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Sample records for isolated rat ventricular

  1. Calcium current in isolated neonatal rat ventricular myocytes.

    PubMed Central

    Cohen, N M; Lederer, W J

    1987-01-01

    1. Calcium currents (ICa) from neonatal rat ventricular heart muscle cells grown in primary culture were examined using the 'whole-cell' voltage-clamp technique (Hamill, Marty, Neher, Sakmann & Sigworth, 1981). Examination of ICa was limited to one calcium channel type, 'L' type (Nilius, Hess, Lansman & Tsien, 1985), by appropriate voltage protocols. 2. We measured transient and steady-state components of ICa, and could generally describe ICa in terms of the steady-state activation (d infinity) and inactivation (f infinity) parameters. 3. We observed that the reduction of ICa by the calcium channel antagonist D600 can be explained by both a shift of d infinity to more positive potentials as well as a slight reduction of ICa conductance. D600 did not significantly alter either the rate of inactivation of ICa or the voltage dependence of f infinity. 4. The calcium channel modulator BAY K8644 shifted both d infinity and f infinity to more negative potentials. Additionally, BAY K8644 increased the rate of inactivation at potentials between +5 and +55 mV. Furthermore, BAY K8644 also increased ICa conductance, a change consistent with a promotion of 'mode 2' calcium channel activity (Hess, Lansman & Tsien, 1984). 5. We conclude that, as predicted by d infinity and f infinity, there is a significant steady-state component of ICa ('window current') at plateau potentials in neonatal rat heart cells. Modulation of the steady-state and transient components of ICa by various agents can be attributed both to specific alterations in d infinity and f infinity and to more complicated alterations in the mode of calcium channel activity. PMID:2451004

  2. The effect of hexane on the ventricular fibrillation threshold of the isolated perfused rat heart.

    PubMed

    Khedun, S M; Maharaj, B; Leary, W P; Lockett, C J

    1992-01-01

    This investigation was conducted to determine the influence of hexane on the ventricular fibrillation threshold of the isolated perfused rat heart and myocardial electrolyte levels. Ventricular fibrillation threshold was measured using the Langendorff perfusion apparatus. Heart rate was measured by a universal digital counter and the cardiac flow by collecting the outflow of the heating chamber below the heart into a graduated measuring cylinder. Magnesium and zinc were measured by atomic absorption spectrophotometry and potassium by flame photometry. Two groups of rats were studied; those in the experimental group were given 0.2 ml of hexane and the control group 0.2 ml olive oil subcutaneously for 90 days. Their hearts were removed under anaesthesia. Half of the experimental and control hearts were mounted on the Langendorff perfusion apparatus and the heart rate, coronary flow and ventricular fibrillation threshold were measured. The hearts of the other half were used to measure myocardial electrolyte levels. In the experimental group the ventricular fibrillation threshold decreased (4.72 (S.D. +/- 1.87) vs 9.48 (S.D. +/- 2.98); P less than 0.001). There was no change in the coronary flow and heart rate in between the groups. The mean myocardial potassium levels (2586 (S.D. +/- 162) vs 2968 (S.D. +/- 218) micrograms/g; P less than 0.001), magnesium levels (164 (S.D. +/- 28) vs 208 (S.D. +/- 18) micrograms/g; P less than 0.001) and zinc levels (19.6 (S.D. +/- 4) vs 33.8 (S.D. +/- 6.8) micrograms/g; P less than 0.001) were significantly lower in the hexane-treated group compared to controls. Hexane, a constituent of glue and benzine, is cardiotoxic; marked derangement in myocardial electrolytes and a reduced ventricular fibrillation threshold, indicating an increased myocardial vulnerability to arrhythmias, was noted in the experimental animals. PMID:1729763

  3. Pharmacological inhibition of IK1 by PA-6 in isolated rat hearts affects ventricular repolarization and refractoriness.

