui-Feng; Liu, Li-Mei; Pan, Chun-Shui; Wang, Chuan-She; Gao, Yuan-Sheng; Fan, Jing-Yu; Han, Jing-Yan

2017-01-01

Objectives: To examine the protective effect of Rhynchophylline (Rhy) on vascular endothelial function in spontaneous hypertensive rats (SHRs) and the underlying mechanism. Methods: Intrarenal arteries of SHRs and Wistar rats were suspended in myograph for force measurement. Expression and phosphorylation of endothelial nitric oxide (NO) synthase (eNOS), Akt, and Src kinase (Src) were examined by Western blotting. NO production was assayed by ELISA. Results: Rhy time- and concentration-dependently improved endothelium-dependent relaxation in the renal arteries from SHRs, but had no effect on endothelium-independent relaxation in SHR renal arteries. Wortmannin (an inhibitor of phosphatidylinositol 3-kinase) or PP2 (an inhibitor of Src) inhibited the improvement of relaxation in response to acetylcholine by 12 h-incubation with 300 μM Rhy. Western blot analysis revealed that Rhy elevated phosphorylations of eNOS, Akt, and Src in SHR renal arteries. Moreover, wortmannin reversed the increased phosphorylations of Akt and eNOS induced by Rhy, but did not affect the phosphorylation of Src. Furthermore, the enhanced phosphorylations of eNOS, Akt, and Src were blunted by PP2. Importantly, Rhy increased NO production and this effect was blocked by inhibition of Src or PI3K/Akt. Conclusion: The present study provides evidences for the first time that Rhy ameliorates endothelial dysfunction in SHRs through the activation of Src-PI3K/Akt-eNOS signaling pathway. PMID:29187825

Dietary restriction but not angiotensin II type 1 receptor blockade improves DNA damage-related vasodilator dysfunction in rapidly aging Ercc1Δ/- mice.

PubMed

Wu, Haiyan; van Thiel, Bibi S; Bautista-Niño, Paula K; Reiling, Erwin; Durik, Matej; Leijten, Frank P J; Ridwan, Yanto; Brandt, Renata M C; van Steeg, Harry; Dollé, Martijn E T; Vermeij, Wilbert P; Hoeijmakers, Jan H J; Essers, Jeroen; van der Pluijm, Ingrid; Danser, A H Jan; Roks, Anton J M

2017-08-01

DNA damage is an important contributor to endothelial dysfunction and age-related vascular disease. Recently, we demonstrated in a DNA repair-deficient, prematurely aging mouse model ( Ercc1 Δ/- mice) that dietary restriction (DR) strongly increases life- and health span, including ameliorating endothelial dysfunction, by preserving genomic integrity. In this mouse mutant displaying prominent accelerated, age-dependent endothelial dysfunction we investigated the signaling pathways involved in improved endothelium-mediated vasodilation by DR, and explore the potential role of the renin-angiotensin system (RAS). Ercc1 Δ/- mice showed increased blood pressure and decreased aortic relaxations to acetylcholine (ACh) in organ bath experiments. Nitric oxide (NO) signaling and phospho-Ser 1177 -eNOS were compromised in Ercc1 Δ / - DR improved relaxations by increasing prostaglandin-mediated responses. Increase of cyclo-oxygenase 2 and decrease of phosphodiesterase 4B were identified as potential mechanisms. DR also prevented loss of NO signaling in vascular smooth muscle cells and normalized angiotensin II (Ang II) vasoconstrictions, which were increased in Ercc1 Δ/- mice. Ercc1 Δ/ - mutants showed a loss of Ang II type 2 receptor-mediated counter-regulation of Ang II type 1 receptor-induced vasoconstrictions. Chronic losartan treatment effectively decreased blood pressure, but did not improve endothelium-dependent relaxations. This result might relate to the aging-associated loss of treatment efficacy of RAS blockade with respect to endothelial function improvement. In summary, DR effectively prevents endothelium-dependent vasodilator dysfunction by augmenting prostaglandin-mediated responses, whereas chronic Ang II type 1 receptor blockade is ineffective. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

Hyperbaric oxygenation affects the mechanisms of acetylcholine-induced relaxation in diabetic rats.

PubMed

Unfirer, Sanela; Mihalj, Martina; Novak, Sanja; Kibel, Aleksandar; Cavka, Ava; Mijalevic, Zrinka; Gros, Mario; Brizic, Ivica; Budimir, Danijela; Cosic, Anita; Boban, Mladen; Drenjancevic, Ines

2016-01-01

The effects of hyperbaric oxygenation (HBO₂) on acetylcholine-induced vasorelaxation (AChIR) were evaluated in male Sprague-Dawley (SD) rats randomized into four groups: healthy controls (Ctrl), diabetic rats (DM), and control and diabetic rats that underwent hyperbaric oxygenation (Ctrl+HBO₂ and DM+HBO₂). AChIR was measured in aortic rings, with L-NAME, indomethacin, or MS-PPOH and a combination of inhibitors. mRNA expression of eNOS, iNOS, COX-1 and COX-2 was assessed by qPCR, and protein expression of CYP4A(1-3) by Western blot. Plasma antioxidative capacity and systemic oxidative stress were determined with the ferric reducing ability of plasma (FRAP) and thiobarbituric acid-reactive substances (TBARS) assays, respectively. AChIR was preserved in all groups of rats, but mediated with different mechanisms. In all experimental groups of rats, AChIR was mediated mainly by NO, with the contribution of CYP450 vasodilator metabolites. This effect was the most prominent in the DM+HBO₂ group of rats. The TBARS was significantly higher in both DM and DM+HBO₂ groups compared to respective controls. eNOS expression was upregulated in the DM+HBO₂ group compared to other groups, COX-1 expression was upregulated in the DM+HBO₂ group compared to the control. CYP450-4A1 / A2/A3protein expression was significantly higher expressed in both hyperbaric groups compared to their respective controls. In conclusion, HBO₂ affected all three vasodilator pathways and shifted AChIR to CYP450 enzymes pathway. Copyright© Undersea and Hyperbaric Medical Society.

Reduction of Mitochondria-Endoplasmic Reticulum Interactions by Acetylcholine Protects Human Umbilical Vein Endothelial Cells From Hypoxia/Reoxygenation Injury.

PubMed

He, Xi; Bi, Xue-Yuan; Lu, Xing-Zhu; Zhao, Ming; Yu, Xiao-Jiang; Sun, Lei; Xu, Man; Wier, W Gil; Zang, Wei-Jin

2015-07-01

We explored the role of endoplasmic reticulum (ER)-mitochondria Ca(2+) cross talk involving voltage-dependent anion channel-1 (VDAC1)/glucose-regulated protein 75/inositol 1,4,5-trisphosphate receptor 1 complex and mitofusin 2 in endothelial cells during hypoxia/reoxygenation (H/R), and investigated the protective effects of acetylcholine. Acetylcholine treatment during reoxygenation prevented intracellular and mitochondrial Ca(2+) increases and alleviated ER Ca(2+) depletion during H/R in human umbilical vein endothelial cells. Consequently, acetylcholine enhanced mitochondrial membrane potential and inhibited proapoptotic cascades, thereby reducing cell death and preserving endothelial ultrastructure. This effect was likely mediated by the type-3 muscarinic acetylcholine receptor and the phosphatidylinositol 3-kinase/Akt pathway. In addition, interactions among members of the VDAC1/glucose-regulated protein 75/inositol 1,4,5-trisphosphate receptor 1 complex were increased after H/R and were associated with mitochondrial Ca(2+) overload and cell death. Inhibition of the partner of the Ca(2+) channeling complex (VDAC1 siRNA) or a reduction in ER-mitochondria tethering (mitofusin 2 siRNA) prevented the increased protein interaction within the complex and reduced mitochondrial Ca(2+) accumulation and subsequent endothelial cell death after H/R. Intriguingly, acetylcholine could modulate ER-mitochondria Ca(2+) cross talk by inhibiting the VDAC1/glucose-regulated protein 75/inositol 1,4,5-trisphosphate receptor 1 complex and mitofusin 2 expression. Phosphatidylinositol 3-kinase siRNA diminished acetylcholine-mediated inhibition of mitochondrial Ca(2+) overload and VDAC1/glucose-regulated protein 75/inositol 1,4,5-trisphosphate receptor 1 complex formation induced by H/R. Our data suggest that ER-mitochondria interplay plays an important role in reperfusion injury in the endothelium and may be a novel molecular target for endothelial protection. Acetylcholine attenuates

Gastrin-releasing peptide induces monocyte adhesion to vascular endothelium by upregulating endothelial adhesion molecules

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

Kim, Mi-Kyoung; Park, Hyun-Joo; Department of Dental Pharmacology, BK21 PLUS Project, School of Dentistry, Pusan National University, Yangsan 626-870

Gastrin-releasing peptide (GRP) is a neuropeptide that plays roles in various pathophysiological conditions including inflammatory diseases in peripheral tissues; however, little is known about whether GRP can directly regulate endothelial inflammatory processes. In this study, we showed that GRP promotes the adhesion of leukocytes to human umbilical vein endothelial cells (HUVECs) and the aortic endothelium. GRP increased the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) by activating nuclear factor-κB (NF-κB) in endothelial cells. In addition, GRP activated extracellular signal-regulated kinase 1/2 (ERK1/2), p38MAPK, and AKT, and the inhibition of these signaling pathways significantly reduced GRP-inducedmore » monocyte adhesion to the endothelium. Overall, our results suggested that GRP may cause endothelial dysfunction, which could be of particular relevance in the development of vascular inflammatory disorders. - Highlights: • GRP induces adhesion of monocytes to vascular endothelium. • GRP increases the expression of endothelial adhesion molecules through the activation of NF-κB. • ERK1/2, p38MAPK, and Akt pathways are involved in the GRP-induced leukocyte adhesiveness to endothelium.« less

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.

Treatment with sodium nitroprusside improves the endothelial function in aortic rings with endothelial dysfunction.

PubMed

Buzinari, Tereza Cristina; Oishi, Jorge Camargo; De Moraes, Thiago Francisco; Vatanabe, Izabela Pereira; Selistre-de-Araújo, Heloisa Sobreiro; Pestana, Cezar Rangel; Rodrigues, Gerson Jhonatan

2017-07-15

Verify if sodium nitroprusside (SNP) is able to improve endothelial function and if this effect is independent of nitric oxide (NO) release of the compound. Normotensive (2K) and hypertensive (2K-1C) wistar rats were used. Intact endothelium aortas were placed in a myograph and incubated with SNP: 0.1nM; 1nM or 10nM during 30min. Cumulative concentration-effect curves for acetylcholine (Ach) were realized to measure the relaxing capacity. Intracellular NO were measured (by DAF-2DA probe) in HUVEC treated with SNP 0.1nM or DETA/NO 0.1μM. The detection of intracellular superoxide radical (O 2 •- ) was obtained by using DHE probe. Treatment of 2K-1C aortic rings with SNP (0.1; 1.0 and 10nM) improved endothelium dependent relaxation induced by acetylcholine. This improvement induced by SNP was verified at the concentration of 0.1nM, which does not release NO, suggesting that this effect was not induced due to NO release by SNP compound. Besides, we show that the cell treatment with 0.1nM of SNP decreased the fluorescence intensity to DHE in cells stimulated with angiotensin II. These results indicate that SNP decreases the concentration of O 2 •- in HUVEC cells. The SNP at a concentration that does not release NO inside the cells is able to attenuate endothelial dysfunction. Acetylcholine (Ach) (PubChem CID:6060); angiotensin II human (Ang II) (PubChem CID: 16211177); diethylenetriamine/nitric oxide (DETA-NO) (PubChem CID 4518); dihydroethidium (DHE) (PubChem CID: 128682); phenylephrine (Phe) (PubChem CID: 5284443); sodium nitroprusside (SNP) (PubChem CID: 11963579); Thiazolyl Blue Tetrazolium Bromide (MTT) (PubChem CID: 64965); 4,5-diaminofluorescein diacetate (DAF-2DA); 4-hidroxy-Tempo (Tempol) (PubChem CID: 137994), were purchased from Sigma-Aldrich (St. Louis, MO, USA). Copyright © 2017 Elsevier B.V. All rights reserved.

Cannabidiol causes endothelium-dependent vasorelaxation of human mesenteric arteries via CB1 activation

PubMed Central

Stanley, Christopher P.; Hind, William H.; Tufarelli, Cristina; O'Sullivan, Saoirse E.

2015-01-01

Aims The protective effects of cannabidiol (CBD) have been widely shown in preclinical models and have translated into medicines for the treatment of multiple sclerosis and epilepsy. However, the direct vascular effects of CBD in humans are unknown. Methods and results Using wire myography, the vascular effects of CBD were assessed in human mesenteric arteries, and the mechanisms of action probed pharmacologically. CBD-induced intracellular signalling was characterized using human aortic endothelial cells (HAECs). CBD caused acute, non-recoverable vasorelaxation of human mesenteric arteries with an Rmax of ∼40%. This was inhibited by cannabinoid receptor 1 (CB1) receptor antagonists, desensitization of transient receptor potential channels using capsaicin, removal of the endothelium, and inhibition of potassium efflux. There was no role for cannabinoid receptor-2 (CB2) receptor, peroxisome proliferator activated receptor (PPAR)γ, the novel endothelial cannabinoid receptor (CBe), or cyclooxygenase. CBD-induced vasorelaxation was blunted in males, and in patients with type 2 diabetes or hypercholesterolemia. In HAECs, CBD significantly reduced phosphorylated JNK, NFκB, p70s6 K and STAT5, and significantly increased phosphorylated CREB, ERK1/2, and Akt levels. CBD also increased phosphorylated eNOS (ser1177), which was correlated with increased levels of ERK1/2 and Akt levels. CB1 receptor antagonism prevented the increase in eNOS phosphorylation. Conclusion This study shows, for the first time, that CBD causes vasorelaxation of human mesenteric arteries via activation of CB1 and TRP channels, and is endothelium- and nitric oxide-dependent. PMID:26092099

Are acetylcholine-induced acetyl groups driving fuel cells in the systems of transducin, t and G proteins?

PubMed

Nyberg-Swenson, B E

2002-05-01

Life is completely dependent on a support of energy which is generated by the direct absorption of light or by the reduction of oxygen. Metabolized food yields ac(et)yl groups which are utilized in the reduction of oxygen with the assistance of many other compounds. Acetylcholine appears to be an important substance for the transportation of acetyl groups. Acetylcholine activates systems regulated by transducin, t and G proteins, probably Se enzymes, reacting by similar mechanisms in triggered reactions ending in nerve or muscle signals. These activations are performed by GTP (or ATP), probably resulting from the reactions of acetylcholine-induced acetyl groups. The inactivation-activation states of these systems are regulated by changes of GTP to cGMP to GMP which form a loop.Diminished support of energy to systems, because of impaired charge transfer to oxygen, may be responsible for many diseases. For example, there is a low level of acetylcholine in the brains of patients with Alzheimer's disease. Copyright 2002 Elsevier Science Ltd. All Rights reserved.

Relaxation model of radiation-induced conductivity in polymers

NASA Astrophysics Data System (ADS)

Zhutayeva, Yu. R.; Khatipov, S. A.

1999-05-01

The paper suggests a relaxation model of radiation-induced conductivity (RIC) in polymers. According to the model, the transfer of charges generated in the polymer volume by ionizing radiation takes place with the participation of molecular relaxation processes. The mechanism of electron transport consists in the transfer of the charge directly between traps when they draw close to one another due to the rotation of macromolecule segments. The numerical solutions of the corresponding kinetic equations for different distribution functions Q( τ) of the times of molecular relaxation and for different functions of the probability P( τ, τ') of charge transfer in the `overlapping' regions of the diffusion spheres of the segments are analyzed. The relaxation model provides an explanation of the non-Arrhenius behavior of the RIC temperature dependence, the power dependence of RIC on the dose rate with a power index in the interval 0.5-1.0, the appearance of maxima in the curves of the RIC temporal dependence and their irreversible character in the region of large dose rates (more than 1 Gy/s). The model can be used for interpreting polymer RIC in conditions of kinetic mobility of macromolecules.

Ergothioneine prevents endothelial dysfunction induced by mercury chloride.

PubMed

Gökçe, Göksel; Arun, Mehmet Zuhuri; Ertuna, Elif

2018-06-01

Exposure to mercury has detrimental effects on the cardiovascular system, particularly the vascular endothelium. The present study aimed to investigate the effects of ergothioneine (EGT) on endothelial dysfunction induced by low-dose mercury chloride (HgCl 2 ). Agonist-induced contractions and relaxations were evaluated in isolated aortic rings from 3-month-old male Wistar rats treated by intra-muscular injection to caudal hind leg muscle with HgCl 2 (first dose, 4.6 µg/kg; subsequent doses, 0.07 µg/kg/day for 15 days) and optionally with EGT (2 µg/kg for 30 days). Reactive oxygen species (ROS) in aortic rings were measured by means of lucigenin- and luminol-enhanced chemiluminescence. The protein level of endothelial nitric oxide synthase was evaluated by ELISA. Blood glutathione (GSH) and catalase levels, lipid peroxidation and total nitrite were measured spectrophotometrically. The results indicated that low-dose HgCl 2 administration impaired acetylcholine (ACh)-induced relaxation and potentiated phenylephrine- and serotonin-induced contractions in rat aortas. In addition, HgCl 2 significantly increased the levels of ROS in the aortic tissue. EGT prevented the loss of ACh-induced relaxations and the increase in contractile responses. These effects were accompanied by a significant decrease in ROS levels. EGT also improved the ratio of reduced GSH to oxidized GSH and catalase levels with a concomitant decrease in lipid peroxidation. In conclusion, to the best of our knowledge, the present study was the first to report that EGT prevents endothelial dysfunction induced by low-dose HgCl 2 administration. EGT may serve as a therapeutic tool to reduce mercury-associated cardiovascular complications via improving the antioxidant status.

Hemodynamic Flow-Induced Mechanotransduction Signaling Influences the Radiation Response of the Vascular Endothelium.

PubMed

Natarajan, Mohan; Aravindan, Natarajan; Sprague, Eugene A; Mohan, Sumathy

2016-08-01

Hemodynamic shear stress is defined as the physical force exerted by the continuous flow of blood in the vascular system. Endothelial cells, which line the inner layer of blood vessels, sense this physiological force through mechanotransduction signaling and adapt to maintain structural and functional homeostasis. Hemodynamic flow, shear stress and mechanotransduction signaling are, therefore, an integral part of endothelial pathophysiology. Although this is a well-established concept in the cardiovascular field, it is largely dismissed in studies aimed at understanding radiation injury to the endothelium and subsequent cardiovascular complications. We and others have reported on the differential response of the endothelium when the cells are under hemodynamic flow shear compared with static culture. Further, we have demonstrated significant differences in the gene expression of static versus shear-stressed irradiated cells in four key pathways, reinforcing the importance of shear stress in understanding radiation injury of the endothelium. This article further emphasizes the influence of hemodynamic shear stress and the associated mechanotransduction signaling on physiological functioning of the vascular endothelium and underscores its significance in understanding radiation injury to the vasculature and associated cardiac complications. Studies of radiation effect on endothelial biology and its implication on cardiotoxicity and vascular complications thus far have failed to highlight the significance of these factors. Factoring in these integral parts of the endothelium will enhance our understanding of the contribution of the endothelium to radiation biology. Without such information, the current approaches to studying radiation-induced injury to the endothelium and its consequences in health and disease are limited.

Mechanism of resveratrol-induced relaxation in the human gallbladder.

PubMed

Tsai, Ching-Chung; Lee, Ming-Che; Tey, Shu-Leei; Liu, Ching-Wen; Huang, Shih-Che

2017-05-08

Resveratrol is a polyphenolic compound extracted from plants and is also a constituent of red wine. Resveratrol produces relaxation of vascular smooth muscle and may prevent cardiovascular diseases. Although resveratrol has been reported to cause relaxation of the guinea pig gallbladder, limited data are available about the effect of resveratrol on the gallbladder smooth muscle in humans. The purpose of this study was to investigate the relaxation effects of resveratrol in human gallbladder muscle strips. We studied the relaxant effects of resveratrol in human gallbladder. In addition, we also investigated mechanism of resveratrol-induced relaxation in human gallbladder by tetraethylammonium (a non-selective potassium channels blocker), iberiotoxin (an inhibitor of large conductance calcium-activated potassium channel), glibenclamide (an ATP-sensitive potassium channel blocker), charybdotoxin (an inhibitor of large conductance calcium-activated potassium channels and slowly inactivating voltage-gated potassium channels), apamine (a selective inhibitor of the small conductance calcium-activated potassium channel), KT 5720 (a cAMP-dependent protein kinase A inhibitor), KT 5823 (a cGMP-dependent protein kinase G inhibitor), NG-Nitro-L-arginine (a competitive inhibitor of nitric oxide synthase), tetrodotoxin (a selective neuronal Na + channel blocker), and ω-conotoxin GVIA (a selective neuronal Ca 2+ channel blocker). The present study showed that resveratrol has relaxant effects in human gallbladder muscle strips. In addition, we found that resveratrol-induced relaxation in human gallbladder is associated with nitric oxide, ATP-sensitive potassium channel, and large conductance calcium-activated potassium channel pathways. This study provides the first evidence concerning the relaxant effects of resveratrol in human gallbladder muscle strips. Furthermore, these results demonstrate that resveratrol is a potential new drug or health supplement in the treatment of

Ferulic acid relaxed rat aortic, small mesenteric and coronary arteries by blocking voltage-gated calcium channel and calcium desensitization via dephosphorylation of ERK1/2 and MYPT1.

PubMed

Zhou, Zhong-Yan; Xu, Jia-Qi; Zhao, Wai-Rong; Chen, Xin-Lin; Jin, Yu; Tang, Nuo; Tang, Jing-Yi

2017-11-15

Ferulic acid, a natural ingredient presents in several Chinese Materia Medica such as Radix Angelicae Sinensis, has been identified as an important multifunctional and physiologically active small molecule. However, its pharmacological activity in different blood vessel types and underlying mechanisms are unclear. The present study was to investigate the vascular reactivity and the possible action mechanism of FA on aorta, small mesenteric arteries and coronary arteries isolated from Wistar rats. We found FA dose-dependently relieved the contraction of aorta, small mesenteric arteries and coronary arteries induced by different contractors, U46619, phenylephrine (Phe) and KCl. The relaxant effect of FA was not affected by L-NAME (eNOS inhibitor), ODQ (soluble guanylate cyclase inhibitor), and mechanical removal of endothelium in thoracic aortas. The contraction caused by 60mM KCl (60K) was concentration-dependently hindered by FA pretreatment in all three types of arteries. In Ca 2+ -free 60K solution, FA weakened Ca 2+ -related contraction in a concentration dependent manner. And FA relaxed both fluoride and phorbol ester which were PKC, ERK and Rho-kinase activators induced contraction in aortic rings with or without Ca 2+ in krebs solution. Western blotting experiments in A7r5 cells revealed that FA inhibited calcium sensitization via dephosphorylation of ERK1/2 and MYPT1. Furthermore, the relaxation effect of FA was attenuated by verapamil (calcium channel blocker), ERK inhibitor, and fasudil (ROCK inhibitor). These results provide evidence that FA exhibits endothelium-independent vascular relaxant effect in different types of arteries. The molecular mechanism of vasorelaxation activity of FA probably involved calcium channel inhibition and calcium desensitization. Copyright © 2017. Published by Elsevier B.V.

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

A Pharmacological Examination of the Cardiovascular Effects of Malayan Krait (Bungarus candidus) Venoms.