    PubMed

    Skarsfeldt, Mark A; Carstensen, Helena; Skibsbye, Lasse; Tang, Chuyi; Buhl, Rikke; Bentzen, Bo H; Jespersen, Thomas

    2016-04-01

    The inwardly rectifying potassium current (IK 1) conducted through Kir2.X channels contribute to repolarization of the cardiac action potential and to stabilization of the resting membrane potential in cardiomyocytes. Our aim was to investigate the effect of the recently discovered IK 1 inhibitor PA-6 on action potential repolarization and refractoriness in isolated rat hearts. Transiently transfected HEK-293 cells expressing IK 1 were voltage-clamped with ramp protocols. Langendorff-perfused heart experiments were performed on male Sprague-Dawley rats, effective refractory period, Wenckebach cycle length, and ventricular effective refractory period were determined following 200 nmol/L PA-6 perfusion. 200 nmol/L PA-6 resulted in a significant time-latency in drug effect on the IK 1 current expressed in HEK-293 cells, giving rise to a maximal effect at 20 min. In the Langendorff-perfused heart experiments, PA-6 prolonged the ventricular action potential duration at 90% repolarization (from 41.8 ± 6.5 msec to 72.6 ± 21.1 msec, 74% compared to baseline, P < 0.01, n = 6). In parallel, PA-6 significantly prolonged the ventricular effective refractory period compared to baseline (from 34.8 ± 4.6 msec to 58.1 ± 14.7 msec, 67%, P < 0.01, n = 6). PA-6 increased the short-term beat-to-beat variability and ventricular fibrillation was observed in two of six hearts. Neither atrial ERP nor duration of atrial fibrillation was altered following PA-6 application. The results show that pharmacological inhibition of cardiac IK 1 affects ventricular action potential repolarization and refractoriness and increases the risk of ventricular arrhythmia in isolated rat hearts. PMID:27117805

  4. Pharmacological inhibition of IK1 by PA-6 in isolated rat hearts affects ventricular repolarization and refractoriness.

    PubMed

    Skarsfeldt, Mark A; Carstensen, Helena; Skibsbye, Lasse; Tang, Chuyi; Buhl, Rikke; Bentzen, Bo H; Jespersen, Thomas

    2016-04-01

    The inwardly rectifying potassium current (IK 1) conducted through Kir2.X channels contribute to repolarization of the cardiac action potential and to stabilization of the resting membrane potential in cardiomyocytes. Our aim was to investigate the effect of the recently discovered IK 1 inhibitor PA-6 on action potential repolarization and refractoriness in isolated rat hearts. Transiently transfected HEK-293 cells expressing IK 1 were voltage-clamped with ramp protocols. Langendorff-perfused heart experiments were performed on male Sprague-Dawley rats, effective refractory period, Wenckebach cycle length, and ventricular effective refractory period were determined following 200 nmol/L PA-6 perfusion. 200 nmol/L PA-6 resulted in a significant time-latency in drug effect on the IK 1 current expressed in HEK-293 cells, giving rise to a maximal effect at 20 min. In the Langendorff-perfused heart experiments, PA-6 prolonged the ventricular action potential duration at 90% repolarization (from 41.8 ± 6.5 msec to 72.6 ± 21.1 msec, 74% compared to baseline, P < 0.01, n = 6). In parallel, PA-6 significantly prolonged the ventricular effective refractory period compared to baseline (from 34.8 ± 4.6 msec to 58.1 ± 14.7 msec, 67%, P < 0.01, n = 6). PA-6 increased the short-term beat-to-beat variability and ventricular fibrillation was observed in two of six hearts. Neither atrial ERP nor duration of atrial fibrillation was altered following PA-6 application. The results show that pharmacological inhibition of cardiac IK 1 affects ventricular action potential repolarization and refractoriness and increases the risk of ventricular arrhythmia in isolated rat hearts.

  5. Calcium influx inhibition: possible mechanism of the negative effect of tetrahydropalmatine on left ventricular pressure in isolated rat heart.

    PubMed

    Chan, P; Chiu, W T; Chen, Y J; Wu, P J; Cheng, J T

    1999-05-01

    The active ingredient dl-tetrahydropalmatine (THP) isolated from the traditional Chinese herb Corydalis racemosa has been found to have antihypertensive effects. However, severe cardiac and neurological toxic effects were reported from using this herb for the treatment of pain. In an isolated perfused rat heart model, THP at the concentration of 100 microM was found to have a negative effect (-45%) on left ventricular pressure and this effect was produced concentration-dependently from concentrations lower than 50 microM. In isolated cardiomyocytes, radioactive calcium influx was also inhibited significantly by THP at the concentration of 100 microM and this effect was also in a concentration-dependent manner (-39%). In a patient with latent heart disease, the use of Corydalis should probably be detrimental, the toxic effect was probably due to calcium influx inhibition.

  6. Characterization and agonist regulation of muscarinic ([3H]N-methyl scopolamine) receptors in isolated ventricular myocytes from rat.