PubMed

Chaisakul, Janeyuth; Rusmili, Muhamad Rusdi Ahmad; Hodgson, Wayne C; Hatthachote, Panadda; Suwan, Kijja; Inchan, Anjaree; Chanhome, Lawan; Othman, Iekhsan; Chootip, Krongkarn

2017-03-29

Cardiovascular effects (e.g., tachycardia, hypo- and/or hypertension) are often clinical outcomes of snake envenoming. Malayan krait ( Bungarus candidus ) envenoming has been reported to cause cardiovascular effects that may be related to abnormalities in parasympathetic activity. However, the exact mechanism for this effect has yet to be determined. In the present study, we investigated the in vivo and in vitro cardiovascular effects of B. candidus venoms from Southern (BC-S) and Northeastern (BC-NE) Thailand. SDS-PAGE analysis of venoms showed some differences in the protein profile of the venoms. B. candidus venoms (50 µg/kg-100 µg/kg, i.v.) caused dose-dependent hypotension in anaesthetised rats. The highest dose caused sudden hypotension (phase I) followed by a return of mean arterial pressure to baseline levels and a decrease in heart rate with transient hypertension (phase II) prior to a small decrease in blood pressure (phase III). Prior administration of monovalent antivenom significantly attenuated the hypotension induced by venoms (100 µg/kg, i.v.). The sudden hypotensive effect of BC-NE venom was abolished by prior administration of hexamethonium (10 mg/kg, i.v.) or atropine (5 mg/kg, i.v.). BC-S and BC-NE venoms (0.1 µg/kg-100 µg/ml) induced concentration-dependent relaxation (EC 50 = 8 ± 1 and 13 ± 3 µg/mL, respectively) in endothelium-intact aorta. The concentration-response curves were markedly shifted to the right by pre-incubation with L-NAME (0.2 mM), or removal of the endothelium, suggesting that endothelium-derived nitric oxide (NO) is likely to be responsible for venom-induced aortic relaxation. Our data indicate that the cardiovascular effects caused by B. candidus venoms may be due to a combination of vascular mediators (i.e., NO) and autonomic adaptation via nicotinic and muscarinic acetylcholine receptors.

Endothelial Arginine Resynthesis Contributes to the Maintenance of Vasomotor Function in Male Diabetic Mice

PubMed Central

Chennupati, Ramesh; Meens, Merlijn J. P. M. T.; Marion, Vincent; Janssen, Ben J.; Lamers, Wouter H.; De Mey, Jo G. R.; Köhler, S. Eleonore

2014-01-01

Aim Argininosuccinate synthetase (ASS) is essential for recycling L-citrulline, the by-product of NO synthase (NOS), to the NOS substrate L-arginine. Here, we assessed whether disturbed arginine resynthesis modulates endothelium-dependent vasodilatation in normal and diabetic male mice. Methods and Results Endothelium-selective Ass-deficient mice (Assfl/fl/Tie2Cretg/− = Ass-KOTie2) were generated by crossing Assfl/fl mice ( = control) with Tie2Cre mice. Gene ablation in endothelial cells was confirmed by immunohistochemistry. Blood pressure (MAP) was recorded in 34-week-old male mice. Vasomotor responses were studied in isolated saphenous arteries of 12- and 34-week-old Ass-KOTie2 and control animals. At the age of 10 weeks, diabetes was induced in control and Ass-KOTie2 mice by streptozotocin injections. Vasomotor responses of diabetic animals were studied 10 weeks later. MAP was similar in control and Ass-KOTie2 mice. Depletion of circulating L-arginine by arginase 1 infusion or inhibition of NOS activity with L-NAME resulted in an increased MAP (10 and 30 mmHg, respectively) in control and Ass-KOTie2 mice. Optimal arterial diameter, contractile responses to phenylephrine, and relaxing responses to acetylcholine and sodium nitroprusside were similar in healthy control and Ass-KOTie2 mice. However, in diabetic Ass-KOTie2 mice, relaxation responses to acetylcholine and endothelium-derived NO (EDNO) were significantly reduced when compared to diabetic control mice. Conclusions Absence of endothelial citrulline recycling to arginine did not affect blood pressure and systemic arterial vasomotor responses in healthy mice. EDNO-mediated vasodilatation was significantly more impaired in diabetic Ass-KOTie2 than in control mice demonstrating that endothelial arginine recycling becomes a limiting endothelial function in diabetes. PMID:25033204

Anti-Platelet Therapy with Clopidogrel Prevents Endothelial Dysfunction and Vascular Remodeling in Aortas from Hypertensive Rats

PubMed Central

Giachini, Fernanda R.; Leite, Romulo; Osmond, David A.; Lima, Victor V.; Inscho, Edward W.; Webb, R. Clinton; Tostes, Rita C.

2014-01-01

The aim was to investigate the beneficial effects of clopidogrel in thoracic aorta function and structure and to characterize if P2Y12 receptors contribute to these effects. Male Sprague Dawley rats were infused with angiotensin II [(Ang II) 60 ng.min−1, 14 days] or saline (control rats) and were simultaneously treated with clopidogrel (10 mg.kg−1.day−1) or vehicle. After 14 days, systolic blood pressure (mmHg) was similar in Ang II-hypertensive rats treated with clopidogrel or vehicle (199±9 vs. 190±11, respectively). Systolic blood pressure in control rats was not altered by clopidogrel treatment (128±1 vs. vehicle, 134±2). Endothelium-dependent relaxation induced by 2-MeS-ADP was decreased in aortas from vehicle-treated Ang II-hypertensive rats, compared to vehicle-treated control rats. This response was elicited via activation of P2Y1 and P2Y12 receptors. In the presence of L-NAME and indomethacin, 2-MeS-ADP induced contraction and this response was augmented in vehicle-treated Ang II-hypertensive rats, compared to vehicle-treated control rats. The contraction to 2-MeS-ADP was evoked by P2Y13 and P2Y12 receptor activation. Clopidogrel-treatment did not normalize relaxation or contractile responses induced by 2-MeS-ADP in aortas from Ang II-hypertensive rats. P2Y1 and P2Y12 protein expression was increased, whereas P2Y13 receptor expression was reduced in aorta from vehicle-treated Ang II-hypertensive rats. Endothelium-dependent relaxation upon acetylcholine-stimulation was reduced in vehicle-treated Ang II-hypertensive rats, and clopidogrel treatment was effective in improving endothelial function. Clopidogrel also prevented vascular remodeling, evidenced by augmented media thickness in aortas from Ang II-hypertensive rats. Clopidogrel has beneficial effects on the aortic endothelium of Ang II-hypertensive rats, but its effects do not seem to be directly related to the presence of P2Y12 receptors in this vessel. PMID:24638017

Mechanisms involved in the relaxant action of testosterone in the renal artery from male normoglycemic and diabetic rabbits.

PubMed

Marrachelli, Vannina G; Miranda, Francisco J; Centeno, José M; Burguete, María C; Castelló-Ruiz, María; Jover-Mengual, Teresa; Pérez, Antonio M; Salom, Juan B; Torregrosa, Germán; Alborch, Enrique

2010-02-01

Kidney disease is a frequent complication in diabetes, and significant differences have been reported between male and female patients. Our working hypothesis was that diabetes might modify the vascular actions of testosterone in isolated rabbit renal arteries and the mechanisms involved in these actions. Testosterone (10(-8) to 10(-4)M) induced relaxation of precontracted arteries, without significant differences between control and diabetic rabbits. Both in control and diabetic rabbits endothelium removal inhibited testosterone relaxant action. In arteries with endothelium, incubation with indomethacin (10(-5)M), N(G)-nitro-l-arginine (10(-5)M) or tetraethylammonium (10(-5)M) did not modify relaxations to testosterone neither in control nor in diabetic rabbits. In endothelium-denuded arteries indomethacin enhanced the relaxant action of testosterone, both in control and diabetic rabbits. In arteries from diabetic rabbits, eNOS, iNOS and COX-1 expression and testosterone-induced release of thromboxane A(2) and prostacyclin were not significantly different from those observed in control rabbits. However, COX-2 expression was significantly lower in diabetic rabbits that in control rabbits. In nominally Ca(2+)-free medium, cumulative addition of CaCl2 (10(-5) to 3x10(-2)M) contracted previously depolarized arteries. Testosterone (10(-4)M) inhibited CaCl2 contractions of the renal artery both in control and diabetic rabbits. These results show that testosterone relaxes the renal artery both in control and diabetic rabbits. This relaxation is modulated by muscular thromboxane A(2), it is partially mediated by endothelial prostacyclin, and it involves the blocking of extracellular Ca2+ entry. Diabetes does not modify the mechanisms involved in the relaxant action of testosterone in the rabbit renal artery. Copyright 2009 Elsevier Ltd. All rights reserved.

Vitamin C Prevents Cigarette Smoke-Induced Leukocyte Aggregation and Adhesion to Endothelium in vivo

NASA Astrophysics Data System (ADS)

Lehr, Hans-Anton; Frei, Balz; Arfors, Karl-E.

1994-08-01

A common feature of cigarette-smoke (CS)-associated diseases such as atherosclerosis and pulmonary emphysema is the activation, aggregation, and adhesion of leukocytes to micro- and macrovascular endothelium. A previous study, using a skinfold chamber model for intravital fluorescence microscopy in awake hamsters, has shown that exposure of hamsters to the smoke generated by one research cigarette elicits the adhesion of fluorescently labeled leukocytes to the endothelium of arterioles and small venules. By the combined use of intravital microscopy and scanning electron microscopy, we now demonstrate in the same animal model that (i) CS-induced leukocyte adhesion is not confined to the microcirculation, but that leukocytes also adhere singly and in clusters to the aortic endothelium; (ii) CS induces the formation in the bloodstream of aggregates between leukocytes and platelets; and (iii) CS-induced leukocyte adhesion to micro- and macrovascular endothelium and leukocyte-platelet aggregate formation are almost entirely prevented by dietary or intravenous pretreatment with the water-soluble antioxidant vitamin C (venules, 21.4 ± 11.0 vs. 149.6 ± 38.7 leukocytes per mm^2, P < 0.01; arterioles, 8.5 ± 4.2 vs. 54.3 ± 21.6 leukocytes per mm^2, P < 0.01; aortas, 0.8 ± 0.4 vs. 12.4 ± 5.6 leukocytes per mm^2, P < 0.01; means ± SD of n = 7 animals, 15 min after CS exposure). No inhibitory effect was observed by pretreatment of the animals with the lipid-soluble antioxidants vitamin E or probucol. The protective effects of vitamin C on CS-induced leukocyte adhesion and aggregation were seen at vitamin C plasma levels (55.6 ± 22.2 μM, n = 7) that can easily be reached in humans by dietary means or supplementation, suggesting that vitamin C effectively contributes to protection from CS-associated cardiovascular and pulmonary diseases in humans.

Size dependence of 13C nuclear spin-lattice relaxation in micro- and nanodiamonds

NASA Astrophysics Data System (ADS)

Panich, A. M.; Sergeev, N. A.; Shames, A. I.; Osipov, V. Yu; Boudou, J.-P.; Goren, S. D.

2015-02-01

Size dependence of physical properties of nanodiamond particles is of crucial importance for various applications in which defect density and location as well as relaxation processes play a significant role. In this work, the impact of defects induced by milling of micron-sized synthetic diamonds was studied by magnetic resonance techniques as a function of the particle size. EPR and 13C NMR studies of highly purified commercial synthetic micro- and nanodiamonds were done for various fractions separated by sizes. Noticeable acceleration of 13C nuclear spin-lattice relaxation with decreasing particle size was found. We showed that this effect is caused by the contribution to relaxation coming from the surface paramagnetic centers induced by sample milling. The developed theory of the spin-lattice relaxation for such a case shows good compliance with the experiment.

Antiatherogenic effects of S-nitroso-N-acetylcysteine in hypercholesterolemic LDL receptor knockout mice.

PubMed

Krieger, M H; Santos, K F R; Shishido, S M; Wanschel, A C B A; Estrela, H F G; Santos, L; De Oliveira, M G; Franchini, K G; Spadari-Bratfisch, R C; Laurindo, F R M

2006-02-01

The pathophysiology of the NO/NO synthase system and dysfunctional changes in the endothelium in the early phases of the atherogenic process are incompletely understood. In this study, we investigated the effects of the nitrosothiol NO donor S-nitroso-N-acetylcysteine (SNAC) in the early prevention of plaque development in the hypercholesterolemic LDLr-/- mice as well as the changes in endothelium-dependent relaxation and NO synthase expression. LDLr-/- mice were fed a 1.25% cholesterol-enriched diet for 15 days. Plasma cholesterol/triglyceride levels increased and this increase was accompanied by the development of aortic root lesions. Aortic vasorelaxation to acetylcholine was increased, although endothelium-independent relaxation in response to sodium nitroprusside did not change, which suggest stimulated NO release enhanced. This dysfunction was associated with enhanced aortic superoxide production and with increased levels of constitutive NOS isoform expression, particularly neuronal NOS. SNAC (S-nitroso-N-acetylcysteine) administration (0.51 micromol/kg/day i.p. for 15 days) decreased the extent of the plaque by 55% in hypercholesterolemic mice, but had no effects on vasomotor changes. It did, however, lead to a decrease in constitutive NOS expression. The SNAC induced only minor changes in plasma lipid profile. The present study has shown that, in early stages of plaque development in LDLr-/- mice, specific changes in NO/NO synthase system develop, that are characterized by increased endothelium-dependent vasorelaxation and increased constitutive NOS expression. Since the development of plaque and the indicator of endothelial cell dysfunction were prevented by SNAC, such treatment may constitute a novel strategy for the halting of progression of early plaque.

Dexmedetomidine-induced Contraction Involves Phosphorylation of Caldesmon by JNK in Endothelium-denuded Rat Aortas

PubMed Central

Baik, Jiseok; Ok, Seong-Ho; Cho, Hyunhoo; Yu, Jongsun; Kim, Woochan; Nam, In-Koo; Choi, Mun-Jeoung; Lee, Heon-Keun; Sohn, Ju-Tae

2014-01-01

Caldesmon, an inhibitory actin binding protein, binds to actin and inhibits actin-myosin interactions, whereas caldesmon phosphorylation reverses the inhibitory effect of caldesmon on actin-myosin interactions, potentially leading to enhanced contraction. The goal of this study was to investigate the cellular signaling pathway responsible for caldesmon phosphorylation, which is involved in the regulation of the contraction induced by dexmedetomidine (DMT), an alpha-2 adrenoceptor agonist, in endothelium-denuded rat aortas. SP600125 (a c-Jun NH2-terminal kinase [JNK] inhibitor) dose-response curves were generated in aortas that were pre-contracted with DMT or phorbol 12,13-dibutyrate (PDBu), a protein kinase C (PKC) activator. Dose-response curves to the PKC inhibitor chelerythrine were generated in rat aortas pre-contracted with DMT. The effects of SP600125 and rauwolscine (an alpha-2 adrenoceptor inhibitor) on DMT-induced caldesmon phosphorylation in rat aortic vascular smooth muscle cells (VSMCs) were investigated by western blot analysis. PDBu-induced caldesmon and DMT-induced PKC phosphorylation in rat aortic VSMCs was investigated by western blot analysis. The effects of GF109203X (a PKC inhibitor) on DMT- or PDBu-induced JNK phosphorylation in VSMCs were assessed. SP600125 resulted in the relaxation of aortas that were pre-contracted with DMT or PDBu, whereas rauwolscine attenuated DMT-induced contraction. Chelerythrine resulted in the vasodilation of aortas pre-contracted with DMT. SP600125 and rauwolscine inhibited DMT-induced caldesmon phosphorylation. Additionally, PDBu induced caldesmon phosphorylation, and GF109203X attenuated the JNK phosphorylation induced by DMT or PDBu. DMT induced PKC phosphorylation in rat aortic VSMCs. These results suggest that alpha-2 adrenoceptor-mediated, DMT-induced contraction involves caldesmon phosphorylation that is mediated by JNK phosphorylation by PKC. PMID:25332685

Time-Dependent Behaviors of Granite: Loading-Rate Dependence, Creep, and Relaxation

NASA Astrophysics Data System (ADS)

Hashiba, K.; Fukui, K.

2016-07-01

To assess the long-term stability of underground structures, it is important to understand the time-dependent behaviors of rocks, such as their loading-rate dependence, creep, and relaxation. However, there have been fewer studies on crystalline rocks than on tuff, mudstone, and rock salt, because the high strength of crystalline rocks makes the detection of their time-dependent behaviors much more difficult. Moreover, studies on the relaxation, temporal change of stress and strain (TCSS) conditions, and relations between various time-dependent behaviors are scarce for not only granites, but also other rocks. In this study, previous reports on the time-dependent behaviors of granites were reviewed and various laboratory tests were conducted using Toki granite. These tests included an alternating-loading-rate test, creep test, relaxation test, and TCSS test. The results showed that the degree of time dependence of Toki granite is similar to other granites, and that the TCSS resembles the stress-relaxation curve and creep-strain curve. A viscoelastic constitutive model, proposed in a previous study, was modified to investigate the relations between the time-dependent behaviors in the pre- and post-peak regions. The modified model reproduced the stress-strain curve, creep, relaxation, and the results of the TCSS test. Based on a comparison of the results of the laboratory tests and numerical simulations, close relations between the time-dependent behaviors were revealed quantitatively.

Differential effects of ascorbate on endothelium-derived hyperpolarizing factor (EDHF)-mediated vasodilatation in the bovine ciliary vascular bed and coronary artery.

PubMed

McNeish, Alister J; Nelli, Silvia; Wilson, William S; Dowell, Fiona J; Martin, William

2003-03-01

1. The ability of ascorbate to inhibit endothelium-derived hyperpolarizing factor (EDHF)-mediated vasodilatation was compared in the bovine perfused ciliary vascular bed and isolated rings of coronary artery. 2. Acetylcholine-induced, EDHF-mediated vasodilatation of the ciliary circulation was blocked following inclusion of ascorbate (50 micro M, 120 min) in the perfusion fluid. The blockade was highly selective since ascorbate had no effect on the vasodilator actions of the K(ATP) channel opener, levcromakalim, nor on the tonic vasodepressor action of basally released nitric oxide. 3. The possibility that concentration of ascorbate by the ciliary body was a prerequisite for blockade to occur was ruled out, since EDHF was still blocked when the anterior and posterior chambers were continuously flushed with Krebs solution or when both the aqueous and vitreous humour were drained. 4. Ascorbate at 50 micro M failed to affect bradykinin- or acetylcholine-induced, EDHF-mediated vasodilatation in rings of bovine coronary artery. Raising the concentration to 3 mM did produce blockade of EDHF, but this was nonselective, since vasodilator responses to endothelium-derived nitric oxide were also inhibited. 5. Thus, ascorbate (50 micro M) is not a universal blocker of EDHF. Whether its ability to block in the bovine ciliary circulation, but not in the coronary artery, is due to differences in the nature of EDHF at the two sites, differences in vessel size (resistance arterioles versus conduit artery), the presence or absence of flow, or to some other factor remains to be determined.

Hindlimb unweighting decreases endothelium-dependent dilation and eNOS expression in soleus not gastrocnemius

NASA Technical Reports Server (NTRS)

Woodman, C. R.; Schrage, W. G.; Rush, J. W.; Ray, C. A.; Price, E. M.; Hasser, E. M.; Laughlin, M. H.

2001-01-01

We tested the hypothesis that hindlimb unweighting (HLU) decreases endothelium-dependent vasodilation and expression of endothelial nitric oxide synthase (eNOS) and superoxide dismutase-1 (SOD-1) in arteries of skeletal muscle with reduced blood flow during HLU. Sprague-Dawley rats (300-350 g) were exposed to HLU (n = 15) or control (n = 15) conditions for 14 days. ACh-induced dilation was assessed in muscle with reduced [soleus (Sol)] or unchanged [gastrocnemius (Gast)] blood flow during HLU. eNOS and SOD-1 expression were measured in feed arteries (FA) and in first-order (1A), second-order (2A), and third-order (3A) arterioles. Dilation to infusion of ACh in vivo was blunted in Sol but not Gast. In arteries of Sol muscle, HLU decreased eNOS mRNA and protein content. eNOS mRNA content was significantly less in Sol FA (35%), 1A arterioles (25%) and 2A arterioles (18%). eNOS protein content was less in Sol FA (64%) and 1A arterioles (65%) from HLU rats. In arteries of Gast, HLU did not decrease eNOS mRNA or protein. SOD-1 mRNA expression was less in Sol 2A arterioles (31%) and 3A arterioles (29%) of HLU rats. SOD-1 protein content was less in Sol FA (67%) but not arterioles. SOD-1 mRNA and protein content were not decreased in arteries from Gast. These data indicate that HLU decreases endothelium-dependent vasodilation, eNOS expression, and SOD-1 expression primarily in arteries of Sol muscle where blood flow is reduced during HLU.

IRAP inhibition using HFI419 prevents moderate to severe acetylcholine mediated vasoconstriction in a rabbit model.

PubMed

El-Hawli, Aisha; Qaradakhi, Tawar; Hayes, Alan; Rybalka, Emma; Smith, Renee; Caprnda, Martin; Opatrilova, Radka; Gazdikova, Katarina; Benckova, Maria; Kruzliak, Peter; Zulli, Anthony

2017-02-01

Coronary artery vasospasm (constriction) caused by reduced nitric oxide bioavailability leads to myocardial infarction. Reduced endothelial release of nitric oxide by the neurotransmitter acetylcholine, leads to paradoxical vasoconstriction as it binds to smooth muscle cell M3 receptors. Thus, inhibition of coronary artery vasospasm will improve clinical outcomes. Inhibition of insulin regulated aminopeptidase has been shown to improve vessel function, thus we tested the hypothesis that HFI419, an inhibitor of insulin regulated aminopeptidase, could reduce blood vessel constriction to acetylcholine. The abdominal aorta was excised from New Zealand white rabbits (n=15) and incubated with 3mM Hcy to induce vascular dysfunction in vitro for 1h. HFI419 was added 5min prior to assessment of vascular function by cumulative doses of acetylcholine. In some rings, vasoconstriction to acetylcholine was observed in aortic rings after pre-incubation with 3mM homocysteine. Incubation with HFI419 inhibited the vasoconstrictive response to acetylcholine, thus improving, but not normalizing, vascular function (11.5±8.9% relaxation vs 79.2±37% constriction, p<0.05). Similarly, in another group with mild vasoconstriction, HFI419 inhibited this effect (34.9±4.6% relaxation vs 11.1±5.2%, constriction, p<0.05). HFI419 had no effect on control aorta or aorta with mild aortic dysfunction. The present study shows that HFI419 prevents acetylcholine mediated vasoconstriction in dysfunctional blood vessels. HFI419 had no effect on normal vasodilation. Our results indicate a therapeutic potential of HFI419 in reducing coronary artery vasospasm. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Endothelial function in pigs transgenic for human complement regulating factor.

PubMed

Warnecke, Gregor; Severson, Sandra R; Ugurlu, Mustafa M; Taner, Cemal B; Logan, John S; Diamond, Lisa E; Miller, Virginia M; McGregor, Christopher G A

2002-04-15

Expression of human complement regulating factor (hCRF) in porcine organs prevents hyperacute rejection of these organs after xenotransplantation to nonhuman primates. Experiments were designed to characterize endothelial and smooth muscle function of arteries from pigs transgenic for hCD46. Arterial blood from outbred pigs transgenic for hCD46 expression and nontransgenic animals of the same lineage was analyzed for angiotensin-converting enzyme (ACE), C-type natriuretic peptide (CNP), and nitric oxide. Aortic endothelial cells were prepared for measurement of mRNA or activity for nitric oxide synthase (NOS). Rings cut from femoral and pulmonary arteries were suspended in organ chambers for measurement of isometric tension. CNP was significantly greater, ACE was similar, and nitric oxide was significantly less in plasma from transgenic compared with nontransgenic pigs. Neither mRNA nor activity of NOS differed between the groups. Endothelium-dependent relaxations to bradykinin and acetylcholine but not the calcium ionophore were shifted significantly to the left in femoral and pulmonary arteries from hCD46 transgenic pigs compared with nontransgenic pigs. The ACE-inhibitor captopril augmented relaxations similarly in both groups, but NG-monomethyl-L-arginine (L-NMMA) did not inhibit relaxations in rings from transgenic pigs. Data suggest that expression of hCD46 on endothelium of pigs selectively augments endothelium-dependent relaxations to bradykinin by increased release of endothelium-derived factors other than nitric oxide. There does not seem to be any change in activity of ACE or NOS with expression of the human protein. Increased relaxations to bradykinin may be beneficial in lowering vascular resistance when transgenic organs are used for xenotransplantation.

Activation of PPARδ prevents endothelial dysfunction induced by overexpression of amyloid-β precursor protein.

PubMed

d'Uscio, Livius V; Das, Pritam; Santhanam, Anantha V R; He, Tongrong; Younkin, Steven G; Katusic, Zvonimir S

2012-12-01

Existing evidence suggests that amyloid-β precursor protein (APP) causes endothelial dysfunction and contributes to pathogenesis of atherosclerosis. In the present study, experiments were designed to: (1) determine the mechanisms underlying endothelial dysfunction and (2) define the effects of peroxisome proliferator-activated receptor delta (PPARδ) ligand on endothelial function in transgenic Tg2576 mice overexpressing mutated human APP. Confocal microscopy and western blot analyses of wild-type mice aortas provided evidence that APP protein is mainly present in endothelial cells. Overexpression of APP significantly impaired endothelium-dependent relaxations to acetylcholine and phosphorylation of endothelial nitric oxide synthase at Ser(1177) in aortas. HPLC analysis revealed that tetrahydrobiopterin (BH(4)) levels were reduced in Tg2576 mice aortas. This was caused by increased oxidation of BH(4) and reduced expression and activity of GTP-cyclohydrolase I. Furthermore, gp91phox protein expression and superoxide anion production were increased in aortas of Tg2576 mice. This augmented superoxide formation was completely prevented by the NADPH oxidase inhibitor VAS2870. Expression of copper-/zinc-superoxide dismutase (Cu/ZnSOD) and extracellular SOD was downregulated. Treatment with PPARδ ligand GW501516 (2 mg/kg/day) for 14 days significantly increased BH(4) bioavailability and improved endothelium-dependent relaxations in Tg2576 mice aortas. GW501516 also normalized protein expression of gp91(phox) and SODs, thereby reducing production of superoxide anion in the aortas. Our results suggest that in APP transgenic mice loss of nitric oxide and increased oxidative stress are the major causes of endothelial dysfunction. The vascular protective effects of GW501516 in Tg2576 mice appear to be critically dependent on prevention of superoxide anion production.

Regular aerobic exercise reduces endothelin-1-mediated vasoconstrictor tone in overweight and obese adults.

PubMed

Dow, Caitlin A; Stauffer, Brian L; Brunjes, Danielle L; Greiner, Jared J; DeSouza, Christopher A

2017-09-01

What is the central question of this study? Does aerobic exercise training reduce endothelin-1 (ET-1)-mediated vasoconstrictor tone in overweight/obese adults? And, if so, does lower ET-1 vasoconstriction underlie the exercise-related enhancement in endothelium-dependent vasodilatation in overweight/obese adults? What is the main finding and its importance? Regular aerobic exercise reduces ET-1-mediated vasoconstrictor tone in previously sedentary overweight/obese adults, independent of weight loss. Decreased ET-1 vasoconstriction is an important mechanism underlying the aerobic exercise-induced improvement in endothelium-dependent vasodilator function in overweight/obese adults. Endothelin-1 (ET-1)-mediated vasoconstrictor tone is elevated in overweight and obese adults, contributing to vasomotor dysfunction and increased cardiovascular disease risk. Although the effects of habitual aerobic exercise on endothelium-dependent vasodilatation in overweight/obese adults have been studied, little is known regarding ET-1-mediated vasoconstriction. Accordingly, the aims of the present study were to determine the following: (i) whether regular aerobic exercise training reduces ET-1-mediated vasoconstrictor tone in overweight and obese adults; and, if so, (ii) whether the reduction in ET-1-mediated vasoconstriction contributes to exercise-induced improvement in endothelium-dependent vasodilatation in this population. Forearm blood flow (FBF) in response to intra-arterial infusion of selective ET A receptor blockade (BQ-123, 100 nmol min -1 for 60 min), acetylcholine [4.0, 8.0 and 16.0 μg (100 ml tissue) -1  min -1 ] in the absence and presence of ET A receptor blockade and sodium nitroprusside [1.0, 2.0 and 4.0 μg (100 ml tissue) -1  min -1 ] were determined before and after a 3 month aerobic exercise training intervention in 25 (16 men and nine women) overweight/obese (body mass index 30.1 ± 0.5 kg m -2 ) adults. The vasodilator response to BQ-123 was

Endothelial mineralocorticoid receptor activation mediates endothelial dysfunction in diet-induced obesity.

PubMed

Schäfer, Nicola; Lohmann, Christine; Winnik, Stephan; van Tits, Lambertus J; Miranda, Melroy X; Vergopoulos, Athanasios; Ruschitzka, Frank; Nussberger, Jürg; Berger, Stefan; Lüscher, Thomas F; Verrey, François; Matter, Christian M

2013-12-01

Aldosterone plays a crucial role in cardiovascular disease. 'Systemic' inhibition of its mineralocorticoid receptor (MR) decreases atherosclerosis by reducing inflammation and oxidative stress. Obesity, an important cardiovascular risk factor, is an inflammatory disease associated with increased plasma aldosterone levels. We have investigated the role of the 'endothelial' MR in obesity-induced endothelial dysfunction, the earliest stage in atherogenesis. C57BL/6 mice were exposed to a normal chow diet (ND) or a high-fat diet (HFD) alone or in combination with the MR antagonist eplerenone (200 mg/kg/day) for 14 weeks. Diet-induced obesity impaired endothelium-dependent relaxation in response to acetylcholine, whereas eplerenone treatment of obese mice prevented this. Expression analyses in aortic endothelial cells isolated from these mice revealed that eplerenone attenuated expression of pro-oxidative NADPH oxidase (subunits p22phox, p40phox) and increased expression of antioxidative genes (glutathione peroxidase-1, superoxide dismutase-1 and -3) in obesity. Eplerenone did not affect obesity-induced upregulation of cyclooxygenase (COX)-1 or prostacyclin synthase. Endothelial-specific MR deletion prevented endothelial dysfunction in obese (exhibiting high 'endogenous' aldosterone) and in 'exogenous' aldosterone-infused lean mice. Pre-incubation of aortic rings from aldosterone-treated animals with the COX-inhibitor indomethacin restored endothelial function. Exogenous aldosterone administration induced endothelial expression of p22phox in the presence, but not in the absence of the endothelial MR. Obesity-induced endothelial dysfunction depends on the 'endothelial' MR and is mediated by an imbalance of oxidative stress-modulating mechanisms. Therefore, MR antagonists may represent an attractive therapeutic strategy in the increasing population of obese patients to decrease vascular dysfunction and subsequent atherosclerotic complications.

Distinct mechanisms of relaxation to bioactive components from chamomile species in porcine isolated blood vessels

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

Roberts, R.E., E-mail: Richard.roberts@nottingham.ac.uk; Allen, S.; Chang, A.P.Y.

2013-11-01

German chamomile (Matricaria recutita L.), a widely-used herbal medicine, has been reported to have a wide range of biological effects, including smooth muscle relaxation. The aim of this study was to compare the effects of representative compounds from chamomile (apigenin, luteolin, (−)-α-bisabolol, farnesene, umbelliferone; 3–30 μM) on vascular tone using porcine coronary and splenic arteries mounted for isometric tension recording in isolated tissue baths and precontracted with the thromboxane-mimetic U46619. Apigenin, luteolin, and (−)-α-bisabolol produced slow, concentration-dependent relaxations in both the coronary and splenic arteries that were not blocked by inhibition of nitric oxide synthase or potassium channels. Removal ofmore » extracellular calcium inhibited the relaxations to all three compounds, and these compounds also inhibited calcium re-addition-evoked contractions, indicating that the relaxation response may be mediated through inhibition of calcium influx. Apigenin and luteolin, but not (−)-α-bisabolol, enhanced the relaxation to the nitric oxide donor sodium nitroprusside, indicating that apigenin and luteolin may act to regulate cyclic GMP levels. Umbelliferone produced a rapid, transient relaxation in the splenic artery, but not the coronary artery, that was inhibited by L-NAME and removal of the endothelium, suggesting an influence on nitric oxide production. Farnesene, at concentrations up to 30 μM, was without effect in either blood vessel. In conclusion, hydroxylated compounds (apigenin, luteolin and (−)-α-bisabolol) found in chamomile all caused a slow relaxation of isolated blood vessels through an effect on calcium influx. Umbelliferone, on the other hand, produced a rapid, transient relaxation dependent upon release of nitric oxide from the endothelium. - Highlights: • Apigenin, luteolin, and (-)-α-bisabolol are present in chamomile. • They produced slow, concentration-dependent relaxations in arteries. �

Dental resin curing blue light induces vasoconstriction through release of hydrogen peroxide.

PubMed

Oktay, Elif Aybala; Tort, Huseyin; Yıldız, Oguzhan; Ulusoy, Kemal Gokhan; Topcu, Fulya Toksoy; Ozer, Cigdem

2018-05-26

Dental resin curing blue light (BL) is frequently used during treatments in dental clinics. However, little is known about the influence of BL irradiation on pulpal blood vessels. The aim of the present study was to investigate the mechanism of effect of BL irradiation on vascular tone. Rat aorta (RA) rings were irradiated with a BL source in organ baths, and the responses were recorded isometrically. Effect of BL irradiation on phenylephrine (PE) -precontraction and acetylcholine (ACh) -induced relaxation after PE -precontraction were obtained and compared in BL -irradiated and control RA rings. Effect of 20 min preincubation with catalase (enzyme that breaks down hydrogene peroxide, 1200 u/ml) on PE -precontraced and BL-irradiated rings was also evaluated. Total oxidative stress (TOS) and total antioxidant capacity (TAC) in BL-irradiated and control RA preparations were measured with special assay kits and spectrophotometry. BL slightly decreased ACh -induced endothelium -dependent relaxations in PE (1 μM) -precontracted RA rings (n = 6, p > 0.05 vs. control). BL induced marked contraction 23.88 + 3.10% of PE (maximum contraction) in isolated RA ring segments precontracted with PE (p < 0.05 vs. control). The contractile effect of BL was inhibited by 1200 u/ml catalase (n = 6, p < 0.05 vs. control). BL irradiation increased the level of TOS in RA rings (n = 6, p < 0.05 vs. control). TAC levels were similar in BL-irradiated and control preparations. These results suggest that BL induces contraction in RA, and the mechanism of this effect may to be through release of hydrogen peroxide. Copyright © 2018 Elsevier B.V. All rights reserved.

A combined oral contraceptive containing 30 mcg ethinyl estradiol and 3.0 mg drospirenone does not impair endothelium-dependent vasodilation

PubMed Central

Meendering, Jessica R.; Torgrimson, Britta N.; Miller, Nicole P.; Kaplan, Paul F.; Minson, Christopher T.

2010-01-01

Background Ethinyl estradiol (EE) increases endothelium-dependent vasodilation in young women, but certain progestins paired with EE in combination OCPs have been shown to antagonize the vasodilatory effects of EE. Therefore, the purpose of this study was to investigate how endothelial function, serum biomarkers, and resting blood pressures change across an OCP cycle in women using a monophasic OCP formulation containing the progestin drospirenone. Study Design Twelve women were studied during two hormone phases of their OCP cycle; once at the end of three weeks of active pills (30 mcg EE and 3.0 mg drospirenone), and once at the end of a week of placebo pills (no exogenous hormones). Results Endothelium-dependent vasodilation was greater during the active phase compared to the placebo phase (p < 0.001). In contrast, there was no difference in endothelium-independent dilation between hormone phases. Conclusion These data suggest that the combination of 30 mcg EE and 3.0 mg drospirenone used in the active phase of this OCP increases endothelium-dependent vasodilation compared to a placebo phase. PMID:20851231

A combined oral contraceptive containing 30 mcg ethinyl estradiol and 3.0 mg drospirenone does not impair endothelium-dependent vasodilation.

PubMed

Meendering, Jessica R; Torgrimson, Britta N; Miller, Nicole P; Kaplan, Paul F; Minson, Christopher T

2010-10-01

Ethinyl estradiol (EE) increases endothelium-dependent vasodilation in young women, but certain progestins paired with EE in combination oral contraceptive pills (OCPs) have been shown to antagonize the vasodilatory effects of EE. Therefore, the purpose of this study was to investigate how endothelial function, serum biomarkers and resting blood pressures change across an OCP cycle in women using a monophasic OCP formulation containing the progestin drospirenone. Twelve women were studied during two hormone phases of their OCP cycle: once at the end of 3 weeks of active pills (30 mcg EE and 3.0 mg drospirenone) and once at the end of a week of placebo pills (no exogenous hormones) Endothelium-dependent vasodilation was greater during the active phase compared to the placebo phase (p<.001). In contrast, there was no difference in endothelium-independent dilation between hormone phases. These data suggest that the combination of 30 mcg EE and 3.0 mg drospirenone used in the active phase of this OCP increases endothelium-dependent vasodilation compared to a placebo phase. Copyright © 2010 Elsevier Inc. All rights reserved.

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.

Brain nicotinic acetylcholine receptors are involved in stress-induced potentiation of nicotine reward in rats.

PubMed

Javadi, Parastoo; Rezayof, Ameneh; Sardari, Maryam; Ghasemzadeh, Zahra

2017-07-01

The aim of the present study was to examine the possible role of nicotinic acetylcholine receptors of the dorsal hippocampus (CA1 regions), the medial prefrontal cortex or the basolateral amygdala in the effect of acute or sub-chronic stress on nicotine-induced conditioned place preference. Our results indicated that subcutaneous administration of nicotine (0.2 mg/kg) induced significant conditioned place preference. Exposure to acute or sub-chronic elevated platform stress potentiated the response of an ineffective dose of nicotine. Pre-conditioning intra-CA1 (0.5-4 µg/rat) or intra-medial prefrontal cortex (0.2-0.3 µg/rat) microinjection of mecamylamine (a non-selective nicotinic acetylcholine receptor antagonist) reversed acute stress-induced potentiation of nicotine reward as measured in the conditioned place preference paradigm. By contrast, pre-conditioning intra-basolateral amygdala microinjection of mecamylamine (4 µg/rat) potentiated the effects of acute stress on nicotine reward. Our findings also showed that intra-CA1 or intra-medial prefrontal cortex, but not intra-basolateral amygdala, microinjection of mecamylamine (4 µg/rat) prevented the effect of sub-chronic stress on nicotine reward. These findings suggest that exposure to elevated platform stress potentiates the rewarding effect of nicotine which may be associated with the involvement of nicotinic acetylcholine receptors. It seems that there is a different contribution of the basolateral amygdala, the medial prefrontal cortex or the CA1 nicotinic acetylcholine receptors in stress-induced potentiation of nicotine-induced conditioned place preference.

Deletion of PRKAA triggers mitochondrial fission by inhibiting the autophagy-dependent degradation of DNM1L.

PubMed

Wang, Qilong; Wu, Shengnan; Zhu, Huaiping; Ding, Ye; Dai, Xiaoyan; Ouyang, Changhan; Han, Young-Min; Xie, Zhonglin; Zou, Ming-Hui

2017-02-01

PRKAA (protein kinase, AMP-activated, α catalytic subunit) regulates mitochondrial biogenesis, function, and turnover. However, the molecular mechanisms by which PRKAA regulates mitochondrial dynamics remain poorly characterized. Here, we report that PRKAA regulated mitochondrial fission via the autophagy-dependent degradation of DNM1L (dynamin 1-like). Deletion of Prkaa1/AMPKα1 or Prkaa2/AMPKα2 resulted in defective autophagy, DNM1L accumulation, and aberrant mitochondrial fragmentation in the mouse aortic endothelium. Furthermore, autophagy inhibition by chloroquine treatment or ATG7 small interfering RNA (siRNA) transfection, upregulated DNM1L expression and triggered DNM1L-mediated mitochondrial fragmentation. In contrast, autophagy activation by overexpression of ATG7 or chronic administration of rapamycin, the MTOR inhibitor, promoted DNM1L degradation and attenuated mitochondrial fragmentation in Prkaa2-deficient (prkaa2 -/- ) mice, suggesting that defective autophagy contributes to enhanced DNM1L expression and mitochondrial fragmentation. Additionally, the autophagic receptor protein SQSTM1/p62, which bound to DNM1L and led to its translocation into the autophagosome, was involved in DNM1L degradation by the autophagy-lysosome pathway. Gene silencing of SQSTM1 markedly reduced the association between SQSTM1 and DNM1L, impaired the degradation of DNM1L, and enhanced mitochondrial fragmentation in PRKAA-deficient endothelial cells. Finally, the genetic (DNM1L siRNA) or pharmacological (mdivi-1) inhibition of DNMA1L ablated mitochondrial fragmentation in the mouse aortic endothelium and prevented the acetylcholine-induced relaxation of isolated mouse aortas. This suggests that aberrant DNM1L is responsible for enhanced mitochondrial fragmentation and endothelial dysfunction in prkaa knockout mice. Overall, our results show that PRKAA deletion promoted mitochondrial fragmentation in vascular endothelial cells by inhibiting the autophagy-dependent

Ca2+ -activated K+ channel (KCa) stimulation improves relaxant capacity of PDE5 inhibitors in human penile arteries and recovers the reduced efficacy of PDE5 inhibition in diabetic erectile dysfunction.

PubMed

González-Corrochano, R; La Fuente, Jm; Cuevas, P; Fernández, A; Chen, Mx; Sáenz de Tejada, I; Angulo, J

2013-05-01

We have evaluated the influence of calcium-activated potassium channels (KCa ) activation on cGMP-mediated relaxation in human penile tissues from non-diabetic and diabetic patients, and on the effects of PDE5 inhibitors on erectile responses in control and diabetic rats. Cavernosal tissues were collected from organ donors and from patients with erectile dysfunction (ED). Relaxations of corpus cavernosum strips (HCC) and penile resistance arteries (HPRA) obtained from these specimens were evaluated. Intracavernosal pressure (ICP) increases to cavernosal nerve electrical stimulation were determined in anaesthetized diabetic and non-diabetic rats. Concentration-dependent vasodilation to the PDE5 inhibitor, sildenafil, in HPRA was sensitive to endothelium removal, NO/cGMP pathway inhibition and KCa blockade. Accordingly, activation of KCa with NS-8 (10 μM) significantly potentiated sildenafil-induced relaxations in HPRA (EC50 0.49 ± 0.22 vs. 5.21 ± 0.63 μM). In HCC, sildenafil-induced relaxation was unaffected by KCa blockade or activation. Potentiating effects in HPRA were reproduced with an alternative PDE5 inhibitor (tadalafil) and KCa activator (NS1619) and prevented by removing the endothelium. Large-conductance KCa (BK) and intermediate-conductance KCa (IK) contribute to NS-8-induced effects and were immunodetected in human and rat penile arteries. NS-8 potentiated sildenafil-induced enhancement of erectile responses in rats. Activation of KCa recovered the impaired relaxation to sildenafil in diabetic HPRA while sildenafil completely reversed diabetes-induced ED in rats only when combined with KCa activation. Activation of KCa improves vasodilatory capacity of PDE5 inhibitors in diabetic and non-diabetic HPRA, resulting in the recovery of erectile function in diabetic rats. These results suggest a therapeutic potential for KCa activation in diabetic ED. © 2013 The Authors. British Journal of Pharmacology © 2013 The British Pharmacological Society.

African Americans with LVH demonstrate depressed sensitivity of the coronary microcirculation to stimulated relaxation.

PubMed

Houghton, Jan Laws; Strogatz, David S; Torosoff, Mikhail T; Smith, Vivienne E; Fein, Steven A; Kuhner, Patricia A; Philbin, Edward F; Carr, Albert A

2003-09-01

Excess coronary heart disease morbidity and mortality among African Americans remains an important yet unexplained public health problem. We hypothesized that adverse outcome is in part due to intrinsic or acquired abnormalities in coronary endothelial function and vasoreactivity. We compared dose-response curves relating changes in coronary blood flow and epicardial diameter to graded infusions of acetylcholine in 50 African American and 65 white subjects with hypertensive left ventricular hypertrophy (LVH) and normal coronary arteries. These groups were similar for age, body mass index, mean arterial pressure, and indexed left ventricular mass. The same protocol was conducted in 24 normotensive African American and 56 similar white subjects. We found significant depression in the coronary blood flow dose-response curve relation among African Americans when compared with white subjects with similar LVH (P<0.03). Racial differences were observed at all doses of acetylcholine but were less precisely estimated at the highest dose. The same testing among normotensive subjects revealed similar dose-response curves with no significant effect of race. Qualitatively similar results were found with respect to coronary diameter. Adenosine responses, a measure of endothelium-independent function, were similar after partitioning by LVH. Our study demonstrates that there are racial differences in sensitivity of coronary arteries to acetylcholine-stimulated relaxation among those with LVH. These results provide a mechanism whereby racial differences in coronary vasoreactivity might contribute to adverse coronary heart disease outcome among African Americans, a group in whom LVH is prevalent.

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

Endothelium dependent and independent responses in coronary artery disease measured at angioplasty.

PubMed Central

Holdright, D R; Clarke, D; Poole-Wilson, P A; Fox, K; Collins, P

1993-01-01

OBJECTIVE--To investigate the effects of substance P and papaverine, two drugs that increase coronary blood flow by different mechanisms, on vasomotion in stenotic coronary arteries at percutaneous transluminal coronary angioplasty (PTCA). DESIGN--Coronary blood flow responses to substance P and papaverine were measured in stenotic coronary arteries at the time of PTCA with quantitative angiography and a Doppler flow probe. SETTING--A cardiothoracic referral centre. PATIENTS--15 patients undergoing elective PTCA of a discrete epicardial coronary artery stenosis. INTERVENTIONS--Pharmacological coronary flow reserve was determined with papaverine 5-10 minutes before and after successful PTCA. Endothelium dependent responses to 2 minute infusions of substance P (10-15 pmol.min-1) were assessed immediately before PTCA. MAIN OUTCOME MEASURES--Coronary blood flow responses and changes in epicardial coronary artery area at stenotic, proximal, and distal sites with papaverine and substance P. RESULTS--Stenotic sites dilated with papaverine before PTCA (17.7%(6.9%) (mean (SEM)) area increase, p < 0.05 v baseline). Substance P dilated stenotic sites (16.8%(5.7%) area increase, p < 0.05) and proximal (14.3%(5.4%), p < 0.05) and distal sites (41.7%(9.3%), p < 0.005). Coronary flow reserve increased but did not reach normal values after PTCA (2.3(0.4) before PTCA v 3.0(0.4) after PTCA, p < 0.05) and was associated with an increase in peak flow with papaverine. Angioplasty did not alter baseline flow. After PTCA papaverine caused significant vasoconstriction at the stenotic site (-13.6%(4.3%) area decrease, p < 0.05). There was a negative correlation (r = -0.68, p < 0.05) between the dilator response with papaverine before PTCA and the constrictor response after PTCA. CONCLUSIONS--Substance P causes endothelium dependent dilatation in atheromatous coronary arteries, even at sites of overt atheroma. The cause of the paradoxical constrictor response to papaverine after PTCA is

Methamphetamine exposure during brain development alters the brain acetylcholine system in adolescent mice

PubMed Central

Siegel, Jessica A.; Park, Byung S.; Raber, Jacob

2013-01-01

Children exposed to methamphetamine during brain development as a result of maternal drug use have long-term hippocampus-dependent cognitive impairments, but the mechanisms underlying these impairments are not understood. The acetylcholine system plays an important role in cognitive function and potential methamphetamine-induced acetylcholine alterations may be related to methamphetamine-induced cognitive impairments. In this study, we investigated the potential long-term effects of methamphetamine exposure during hippocampal development on the acetylcholine system in adolescence mice on postnatal day 30 and in adult mice on postnatal day 90. Methamphetamine exposure increased the density of acetylcholine neurons in regions of the basal forebrain and the area occupied by acetylcholine axons in the hippocampus in adolescent female mice. In contrast, methamphetamine exposure did not affect the density of GABA cells or total neurons in the basal forebrain. Methamphetamine exposure also increased the number of muscarinic acetylcholine receptors in the hippocampus of adolescent male and female mice. Our results demonstrate for the first time that methamphetamine exposure during hippocampal development affects the acetylcholine system in adolescent mice and that these changes are more profound in females than males. PMID:21824143

Effects of sub-chronic oral cyanide on endothelial function in rabbit aortic rings.