    PubMed

    Horackova, M; Robinson, B; Wilkinson, M

    1990-11-01

    Cell surface muscarinic cholinergic receptors have been characterized and quantified for the first time, in intact, isolated adult rat cardiomyocytes. The cells were previously established as functionally fully compatible with cellular responses in intact cardiac tissue. The specific binding of the hydrophilic radioligand, [3H]-NMS, (N-methyl-[3H]-scopolamine methylchloride) was found to be stereo-specific, saturable, reversible and of high affinity. Binding of [3H]-NMS demonstrated appropriate drug specificity and was positively correlated with increasing cell concentrations. Bmax for [3H]-NMS binding to ventricular myocytes, enzymatically dissociated from adult male rats, was 15.8 +/- 1.03 fmol/25 x 10(3) cells (at 4 degrees C) and KD was 0.27 +/- 0.05 nM (n = 14). Binding assays performed at a higher incubation temperature (30 degrees C) yielded a higher Bmax value (22.1 +/- 1.6 fmol/25 x 10(3) cells; n = 11; P less than 0.005 vs. Bmax at 4 degrees C) but an unchanged KD (0.23 +/- 0.06 nM). Pretreatment of myocytes with the muscarinic agonist carbachol (1 mM) at 37 degrees C resulted in a reduction (down-regulation) in specific binding of the hydrophilic ligand [3H]-NMS. The magnitude of this reduction and its rate of recovery were dependent on the time of the exposure to carbachol. Exposures of 30-60 min elicited down-regulated by 35% (Bmax = 14.29 +/- 1.66 changed to 9.5 +/- 1.79 fmol/25 x 10(3) cells, without change in KD P less than 0.01, n = 4). The down-regulation of the muscarinic receptors by carbachol was insensitive to application of bacitracin - an inhibitor of endocytosis. On the other hand preincubation with 10(-9)M atropine, a muscarinic antagonist, hindered the agonist-induced receptor "loss" from the cell surface confirming the muscarinic nature of these receptors. We conclude that our preparation of intact, isolated ventricular cardiomyocytes is ideally suited for the study of cell surface muscarinic receptor regulation under physiological and

  7. Characterization and agonist regulation of muscarinic ([3H]N-methyl scopolamine) receptors in isolated ventricular myocytes from rat.

    PubMed

    Horackova, M; Robinson, B; Wilkinson, M

    1990-11-01

    Cell surface muscarinic cholinergic receptors have been characterized and quantified for the first time, in intact, isolated adult rat cardiomyocytes. The cells were previously established as functionally fully compatible with cellular responses in intact cardiac tissue. The specific binding of the hydrophilic radioligand, [3H]-NMS, (N-methyl-[3H]-scopolamine methylchloride) was found to be stereo-specific, saturable, reversible and of high affinity. Binding of [3H]-NMS demonstrated appropriate drug specificity and was positively correlated with increasing cell concentrations. Bmax for [3H]-NMS binding to ventricular myocytes, enzymatically dissociated from adult male rats, was 15.8 +/- 1.03 fmol/25 x 10(3) cells (at 4 degrees C) and KD was 0.27 +/- 0.05 nM (n = 14). Binding assays performed at a higher incubation temperature (30 degrees C) yielded a higher Bmax value (22.1 +/- 1.6 fmol/25 x 10(3) cells; n = 11; P less than 0.005 vs. Bmax at 4 degrees C) but an unchanged KD (0.23 +/- 0.06 nM). Pretreatment of myocytes with the muscarinic agonist carbachol (1 mM) at 37 degrees C resulted in a reduction (down-regulation) in specific binding of the hydrophilic ligand [3H]-NMS. The magnitude of this reduction and its rate of recovery were dependent on the time of the exposure to carbachol. Exposures of 30-60 min elicited down-regulated by 35% (Bmax = 14.29 +/- 1.66 changed to 9.5 +/- 1.79 fmol/25 x 10(3) cells, without change in KD P less than 0.01, n = 4). The down-regulation of the muscarinic receptors by carbachol was insensitive to application of bacitracin - an inhibitor of endocytosis. On the other hand preincubation with 10(-9)M atropine, a muscarinic antagonist, hindered the agonist-induced receptor "loss" from the cell surface confirming the muscarinic nature of these receptors. We conclude that our preparation of intact, isolated ventricular cardiomyocytes is ideally suited for the study of cell surface muscarinic receptor regulation under physiological and