PubMed

Ozolu, R I; Okolie, N P; Ebeigbe, A B; Karikari, N

2007-02-01

We have investigated how the endothelium affects vascular responses following sub-chronic low dose cyanide administration. Cyanide exists in low levels in cassava foods, which are widely consumed in tropical Africa. Adult rabbits were administered 0.38 mg/kg per day KCN po for 25 days, and responses of the isolated aortic rings to noradrenaline (NA), calcium chloride (Ca2+) and acetylcholine (ACh) were measured in vitro in the presence and absence of the endothelium. In order to establish that the dose was not toxic, animal weight, some haematological indices, plasma alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were measured. Results show that endothelium denudation significantly (P <0.05) attenuates NA-induced contraction in rings from cyanide-treated rabbits. There was a similar reduction in response in Ca2+-depleted NA-precontracted endothelium-denuded aortic rings from cyanide-treated rabbits. Endothelium-denuded rings from cyanide-treated rabbits showed significantly (P <0.05) enhanced relaxation to ACh. In rings from control animals, the responses to NA and Ca2+ were not significantly altered, whether in the presence or absence of the endothelium. There were no significant changes in the studied toxicological indices. We conclude that endothelial compromise is necessary for low-dose sub-chronic cyanide-induced to alter vascular reactivity to NA and ACh.

Prostatic relaxation induced by agmatine is decreased in spontaneously hypertensive rats.

PubMed

Lee, Liang-Ming; Tsai, Tsung-Chin; Chung, Hsien-Hui; Tong, Yat-Ching; Cheng, Juei-Tang

2012-09-01

What's known on the subject? and What does the study add? Neurotransmitters are known to control prostate contractility. Agmatine is one of them and induces relaxation through imidazoline receptors. The paper shows that the action of agmatine is reduced in hypertensive rats, and that this change is related to the decrease of ATP-sensitive potassium channels in the prostate. The findings can increase our understanding of the possible underlying mechanism for the development of clinical benign prostatic hyperplasia. To compare agmatine-induced prostatic relaxation in hypertensive and control rats. To investigate the responsible mechanism(s) and the role of the ATP-sensitive potassium channel. Prostate strips were isolated from male spontaneously hypertensive (SH) rats and normal Wistar-Kyoto (WKY) rats for measurement of isometric tension. The strips were precontracted with 1 µmol/L phenylephrine or 50 mmol/L KCl. Dose-dependent relaxation of the prostatic strips was studied by cumulative administration of agmatine, 1 to 100 µmol/L, into the organ bath. Effects of specific antagonists on agmatine-induced relaxation were studied. Western blotting analysis was used to measure the gene expression of the ATP-sensitive potassium channel in the rat prostate. Prostatic relaxation induced by agmatine was markedly reduced in SH rats compared with WKY rats. The relaxation caused by agmatine was abolished by BU224, a selective imidazoline I(2)-receptor antagonist, but was not modified by efaroxan at a dose sufficient to block imidazoline I(1)-receptors. The relaxation induced by diazoxide at a concentration sufficient to activate ATP-sensitive potassium channels was markedly reduced in the SH rat prostate. Expressions of ATP-sensitive potassium channel sulphonylurea receptor and inwardly rectifying potassium channel (Kir) 6.2 subunits were both decreased in the prostate of SH rats. The decrease of agmatine-induced prostatic relaxation in SH rats is related to the change in

Exercise reverses metabolic syndrome in high-fat diet-induced obese rats.

PubMed

Touati, Sabeur; Meziri, Fayçal; Devaux, Sylvie; Berthelot, Alain; Touyz, Rhian M; Laurant, Pascal

2011-03-01

Chronic consumption of a high-fat diet induces obesity. We investigated whether exercise would reverse the cardiometabolic disorders associated with obesity without it being necessary to change from a high- to normal-fat diet. Sprague-Dawley rats were placed on a high-fat (HFD) or control diet (CD) for 12 wk. HFD rats were then divided into four groups: sedentary HFD (HFD-S), exercise trained (motor treadmill for 12 wk) HFD (HFD-Ex), modified diet (HFD to CD; HF/CD-S), and exercise trained with modified diet (HF/CD-Ex). Cardiovascular risk parameters associated with metabolic syndrome were measured, and contents of aortic Akt, phospho-Akt at Ser (473), total endothelial nitric oxide synthase (eNOS), and phospho-eNOS at Ser (1177) were determined by Western blotting. Chronic consumption of HFD induced a metabolic syndrome. Exercise and dietary modifications reduced adiposity, improved glucose and insulin levels and plasma lipid profile, and exerted an antihypertensive effect. Exercise was more effective than dietary modification in improving plasma levels of thiobarbituric acid-reacting substance and in correcting the endothelium-dependent relaxation to acetylcholine and insulin. Furthermore, independent of the diet used, exercise increased Akt and eNOS phosphorylation. Metabolic syndrome induced by HFD is reversed by exercise and diet modification. It is demonstrated that exercise training induces these beneficial effects without the requirement for dietary modification, and these beneficial effects may be mediated by shear stress-induced Akt/eNOS pathway activation. Thus, exercise may be an effective strategy to reverse almost all the atherosclerotic risk factors linked to obesity, particularly in the vasculature.

Acetylcholine affects osteocytic MLO-Y4 cells via acetylcholine receptors.

PubMed

Ma, Yuanyuan; Li, Xianxian; Fu, Jing; Li, Yue; Gao, Li; Yang, Ling; Zhang, Ping; Shen, Jiefei; Wang, Hang

2014-03-25

The identification of the neuronal control of bone remodeling has become one of the many significant recent advances in bone biology. Cholinergic activity has recently been shown to favor bone mass accrual by complex cellular regulatory networks. Here, we identified the gene expression of the muscarinic and nicotinic acetylcholine receptors (m- and nAChRs) in mice tibia tissue and in osteocytic MLO-Y4 cells. Acetylcholine, which is a classical neurotransmitter and an osteo-neuromediator, not only influences the mRNA expression of the AChR subunits but also significantly induces the proliferation and viability of osteocytes. Moreover, acetylcholine treatment caused the reciprocal regulation of RANKL and OPG mRNA expression, which resulted in a significant increase in the mRNA ratio of RANKL:OPG in osteocytes via acetylcholine receptors. The expression of neuropeptide Y and reelin, which are two neurogenic markers, was also modulated by acetylcholine via m- and nAChRs in MLO-Y4 cells. These results indicated that osteocytic acetylcholine receptors might be a new valuable mediator for cell functions and even for bone remodeling. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

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.

Parasympathomimetic effect of shilajit accounts for relaxation of rat corpus cavernosum.

PubMed

Kaur, Sarabjeet; Kumar, Pravin; Kumar, Deo; Kharya, M D; Singh, Nityanand

2013-03-01

Previous studies have reported an enhancement of central cholinergic signal cascade by shilajit. For the present study, it was hypothesized that parasympathomimetic effect of shilajit accounting for relaxation of rat corpus cavernosum may be one of the major mechanisms attributing to its traditional role as an aphrodisiac. To test this hypothesis, the acute peripheral effect of standard acetylcholine (ACh), shilajit, and their combination was evaluated on cardiorespiratory parameters such as mean arterial blood pressure (MABP), heart rate (HR), respiratory rate (RR), and neuromuscular transmission (NMT). Furthermore, in vitro effect of standard ACh, shilajit, and their combination was tested on the rat corpus cavernosum. Six groups were used for the in vivo study (N = 5): Group I (control-saline), Group II (ACh), Group III (Sh), Group IV (Sh followed by ACh), Group V (Atropine followed by ACh), and Group VI (Atropine followed by Sh). The in vitro study included four groups: Group I (control-saline), Group II (ACh), Group III (Sh), and Group IV (Sh followed by ACh). The results of the in vivo study confirmed the peripheral parasympathomimetic effect of shilajit (400 µg/mL). The in vitro results revealed that shilajit (400 and 800 µg/mL) relaxed cavernous strips' concentration dependently and enhanced ACh-mediated relaxations. The peripheral parasympathomimetic effects of shilajit were confirmed by blockade of shilajit-induced relaxations (in vitro) and shilajit-induced lowering of MABP and HR (in vivo) by atropine.

Acute effect of sidestream cigarette smoke extract on vascular endothelial function.

PubMed

Argacha, J F; Fontaine, D; Adamopoulos, D; Ajose, A; van de Borne, P; Fontaine, J; Berkenboom, G

2008-09-01

Acute exposure to passive smoking adversely affects vascular function by promoting oxidative stress and endothelial dysfunction. However, it is not known whether tobacco sidestream (SS) smoke has a greater deleterious effect on the endothelium than non-tobacco SS smoke and whether these effects are related to nicotinic endothelial stimulation. To test these hypotheses, endothelial-dependent relaxation and superoxide anion production were assessed in isolated rat aortas incubated with tobacco SS smoke, non-tobacco SS smoke, or pure nicotine. Tobacco SS smoke decreased the maximal relaxation to acetylcholine (Ach) from 79 +/- 6% to 57 +/- 7.3% (% inhibition of phenylephrine-induced plateau, P < 0.001) and increased superoxide anion production from 31 +/- 9.7 to 116 +/- 24 count/10 sec/mg (P < 0.01, lucigenin-enhanced chemiluminescence technique). The non-tobacco SS smoke extract had no significant effect on the response to Ach but increased superoxide anion production in the aortic wall to 133 +/- 2 count/10 sec/mg (P < 0.001). Furthermore, concentration-response curves to Ach and superoxide production remained unaltered with nicotine (0.001, 0.01, or 0.1 mM). In conclusion, despite similar increases in vascular wall superoxide production with tobacco and non-tobacco SS smoke, only the tobacco SS smoke extracts affected endothelium-dependent vasorelaxation. Nicotine alone does not reproduce the effects seen with tobacco SS smoke, suggesting that the acute endothelial toxicity of passive smoking cannot simply be ascribed to a nicotine-dependent mechanism.

Propofol preferentially relaxes neurokinin receptor-2-induced airway smooth muscle contraction in guinea pig trachea.

PubMed

Gleason, Neil R; Gallos, George; Zhang, Yi; Emala, Charles W

2010-06-01

Propofol is the anesthetic of choice for patients with reactive airway disease and is thought to reduce intubation- or irritant-induced bronchoconstriction by decreasing the cholinergic component of vagal nerve activation. However, additional neurotransmitters, including neurokinins, play a role in irritant-induced bronchoconstriction. We questioned the mechanistic assumption that the clinically recognized protective effect of propofol against irritant-induced bronchoconstriction during intubation was due to attenuation of airway cholinergic reflexes. Muscle force was continuously recorded from isolated guinea pig tracheal rings in organ baths. Rings were subjected to exogenous contractile agonists (acetylcholine, histamine, endothelin-1, substance P, acetyl-substance P, and neurokinin A) or to electrical field stimulation (EFS) to differentiate cholinergic or nonadrenergic, noncholinergic nerve-mediated contraction with or without cumulatively increasing concentrations of propofol, thiopental, etomidate, or ketamine. Propofol did not attenuate the cholinergic component of EFS-induced contraction at clinically relevant concentrations. In contrast, propofol relaxed nonadrenergic, noncholinergic-mediated EFS contraction at concentrations within the clinical range (20-100 mum, n = 9; P < 0.05), and propofol was more potent against an exogenous selective neurokinin-2 receptor versus neurokinin-1 receptor agonist contraction (n = 6, P < 0.001). Propofol, at clinically relevant concentrations, relaxes airway smooth muscle contracted by nonadrenergic, noncholinergic-mediated EFS and exogenous neurokinins but not contractions elicited by the cholinergic component of EFS. These findings suggest that the mechanism of protective effects of propofol against irritant-induced bronchoconstriction involves attenuation of tachykinins released from nonadrenergic, noncholinergic nerves acting at neurokinin-2 receptors on airway smooth muscle.

Intracellular calcium dynamics and acetylcholine-induced triggered activity in the pulmonary veins of dogs with pacing-induced heart failure

PubMed Central

Chou, Chung-Chuan; Nguyen, Bich Lien; Tan, Alex Y.; Chang, Po-Cheng; Lee, Hui-Ling; Lin, Fun-Chung; Yeh, San-Jou; Fishbein, Michael C.; Lin, Shien-Fong; Wu, Delon; Wen, Ming-Shien; Chen, Peng-Sheng

2009-01-01

BACKGROUND Heart failure increases autonomic nerve activities and changes intracellular calcium (Cai) dynamics. OBJECTIVE The purpose of this study was to investigate the hypothesis that abnormal Cai dynamics are responsible for triggered activity in the pulmonary veins (PVs) during acetylcholine infusion in a canine model of heart failure. METHODS Simultaneous optical mapping of and membrane Cai potential was performed in isolated Langendorff-perfused PV–left atrial (LA) preparations from nine dogs with ventricular pacing-induced heart failure. Mapping was performed at baseline, during acetylcholine (1 μmol/L) infusion (N = 9), and during thapsigargin and ryanodine infusion (N = 6). RESULTS Acetylcholine abbreviated the action potential. In four tissues, long pauses were followed by elevated diastolic Cai, late phase 3 early afterdepolarizations, and atrial fibrillation (AF). The incidence of PV focal discharges during AF was increased by acetylcholine from 2.4 ± 0.6 beats/s (N = 4) to 6.5 ± 2.2 beats/s (N = 8; P = .003). PV focal discharge and PV–LA microreentry coexisted in 6 of 9 preparations. The spatial distribution of dominant frequency demonstrated a focal source pattern, with the highest dominant frequency areas colocalized with PV focal discharge sites in 35 (95%) of 37 cholinergic AF episodes (N = 8). Thapsigargin and ryanodine infusion eliminated focal discharges in 6 of 6 preparations and suppressed the inducibility of AF in 4 of 6 preparations. PVs with focal discharge have higher densities of parasympathetic nerves than do PVs without focal discharges (P = .01), and periodic acid–Schiff (PAS)-positive cells were present at the focal discharge sites. CONCLUSION Cai dynamics are important in promoting triggered activity during acetylcholine infusion in PVs from pacing-induced heart failure. PV focal discharge sites have PAS-positive cells and high densities of parasympathetic nerves. PMID:18554987

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.

Relaxations of the isolated portal vein of the rabbit induced by nicotine and electrical stimulation

PubMed Central

Hughes, J.; Vane, J. R.

1970-01-01

1. A pharmacological analysis of the inhibitory innervation of the isolated portal vein of the rabbit has been made. 2. In untreated preparations, transmural stimulation elicited a long-lasting relaxation at low frequencies (0·2-1 Hz); at higher frequencies a contraction followed by a prolonged after-relaxation occurred. Tetrodotoxin abolished the contractions but a higher dose was required to abolish the relaxations. Veratrine lowered the threshold of stimulation for producing relaxations in the untreated vein. The relaxations were unaffected by hyoscine or hexamethonium. They were reduced or altered by antagonists of α-adrenoceptors for catecholamines and by adrenergic neurone blockade. They were sometimes slightly reduced by antagonists of β-adrenoceptors. 3. In the presence of antagonists of α-adrenoceptors, electrical stimulation elicited relaxations which increased with frequency of stimulation and became maximal at 20-30 Hz. These relaxations were partially reduced by antagonists of β-adrenoceptors, or by adrenergic neurone block; the antagonisms were more pronounced at the higher frequencies of stimulation. Noradrenaline also caused relaxations which were abolished by β-adrenoceptor blocking drugs. Cocaine increased the sensitivity to noradrenaline by 7-8 fold after α-adrenoceptor blockade but had little or no effect on the relaxations induced by electrical stimulation at high frequencies. 4. In the presence of antagonists of α- and β-adrenoceptors, or adrenergic neurone blocking agents, or in veins taken from rabbits pretreated with reserpine, electrical stimulation elicited rapid relaxations which were greatest at 20-30 Hz. These relaxations were increased by veratrine and abolished by tetrodotoxin or by storing the vein for 9 days at 4° C. They were unaffected by antagonists of acetylcholine, or by dipyridamole. 5. Prostaglandins E1, E2 and F2α inhibited contractions elicited by electrical stimulation and noradrenaline, but in higher doses

The relaxant 5-HT receptor in the dog coronary artery smooth muscle: pharmacological resemblance to the cloned 5-ht7 receptor subtype.

PubMed Central

Terrón, J. A.

1996-01-01

1. The relaxant effect of 5-hydroxytryptamine (5-HT) in the dog isolated coronary artery deprived of endothelium is mediated by a receptor unrelated to the 5-HT1, 5-HT2, 5-HT3 or 5-HT4 types. Based upon the pharmacological characteristics of this relaxant 5-HT receptor and those reported for the new members of the 5-HT receptor family, the present study explored the possibility that the relaxant 5-HT receptor referred to above, corresponds to the cloned 5-ht7 subtype. Thus, the relaxing and/or blocking effects of several 5-HT receptor drugs as well as some typical and atypical antipsychotic drugs with high affinity for the cloned 5-ht7 receptor in precontracted ring segments were analyzed. 2. 5-HT, 5-carboxamidotryptamine (5-CT) and 5-methoxytryptamine, but not 8-OH-DPAT or sumatriptan, produced concentration-dependent relaxations in endothelium-denuded canine coronary artery rings precontracted with prostaglandin F2a (2 microM). Clozapine (1 microM) produced in some cases a small relaxing effect and antagonized 5-HT- and 5-CT-induced relaxation suggesting a partial agonist effect. In the presence of the 5-HT1D receptor antagonist, GR127935 (100 nM), the rank order of agonist potency was 5-CT > 5-HT > clozapine > or = 5-methoxytryptamine. 8-OH-DPAT and sumatriptan remained inactive as agonists. 3. In GR127935-treated preparations, methiothepin (3 nM) and mianserin (1 microM), as well as the antipsychotics, clozapine (1 microM), pimozide (300 nM), risperidone (3 nM) and spiperone (1 microM), failed to induce a significant relaxation in prostaglandin F2x-precontracted vessels, but produced significant rightward displacements of the concentration-response curves to 5-HT and 5-CT without significantly reducing the Emax. In a final set of experiments with 5-CT, metergoline (100 nM) and mesulergine (300 nM) behaved as competitive antagonists. In contrast, lisuride (3 nM) noncompetitively antagonized 5-CT-induced relaxation. The estimated affinity (apparent pKa values) of

Vascular Reactivity Profile of Novel KCa3.1-Selective Positive-Gating Modulators in the Coronary Vascular Bed

PubMed Central

Oliván-Viguera, Aida; Valero, Marta Sofía; Pinilla, Estéfano; Amor, Sara; García-Villalón, Ángel Luis; Coleman, Nichole; Laría, Celia; Calvín-Tienza, Víctor; García-Otín, Ángel-Luis; Fernández-Fernández, José M.; Murillo, Ma Divina; Gálvez, José A.; Díaz-de-Villegas, María D.; Badorrey, Ramón; Simonsen, Ulf; Rivera, Luis; Wulff, Heike; Köhler, Ralf

2017-01-01

Opening of intermediate-conductance calcium-activated potassium channels (KCa3.1) produces membrane hyperpolarization in the vascular endothelium. Here, we studied the ability of two new KCa3.1-selective positive-gating modulators, SKA-111 and SKA-121, to (1) evoke porcine endothelial cell KCa3.1 membrane hyperpolarization, (2) induce endothelium-dependent and, particularly, endothelium-derived hyperpolarization (EDH)-type relaxation in porcine coronary arteries (PCA) and (3) influence coronary artery tone in isolated rat hearts. In whole-cell patch-clamp experiments on endothelial cells of PCA (PCAEC), KCa currents evoked by bradykinin (BK) were potentiated ≈7-fold by either SKA-111 or SKA-121 (both at 1 μM) and were blocked by a KCa3.1 blocker, TRAM-34. In membrane potential measurements, SKA-111 and SKA-121 augmented bradykinin-induced hyperpolarization. Isometric tension measurements in large- and small-calibre PCA showed that SKA-111 and SKA-121 potentiated endothelium-dependent relaxation with intact NO synthesis and EDH-type relaxation to BK by ≈2-fold. Potentiation of the BK response was prevented by KCa3.1 inhibition. In Langendorff-perfused rat hearts, SKA-111 potentiated coronary vasodilation elicited by BK. In conclusion, our data show that positive-gating modulation of KCa3.1 channels improves BK-induced membrane hyperpolarization and endothelium-dependent relaxation in small and large PCA as well as in the coronary circulation of rats. Positive-gating modulators of KCa3.1 could be therapeutically useful to improve coronary blood flow and counteract impaired coronary endothelial dysfunction in cardiovascular disease. PMID:26821335

Distinct mechanisms of relaxation to bioactive components from chamomile species in porcine isolated blood vessels.

PubMed

Roberts, R E; Allen, S; Chang, A P Y; Henderson, H; Hobson, G C; Karania, B; Morgan, K N; Pek, A S Y; Raghvani, K; Shee, C Y; Shikotra, J; Street, E; Abbas, Z; Ellis, K; Heer, J K; Alexander, S P H

2013-11-01

German chamomile (Matricaria recutita L.), a widely-used herbal medicine, has been reported to have a wide range of biological effects, including smooth muscle relaxation. The aim of this study was to compare the effects of representative compounds from chamomile (apigenin, luteolin, (-)-α-bisabolol, farnesene, umbelliferone; 3-30 μM) on vascular tone using porcine coronary and splenic arteries mounted for isometric tension recording in isolated tissue baths and precontracted with the thromboxane-mimetic U46619. Apigenin, luteolin, and (-)-α-bisabolol produced slow, concentration-dependent relaxations in both the coronary and splenic arteries that were not blocked by inhibition of nitric oxide synthase or potassium channels. Removal of extracellular calcium inhibited the relaxations to all three compounds, and these compounds also inhibited calcium re-addition-evoked contractions, indicating that the relaxation response may be mediated through inhibition of calcium influx. Apigenin and luteolin, but not (-)-α-bisabolol, enhanced the relaxation to the nitric oxide donor sodium nitroprusside, indicating that apigenin and luteolin may act to regulate cyclic GMP levels. Umbelliferone produced a rapid, transient relaxation in the splenic artery, but not the coronary artery, that was inhibited by L-NAME and removal of the endothelium, suggesting an influence on nitric oxide production. Farnesene, at concentrations up to 30 μM, was without effect in either blood vessel. In conclusion, hydroxylated compounds (apigenin, luteolin and (-)-α-bisabolol) found in chamomile all caused a slow relaxation of isolated blood vessels through an effect on calcium influx. Umbelliferone, on the other hand, produced a rapid, transient relaxation dependent upon release of nitric oxide from the endothelium. © 2013.

Activation of PPARδ prevents endothelial dysfunction induced by overexpression of amyloid-β precursor protein

PubMed Central

d'Uscio, Livius V.; Das, Pritam; Santhanam, Anantha V.R.; He, Tongrong; Younkin, Steven G.; Katusic, Zvonimir S.

2012-01-01

Aims Existing evidence suggests that amyloid-β precursor protein (APP) causes endothelial dysfunction and contributes to pathogenesis of atherosclerosis. In the present study, experiments were designed to: (1) determine the mechanisms underlying endothelial dysfunction and (2) define the effects of peroxisome proliferator-activated receptor delta (PPARδ) ligand on endothelial function in transgenic Tg2576 mice overexpressing mutated human APP. Methods and results Confocal microscopy and western blot analyses of wild-type mice aortas provided evidence that APP protein is mainly present in endothelial cells. Overexpression of APP significantly impaired endothelium-dependent relaxations to acetylcholine and phosphorylation of endothelial nitric oxide synthase at Ser1177 in aortas. HPLC analysis revealed that tetrahydrobiopterin (BH4) levels were reduced in Tg2576 mice aortas. This was caused by increased oxidation of BH4 and reduced expression and activity of GTP-cyclohydrolase I. Furthermore, gp91phox protein expression and superoxide anion production were increased in aortas of Tg2576 mice. This augmented superoxide formation was completely prevented by the NADPH oxidase inhibitor VAS2870. Expression of copper-/zinc-superoxide dismutase (Cu/ZnSOD) and extracellular SOD was downregulated. Treatment with PPARδ ligand GW501516 (2 mg/kg/day) for 14 days significantly increased BH4 bioavailability and improved endothelium-dependent relaxations in Tg2576 mice aortas. GW501516 also normalized protein expression of gp91phox and SODs, thereby reducing production of superoxide anion in the aortas. Conclusion Our results suggest that in APP transgenic mice loss of nitric oxide and increased oxidative stress are the major causes of endothelial dysfunction. The vascular protective effects of GW501516 in Tg2576 mice appear to be critically dependent on prevention of superoxide anion production. PMID:22886847

Endothelial mineralocorticoid receptor activation mediates endothelial dysfunction in diet-induced obesity

PubMed Central

Schäfer, Nicola; Lohmann, Christine; Winnik, Stephan; van Tits, Lambertus J.; Miranda, Melroy X.; Vergopoulos, Athanasios; Ruschitzka, Frank; Nussberger, Jürg; Berger, Stefan; Lüscher, Thomas F.; Verrey, François; Matter, Christian M.

2013-01-01

Received 22 July 2012; revised 29 January 2013; accepted 4 March 2013 Aims Aldosterone plays a crucial role in cardiovascular disease. ‘Systemic’ inhibition of its mineralocorticoid receptor (MR) decreases atherosclerosis by reducing inflammation and oxidative stress. Obesity, an important cardiovascular risk factor, is an inflammatory disease associated with increased plasma aldosterone levels. We have investigated the role of the ‘endothelial’ MR in obesity-induced endothelial dysfunction, the earliest stage in atherogenesis. Methods and results C57BL/6 mice were exposed to a normal chow diet (ND) or a high-fat diet (HFD) alone or in combination with the MR antagonist eplerenone (200 mg/kg/day) for 14 weeks. Diet-induced obesity impaired endothelium-dependent relaxation in response to acetylcholine, whereas eplerenone treatment of obese mice prevented this. Expression analyses in aortic endothelial cells isolated from these mice revealed that eplerenone attenuated expression of pro-oxidative NADPH oxidase (subunits p22phox, p40phox) and increased expression of antioxidative genes (glutathione peroxidase-1, superoxide dismutase-1 and -3) in obesity. Eplerenone did not affect obesity-induced upregulation of cyclooxygenase (COX)-1 or prostacyclin synthase. Endothelial-specific MR deletion prevented endothelial dysfunction in obese (exhibiting high ‘endogenous’ aldosterone) and in ‘exogenous’ aldosterone-infused lean mice. Pre-incubation of aortic rings from aldosterone-treated animals with the COX-inhibitor indomethacin restored endothelial function. Exogenous aldosterone administration induced endothelial expression of p22phox in the presence, but not in the absence of the endothelial MR. Conclusion Obesity-induced endothelial dysfunction depends on the ‘endothelial’ MR and is mediated by an imbalance of oxidative stress-modulating mechanisms. Therefore, MR antagonists may represent an attractive therapeutic strategy in the increasing population

Influenza Infects Lung Microvascular Endothelium Leading to Microvascular Leak: Role of Apoptosis and Claudin-5

PubMed Central

Armstrong, Susan M.; Wang, Changsen; Tigdi, Jayesh; Si, Xiaoe; Dumpit, Carlo; Charles, Steffany; Gamage, Asela; Moraes, Theo J.; Lee, Warren L.

2012-01-01

Severe influenza infections are complicated by acute lung injury, a syndrome of pulmonary microvascular leak. The pathogenesis of this complication is unclear. We hypothesized that human influenza could directly infect the lung microvascular endothelium, leading to loss of endothelial barrier function. We infected human lung microvascular endothelium with both clinical and laboratory strains of human influenza. Permeability of endothelial monolayers was assessed by spectrofluorimetry and by measurement of the transendothelial electrical resistance. We determined the molecular mechanisms of flu-induced endothelial permeability and developed a mouse model of severe influenza. We found that both clinical and laboratory strains of human influenza can infect and replicate in human pulmonary microvascular endothelium, leading to a marked increase in permeability. This was caused by apoptosis of the lung endothelium, since inhibition of caspases greatly attenuated influenza-induced endothelial leak. Remarkably, replication-deficient virus also caused a significant degree of endothelial permeability, despite displaying no cytotoxic effects to the endothelium. Instead, replication-deficient virus induced degradation of the tight junction protein claudin-5; the adherens junction protein VE-cadherin and the actin cytoskeleton were unaffected. Over-expression of claudin-5 was sufficient to prevent replication-deficient virus-induced permeability. The barrier-protective agent formoterol was able to markedly attenuate flu-induced leak in association with dose-dependent induction of claudin-5. Finally, mice infected with human influenza developed pulmonary edema that was abrogated by parenteral treatment with formoterol. Thus, we describe two distinct mechanisms by which human influenza can induce pulmonary microvascular leak. Our findings have implications for the pathogenesis and treatment of acute lung injury from severe influenza. PMID:23115643

In smokers, Sonic hedgehog modulates pulmonary endothelial function through vascular endothelial growth factor.

PubMed

Henno, Priscilla; Grassin-Delyle, Stanislas; Belle, Emeline; Brollo, Marion; Naline, Emmanuel; Sage, Edouard; Devillier, Philippe; Israël-Biet, Dominique

2017-05-23

Tobacco-induced pulmonary vascular disease is partly driven by endothelial dysfunction. The Sonic hedgehog (SHH) pathway is involved in vascular physiology. We sought to establish whether the SHH pathway has a role in pulmonary endothelial dysfunction in smokers. The ex vivo endothelium-dependent relaxation of pulmonary artery rings in response to acetylcholine (Ach) was compared in 34 current or ex-smokers and 8 never-smokers. The results were expressed as a percentage of the contraction with phenylephrine. We tested the effects of SHH inhibitors (GANT61 and cyclopamine), an SHH activator (SAG) and recombinant VEGF on the Ach-induced relaxation. The level of VEGF protein in the pulmonary artery ring was measured in an ELISA. SHH pathway gene expression was quantified in reverse transcriptase-quantitative polymerase chain reactions. Ach-induced relaxation was much less intense in smokers than in never-smokers (respectively 24 ± 6% and 50 ± 7% with 10 -4 M Ach; p = 0.028). All SHH pathway genes were expressed in pulmonary artery rings from smokers. SHH inhibition by GANT61 reduced Ach-induced relaxation and VEGF gene expression in the pulmonary artery ring. Recombinant VEGF restored the ring's endothelial function. VEGF gene and protein expression levels in the pulmonary artery rings were positively correlated with the degree of Ach-induced relaxation and negatively correlated with the number of pack-years. SHH pathway genes and proteins are expressed in pulmonary artery rings from smokers, where they modulate endothelial function through VEGF.

Endothelium-specific insulin resistance leads to accelerated atherosclerosis in areas with disturbed flow patterns: a role for reactive oxygen species.

PubMed

Gage, Matthew C; Yuldasheva, Nadira Y; Viswambharan, Hema; Sukumar, Piruthivi; Cubbon, Richard M; Galloway, Stacey; Imrie, Helen; Skromna, Anna; Smith, Jessica; Jackson, Christopher L; Kearney, Mark T; Wheatcroft, Stephen B

2013-09-01

Systemic insulin resistance is associated with a portfolio of risk factors for atherosclerosis development. We sought to determine whether insulin resistance specifically at the level of the endothelium promotes atherosclerosis and to examine the potential involvement of reactive oxygen species. We cross-bred mice expressing a dominant negative mutant human insulin receptor specifically in the endothelium (ESMIRO) with ApoE(-/-) mice to examine the effect of endothelium-specific insulin resistance on atherosclerosis. ApoE(-/-)/ESMIRO mice had similar blood pressure, plasma lipids and whole-body glucose tolerance, but blunted endothelial insulin signalling, in comparison to ApoE(-/-) mice. Atherosclerosis was significantly increased in ApoE(-/-)/ESMIRO mice at the aortic sinus (226 ± 16 versus 149 ± 24 × 10(3) μm(2), P = 0.01) and lesser curvature of the aortic arch (12.4 ± 1.2% versus 9.4 ± 0.9%, P = 0.035). Relaxation to acetylcholine was blunted in aorta from ApoE(-/-)/ESMIRO mice (Emax 65 ± 41% versus 103 ± 6%, P = 0.02) and was restored by the superoxide dismutase mimetic MnTMPyP (Emax 112 ± 15% versus 65 ± 41%, P = 0.048). Basal generation of superoxide was increased 1.55 fold (P = 0.01) in endothelial cells from ApoE(-/-)/ESMIRO mice and was inhibited by the NADPH oxidase inhibitor gp91ds-tat (-12 ± 0.04%, P = 0.04), the NO synthase inhibitor L-NMMA (-8 ± 0.02%, P = 0.001) and the mitochondrial specific inhibitor rotenone (-23 ± 0.04%, P = 0.006). Insulin resistance specifically at the level of the endothelium leads to acceleration of atherosclerosis in areas with disturbed flow patterns such as the aortic sinus and the lesser curvature of the aorta. We have identified a potential role for increased generation of reactive oxygen species from multiple enzymatic sources in promoting atherosclerosis in this setting. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Rho-kinase inhibition acutely augments blood flow in focal cerebral ischemia via endothelial mechanisms.

PubMed

Shin, Hwa Kyoung; Salomone, Salvatore; Potts, E Michelle; Lee, Sae-Won; Millican, Eric; Noma, Kensuke; Huang, Paul L; Boas, David A; Liao, James K; Moskowitz, Michael A; Ayata, Cenk

2007-05-01

Rho-kinase is a serine threonine kinase that increases vasomotor tone via its effects on both endothelium and smooth muscle. Rho-kinase inhibition reduces cerebral infarct size in wild type, but not endothelial nitric oxide synthase deficient (eNOS-/-) mice. The mechanism may be related to Rho-kinase activation under hypoxic/ischemic conditions and impaired vasodilation because of downregulation of eNOS activity. To further implicate Rho-kinase in impaired vascular relaxation during hypoxia/ischemia, we exposed isolated vessels from rat and mouse to 60 mins of hypoxia, and showed that hypoxia reversibly abolished acetylcholine-induced eNOS-dependent relaxation, and that Rho-kinase inhibitor hydroxyfasudil partially preserved this relaxation during hypoxia. We, therefore, hypothesized that if hypoxia-induced Rho-kinase activation acutely impairs vasodilation in ischemic cortex, in vivo, then Rho-kinase inhibitors would acutely augment cerebral blood flow (CBF) as a mechanism by which they reduce infarct size. To test this, we studied the acute cerebral hemodynamic effects of Rho-kinase inhibitors in ischemic core and penumbra during distal middle cerebral artery occlusion (dMCAO) in wild-type and eNOS-/- mice using laser speckle flowmetry. When administered 60 mins before or immediately after dMCAO, Rho-kinase inhibitors hydroxyfasudil and Y-27632 reduced the area of severely ischemic cortex. However, hydroxyfasudil did not reduce the area of CBF deficit in eNOS-/- mice, suggesting that its effect on CBF within the ischemic cortex is primarily endothelium-dependent, and not mediated by its direct vasodilator effect on vascular smooth muscle. Our results suggest that Rho-kinase negatively regulates eNOS activity in acutely ischemic brain, thereby worsening the CBF deficit. Therefore, rapid nontranscriptional upregulation of eNOS activity by small molecule inhibitors of Rho-kinase may be a viable therapeutic approach in acute stroke.

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.

Virodhamine relaxes the human pulmonary artery through the endothelial cannabinoid receptor and indirectly through a COX product

PubMed Central

Kozłowska, H; Baranowska, M; Schlicker, E; Kozłowski, M; Laudañski, J; Malinowska, B

2008-01-01

Background and purpose: The endocannabinoid virodhamine is a partial agonist at the cannabinoid CB1 receptor and a full agonist at the CB2 receptor, and relaxes rat mesenteric arteries through endothelial cannabinoid receptors. Its concentration in the periphery exceeds that of the endocannabinoid anandamide. Here, we examined the influence of virodhamine on the human pulmonary artery. Experimental approach: Isolated human pulmonary arteries were obtained during resections for lung carcinoma. Vasorelaxant effects of virodhamine were examined on endothelium-intact vessels precontracted with 5-HT or KCl. Key results: Virodhamine, unlike WIN 55,212-2, relaxed 5-HT-precontracted vessels concentration dependently. The effect of virodhamine was reduced by endothelium denudation, two antagonists of the endothelial cannabinoid receptor, cannabidiol and O-1918, and a high concentration of the CB1 receptor antagonist rimonabant (5 μM), but only slightly attenuated by the NOS inhibitor L-NAME and not affected by a lower concentration of rimonabant (100 nM) or by the CB2 and vanilloid receptor antagonists SR 144528 and capsazepine, respectively. The COX inhibitor indomethacin and the fatty acid amide hydrolase inhibitor URB597 and combined administration of selective blockers of small (apamin) and intermediate and large (charybdotoxin) conductance Ca2+-activated K+ channels attenuated virodhamine-induced relaxation. The vasorelaxant potency of virodhamine was lower in KCl- than in 5-HT-precontracted preparations. Conclusions and implications: Virodhamine relaxes the human pulmonary artery through the putative endothelial cannabinoid receptor and indirectly through a COX-derived vasorelaxant prostanoid formed from the virodhamine metabolite, arachidonic acid. One or both of these mechanisms may stimulate vasorelaxant Ca2+-activated K+ channels. PMID:18806815

Acetylcholine Attenuates Hydrogen Peroxide-Induced Intracellular Calcium Dyshomeostasis Through Both Muscarinic and Nicotinic Receptors in Cardiomyocytes.

PubMed

Palee, Siripong; Apaijai, Nattayaporn; Shinlapawittayatorn, Krekwit; Chattipakorn, Siriporn C; Chattipakorn, Nipon

2016-01-01

Oxidative stress induced intracellular Ca2+ overload plays an important role in the pathophysiology of several heart diseases. Acetylcholine (ACh) has been shown to suppress reactive oxygen species generation during oxidative stress. However, there is little information regarding the effects of ACh on the intracellular Ca2+ regulation in the presence of oxidative stress. Therefore, we investigated the effects of ACh applied before or after hydrogen peroxide (H2O2) treatment on the intracellular Ca2+ regulation in isolated cardiomyocytes. Single ventricular myocytes were isolated from the male Wistar rats for the intracellular Ca2+ transient study by a fluorimetric ratio technique. H2O2 significantly decreased both of intracellular Ca2+ transient amplitude and decay rate. ACh applied before, but not after, H2O2 treatment attenuated the reduction of intracellular Ca2+ transient amplitude and decay rate. Both atropine (a muscarinic acetylcholine receptor blocker) and mecamylamine (a nicotinic acetylcholine receptor blocker) significantly decreased the protective effects of acetylcholine on the intracellular Ca2+ regulation. Moreover, the combination of atropine and mecamylamine completely abolished the protective effects of acetylcholine on intracellular Ca2+ transient amplitude and decay rate. ACh pretreatment attenuates H2O2-induced intracellular Ca2+ dyshomeostasis through both muscarinic and nicotinic receptors. © 2016 The Author(s) Published by S. Karger AG, Basel.

Impairment of Coronary Arteriolar Endothelium-Dependent Dilation after Multi-Walled Carbon Nanotube Inhalation: A Time-Course Study

PubMed Central

Stapleton, Phoebe A.; Minarchick, Valerie C.; Cumpston, Amy M.; McKinney, Walter; Chen, Bean T.; Sager, Tina M.; Frazer, David G.; Mercer, Robert R.; Scabilloni, James; Andrew, Michael E.; Castranova, Vincent; Nurkiewicz, Timothy R.

2012-01-01

Engineered nanomaterials have been developed for widespread applications due to many highly unique and desirable characteristics. The purpose of this study was to assess pulmonary inflammation and subepicardial arteriolar reactivity in response to multi-walled carbon nanotube (MWCNT) inhalation and evaluate the time course of vascular alterations. Rats were exposed to MWCNT aerosols producing pulmonary deposition. Pulmonary inflammation via bronchoalveolar lavage and MWCNT translocation from the lungs to systemic organs was evident 24 h post-inhalation. Coronary arterioles were evaluated 24–168 h post-exposure to determine microvascular response to changes in transmural pressure, endothelium-dependent and -independent reactivity. Myogenic responsiveness, vascular smooth muscle reactivity to nitric oxide, and α-adrenergic responses all remained intact. However, a severe impact on endothelium-dependent dilation was observed within 24 h after MWCNT inhalation, a condition which improved, but did not fully return to control after 168 h. In conclusion, results indicate that MWCNT inhalation not only leads to pulmonary inflammation and cytotoxicity at low lung burdens, but also a low level of particle translocation to systemic organs. MWCNT inhalation also leads to impairments of endothelium-dependent dilation in the coronary microcirculation within 24 h, a condition which does not fully dissipate within 168 h. The innovations within the field of nanotechnology, while exciting and novel, can only reach their full potential if toxicity is first properly assessed. PMID:23203034

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

Treatment with salvianolic acid B restores endothelial function in angiotensin II-induced hypertensive mice.

PubMed

Ling, Wei Chih; Liu, Jian; Lau, Chi Wai; Murugan, Dharmani Devi; Mustafa, Mohd Rais; Huang, Yu

2017-07-15

Salvianolic acid B (Sal B) is one of the most abundant phenolic acids derived from the root of Danshen with potent anti-oxidative properties. The present study examined the vasoprotective effect of Sal B in hypertensive mice induced by angiotensin II (Ang II). Sal B (25mg/kg/day) was administered via oral gavage for 11days to Ang II (1.2mg/kg/day)-infused C57BL/6J mice (8-10weeks old). The vascular reactivity (both endothelium-dependent relaxations and contractions) in mouse arteries was examined by wire myography. The production of reactive oxygen species (ROS), protein level and localization of angiotensin AT 1 receptors and the proteins involved in ROS formation were evaluated using dihydroethidium (DHE) fluorescence, lucigenin-enhanced chemiluminescence, immunohistochemistry and Western blotting, respectively. The changes of ROS generating proteins were also assessed in vitro in human umbilical vein endothelial cells (HUVECs) exposed to Ang II with and without co-treatment with Sal B (0.1-10nM). Oral administration of Sal B reversed the Ang II-induced elevation of arterial systolic blood pressure in mice, augmented the impaired endothelium-dependent relaxations and attenuated the exaggerated endothelium-dependent contractions in both aortas and renal arteries of Ang II-infused mice. In addition, Sal B treatment normalized the elevated levels of AT 1 receptors, NADPH oxidase subunits (NOx-2 and NOx-4) and nitrotyrosine in arteries of Ang II-infused mice or in Ang II-treated HUVECs. In summary, the present study provided additional evidence demonstrating that Sal B treatment for 11days reverses the impaired endothelial function and with a marked inhibition of AT 1 receptor-dependent vascular oxidative stress. This vasoprotective and anti-oxidative action of Sal B most likely contributes to the anti-hypertensive action of the plant-derived compound. Copyright © 2017 Elsevier Inc. All rights reserved.

Abacavir induces platelet-endothelium interactions by interfering with purinergic signalling: A step from inflammation to thrombosis.

PubMed

Alvarez, Angeles; Rios-Navarro, Cesar; Blanch-Ruiz, Maria Amparo; Collado-Diaz, Victor; Andujar, Isabel; Martinez-Cuesta, Maria Angeles; Orden, Samuel; Esplugues, Juan V

2017-05-01

The controversy connecting Abacavir (ABC) with cardiovascular disease has been fuelled by the lack of a credible mechanism of action. ABC shares structural similarities with endogenous purines, signalling molecules capable of triggering prothrombotic/proinflammatory programmes. Platelets are leading actors in the process of thrombosis. Our study addresses the effects of ABC on interactions between platelets and other vascular cells, while exploring the adhesion molecules implicated and the potential interference with the purinergic signalling pathway. The effects of ABC on platelet aggregation and platelet-endothelium interactions were evaluated, respectively, with an aggregometer and a flow chamber system that reproduced conditions in vivo. The role of adhesion molecules and purinergic receptors in endothelial and platelet populations was assessed by selective pre-incubation with specific antagonists and antibodies. ABC and carbovir triphosphate (CBT) levels were evaluated by HPLC. The results showed that ABC promoted the adherence of platelets to endothelial cells, a crucial step for the formation of thrombi. This was not a consequence of a direct effect of ABC on platelets, but resulted from activation of the endothelium via purinergic ATP-P2X 7 receptors, which subsequently triggered an interplay between P-selectin and ICAM-1 on endothelial cells with constitutively expressed GPIIb/IIIa and GPIbα on platelets. ABC did not induce platelet activation (P-selectin expression or Ca 2+ mobilization) or aggregation, even at high concentrations. CBT levels in endothelial cells were lower than those required to induce platelet-endothelium interactions. Thus, ABC interference with endothelial purinergic signalling leads to platelet recruitment. This highlights the endothelium as the main cell target of ABC in this interaction, which is in line with previous experimental evidence that ABC induces manifestations of vascular inflammation. Copyright © 2017 Elsevier B

Vascular Reactivity Profile of Novel KCa 3.1-Selective Positive-Gating Modulators in the Coronary Vascular Bed.

PubMed

Oliván-Viguera, Aida; Valero, Marta Sofía; Pinilla, Estéfano; Amor, Sara; García-Villalón, Ángel Luis; Coleman, Nichole; Laría, Celia; Calvín-Tienza, Víctor; García-Otín, Ángel-Luis; Fernández-Fernández, José M; Murillo, M Divina; Gálvez, José A; Díaz-de-Villegas, María D; Badorrey, Ramón; Simonsen, Ulf; Rivera, Luis; Wulff, Heike; Köhler, Ralf

2016-08-01

Opening of intermediate-conductance calcium-activated potassium channels (KC a 3.1) produces membrane hyperpolarization in the vascular endothelium. Here, we studied the ability of two new KC a 3.1-selective positive-gating modulators, SKA-111 and SKA-121, to (1) evoke porcine endothelial cell KC a 3.1 membrane hyperpolarization, (2) induce endothelium-dependent and, particularly, endothelium-derived hyperpolarization (EDH)-type relaxation in porcine coronary arteries (PCA) and (3) influence coronary artery tone in isolated rat hearts. In whole-cell patch-clamp experiments on endothelial cells of PCA (PCAEC), KC a currents evoked by bradykinin (BK) were potentiated ≈7-fold by either SKA-111 or SKA-121 (both at 1 μM) and were blocked by a KC a 3.1 blocker, TRAM-34. In membrane potential measurements, SKA-111 and SKA-121 augmented bradykinin-induced hyperpolarization. Isometric tension measurements in large- and small-calibre PCA showed that SKA-111 and SKA-121 potentiated endothelium-dependent relaxation with intact NO synthesis and EDH-type relaxation to BK by ≈2-fold. Potentiation of the BK response was prevented by KC a 3.1 inhibition. In Langendorff-perfused rat hearts, SKA-111 potentiated coronary vasodilation elicited by BK. In conclusion, our data show that positive-gating modulation of KC a 3.1 channels improves BK-induced membrane hyperpolarization and endothelium-dependent relaxation in small and large PCA as well as in the coronary circulation of rats. Positive-gating modulators of KC a 3.1 could be therapeutically useful to improve coronary blood flow and counteract impaired coronary endothelial dysfunction in cardiovascular disease. © 2016 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

Chloride channels mediate sodium sulphide-induced relaxation in rat uteri

PubMed Central

Mijušković, Ana; Kokić, Aleksandra Nikolić; Dušić, Zorana Oreščanin; Slavić, Marija; Spasić, Mihajlo B; Blagojević, Duško

2015-01-01

Background and Purpose Hydrogen sulphide reduces uterine contractility and is of potential interest as a treatment for uterine disorders. The aim of this study was to explore the mechanism of sodium sulphide (Na2S)-induced relaxation of rat uterus, investigate the importance of redox effects and ion channel-mediated mechanisms, and any interactions between these two mechanisms. Experimental Approach Organ bath studies were employed to assess the pharmacological effects of Na2S in uterine strips by exposing them to Na2S with or without Cl− channel blockers (DIDS, NFA, IAA-94, T16Ainh-A01, TA), raised KCl (15 and 75 mM), K+ channel inhibitors (glibenclamide, TEA, 4-AP), L-type Ca2+ channel activator (S-Bay K 8644), propranolol and methylene blue. The activities of antioxidant enzymes were measured in homogenates of treated uteri. The expression of bestrophin channel 1 (BEST-1) was determined by Western blotting and RT-PCR. Key Results Na2S caused concentration-dependent reversible relaxation of spontaneously active and calcium-treated uteri, affecting both amplitude and frequency of contractions. Uteri exposed to 75 mM KCl were less sensitive to Na2S compared with uteri in 15 mM KCl. Na2S-induced relaxations were abolished by DIDS, but unaffected by other modulators or by the absence of extracellular HCO3−, suggesting the involvement of chloride ion channels. Na2S in combination with different modulators provoked specific changes in the anti-oxidant profiles of uteri. The expression of BEST-1, both mRNA and protein, was demonstrated in rat uteri. Conclusions and Implications The relaxant effects of Na2S in rat uteri are mediated mainly via a DIDS-sensitive Cl−-pathway. Components of the relaxation are redox- and Ca2+-dependent. PMID:25857480

Chloride channels mediate sodium sulphide-induced relaxation in rat uteri.