  8. Inhibitory Effect of Cinobufagin on L-Type Ca2+ Currents, Contractility, and Ca2+ Homeostasis of Isolated Adult Rat Ventricular Myocytes

    PubMed Central

    Li, Pinya; Song, Qiongtao; Liu, Tao; Wu, Zhonglin; Chu, Xi; Zhang, Xuan; Zhang, Ying; Gao, Yonggang; Zhang, Jianping; Chu, Li

    2014-01-01

    Cinobufagin (CBG), a major bioactive ingredient of the bufanolide steroid compounds of Chan Su, has been widely used to treat coronary heart disease. At present, the effect of CBG on the L-type Ca2+ current (ICa-L) of ventricular myocytes remains undefined. The aim of the present study was to characterize the effect of CBG on intracellular Ca2+ ([Ca2+]i) handling and cell contractility in rat ventricular myocytes. CBG was investigated by determining its influence on ICa-L, Ca2+ transient, and contractility in rat ventricular myocytes using the whole-cell patch-clamp technique and video-based edge-detection and dual-excitation fluorescence photomultiplier systems. The dose of CBG (10−8 M) decreased the maximal inhibition of CBG by 47.93%. CBG reduced ICa-L in a concentration-dependent manner with an IC50 of 4 × 10−10 M, upshifted the current-voltage curve of ICa-L, and shifted the activation and inactivation curves of ICa-L leftward. Moreover, CBG diminished the amplitude of the cell shortening and Ca2+ transients with a decrease in the time to peak (Tp) and the time to 50% of the baseline (Tr). CBG inhibited L-type Ca2+ channels, and reduced [Ca2+]i and contractility in adult rat ventricular myocytes. These findings contribute to the understanding of the cardioprotective efficacy of CBG. PMID:24977199

  9. [Isolated left ventricular noncompaction causing refractory heart failure].

    PubMed

    Meneguz-Moreno, Rafael Alexandre; Rodrigues da Costa Teixeira, Felipe; Rossi Neto, João Manoel; Finger, Marco Aurélio; Casadei, Carolina; Castillo, Maria Teresa; Sanchez de Almeida, Antonio Flávio

    2016-03-01

    Left ventricular noncompaction is a rare congenital anomaly characterized by excessive left ventricular trabeculation, deep intertrabecular recesses and a thin compacted layer due to the arrest of compaction of myocardial fibers during embryonic development. We report the case of a young patient with isolated left ventricular noncompaction, leading to refractory heart failure that required extracorporeal membrane oxygenation followed by emergency heart transplantation. PMID:26928017

  10. Effects of the Selective Stretch-Activated Channel Blocker GsMtx4 on Stretch-Induced Changes in Refractoriness in Isolated Rat Hearts and on Ventricular Premature Beats and Arrhythmias after Coronary Occlusion in Swine

    PubMed Central

    Barrabés, José A.; Inserte, Javier; Agulló, Luis; Rodríguez-Sinovas, Antonio; Alburquerque-Béjar, Juan J.; Garcia-Dorado, David

    2015-01-01

    Mechanical factors may contribute to ischemic ventricular arrhythmias. GsMtx4 peptide, a selective stretch-activated channel blocker, inhibits stretch-induced atrial arrhythmias. We aimed to assess whether GsMtx4 protects against ventricular ectopy and arrhythmias following coronary occlusion in swine. First, the effects of 170-nM GsMtx4 on the changes in the effective refractory period (ERP) induced by left ventricular (LV) dilatation were assessed in 8 isolated rat hearts. Then, 44 anesthetized, open-chest pigs subjected to 50-min left anterior descending artery occlusion and 2-h reperfusion were blindly allocated to GsMtx4 (57 μg/kg iv. bolus and 3.8 μg/kg/min infusion, calculated to attain the above concentration in plasma) or saline, starting 5-min before occlusion and continuing until after reflow. In rat hearts, LV distension induced progressive reductions in ERP (35±2, 32±2, and 29±2 ms at 0, 20, and 40 mmHg of LV end-diastolic pressure, respectively, P<0.001) that were prevented by GsMTx4 (33±2, 33±2, and 32±2 ms, respectively, P=0.002 for the interaction with LV end-diastolic pressure). Pigs receiving GsMtx4 had similar number of ventricular premature beats during the ischemic period as control pigs (110±28 vs. 103±21, respectively, P=0.842). There were not significant differences among treated and untreated animals in the incidence of ventricular fibrillation (13.6 vs. 22.7%, respectively, P=0.696) or tachycardia (36.4 vs. 50.0%, P=0.361) or in the number of ventricular tachycardia episodes during the occlusion period (1.8±0.7 vs. 5.5±2.6, P=0.323). Thus, GsMtx4 administered under these conditions does not suppress ventricular ectopy following coronary occlusion in swine. Whether it might protect against malignant arrhythmias should be tested in studies powered for these outcomes. PMID:25938516

  11. Resveratrol reduces intracellular free calcium concentration in rat ventricular myocytes.

    PubMed

    Liu, Zheng; Zhang, Li-Ping; Ma, Hui-Jie; Wang, Chuan; Li, Ming; Wang, Qing-Shan

    2005-10-25

    Resveratrol (trans-3, 4', 5-trihydroxy stilbene), a phytoalexin found in grape skins and red wine, has been reported to have a wide range of biological and pharmacological properties. It has been speculated that resveratrol may have cardioprotective activity. The objective of our study was to investigate the effects of resveratrol on intracellular calcium concentration ([Ca(2+)](i)) in rat ventricular myocytes. [Ca(2+)](i) was detected by laser scanning confocal microscopy. The results showed that resveratrol (15~60 mumol/L) reduced [Ca(2+)](i) in normal and Ca(2+)-free Tyrode's solution in a concentration-dependent manner. The effects of resveratrol on [Ca(2+)](i) in normal Tyrode's solution was partially inhibited by pretreatment with sodium orthovanadate (Na3VO4, 1.0 mmol/L, P<0.01), an inhibitor of protein tyrosine phosphatase, or L-type Ca(2+) channel agonist Bay K8644 (10 mumol/L, P<0.05), but could not be antagonized by NO synthase inhibitor L-NAME (1.0 mmol/L). Resveratrol also markedly inhibited the ryanodine-induced [Ca(2+)](i) increase in Ca(2+)-free Tyrode's solution (P<0.01). When Ca(2+) waves were produced by increasing extracellular Ca(2+) concentration from 1 to 10 mmol/L, resveratrol (60 mumol/L) could reduce the velocity and duration of propagating waves, and block the propagating waves of elevated [Ca(2+)](i). These results suggest that resveratrol may reduce the [Ca(2+)](i) in isolated rat ventricular myocytes. The inhibition of voltage-dependent Ca(2+) channel and tyrosine kinase, and alleviation of Ca(2+) release from sarcoplasmic reticulum (SR) are possibly involved in the effects of resveratrol on rat ventricular myocytes. These findings could help explain the protective activity of resveratrol against cardiovascular disease. PMID:16220198

  12. Ventricular repolarization in a rat model of global heart failure.

    PubMed

    Krandycheva, Valeria; Kharin, Sergey; Strelkova, Marina; Shumikhin, Konstantin; Sobolev, Aleksey; Shmakov, Dmitry

    2013-07-01

    Isoproterenol in high doses induces infarction-like myocardial damage and structural and functional remodelling of the ventricular myocardium. The purpose of the present study was to investigate ventricular repolarization in a rat model of isoproterenol-induced heart failure. Isoproterenol was administered twice to female Wistar rats (170 mg/kg, s.c., 24 h apart). Four weeks after the injections, cardiac output was measured and unipolar epicardial ventricular electrograms were recorded in situ. Activation-recovery intervals were calculated to assess repolarization. Histological examination of the heart ventricles was also performed. Heart failure in rats treated with isoproterenol was indicated by myocardial histopathological damage and reduced cardiac output. In rats with heart failure, the regional differences in activation-recovery interval prolongation over the ventricular epicardium resulted in increasing heterogeneity in the activation-recovery interval distribution and increasing repolarization heterogeneity of the ventricular subepicardium. Myocardial damage and haemodynamic changes in heart failure induced by isoproterenol were accompanied by significant changes in ventricular repolarization, which were not associated with myocardial hypertrophy.

  13. Isolated right ventricular failure in hyperthyroidism: a clinical dilemma

    PubMed Central

    McDonough, Ryan J.; Moul, Marvin S.; Beckman, Darrick; Slim, Ahmad M.