PubMed

Mijušković, Ana; Kokić, Aleksandra Nikolić; Dušić, Zorana Oreščanin; Slavić, Marija; Spasić, Mihajlo B; Blagojević, Duško

2015-07-01

Hydrogen sulphide reduces uterine contractility and is of potential interest as a treatment for uterine disorders. The aim of this study was to explore the mechanism of sodium sulphide (Na2 S)-induced relaxation of rat uterus, investigate the importance of redox effects and ion channel-mediated mechanisms, and any interactions between these two mechanisms. Organ bath studies were employed to assess the pharmacological effects of Na2 S in uterine strips by exposing them to Na2 S with or without Cl(-) channel blockers (DIDS, NFA, IAA-94, T16Ainh-A01, TA), raised KCl (15 and 75 mM), K(+) channel inhibitors (glibenclamide, TEA, 4-AP), L-type Ca(2+) channel activator (S-Bay K 8644), propranolol and methylene blue. The activities of antioxidant enzymes were measured in homogenates of treated uteri. The expression of bestrophin channel 1 (BEST-1) was determined by Western blotting and RT-PCR. Na2 S caused concentration-dependent reversible relaxation of spontaneously active and calcium-treated uteri, affecting both amplitude and frequency of contractions. Uteri exposed to 75 mM KCl were less sensitive to Na2 S compared with uteri in 15 mM KCl. Na2 S-induced relaxations were abolished by DIDS, but unaffected by other modulators or by the absence of extracellular HCO3 (-) , suggesting the involvement of chloride ion channels. Na2 S in combination with different modulators provoked specific changes in the anti-oxidant profiles of uteri. The expression of BEST-1, both mRNA and protein, was demonstrated in rat uteri. The relaxant effects of Na2 S in rat uteri are mediated mainly via a DIDS-sensitive Cl(-) -pathway. Components of the relaxation are redox- and Ca(2+) -dependent. © 2015 The British Pharmacological Society.

Opiate-induced constipation related to activation of small intestine opioid μ2-receptors.

PubMed

Chen, Wency; Chung, Hsien-Hui; Cheng, Juei-Tang

2012-03-28

To investigate the role of opioid μ-receptor subtype in opiate-induced constipation (OIC). The effect of loperamide on intestinal transit was investigated in mice. Ileum strips were isolated from 12-wk-old male BALB/c mice for identification of isometric tension. The ileum strips were precontracted with 1 μmol/L acetylcholine (ACh). Then, decrease in muscle tone (relaxation) was characterized after cumulative administration of 0.1-10 μmol/L loperamide into the organ bath, for a concentration-dependent study. Specific blockers or antagonists were used for pretreatment to compare the changes in loperamide-induced relaxation. In addition to the delay in intestinal transit, loperamide produced a marked relaxation in isolated ileum precontracted with ACh, in a dose-dependent manner. This relaxation was abolished by cyprodime, a selective opioid μ-receptor antagonist, but not modified by naloxonazine at a dose sufficient to block opioid μ-1 receptors. Also, treatment with opioid μ-1 receptor agonist failed to modify the muscle tone. Moreover, the relaxation by loperamide was attenuated by glibenclamide at a dose sufficient to block ATP-sensitive K+ (K(ATP)) channels, and by protein kinase A (PKA) inhibitor, but was enhanced by an inhibitor of phosphodiesterase for cyclic adenosine monophosphate (cAMP). Loperamide induces intestinal relaxation by activation of opioid μ-2 receptors via the cAMP-PKA pathway to open K(ATP) channels, relates to OIC.

[Significance of heterogenity in endothelium-dependent vasodilatation occurrence in healthy individuals with or without coronary risk factors].

PubMed

Polovina, Marija; Potpara, Tatjana; Giga, Vojislav; Ostojić, Miodrag

2009-10-01

Brachial artery flow-mediated dilation (FMD) is extensively used for non-invasive assessment of endothelial function. Traditionally, FMD is calculated as a percent change of arterial diameter from the baseline value at an arbitrary time point after cuff deflation (usually 60 seconds). Considerable individual differences in brachial artery temporal response to hyperemic stimulus have been observed, potentially influenced by the presence of atherosclerotic risk factors (RF). The importance of such differences for the evaluation of endothelial function has not been well established. The aim of the study was to determine the time course of maximal brachial artery endothelium-dependent dilation in healthy adults with and without RF, to explore the correlation of RF with brachial artery temporal response and to evaluate the importance of individual differences in temporal response for the assessment of endothelial function. A total of 115 healthy volunteers were included in the study. Out of them, 58 had no RF (26 men, mean age 44 +/-14 years) and 57 had at least one RF (29 men, mean age 45 +/-14 years). High-resolution color Doppler vascular ultrasound was used for brachial artery imaging. To determine maximal arterial diameter after cuff deflation and the time-point of maximal vasodilation off-line sequential measurements were performed every 10 seconds from 0 to 240 seconds after cuff release. True maximal FMD value was calculated as a percent change of the true maximal diameter from the baseline, and compared with FMD value calculated assuming that every participant reached maximal dilation at 60 seconds post cuff deflation (FMD60). Correlation of different RF with brachial artery temporal response was assessed. A maximal brachial artery endothelium-dependent vasodilation occurred from 30-120 seconds after cuff release, and the mean time of endothelium-dependent dilation was 68 +/-20 seconds. Individuals without RF had faster endothelium-dependent dilation (mean time

Choline acetyltransferase and organic cation transporters are responsible for synthesis and propionate-induced release of acetylcholine in colon epithelium.

PubMed

Bader, Sandra; Klein, Jochen; Diener, Martin

2014-06-15

Acetylcholine is not only a neurotransmitter, but is found in a variety of non-neuronal cells. For example, the enzyme choline acetyltransferase (ChAT), catalyzing acetylcholine synthesis, is expressed by the colonic epithelium of different species. These cells release acetylcholine across the basolateral membrane after luminal exposure to propionate, a short-chain fatty acid. The functional consequence is the induction of chloride secretion, measurable as increase in short-circuit current (Isc) in Ussing chamber experiments. It is unclear how acetylcholine is produced and released by colonic epithelium. Therefore, the aim of the present study was the identification (on mRNA and protein level) and functional characterization (in Ussing chamber experiments combined with HPLC detection of acetylcholine) of transporters/enzymes in the cholinergic system of rat colonic epithelium. Immunohistochemical staining as well as RT-PCR revealed the expression of high-affinity choline transporter, ChAT, carnitine acetyltransferase (CarAT), vesicular acetylcholine transporter (VAChT), and organic cation transporters (OCT 1, 2, 3) in colonic epithelium. In contrast to blockade of ChAT with bromoacetylcholine, inhibition of CarAT with mildronate did not inhibit the propionate-induced increase in Isc, suggesting a predominant synthesis of epithelial acetylcholine by ChAT. Although being expressed, blockade of VAChT with vesamicol was ineffective, whereas inhibition of OCTs with omeprazole and corticosterone inhibited propionate-induced Isc and the release of acetylcholine into the basolateral compartment. In summary, OCTs seem to be involved in regulated acetylcholine release by colonic epithelium, which is assumed to be involved in chemosensing of luminal short-chain fatty acids by the intestinal epithelium. Copyright © 2014 Elsevier B.V. All rights reserved.

Competitive inhibition of the nondepolarizing muscle relaxant rocuronium on nicotinic acetylcholine receptor channels in the rat superior cervical ganglia.

PubMed

Zhang, Chengmi; Wang, Zhenmeng; Zhang, Jinmin; Qiu, Haibo; Sun, Yuming; Yang, Liqun; Wu, Feixiang; Zheng, Jijian; Yu, Weifeng

2014-05-01

A number of case reports now indicate that rocuronium can induce a number of serious side effects. We hypothesized that these side effects might be mediated by the inhibition of nicotinic acetylcholine receptors (nAChRs) at superior cervical ganglion (SCG) neurons. Conventional patch clamp recordings were used to study the effects of rocuronium on nAChR currents from enzymatically dissociated rat SCG neurons. We found that ACh induced a peak transient inward current in rat SCG neurons. Additionally, rocuronium suppressed the peak ACh-evoked currents in rat SCG neurons in a concentration-dependent and competitive manner, and it increased the extent of desensitization of nAChRs. The inhibitory rate of rocuronium on nAChR currents did not change significantly at membrane potentials between -70 and -20 mV, suggesting that this inhibition was voltage independent. Lastly, rocuronium preapplication enhanced its inhibitory effect, indicating that this drug might prefer to act on the closed state of nAChR channels. In conclusion, rocuronium, at clinically relevant concentrations, directly inhibits nAChRs at the SCG by interacting with both opened and closed states. This inhibition is competitive, dose dependent, and voltage independent. Blockade of synaptic transmission in the sympathetic ganglia by rocuronium might have potentially inhibitory effects on the cardiovascular system.

Repeatability and reliability of muscle relaxation properties induced by motor cortical stimulation.

PubMed

Molenaar, Joery P; Voermans, Nicol C; de Jong, Lysanne A; Stegeman, Dick F; Doorduin, Jonne; van Engelen, Baziel G

2018-03-15

Impaired muscle relaxation is a feature of many neuromuscular disorders. However, there are few tests available to quantify muscle relaxation. Transcranial magnetic stimulation (TMS) of the motor cortex can induce muscle relaxation by abruptly inhibiting corticospinal drive. The aim of our study is to investigate if repeatability and reliability of TMS-induced relaxation is greater than voluntary relaxation. Furthermore, effects of sex, cooling and fatigue on muscle relaxation properties were studied. Muscle relaxation of deep finger flexors was assessed in twenty-five healthy subjects (14 M and 11 F, aged 39.1{plus minus}12.7 and 45.3{plus minus}8.7 years old, respectively) using handgrip dynamometry. All outcome measures showed greater repeatability and reliability in TMS-induced relaxation compared to voluntary relaxation. The within-subject coefficient of variability of normalized peak relaxation rate was lower in TMS-induced relaxation than in voluntary relaxation (3.0 vs 19.7% in men, and 6.1 vs 14.3% in women). The repeatability coefficient was lower (1.3 vs 6.1 s -1 in men and 2.3 vs 3.1 s -1 in women), and the intraclass correlation coefficient was higher (0.95 vs 0.53 in men and 0.78 vs 0.69 in women), for TMS-induced relaxation compared to voluntary relaxation. TMS enabled to demonstrate slowing effects of sex, muscle cooling, and muscle fatigue on relaxation properties that voluntary relaxation could not. In conclusion, repeatability and reliability of TMS-induced muscle relaxation was greater compared to voluntary muscle relaxation. TMS-induced muscle relaxation has the potential to be used in clinical practice for diagnostic purposes and therapy effect monitoring in patients with impaired muscle relaxation.

Effect of medication on microvascular vasodilatation in patients with systemic lupus erythematosus.

PubMed

Bengtsson, Christine; Andersson, Sven E; Edvinsson, Lars; Edvinsson, Marie-Louise; Sturfelt, Gunnar; Nived, Ola

2010-12-01

The aim of this study was to investigate the microvascular responses in the skin, to local heat, iontophoretically administered acetylcholine and to sodium nitroprusside in relation to cardiovascular damage in patients with systemic lupus erythematosus (SLE) and matched controls. We also wanted to examine if the ongoing medication in SLE patients influenced this vascular response. We investigated 30 women with SLE and compared them with 20 age and sex-matched controls. The cutaneous blood flow response to local heat (+44°C), iontophoretically administered endothelium-dependent (acetylcholine), as well as independent (sodium nitroprusside) vasodilatation, was measured by laser Doppler flowmetry. Clinical data and medication were retrieved from the clinical database and patient records. The cutaneous microvascular reactivity did not differ between SLE patients and a group of matched controls nor did it correlate with cardiovascular damage [assessed by Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SLICC/ACR-DI)]. However, patients on antimalarial drugs (hydroxychloroquine n = 8 and chloroquine diphosphate n = 3) responded more strongly to sodium nitroprusside (endothelium-independent vasodilatation) compared with those without antimalarial drugs (p < 0.01). The response to acetylcholine was higher among patients on warfarin compared with those without (p < 0.05), whereas glucocorticoid use (≥5 mg daily) was associated with reduced response to acetylcholine (p < 0.05). Smokers in general tended to have a lower response to acetylcholine (p = 0.064). Smoking SLE patients versus non-smoking SLE patients had a significantly lower response to acetylcholine (p = 0.01). Medication with antimalarial drugs-enhanced endothelium-independent vasodilatation, while glucocorticoid use was associated with reduction and warfarin-treatment with enhancement of endothelium-dependent vasodilatation. Therefore, despite there is no

COX-2 is involved in vascular oxidative stress and endothelial dysfunction of renal interlobar arteries from obese Zucker rats.

PubMed

Muñoz, Mercedes; Sánchez, Ana; Pilar Martínez, María; Benedito, Sara; López-Oliva, Maria-Elvira; García-Sacristán, Albino; Hernández, Medardo; Prieto, Dolores

2015-07-01

Obesity is related to vascular dysfunction through inflammation and oxidative stress and it has been identified as a risk factor for chronic renal disease. In the present study, we assessed the specific relationships among reactive oxygen species (ROS), cyclooxygenase 2 (COX-2), and endothelial dysfunction in renal interlobar arteries from a genetic model of obesity/insulin resistance, the obese Zucker rats (OZR). Relaxations to acetylcholine (ACh) were significantly reduced in renal arteries from OZR compared to their counterpart, the lean Zucker rat (LZR), suggesting endothelial dysfunction. Blockade of COX with indomethacin and with the selective blocker of COX-2 restored the relaxations to ACh in obese rats. Selective blockade of the TXA2/PGH2 (TP) receptor enhanced ACh relaxations only in OZR, while inhibition of the prostacyclin (PGI2) receptor (IP) enhanced basal tone and inhibited ACh vasodilator responses only in LZR. Basal production of superoxide was increased in arteries of OZR and involved NADPH and xanthine oxidase activation and NOS uncoupling. Under conditions of NOS blockade, ACh induced vasoconstriction and increased ROS generation that were augmented in arteries from OZR and blunted by COX-2 inhibition and by the ROS scavenger tempol. Hydrogen peroxide (H2O2) evoked both endothelium- and vascular smooth muscle (VSM)-dependent contractions, as well as ROS generation that was reduced by COX-2 inhibition. In addition, COX-2 expression was enhanced in both VSM and endothelium of renal arteries from OZR. These results suggest that increased COX-2-dependent vasoconstriction contributes to renal endothelial dysfunction through enhanced (ROS) generation in obesity. COX-2 activity is in turn upregulated by ROS. Copyright © 2015 Elsevier Inc. All rights reserved.

Neural correlates of stress-induced and cue-induced drug craving: influences of sex and cocaine dependence.

PubMed

Potenza, Marc N; Hong, Kwang-ik Adam; Lacadie, Cheryl M; Fulbright, Robert K; Tuit, Keri L; Sinha, Rajita

2012-04-01

Although stress and drug cue exposure each increase drug craving and contribute to relapse in cocaine dependence, no previous research has directly examined the neural correlates of stress-induced and drug cue-induced craving in cocaine-dependent women and men relative to comparison subjects. Functional MRI was used to assess responses to individualized scripts for stress, drug/alcohol cue and neutral-relaxing-imagery conditions in 30 abstinent cocaine-dependent individuals (16 women, 14 men) and 36 healthy recreational-drinking comparison subjects (18 women, 18 men). Significant three-way interactions between diagnostic group, sex, and script condition were observed in multiple brain regions including the striatum, insula, and anterior and posterior cingulate. Within women, group-by-condition interactions were observed involving these regions and were attributable to relatively increased regional activations in cocaine-dependent women during the stress and, to a lesser extent, neutral-relaxing conditions. Within men, group main effects were observed involving these same regions, with cocaine-dependent men demonstrating relatively increased activation across conditions, with the main contributions from the drug and neutral-relaxing conditions. In men and women, subjective drug-induced craving measures correlated positively with corticostriatal-limbic activations. In cocaine dependence, corticostriatal-limbic hyperactivity appears to be linked to stress cues in women, drug cues in men, and neutral-relaxing conditions in both. These findings suggest that sex should be taken into account in the selection of therapies in the treatment of addiction, particularly those targeting stress reduction.

Phospholemman does not participate in forskolin-induced swine carotid artery relaxation.

PubMed

Meeks, M K; Han, S; Tucker, A L; Rembold, C M

2008-01-01

Phosphorylation of phospholemman (PLM) on ser68 has been proposed to at least partially mediate cyclic AMP (cAMP) mediated relaxation of arterial smooth muscle. We evaluated the time course of the phosphorylation of phospholemman (PLM) on ser68, myosin regulatory light chains (MRLC) on ser19, and heat shock protein 20 (HSP20) on ser16 during a transient forskolin-induced relaxation of histamine-stimulated swine carotid artery. We also evaluated the dose response for forskolin- and nitroglycerin-induced relaxation in phenylephrine-stimulated PLM-/- and PLM+/+ mice. The time course for changes in ser19 MRLC dephosphorylation and ser16 HSP20 phosphorylation was appropriate to explain the forskolin-induced relaxation and the recontraction observed upon washout of forskolin. However, the time course for changes in ser68 PLM phosphorylation was too slow to explain forskolin-induced changes in force. There was no difference in the phenylephrine contractile dose response or in forskolin-induced relaxation dose response observed in PLM-/- and PLM+/+ aortae. In aortae precontracted with phenylephrine, nitroglycerin induced a slightly, but significantly greater relaxation in PLM-/- compared to PLM+/+ aortae. These data are consistent with the hypothesis that ser19 MRLC dephosphorylation and ser16 HSP20 phosphorylation are involved in forskolin-induced relaxation. Our data suggest that PLM phosphorylation is not significantly involved in forskolin-induced arterial relaxation.

Gingerol Inhibits Serum-Induced Vascular Smooth Muscle Cell Proliferation and Injury-Induced Neointimal Hyperplasia by Suppressing p38 MAPK Activation.

PubMed

Jain, Manish; Singh, Ankita; Singh, Vishal; Maurya, Preeti; Barthwal, Manoj Kumar

2016-03-01

Gingerol inhibits growth of cancerous cells; however, its role in vascular smooth muscle cell (VSMC) proliferation is not known. The present study investigated the effect of gingerol on VSMC proliferation in cell culture and during neointima formation after balloon injury. Rat VSMCs or carotid arteries were harvested at 15 minutes, 30 minutes, 1, 6, 12, and 24 hours of fetal bovine serum (FBS; 10%) stimulation or balloon injury, respectively. Gingerol prevented FBS (10%)-induced proliferation of VSMCs in a dose-dependent manner (50 μmol/L-400 μmol/L). The FBS-induced proliferating cell nuclear antigen (PCNA) upregulation and p27(Kip1) downregulation were also attenuated in gingerol (200 μmol/L) pretreated cells. Fetal bovine serum-induced p38 mitogen-activated protein kinase (MAPK) activation, PCNA upregulation, and p27(Kip1) downregulation were abrogated in gingerol (200 μmol/L) and p38 MAPK inhibitor (SB203580, 10 μmol/L) pretreated cells. Balloon injury induced time-dependent p38 MAPK activation in the carotid artery. Pretreatment with gingerol (200 μmol/L) significantly attenuated injury-induced p38 MAPK activation, PCNA upregulation, and p27(Kip1) downregulation. After 14 days of balloon injury, intimal thickening, neointimal proliferation, and endothelial dysfunction were significantly prevented in gingerol pretreated arteries. In isolated organ bath studies, gingerol (30 nmol/L-300 μmol/L) inhibited phenylephrine-induced contractions and induced dose-dependent relaxation of rat thoracic aortic rings in a partially endothelium-dependent manner. Gingerol prevented FBS-induced VSMC proliferation and balloon injury-induced neointima formation by regulating p38 MAPK. Vasodilator effect of gingerol observed in the thoracic aorta was partially endothelium dependent. Gingerol is thus proposed as an attractive agent for modulating VSMC proliferation, vascular reactivity, and progression of vascular proliferative diseases. © The Author(s) 2015.

Nanoparticle Inhalation Impairs Coronary Microvascular Reactivity via a Local Reactive Oxygen Species-Dependent Mechanism

PubMed Central

LeBlanc, A. J.; Moseley, A. M.; Chen, B. T.; Frazer, D.; Castranova, V.

2010-01-01

We have shown that nanoparticle inhalation impairs endothelium-dependent vasodilation in coronary arterioles. It is unknown whether local reactive oxygen species (ROS) contribute to this effect. Rats were exposed to TiO2 nanoparticles via inhalation to produce a pulmonary deposition of 10 µg. Coronary arterioles were isolated from the left anterior descending artery distribution, and responses to acetylcholine, arachidonic acid, and U46619 were assessed. Contributions of nitric oxide synthase and prostaglandin were assessed via competitive inhibition with NG-Monomethyl-L-Arginine (L-NMMA) and indomethacin. Microvascular wall ROS were quantified via dihydroethidium (DHE) fluorescence. Coronary arterioles from rats exposed to nano-TiO2 exhibited an attenuated vasodilator response to ACh, and this coincided with a 45% increase in DHE fluorescence. Coincubation with 2,2,6,6-tetramethylpiperidine-N-oxyl and catalase ameliorated impairments in ACh-induced vasodilation from nanoparticle exposed rats. Incubation with either L-NMMA or indomethacin significantly attenuated Ach-induced vasodilation in sham-control rats, but had no effect in rats exposed to nano-TiO2. Arachidonic acid induced vasoconstriction in coronary arterioles from rats exposed to nano-TiO2, but dilated arterioles from sham-control rats. These results suggest that nanoparticle exposure significantly impairs endothelium-dependent vasoreactivity in coronary arterioles, and this may be due in large part to increases in microvascular ROS. Furthermore, altered prostanoid formation may also contribute to this dysfunction. Such disturbances in coronary microvascular function may contribute to the cardiac events associated with exposure to particles in this size range. PMID:20033351

Relaxation of Isolated Ventricular Cardiomyocytes by a Voltage-Dependent Process

NASA Astrophysics Data System (ADS)

Bridge, John H. B.; Spitzer, Kenneth W.; Ershler, Philip R.

1988-08-01

Cell contraction and relaxation were measured in single voltage-clamped guinea pig cardiomyocytes to investigate the contribution of sarcolemmal Na+-Ca2+ exchange to mechanical relaxation. Cells clamped from -80 to 0 millivolts displayed initial phasic and subsequent tonic contractions; caffeine reduced or abolished the phasic and enlarged the tonic contraction. The rate of relaxation from tonic contractions was steeply voltage-dependent and was significantly slowed in the absence of a sarcolemmal Na+ gradient. Tonic contractions elicited in the absence of a Na+ gradient promptly relaxed when external Na+ was applied, reflecting activation of Na+-Ca2+ exchange. It appears that a voltage-dependent Na+-Ca2+ exchange can rapidly mechanically relax mammalian heart muscle.