    2011-01-01

    We present a unique case of a 42-year-old gentleman with newly diagnosed Graves’ disease and isolated right ventricular failure. Extensive evaluation to include echocardiogram and cardiac catheterization were negative for significant pulmonary hypertension or coronary artery disease as potential etiologies. Hyperthyroid induced vasospasm is a rare but reported clinical entity that serves to be a clinical and diagnostic dilemma. PMID:22049310

  14. Calcium-sensing receptor induces rat neonatal ventricular cardiomyocyte apoptosis

    SciTech Connect

    Sun Yihua; Liu Meina; Li Hong; Shi Sa; Zhao Yajun; Wang Rui; Xu Changqing . E-mail: syh200415@yahoo.com.cn

    2006-12-01

    The calcium-sensing receptor (CaSR) exists in many tissues, and its expression has been identified in rat cardiac tissue. However, Physiological importance and pathophysiological involvement of CaSR in homeostatic regulation of cardiac function are unclear. To investigate the relation of CaSR and apoptosis in cardiomyocytes, we examined the role of the CaSR activator gadolinium chloride (GdCl{sub 3}) in rat neonatal ventricular cardiomyocytes. Expression of the CaSR protein was observed by Western blot. The apoptotic ratio of rat neonatal ventricular cardiomyocytes was measured with flow cytometry and immunofluorescence techniques. A laser scan confocal microscope was used to detect the intracellular concentration of calcium ([Ca{sup 2+}]{sub i}) in rat neonatal ventricular cardiomyocytes using the acetoxymethyl ester of fluo-3 (fluo-3/(AM)) as a fluorescent dye. The results showed that GdCl{sub 3} increased the phosphorylation of extracellular signal-regulated protein kinase (ERK), c-Jun NH{sub 2}-terminal protein kinases (JNK), and p38. GdCl{sub 3} also activated caspase 9 and increased apoptosis in myocyte by increasing [Ca{sup 2+}]{sub i}. In conclusion, these results suggest that CaSR promotes cardiomyocyte apoptosis in rat neonatal ventricular cardiomyocytes through activation of mitogen-activated protein kinases and caspase 9 signaling pathways.

  15. Mechanisms by which calcium receptor stimulation modifies electromechanical coupling in isolated ventricular cardiomyocytes.

    PubMed

    Schreckenberg, Rolf; Dyukova, Elena; Sitdikova, Guzel; Abdallah, Yaser; Schlüter, Klaus-Dieter

    2015-02-01

    The calcium-sensing receptor (CaR) is widely expressed throughout the entire cardiovascular system and is capable of activating signaling pathways in different cells. Alongside calcium, the CaR also responds to physiological polycations such as putrescine underlining a participation in physiological and pathophysiological processes. Here, we aimed to determine mechanisms as to how CaR activation affects the contractile responsiveness of ventricular cardiomyocytes under basal and stimulated conditions. For that purpose, cardiac myocytes from 3-month-old male Wistar rats were isolated, and the acute effects of an antagonist (NPS2390), agonists (putrescine and gadolinium), or of downregulation of the CaR by siRNA on cell shortening were recorded in a cell-edge-detection system. In addition, experiments were performed on muscle stripes and Langendorff preparations. Mechanistic insights were taken from calcium transients of beating fura-2 AM-loaded cardiomyocytes and western blots. Isolated ventricular cardiomyocytes constitutively express CaR. The expression in the atria is less pronounced. Acute inhibition of CaR reduced basal cell shortening of ventricular myocytes at nearly physiological levels of extracellular calcium. Inhibition of CaR strongly reduced contractility of ventricular muscle stripes but not of atria. Activation of CaR by putrescine and gadolinium influences the contractile responsiveness of isolated cardiomyocytes. Increased calcium mobilization from the sarcoplasmic reticulum via an IP3-dependent mechanism was responsible for amplified systolic calcium transients and a subsequent improvement in cell shortening. Alongside with these effects, activation of CaR increased relaxation velocity of the cells. In conclusion, ventricular CaR expression affects contractile parameters of ventricular heart muscle cells and modifies electromechanical coupling of cardiomyocytes.

  16. Dual Endothelin Receptor Blockade Abrogates Right Ventricular Remodeling and Biventricular Fibrosis in Isolated Elevated Right Ventricular Afterload

    PubMed Central

    Nielsen, Eva Amalie; Sun, Mei; Honjo, Osami; Hjortdal, Vibeke E.; Redington, Andrew N.; Friedberg, Mark K.

    2016-01-01

    Background Pulmonary arterial hypertension is usually fatal due to right ventricular failure and is frequently associated with co-existing left ventricular dysfunction. Endothelin-1 is a powerful pro-fibrotic mediator and vasoconstrictor that is elevated in pulmonary arterial hypertension. Endothelin receptor blockers are commonly used as pulmonary vasodilators, however their effect on biventricular injury, remodeling and function, despite elevated isolated right ventricular afterload is unknown. Methods Elevated right ventricular afterload was induced by progressive pulmonary artery banding. Seven rabbits underwent pulmonary artery banding without macitentan; 13 received pulmonary artery banding + macitentan; and 5 did not undergo inflation of the pulmonary artery band (sham-operated controls). Results: Right and left ventricular collagen content was increased with pulmonary artery banding compared to sham-operated controls and ameliorated by macitentan. Right ventricular fibrosis signaling (connective tissue growth factor and endothelin-1 protein levels); extra-cellular matrix remodeling (matrix-metalloproteinases 2 and 9), apoptosis and apoptosis-related peptides (caspases 3 and 8) were increased with pulmonary artery banding compared with sham-operated controls and decreased with macitentan. Conclusion Isolated right ventricular afterload causes biventricular fibrosis, right ventricular apoptosis and extra cellular matrix remodeling, mediated by up-regulation of endothelin-1 and connective tissue growth factor signaling. These pathological changes are ameliorated by dual endothelin receptor blockade despite persistent elevated right ventricular afterload. PMID:26765263

  17. Acquired Fontan paradox in isolated right ventricular cardiomyopathy.

    PubMed

    Saran, Mahim; Sivasubramonian, Sivasankaran; Abhilash, Sreevilasam P; Tharakan, Jaganmohan A

    2016-01-01

    A 44-year-old woman presented with features of congestive heart failure. Echocardiography revealed severe right ventricular dysfunction along with passive minimally pulsatile pulmonary blood flow suggesting very high systemic venous pressures. This was confirmed with cardiac catheterization in which the pressures of superior vena cava and inferior vena cava (19 mmHg) were higher than the pulmonary artery pressures (17 mmHg). Elevation of systemic venous pressures above the pulmonary venous pressures, Fontan paradox, to drive the forward flow, is a specific feature of artificially created cavopulmonary shunts. Late stage of isolated right ventricular cardiomyopathy resulted in the spontaneous evolution of Fontan circulation with a nonfunctional right ventricle in this patient. PMID:27625525

  18. Acquired Fontan paradox in isolated right ventricular cardiomyopathy

    PubMed Central

    Saran, Mahim; Sivasubramonian, Sivasankaran; Abhilash, Sreevilasam P; Tharakan, Jaganmohan A

    2016-01-01

    A 44-year-old woman presented with features of congestive heart failure. Echocardiography revealed severe right ventricular dysfunction along with passive minimally pulsatile pulmonary blood flow suggesting very high systemic venous pressures. This was confirmed with cardiac catheterization in which the pressures of superior vena cava and inferior vena cava (19 mmHg) were higher than the pulmonary artery pressures (17 mmHg). Elevation of systemic venous pressures above the pulmonary venous pressures, Fontan paradox, to drive the forward flow, is a specific feature of artificially created cavopulmonary shunts. Late stage of isolated right ventricular cardiomyopathy resulted in the spontaneous evolution of Fontan circulation with a nonfunctional right ventricle in this patient. PMID:27625525

  19. Cardiac Muscle Studies with Rat Ventricular Strips

    ERIC Educational Resources Information Center

    Whitten, Bert K.; Faleschini, Richard J.

    1977-01-01

    Details undergraduate physiology laboratory experiments that demonstrate mechanical properties of cardiac muscle, using strips from the ventricle of a rat heart. Includes procedures for obtaining length-tension curves, demonstrating the role of calcium in excitation-contraction coupling, and showing effects of several cardiovascular drugs…

  20. Isolated Right Ventricular Infarction Mimicking Anterior ST-Segment Elevation

    PubMed Central

    Oktay, Veysel; Coskun, Ugur; Yildiz, Ahmet; Gurmen, Tevfik

    2016-01-01

    Acute coronary syndromes in patients with presence of ST-segment elevation in the anterior precordial leads indicates left anterior descending coronary artery occlusion. However, anterior ST-segment elevation has also been described in right ventricular myocardial infarction and is thought to be due to right coronary artery (RCA) occlusion. We present a rare case of isolated RVMI presenting with anterior ST-segment elevation due to proximal occlusion of a right coronary artery that was treated by primary coronary angioplasty. Primary coronary angioplasty and stenting of this artery was performed resulting in resolution of the chest pain and ST- segment elevation. PMID:27190867