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

Characterization of muscarinic receptors mediating relaxation and contraction in the rat iris dilator muscle.

PubMed Central

Masuda, Y; Yamahara, N S; Tanaka, M; Ryang, S; Kawai, T; Imaizumi, Y; Watanabe, M

1995-01-01

1. The characteristics of muscarinic receptors mediating relaxation and/or contraction in the rat iris dilator muscle were examined. 2. Relaxation was induced in a dilator muscle by application of acetylcholine (ACh) at low doses (3 microM or less) and contraction was induced by high doses. Methacholine and carbachol also showed biphasic effects similar to those of ACh; in contrast, bethanechol, arecoline, pilocarpine and McN-A-343 induced mainly relaxation but no substantial contraction. 3. After parasympathetic denervation by ciliary ganglionectomy, the relaxant response to muscarinic agonists disappeared upon nerve stimulation. Application of McN-A-343 and pilocarpine induced only small contractions in denervated dilator muscles, indicating that these are partial agonists for contraction. 4. pA2 values of pirenzepine, methoctramine, AF-DX 116, himbacine, and 4-DAMP for antagonism to pilocarpine-induced relaxation in normal dilator muscles and those for antagonism to ACh-induced contraction in denervated dilator muscles were determined. The pA2 values for antagonism to relaxation of all these antagonists were most similar to those for M3-type muscarinic receptors. 5. Although pA2 values for contraction of these antagonists, except for methoctramine, were very close to those for relaxation, contraction was not significantly antagonized by methoctramine. Contraction might be mediated by M3-like receptors which have a very low affinity for methoctramine. 6. In conclusion, ACh-induced biphasic responses in rat iris dilator muscles were clearly distinguished from each other by specific muscarinic agonists and parasympathetic denervation, whereas muscarinic receptors could not be subclassified according to the pA2 values of 5 specific antagonists only. PMID:7539696

Epigallocatechin gallate attenuates ET-1-induced contraction in carotid artery from type 2 diabetic OLETF rat at chronic stage of disease.

PubMed

Matsumoto, Takayuki; Watanabe, Shun; Kawamura, Ryusuke; Taguchi, Kumiko; Kobayashi, Tsuneo

2014-11-24

There is a growing body of evidence suggesting that epigallocatechin gallate (EGCG), a major catechin isolated from green tea, has several beneficial effects, such as anti-oxidant and anti-inflammatory activities. However, whether treatment with EGCG can suppress the endothelin-1 (ET-1)-induced contraction in carotid arteries from type 2 diabetic rats is unknown, especially at the chronic stage of the disease. We hypothesized that long-term treatment with EGCG would attenuate ET-1-induced contractions in type 2 diabetic arteries. Otsuka Long-Evans Tokushima fatty (OLETF) rats (43 weeks old) were treated with EGCG (200 mg/kg/day for 2 months, p.o.), and the responsiveness to ET-1, phenylephrine (PE), acetylcholine (ACh) and sodium nitroprusside (SNP) was measured in common carotid artery (CA) from EGCG-treated and -untreated OLETF rats and control Long-Evans Tokushima Otsuka (LETO) rats. In OLETF rats, EGCG attenuated responsiveness to ET-1 in CA compared to untreated groups. However, EGCG did not alter PE-induced contractions in CA from OLETF rats. In endothelium-denuded arteries, EGCG did not affect ET-1-induced contractions in either the OLETF or LETO group. Acetylcholine-induced relaxation was increased by EGCG treatment in CA from the OLETF group. The expressions of ET receptors, endothelial nitric oxide synthase, superoxide dismutases, and gp91(phox) [an NAD(P)H oxidase component] in CA were not altered by EGCG treatment in either group. Our data suggest that, within the timescale investigated here, EGCG attenuates ET-1-induced contractions in CA from type 2 diabetic rats, and one of the mechanisms may involve normalizing endothelial function. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

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.

a2* Nicotinic Acetylcholine Receptors Influence Hippocampus-Dependent Learning and Memory in Adolescent Mice

ERIC Educational Resources Information Center

Lotfipour, Shahrdad; Mojica, Celina; Nakauchi, Sakura; Lipovsek, Marcela; Silverstein, Sarah; Cushman, Jesse; Tirtorahardjo, James; Poulos, Andrew; Elgoyhen, Ana Belén; Sumikawa, Katumi; Fanselow, Michael S.; Boulter, Jim

2017-01-01

The absence of a2* nicotinic acetylcholine receptors (nAChRs) in oriens lacunosum moleculare (OLM) GABAergic interneurons ablate the facilitation of nicotine-induced hippocampal CA1 long-term potentiation and impair memory. The current study delineated whether genetic mutations of a2* nAChRs ("Chrna2"[superscript L9'S/L9'S] and…

Characterization of P2Y receptors mediating ATP induced relaxation in guinea pig airway smooth muscle: involvement of prostaglandins and K+ channels.

PubMed

Montaño, Luis M; Cruz-Valderrama, José E; Figueroa, Alejandra; Flores-Soto, Edgar; García-Hernández, Luz M; Carbajal, Verónica; Segura, Patricia; Méndez, Carmen; Díaz, Verónica; Barajas-López, Carlos

2011-10-01

In airway smooth muscle (ASM), adenosine 5'-triphosphate (ATP) induces a relaxation associated with prostaglandin production. We explored the role of K(+) currents (I (K)) in this relaxation. ATP relaxed the ASM, and this effect was abolished by indomethacin. Removal of airway epithelium slightly diminished the ATP-induced relaxation at lower concentration without modifying the responses to ATP at higher concentrations. ATPγS and UTP induced a concentration-dependent relaxation similar to ATP; α,β-methylene-ATP was inactive from 1 to 100 μM. Suramin or reactive blue 2 (RB2), P2Y receptor antagonists, did not modify the relaxation, but their combination significantly reduced this effect of ATP. The relaxation was also inhibited by N-ethylmaleimide (NEM; which uncouples G proteins). In myocytes, the ATP-induced I (K) increment was not modified by suramin or RB2 but the combination of both drugs abolished it. This increment in the I (K) was also completely nullified by NEM and SQ 22,536. 4-Amynopyridine or iberiotoxin diminished the ATP-induced I (K) increment, and the combination of both substances diminished ATP-induced relaxation. The presence of P2Y(2) and P2Y(4) receptors in smooth muscle was corroborated by Western blot and confocal images. In conclusion, ATP: (1) produces relaxation by inducing the production of bronchodilator prostaglandins in airway smooth muscle, most likely by acting on P2Y(4) and P2Y(2) receptors; (2) induces I (K) increment through activation of the delayed rectifier K(+) channels and the high-conductance Ca(2+)-dependent K(+) channels, therefore both channels are implicated in the ATP-induced relaxation; and (3) this I (K) increment is mediated by prostaglandin production which in turns increase cAMP signaling pathway.

Exercise Protects against PCB-Induced Inflammation and Associated Cardiovascular Risk Factors

PubMed Central

Murphy, Margaret O.; Petriello, Michael C.; Han, Sung Gu; Sunkara, Manjula; Morris, Andrew J; Esser, Karyn; Hennig, Bernhard

2015-01-01

Polychlorinated biphenyls (PCBs) are persistent environmental pollutants that contribute to the initiation of cardiovascular disease. Exercise has been shown to reduce the risk of cardiovascular disease; however, whether exercise can modulate PCB-induced vascular endothelial dysfunction and associated cardiovascular risk factors is unknown. We examined the effects of exercise on coplanar PCB- induced cardiovascular risk factors including oxidative stress, inflammation, impaired glucose tolerance, hypercholesteremia, and endothelium-dependent relaxation. Male ApoE−/− mice were divided into sedentary and exercise groups (voluntary wheel running) over a 12 week period. Half of each group was exposed to vehicle or PCB 77 at weeks 1, 2, 9, and 10. For ex vivo studies, male C57BL/6 mice exercised via voluntary wheel training for 5 weeks and then were administered with vehicle or PCB 77 24 hours before vascular reactivity studies were performed. Exposure to coplanar PCB increased risk factors associated with cardiovascular disease, including oxidative stress and systemic inflammation, glucose intolerance, and hypercholesteremia. The 12 week exercise intervention significantly reduced these pro-atherogenic parameters. Exercise also upregulated antioxidant enzymes including phase II detoxification enzymes. Sedentary animals exposed to PCB 77 exhibited endothelial dysfunction as demonstrated by significant impairment of endothelium-dependent relaxation, which was prevented by exercise. Lifestyle modifications such as aerobic exercise could be utilized as a therapeutic approach for the prevention of adverse cardiovascular health effects induced by environmental pollutants such as PCBs. Keywords: exercise, polychlorinated biphenyl, endothelial function, antioxidant response, cardiovascular disease, inflammation, oxidative stress PMID:25586614

Opiate-induced constipation related to activation of small intestine opioid μ2-receptors

PubMed Central

Chen, Wency; Chung, Hsien-Hui; Cheng, Juei-Tang

2012-01-01

AIM: To investigate the role of opioid μ-receptor subtype in opiate-induced constipation (OIC). METHODS: The effect of loperamide on intestinal transit was investigated in mice. Ileum strips were isolated from 12-wk-old male BALB/c mice for identification of isometric tension. The ileum strips were precontracted with 1 μmol/L acetylcholine (ACh). Then, decrease in muscle tone (relaxation) was characterized after cumulative administration of 0.1-10 μmol/L loperamide into the organ bath, for a concentration-dependent study. Specific blockers or antagonists were used for pretreatment to compare the changes in loperamide-induced relaxation. RESULTS: In addition to the delay in intestinal transit, loperamide produced a marked relaxation in isolated ileum precontracted with ACh, in a dose-dependent manner. This relaxation was abolished by cyprodime, a selective opioid μ-receptor antagonist, but not modified by naloxonazine at a dose sufficient to block opioid μ-1 receptors. Also, treatment with opioid μ-1 receptor agonist failed to modify the muscle tone. Moreover, the relaxation by loperamide was attenuated by glibenclamide at a dose sufficient to block ATP-sensitive K+ (KATP) channels, and by protein kinase A (PKA) inhibitor, but was enhanced by an inhibitor of phosphodiesterase for cyclic adenosine monophosphate (cAMP). CONCLUSION: Loperamide induces intestinal relaxation by activation of opioid μ-2 receptors via the cAMP-PKA pathway to open KATP channels, relates to OIC. PMID:22493554

Chloride channel function is linked to epithelium-dependent airway relaxation.

PubMed

Fortner, C N; Lorenz, J N; Paul, R J

2001-02-01

We previously reported that substance P (SP) and ATP evoke transient, epithelium-dependent relaxation of mouse tracheal smooth muscle. Since both SP and ATP are known to evoke transepithelial Cl- secretion across epithelial monolayers, we tested the hypothesis that epithelium-dependent relaxation of mouse trachea depends on Cl- channel function. In perfused mouse tracheas, the responses to SP and ATP were both inhibited by the Cl- channel inhibitors diphenylamine-2-carboxylate and 5-nitro-2-(3-phenylpropylamino)benzoate. Relaxation to ATP or SP was unaffected by 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNDS), and relaxation to SP was unaffected by either DIDS or DNDS. Replacing Cl- in the buffer solutions with the impermeable anion gluconate on both sides of the trachea inhibited relaxation to SP or ATP. In contrast, increasing the gradient for Cl- secretion using Cl- free medium only in the tracheal lumen enhanced the relaxation to SP or ATP. We conclude that Cl- channel function is linked to receptor-mediated, epithelium-dependent relaxation. The finding that relaxation to SP was not blocked by DIDS suggested the involvement of a DIDS-insensitive Cl- channel, potentially the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel. To test this hypothesis, we evaluated tracheas from CFTR-deficient mice and found that the peak relaxation to SP or ATP was not significantly different from those responses in wild-type littermates. This suggests that a DIDS-insensitive Cl- channel other than CFTR is active in the SP response. This work introduces a possible role for Cl- pathways in the modulation of airway smooth muscle function and may have implications for fundamental studies of airway function as well as therapeutic approaches to pulmonary disease.

The dopamine D1 receptor is expressed and facilitates relaxation in airway smooth muscle.

PubMed

Mizuta, Kentaro; Zhang, Yi; Xu, Dingbang; Mizuta, Fumiko; D'Ovidio, Frank; Masaki, Eiji; Emala, Charles W

2013-09-02

Dopamine signaling is mediated by Gs protein-coupled "D1-like" receptors (D1 and D5) and Gi-coupled "D2-like" receptors (D2-4). In asthmatic patients, inhaled dopamine induces bronchodilation. Although the Gi-coupled dopamine D2 receptor is expressed and sensitizes adenylyl cyclase activity in airway smooth muscle (ASM) cells, the Gs-coupled dopamine D1-like receptor subtypes have never been identified on these cells. Activation of Gs-coupled receptors stimulates cyclic AMP (cAMP) production through the stimulation of adenylyl cyclase, which promotes ASM relaxation. We questioned whether the dopamine D1-like receptor is expressed on ASM, and modulates its function through Gs-coupling. The mRNA and protein expression of dopamine D1-like receptor subtypes in both native human and guinea pig ASM tissue and cultured human ASM (HASM) cells was measured. To characterize the stimulation of cAMP through the dopamine D1 receptor, HASM cells were treated with dopamine or the dopamine D1-like receptor agonists (A68930 or SKF38393) before cAMP measurements. To evaluate whether the activation of dopamine D1 receptor induces ASM relaxation, guinea pig tracheal rings suspended under isometric tension in organ baths were treated with cumulatively increasing concentrations of dopamine or A68930, following an acetylcholine-induced contraction with or without the cAMP-dependent protein kinase (PKA) inhibitor Rp-cAMPS, the large-conductance calcium-activated potassium (BKCa) channel blocker iberiotoxin, or the exchange proteins directly activated by cAMP (Epac) antagonist NSC45576. Messenger RNA encoding the dopamine D1 and D5 receptors were detected in native human ASM tissue and cultured HASM cells. Immunoblots confirmed the protein expression of the dopamine D1 receptor in both native human and guinea pig ASM tissue and cultured HASM cells. The dopamine D1 receptor was also immunohistochemically localized to both human and guinea pig ASM. The dopamine D1-like receptor agonists

Cardiopulmonary protective effects of the selective FXR agonist obeticholic acid in the rat model of monocrotaline-induced pulmonary hypertension.

PubMed

Vignozzi, Linda; Morelli, Annamaria; Cellai, Ilaria; Filippi, Sandra; Comeglio, Paolo; Sarchielli, Erica; Maneschi, Elena; Vannelli, Gabriella Barbara; Adorini, Luciano; Maggi, Mario

2017-01-01

Farnesoid X receptor (FXR) activation by obeticholic acid (OCA) has been demonstrated to inhibit inflammation and fibrosis development and even induce fibrosis regression in liver, kidney and intestine in multiple disease models. OCA also inhibits liver fibrosis in nonalcoholic steatohepatitis patients. FXR activation has also been demonstrated to suppress the inflammatory response and to promote lung repair after lung injury. This study investigated the effects of OCA treatment (3, 10 or 30mg/kg, daily for 5days a week, for 7 and/or 28 days) on inflammation, tissue remodeling and fibrosis in the monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) rat model. Treatment with OCA attenuated MCT-induced increased pulmonary arterial wall thickness and right ventricular hypertrophy, by i) blunting pathogenic inflammatory mechanisms (downregulation of interleukin 6, IL-6, and monocyte chemoattractant protein-1, MCP-1) and ii) enhancing protective mechanisms counteracting fibrosis and endothelial/mesenchymal transition. MCT-injected rats also showed a marked decrease of pulmonary artery responsiveness to both endothelium-dependent and independent relaxant stimuli, such as acetylcholine and a nitric oxide donor, sodium nitroprusside. Administration of OCA (30mg/kg) normalized this decreased responsiveness. Accordingly, OCA treatment induced profound beneficial effects on lung histology. In particular, both OCA doses markedly reduced the MCT-induced medial wall thickness increase in small pulmonary arteries. To evaluate the objective functional improvement by OCA treatment of MCT-induced PAH, we performed a treadmill test and measured duration of exercise. MCT significantly reduced, and OCA normalized treadmill endurance. Results with OCA were similar, or even superior, to those obtained with tadalafil, a well-established treatment of PAH. In conclusion, OCA treatment demonstrates cardiopulmonary protective effects, modulating lung vascular remodeling, reducing

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.

Acetylcholine-evoked currents in cultured neurones dissociated from rat parasympathetic cardiac ganglia.

PubMed Central

Fieber, L A; Adams, D J

1991-01-01

1. The properties of acetylcholine (ACh)-activated ion channels of parasympathetic neurones from neonatal rat cardiac ganglia grown in tissue culture were examined using patch clamp recording techniques. Membrane currents evoked by ACh were mimicked by nicotine, attenuated by neuronal bungarotoxin, and unaffected by atropine, suggesting that the ACh-induced currents are mediated by nicotinic receptor activation. 2. The current-voltage (I-V) relationship for whole-cell ACh-evoked currents exhibited strong inward rectification and a reversal (zero current) potential of -3 mV (NaCl outside, CsCl inside). The rectification was not alleviated by changing the main permeant cation or by removal of divalent cations from the intracellular or extracellular solutions. Unitary ACh-activated currents exhibited a linear I-V relationship with slope conductances of 32 pS in cell-attached membrane patches and 38 pS in excised membrane patches with symmetrical CsCl solutions. 3. Acetylcholine-induced currents were reversibly inhibited in a dose-dependent manner by the ganglionic antagonists, mecamylamine (Kd = 37 nM) and hexamethonium (IC50 approximately 1 microM), as well as by the neuromuscular relaxant, d-tubocurarine (Kd = 3 microM). Inhibition of ACh-evoked currents by hexamethonium could not be described by a simple blocking model for drug-receptor interaction. 4. The amplitude of the ionic current through the open channel was dependent on the extracellular Na+ concentration. The direction of the shift in reversal potential upon replacement of NaCl by mannitol indicates that the neuronal nicotinic receptor channel is cation selective and the magnitude suggests a high cation to anion permeability ratio. The cation permeability (PX/PNa) followed the ionic selectivity sequence Cs+ (1.06) greater than Na+ (1.0) greater than Ca2+ (0.93). Anion substitution experiments showed a relative anion permeability, PCl/PNa less than or equal to 0.05. 5. The nicotinic ACh-activated channels

Adiponectin improves coronary no-reflow injury by protecting the endothelium in rats with type 2 diabetes mellitus.

PubMed

Han, Xue; Wu, Ye; Liu, Xin; Ma, Lu; Lv, Tingting; Sun, Qi; Xu, Wenli; Zhang, Suli; Wang, Ke; Wang, Wen; Ma, Xinliang; Liu, Huirong

2017-08-31

To determine the effect of adiponectin (APN) on the coronary no-reflow (NR) injury in rats with Type 2 diabetes mellitus (T2DM), 80 male Sprague-Dawley rats were fed with a high-sugar-high-fat diet to build a T2DM model. Rats received vehicle or APN in the last week and then were subjected to myocardial ischemia reperfusion (MI/R) injury. Endothelium-dependent vasorelaxation of the thoracic aorta was significantly decreased and serum levels of endothelin-1 (ET-1), intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were noticably increased in T2DM rats compared with rats without T2DM. Serum APN was positively correlated with the endothelium-dependent vasorelaxation, but negatively correlated with the serum level of ET-1. Treatment with APN improved T2DM-induced endothelium-dependent vasorelaxation, recovered cardiac function, and decreased both NR size and the levels of ET-1, ICAM-1 and VCAM-1. Hypoadiponectinemia was associated with the aggravation of coronary NR in T2DM rats. APN could alleviate coronary NR injury in T2DM rats by protecting the endothelium and improving microcirculation. © 2017 The Author(s).

GPER Mediates Functional Endothelial Aging in Renal Arteries.

PubMed

Meyer, Matthias R; Rosemann, Thomas; Barton, Matthias; Prossnitz, Eric R

2017-01-01

Aging is associated with impaired renal artery function, which is partly characterized by arterial stiffening and a reduced vasodilatory capacity due to excessive generation of reactive oxygen species by NADPH oxidases (Nox). The abundance and activity of Nox depends on basal activity of the heptahelical transmembrane receptor GPER; however, whether GPER contributes to age-dependent functional changes in renal arteries is unknown. This study investigated the effect of aging and Nox activity on renal artery tone in wild-type and GPER-deficient (Gper-/-) mice (4 and 24 months old). In wild-type mice, aging markedly impaired endothelium-dependent, nitric oxide (NO)-mediated relaxations to acetylcholine, which were largely preserved in renal arteries of aged Gper-/- mice. The Nox inhibitor gp91ds-tat abolished this difference by greatly enhancing relaxations in wild-type mice, while having no effect in Gper-/- mice. Contractions to angiotensin II and phenylephrine in wild-type mice were partly sensitive to gp91ds-tat but unaffected by aging. Again, deletion of GPER abolished effects of Nox inhibition on contractile responses. In conclusion, basal activity of GPER is required for the age-dependent impairment of endothelium-dependent, NO-mediated relaxation in the renal artery. Restoration of relaxation by a Nox inhibitor in aged wild-type but not Gper-/- mice strongly supports a role for Nox-derived reactive oxygen species as the underlying cause. Pharmacological blockers of GPER signaling may thus be suitable to inhibit functional endothelial aging of renal arteries by reducing Nox-derived oxidative stress and, possibly, the associated age-dependent deterioration of kidney function. © 2017 S. Karger AG, Basel.

Presynaptic facilitatory adenosine A2A receptors mediate fade induced by neuromuscular relaxants that exhibit anticholinesterase activity.

PubMed

Bornia, Elaine Cs; Correia-de-Sá, Paulo; Alves-Do-Prado, Wilson

2011-03-01

1. Pancuronium, cisatracurium and vecuronium are antinicotinic agents that, in contrast with d-tubocurarine and hexamethonium, exhibit anticholinesterase activity. Pancuronium-, cisatracurium- and vecuronium-induced fade results from blockade of facilitatory nicotinic receptors on motor nerves, but fade produced by such agents also depends on the presynaptic activation of inhibitory muscarinic M2 receptors by acetylcholine released from motor nerve terminals and activation of inhibitory adenosine A1 receptors by adenosine released from motor nerves and muscles. The participation of presynaptic facilitatory A2A receptors in fade caused by pancuronium, cisatracurium and vecuronium has not yet been investigated. In the present study, we determined the effects of ZM241385, an antagonist of presynaptic facilitatory A2A receptors, on fade produced by these neuromuscular relaxants in the rat phrenic nerve-diaphragm (PND) preparation. 2. The muscles were stimulated indirectly at 75±3Hz to induce a sustained tetanizing muscular contraction. The lowest concentration at which each antinicotinic agent produced fade without modifying initial tetanic tension (presynaptic action) was determined. 3. d-Tubocurarine-induced fade occurred only at 55 nmol/L, a concentration that also reduced maximal tetanic tension (post-synaptic action). At 10 nmol/L, ZM 241385 alone did not produce fade, but it did attenuate pancuronium (0.32 μmol/L)-, cisatracurium (0.32 μmol/L)- and vecuronium (0.36 μmol/L)-induced fade. 4. The fade induced by the 'pure' antinicotinic agents d-tubocurarine (55 nmol/L) and hexamethonium (413 μmol/L) was not altered by 10 nmol/L ZM 241385, indicating that presynaptic adenosine A2A receptors play a significant role in the fade produced by antinicotinic agents when such agents have anticholinesterase activity. © 2011 The Authors. Clinical and Experimental Pharmacology and Physiology © 2011 Blackwell Publishing Asia Pty Ltd.

The effect of streptozotocin-induced diabetes on the EDHF-type relaxation and cardiac function in rats.

PubMed

Absi, Mais; Oso, Hani; Khattab, Marwan

2013-07-01

The endothelium-derived hyperpolarizing factor (EDHF) response is a critical for the functioning of small blood vessels. We investigated the effect of streptozotocin-induced diabetes on the EDHF response and its possible role in the regulation of cardiac function. The vasorelaxant response to ACh- or NS309- (direct opener endothelial small- (SKCa)- and intermediate-conductance (IKCa) calcium-activated potassium channels; main components of EDHF response) were measured in pressurized mesenteric arteries (diameter 300-350 μm). The response to 1 μM ACh was reduced in diabetes (84.8 ± 2.8% control vs 22.5 ± 5.8% diabetics; n ⩾ 8; P < 0.001). NS309 (1 μM) relaxations were also decreased in diabetic arteries (78.5 ± 8.7% control vs 32.1 ± 5.8% diabetics; n ⩾ 5; P < 0.001). SKCa and IKCa-mediated EDHF relaxations in response ACh or NS309 were also significantly reduced by diabetes. Ruthenium red, RuR, a blocker of TRP channels, strongly depress the response to ACh and NS309 in control and diabetic arteries. RuR decreased SKCa and IKCa-mediated EDHF vasodilatation in response to NS309 but not to ACh. An elevation in systolic blood pressure was observed in diabetic animals. ECG recording of control hearts showed shortening of PR interval. RuR reduced PR interval and R wave amplitude in diabetic hearts. In conclusion, the reduced EDHF-type relaxations in STZ-induced diabetes is due impairment of KCa channels function. TRP channels possibly contribute to EDHF vasodilatation via direct opening of endothelial KCa. It is possible that EDHF and TRP channels contribute to the regulation of cardiac function and therefore can be considered as therapeutic targets to improve cardiovascular complications of diabetes.

The effect of streptozotocin-induced diabetes on the EDHF-type relaxation and cardiac function in rats

PubMed Central

Absi, Mais; Oso, Hani; Khattab, Marwan

2012-01-01

The endothelium-derived hyperpolarizing factor (EDHF) response is a critical for the functioning of small blood vessels. We investigated the effect of streptozotocin-induced diabetes on the EDHF response and its possible role in the regulation of cardiac function. The vasorelaxant response to ACh- or NS309- (direct opener endothelial small- (SKCa)- and intermediate-conductance (IKCa) calcium-activated potassium channels; main components of EDHF response) were measured in pressurized mesenteric arteries (diameter 300–350 μm). The response to 1 μM ACh was reduced in diabetes (84.8 ± 2.8% control vs 22.5 ± 5.8% diabetics; n ⩾ 8; P < 0.001). NS309 (1 μM) relaxations were also decreased in diabetic arteries (78.5 ± 8.7% control vs 32.1 ± 5.8% diabetics; n ⩾ 5; P < 0.001). SKCa and IKCa-mediated EDHF relaxations in response ACh or NS309 were also significantly reduced by diabetes. Ruthenium red, RuR, a blocker of TRP channels, strongly depress the response to ACh and NS309 in control and diabetic arteries. RuR decreased SKCa and IKCa-mediated EDHF vasodilatation in response to NS309 but not to ACh. An elevation in systolic blood pressure was observed in diabetic animals. ECG recording of control hearts showed shortening of PR interval. RuR reduced PR interval and R wave amplitude in diabetic hearts. In conclusion, the reduced EDHF-type relaxations in STZ-induced diabetes is due impairment of KCa channels function. TRP channels possibly contribute to EDHF vasodilatation via direct opening of endothelial KCa. It is possible that EDHF and TRP channels contribute to the regulation of cardiac function and therefore can be considered as therapeutic targets to improve cardiovascular complications of diabetes. PMID:25685443

Elemental maps in human allantochorial placental vessels cells: 1. High K + and acetylcholine effects

NASA Astrophysics Data System (ADS)

Michelet-Habchi, C.; Barberet, Ph.; Dutta, R. K.; Guiet-Bara, A.; Bara, M.; Moretto, Ph.

2003-09-01

Regulation of vascular tone in the fetal extracorporeal circulation most likely depends on circulating hormones, local paracrine mechanisms and changes in membrane potential of vascular smooth muscle cells (VSMCs) and of vascular endothelial cells (VECs). The membrane potential is a function of the physiological activities of ionic channels (particularly, K + and Ca 2+ channels in these cells). These channels regulate the ionic distribution into these cells. Micro-particle induced X-ray emission (PIXE) analysis was applied to determine the ionic composition of VSMC and of VEC in the placental human allantochorial vessels in a physiological survival medium (Hanks' solution) modified by the addition of acetylcholine (ACh: which opens the calcium-sensitive K + channels, K Ca) and of high concentration of K + (which blocks the voltage-sensitive K + channels, K df). In VSMC (media layer), the addition of ACh induced no modification of the Na, K, Cl, P, S, Mg and Ca concentrations and high K + medium increased significantly the Cl and K concentrations, the other ion concentrations remaining constant. In endothelium (VEC), ACh addition implicated a significant increase of Na and K concentration, and high K + medium, a significant increase in Cl and K concentration. These results indicated the importance of K df, K Ca and K ATP channels in the regulation of K + intracellular distribution in VSMC and VEC and the possible intervention of a Na-K-2Cl cotransport and corroborated the previous electrophysiological data.

Acetylcholine as a neuromodulator: cholinergic signaling shapes nervous system function and behavior

PubMed Central

Picciotto, Marina R.; Higley, Michael J.; Mineur, Yann S.

2012-01-01

Acetylcholine in the brain alters neuronal excitability, influences synaptic transmission, induces synaptic plasticity and coordinates the firing of groups of neurons. As a result, it changes the state of neuronal networks throughout the brain and modifies their response to internal and external inputs: the classical role of a neuromodulator. Here we identify actions of cholinergic signaling on cellular and synaptic properties of neurons in several brain areas and discuss the consequences of this signaling on behaviors related to drug abuse, attention, food intake, and affect. The diverse effects of acetylcholine depend on the site of release, the receptor subtypes, and the target neuronal population, however, a common theme is that acetylcholine potentiates behaviors that are adaptive to environmental stimuli and decreases responses to ongoing stimuli that do not require immediate action. The ability of acetylcholine to coordinate the response of neuronal networks in many brain areas makes cholinergic modulation an essential mechanism underlying complex behaviors. PMID:23040810

Vasorelaxation induced by common edible tropical plant extracts in isolated rat aorta and mesenteric vascular bed.

PubMed

Runnie, I; Salleh, M N; Mohamed, S; Head, R J; Abeywardena, M Y

2004-06-01

In this study, the vasodilatory actions of nine edible tropical plant extracts were investigated. Ipomoea batatas (sweet potato leaf), Piper betle (betel leaf), Anacardium occidentale (cashew leaf), Gynandropsis gynandra (maman leaf), Carica papaya (papaya leaf), and Mentha arvensis (mint leaf) extracts exhibited more than 50% relaxing effect on aortic ring preparations, while Piper betle and Cymbopogon citratus (lemongrass stalk) showed comparable vasorelaxation on isolated perfused mesenteric artery preparation. The vascular effect on the aortic ring preparations were mainly endothelium-dependent, and mediated by nitric oxide (NO) as supported by the inhibition of action in the presence of N(omega)-nitro-L-arginine (NOLA), an nitric oxide synthase (NOS) inhibitor, or by the removal of endothelium. In contrast, vasodilatory actions in resistance vessels (perfused mesenteric vascular beds) appear to involve several biochemical mediators, including NO, prostanoids, and endothelium-dependent hyperpolarizing factors (EDHFs). Total phenolic contents and antioxidant capacities varied among different extracts and found to be independent of vascular relaxation effects. This study demonstrates that many edible plants common in Asian diets to possess potential health benefits, affording protection at the vascular endothelium level.

Increased levels of circulating nitrates and impaired endothelium-mediated vasodilation suggest multiple roles of nitric oxide during acute rejection of pulmonary allografts.

PubMed

Wiklund, L; Lewis, D H; Sjöquist, P O; Nilsson, F; Tazelaar, H; Miller, V M; McGregor, C G

1997-05-01

Experiments were designed to determine whether changes in pulmonary artery function could be reduced by treatment with a lipid peroxidation inhibitor (H 290/51) during acute rejection of pulmonary allografts. Single lung transplantation was performed in three groups of dogs: group 1 was maintained on immunosuppression for 8 days after operation (immunosuppressed, n = 5); in group 2, immunosuppression was discontinued on postoperative day 5, so that rejection occurred on postoperative day 8 (rejecting, n = 6); in group 3, immunosuppression was discontinued after 5 days, and the lipid peroxidation inhibitor H 290/51 (25 mg/kg) was given perorally for 3 days (rejecting + H 290/51, n = 6). Plasma nitric oxide (NO(x)) was measured by use of chemoluminescence. On postoperative day 8 rejection was observed in groups 2 and 3. Contractions to angiotensin I and endothelium-dependent relaxations to adenosine diphosphate were reduced in pulmonary arteries from rejecting lungs. Responses of rings from dogs treated with H 290/51 were similar to those from rejecting lungs. Rejection did not alter relaxations to exogenous nitric oxide. However, plasma levels of NO(x) increased significantly during rejection independently of treatment with H 290/51. Results of this study confirm that endothelium-dependent relaxation of pulmonary arteries is reduced during acute rejection of lung allografts. The result extends these observations to suggest that treatment with a lipid peroxidation inhibitor neither protects the pulmonary artery function nor affects levels of circulating NO(x). Therefore mechanisms other than lipid peroxidation participate in vascular changes associated with allograft rejection.

Strong size-dependent stress relaxation in electrospun polymer nanofibers

NASA Astrophysics Data System (ADS)

Wingert, Matthew C.; Jiang, Zhang; Chen, Renkun; Cai, Shengqiang

2017-01-01

Electrospun polymer nanofibers have garnered significant interest due to their strong size-dependent material properties, such as tensile moduli, strength, toughness, and glass transition temperatures. These properties are closely correlated with polymer chain dynamics. In most applications, polymers usually exhibit viscoelastic behaviors such as stress relaxation and creep, which are also determined by the motion of polymer chains. However, the size-dependent viscoelasticity has not been studied previously in polymer nanofibers. Here, we report the first experimental evidence of significant size-dependent stress relaxation in electrospun Nylon-11 nanofibers as well as size-dependent viscosity of the confined amorphous regions. In conjunction with the dramatically increasing stiffness of nano-scaled fibers, this strong relaxation enables size-tunable properties which break the traditional damping-stiffness tradeoff, qualifying electrospun nanofibers as a promising set of size-tunable materials with an unusual and highly desirable combination of simultaneously high stiffness and large mechanical energy dissipation.

Strong size-dependent stress relaxation in electrospun polymer nanofibers

DOE PAGES

Wingert, Matthew C.; Jiang, Zhang; Chen, Renkun; ...

2017-01-04

Here, electrospun polymer nanofibers have garnered significant interest due to their strong size-dependent material properties, such as tensile moduli, strength, toughness, and glass transition temperatures. These properties are closely correlated with polymer chain dynamics. In most applications, polymers usually exhibit viscoelastic behaviors such as stress relaxation and creep, which are also determined by the motion of polymer chains. However, the size-dependent viscoelasticity has not been studied previously in polymer nanofibers. Here, we report the first experimental evidence of significant size-dependent stress relaxation in electrospun Nylon-11 nanofibers as well as size-dependent viscosity of the confined amorphous regions. In conjunction with themore » dramatically increasing stiffness of nano-scaled fibers, this strong relaxation enables size-tunable properties which break the traditional damping-stiffness tradeoff, qualifying electrospun nanofibers as a promising set of size-tunable materials with an unusual and highly desirable combination of simultaneously high stiffness and large mechanical energy dissipation.« less

Elevated pressure causes endothelial dysfunction in mouse carotid arteries by increasing local angiotensin signaling

PubMed Central

Zhao, Yingzi; Flavahan, Sheila; Leung, Susan W.; Xu, Aimin; Vanhoutte, Paul M.

2014-01-01

Experiments were performed to determine whether or not acute exposure to elevated pressure would disrupt endothelium-dependent dilatation by increasing local angiotensin II (ANG II) signaling. Vasomotor responses of mouse-isolated carotid arteries were analyzed in a pressure myograph at a control transmural pressure (PTM) of 80 mmHg. Acetylcholine-induced dilatation was reduced by endothelial denudation or by inhibition of nitric oxide synthase (NG-nitro-l-arginine methyl ester, 100 μM). Transient exposure to elevated PTM (150 mmHg, 180 min) inhibited dilatation to acetylcholine but did not affect responses to the nitric oxide donor diethylamine NONOate. Elevated PTM also increased endothelial reactive oxygen species, and the pressure-induced endothelial dysfunction was prevented by the direct antioxidant and NADPH oxidase inhibitor apocynin (100 μM). The increase in endothelial reactive oxygen species in response to elevated PTM was reduced by the ANG II type 1 receptor (AT1R) antagonists losartan (3 μM) or valsartan (1 μM). Indeed, elevated PTM caused marked expression of angiotensinogen, the precursor of ANG II. Inhibition of ANG II signaling, by blocking angiotensin-converting enzyme (1 μM perindoprilat or 10 μM captopril) or blocking AT1Rs prevented the impaired response to acetylcholine in arteries exposed to 150 mmHg but did not affect dilatation to the muscarinic agonist in arteries maintained at 80 mmHg. After the inhibition of ANG II, elevated pressure no longer impaired endothelial dilatation. In arteries treated with perindoprilat to inhibit endogenous formation of the peptide, exogenous ANG II (0.3 μM, 180 min) inhibited dilatation to acetylcholine. Therefore, elevated pressure rapidly impairs endothelium-dependent dilatation by causing ANG expression and enabling ANG II-dependent activation of AT1Rs. These processes may contribute to the pathogenesis of hypertension-induced vascular dysfunction and organ injury. PMID:25485905

Elevated pressure causes endothelial dysfunction in mouse carotid arteries by increasing local angiotensin signaling.

PubMed

Zhao, Yingzi; Flavahan, Sheila; Leung, Susan W; Xu, Aimin; Vanhoutte, Paul M; Flavahan, Nicholas A

2015-02-15

Experiments were performed to determine whether or not acute exposure to elevated pressure would disrupt endothelium-dependent dilatation by increasing local angiotensin II (ANG II) signaling. Vasomotor responses of mouse-isolated carotid arteries were analyzed in a pressure myograph at a control transmural pressure (PTM) of 80 mmHg. Acetylcholine-induced dilatation was reduced by endothelial denudation or by inhibition of nitric oxide synthase (NG-nitro-L-arginine methyl ester, 100 μM). Transient exposure to elevated PTM (150 mmHg, 180 min) inhibited dilatation to acetylcholine but did not affect responses to the nitric oxide donor diethylamine NONOate. Elevated PTM also increased endothelial reactive oxygen species, and the pressure-induced endothelial dysfunction was prevented by the direct antioxidant and NADPH oxidase inhibitor apocynin (100 μM). The increase in endothelial reactive oxygen species in response to elevated PTM was reduced by the ANG II type 1 receptor (AT1R) antagonists losartan (3 μM) or valsartan (1 μM). Indeed, elevated PTM caused marked expression of angiotensinogen, the precursor of ANG II. Inhibition of ANG II signaling, by blocking angiotensin-converting enzyme (1 μM perindoprilat or 10 μM captopril) or blocking AT1Rs prevented the impaired response to acetylcholine in arteries exposed to 150 mmHg but did not affect dilatation to the muscarinic agonist in arteries maintained at 80 mmHg. After the inhibition of ANG II, elevated pressure no longer impaired endothelial dilatation. In arteries treated with perindoprilat to inhibit endogenous formation of the peptide, exogenous ANG II (0.3 μM, 180 min) inhibited dilatation to acetylcholine. Therefore, elevated pressure rapidly impairs endothelium-dependent dilatation by causing ANG expression and enabling ANG II-dependent activation of AT1Rs. These processes may contribute to the pathogenesis of hypertension-induced vascular dysfunction and organ injury. Copyright © 2015 the American

Chronic stimulation of farnesoid X receptor impairs nitric oxide sensitivity of vascular smooth muscle.

PubMed

Kida, Taiki; Murata, Takahisa; Hori, Masatoshi; Ozaki, Hiroshi

2009-01-01

Farnesoid X receptor (FXR), a member of the nuclear receptor superfamily that is highly expressed in enterohepatic tissue, is implicated in bile acid, lipid, and glucose metabolisms. Although recent studies showed that FXR is also expressed in vascular endothelial cells and smooth muscle cells, its physiological and/or pathological roles in vasculature tissue remain unknown. The aim of this study is to examine the chronic effect of synthetic FXR agonist GW4064 on vascular contraction and endothelium-dependent relaxation using tissue culture procedure. In cultured rabbit mesenteric arteries, the treatment with 0.1-10 microM GW4064 for 7 days did not influence vascular contractility induced by high K(+) (15-65 mM), norepinephrine (0.1-100 microM), and endothelin-1 (0.1-100 nM). However, the chronic treatment with GW4064 (1-10 microM for 7 days) dose dependently impaired endothelium-dependent relaxation induced by substance P (0.1-30 nM). In hematoxylin-eosin cross sectioning and en face immunostaining, GW4064 had no effects on the morphology of endothelial and smooth muscle cells. In endothelium-denuded arteries treated with GW4064 (1-10 microM) for 7 days, 3 nM-100 microM sodium nitroprusside-induced vasorelaxation, but not membrane-permeable cGMP analog 8-bromoguanosine-cGMP (8-Br-cGMP; 1-100 microM)-induced vasorelaxation, was significantly impaired. In these GW4064-treated arteries, 1 muM sodium nitroprusside-induced intracellular cGMP elevations were impaired. In RT-PCR, any changes were detected in mRNA expression level of alpha(1)- and beta(1)-subunit of soluble guanylyl cyclase. These results suggest that chronic stimulation of FXR impairs endothelium-dependent relaxation, which is due to decreased sensitivity of smooth muscle cells to nitric oxide.

Pathophysiological levels of soluble P-selectin mediate adhesion of leukocytes to the endothelium through Mac-1 activation.

PubMed

Woollard, Kevin J; Suhartoyo, Andreas; Harris, Emma E; Eisenhardt, Steffen U; Jackson, Shaun P; Peter, Karlheinz; Dart, Anthony M; Hickey, Michael J; Chin-Dusting, Jaye P F

2008-11-07

Plasma soluble P-selectin (sP-selectin) levels are increased in pathologies associated with atherosclerosis, including peripheral arterial occlusive disease (PAOD). However, the role of sP-selectin in regulating leukocyte-endothelial adhesion is unclear. The aim of this study was to assess the ability of exogenous and endogenous sP-selectin to induce leukocyte responses that promote their adhesion to various forms of endothelium. In flow chamber assays, sP-selectin dose-dependently increased neutrophil adhesion to resting human iliac artery endothelial cells. Similarly, sP-selectin induced neutrophil adhesion to the endothelial surface of murine aortae and human radial venous segments in ex vivo flow chamber experiments. Using intravital microscopy to examine postcapillary venules in the mouse cremaster muscle, in vivo administration of sP-selectin was also found to significantly increase leukocyte rolling and adhesion in unstimulated postcapillary venules. Using a Mac-1-specific antibody and P-selectin knockout mouse, it was demonstrated that this finding was dependent on a contribution of Mac-1 to leukocyte rolling and endothelial P-selectin expression. This was confirmed in an ex vivo perfusion model using viable mouse aorta and human radial vessels. In contrast, with tumor necrosis factor-alpha-activated endothelial cells and intact endothelium, where neutrophil adhesion was already elevated, sP-selectin failed to further increase adhesion. Plasma samples from PAOD patients containing pathologically elevated concentrations of sP-selectin also increased neutrophil adhesion to the endothelium in a sP-selectin-dependent manner, as demonstrated by immunodepletion of sP-selectin. These studies demonstrate that raised plasma sP-selectin may influence the early progression of vascular disease by promoting leukocyte adhesion to the endothelium in PAOD, through Mac-1-mediated rolling and dependent on endothelial P-selectin expression.

Quercetin and pioglitazone synergistically reverse endothelial dysfunction in isolated aorta from fructose-streptozotocin (F-STZ)-induced diabetic rats.

PubMed

Kunasegaran, Thubasni; Mustafa, Mohd Rais; Achike, Francis I; Murugan, Dharmani Devi

2017-03-15

Pioglitazone is an anti-diabetic drug with potential to cause adverse effects following prolonged use. This study, therefore, investigated the effects of combination treatment of a subliminal concentration of pioglitazone and quercetin, a potent antioxidant, on vascular reactivity of aorta isolated from fructose-streptozotocin (F-STZ)-induced diabetic rats. Relaxation to acetylcholine and sodium nitroprusside, and contraction to phenylephrine were tested in organ bath chambers following pre-incubation with vehicle (DMSO; 0.05%), quercetin (10-7 M), pioglitazone (10-7 M), or their combination (P+Q; 10-7 M each drug). Subliminal concentration of quercetin or pioglitazone did not alter the acetylcholine- induced relaxation nor the phenylephrine-induced contraction in both normal rat and diabetic F-STZ induced tissues. However, P+Q combination synergistically improved the impaired acetylcholine-induced relaxation and decreased the elevated phenylephrine-induced contraction in aortic rings from diabetic, but not in the normal rats. Neither mono nor combination treatment altered sodium nitroprusside-induced relaxation. The combination also synergistically decreased superoxide anion and increased nitric oxide production compared to the individual treatments in aorta from diabetic rats. Overall, these data demonstrated a synergistic effect, in which, a combination (P+Q; 10-7 M each drug) caused a significantly greater effect than 10-6 M of either agent in improving endothelial function of isolated diabetic aorta. In conclusion, a combination of subliminal concentrations of pioglitazone and quercetin is able to decrease oxidative stress and provide synergistic vascular protection in type 2 diabetes mellitus and thus the possibility of using quercetin as a supplement to pioglitazone in the treatment of diabetes with the goal of reducing pioglitazone toxicity. Copyright © 2017 Elsevier B.V. All rights reserved.

The relaxation induced by S-nitroso-glutathione and S-nitroso-N-acetylcysteine in rat aorta is not related to nitric oxide production.

PubMed

Ceron, P I; Cremonez, D C; Bendhack, L M; Tedesco, A C

2001-08-01

S-nitroso-glutathione (GSNO) and S-nitroso-N-acetylcysteine (NACysNO) are nitrosothiols that release nitric oxide (NO) and mimic the effects of endogenous NO. This study investigated the relaxation induced by GSNO and NACysNO in rat aorta and the relation between relaxation and NO formation. Both compounds at concentrations from 10(-9) M to 10(-4) M relaxed the rat aorta in a concentration-dependent manner. However, NO production depended on the concentration of nitrosothiols present and was detected only above 100 microM GSNO or NACysNO. To determine whether K+ channels are involved in the relaxation induced by nitrosothiols, the contractions were induced with KCl at concentrations of 30, 60, or 90 mM. The concentration-effect curves for the relaxation induced by nitrosothiols were shifted to the right for all the K+ concentrations compared with aortas precontracted with phenylephrine. These results indicate the participation of K+ channels in the relaxation induced by GSNO and NACysNO. A selective inhibitor of soluble guanylyl cyclase, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, significantly inhibited the relaxation induced by the nitrosothiols. The relaxation induced by GSNO and NACysNO was inhibited by the K+ channel blockers glibenclamide, selective K(ATP) channels, and apamin, selective for low-conductance Ca2+-activated K+ channels in rat aorta, but was not inhibited by charybdotoxin, a potent and selective Ca2+-activated K+ channel blocker, or by 4-aminopyridine, a voltage-gated K+ channel blocker. These results indicate that relaxation induced by GSNO and NACysNO is partially due to activation of K(ATP) channels and partially due to activation of low-conductance Ca2+-activated K+ channels. However, the ability of the nitrosothiol compounds to overcome the inhibitory effect of high extracellular K+ concentrations suggests another mechanism of relaxation contributing to the nitrosothiol response. The most intriguing finding is that relaxation is not