  1. Dioxin (TCDD) enhances triggered-afterdepolarizations in rat ventricular myocytes

    PubMed Central

    Xie, An; Walker, Nigel J.; Wang, Desuo

    2007-01-01

    The effects of TCDD (2,3,7,8-Tetrachlorodibenzo-p-dioxin) on action potential and afterdepolarizations were studied in rat ventricular myocytes using nystatin-perforated whole-cell patch-clamp technique. TCDD treatment, in the concentration range of 1 to 100 nM, significantly prolonged action potential duration measured at 90% of repolarization (APD90). The triggered delayed-afterdepolarizations (DADs) was observed in 6 out of 8 cells after exposure of TCDD (10 nM). In the presence of isoproterenol (ISO, 10 nM) or Bay K 8644 (1 μM), TCDD (10 nM) markedly augmented the amplitude and frequency of the arrhythmogenic DADs and triggered sustained spontaneous firings in ventricular myocytes. Voltage-clamp data indicated that TCDD (10 nM) exposure significantly enhanced the transient inward current (Iti). The triggered early-afterdepolarizations (EADs) were evoked only in cells simultaneously exposed to TCDD (10 nM) and ISO (or Bay K 8644). Further study indicated that TCDD treatment increased L-type Ca2+ current. These results indicate that activation of TCDD signaling pathway can prolong action potential duration and cause abnormal triggered afterdepolarizations. These effects may lead to clinically relevant ventricular arrhythmia especially when susceptible individuals are under elevated sympathetic stress or suffering from other myocardiopathies coincided with Ca2+-overload. PMID:17303918

  2. Dietary salt restriction in hyperthyroid rats. Differential influence on left and right ventricular mass

    PubMed Central

    Wangensteen, Rosemary; Rodríguez-Gómez, Isabel; Perez-Abud, Rocío; Quesada, Andrés; Montoro-Molina, Sebastián; Osuna, Antonio

    2015-01-01

    This study assessed the impact of salt restriction on cardiac morphology and biochemistry and its effects on hemodynamic and renal variables in experimental hyperthyroidism. Four groups of male Wistar rats were used: control, hyperthyroid, and the same groups under low salt intake. Body weight, blood pressure (BP), and heart rate (HR) were recorded weekly for 4 weeks. Morphologic, metabolic, plasma, cardiac, and renal variables were also measured. Low salt intake decreased BP in T4-treated rats but not in controls. Low salt intake reduced relative left ventricular mass but increased absolute right ventricular weight and right ventricular weight/BW ratio in both control and hyperthyroid groups. Low salt intake increased Na+/H+ exchanger-1 (NHE-1) protein abundance in both ventricles in normal rats but not in hyperthyroid rats, independently of its effect on ventricular mass. Mammalian target of rapamycin (mTOR) protein abundance was not related to left or right ventricular mass in hyperthyroid or controls rats under normal or low salt conditions. Proteinuria was increased in hyperthyroid rats and attenuated by low salt intake. In this study, low salt intake produced an increase in right ventricular mass in normal and hyperthyroid rats. Changes in the left or right ventricular mass of control and hyperthyroid rats under low salt intake were not explained by the NHE-1 or mTOR protein abundance values observed. In hyperthyroid rats, low salt intake also slightly reduced BP and decreased HR, proteinuria, and water and sodium balances. PMID:25030483

  3. Isolation of rat adrenocortical mitochondria

    SciTech Connect

    Solinas, Paola; Fujioka, Hisashi; Tandler, Bernard; Hoppel, Charles L.

    2012-10-12

    Highlights: Black-Right-Pointing-Pointer A method for isolation of adrenocortical mitochondria from the adrenal gland of rats is described. Black-Right-Pointing-Pointer The purified isolated mitochondria show excellent morphological integrity. Black-Right-Pointing-Pointer The properties of oxidative phosphorylation are excellent. Black-Right-Pointing-Pointer The method increases the opportunity of direct analysis of adrenal mitochondria from small animals. -- Abstract: This report describes a relatively simple and reliable method for isolating adrenocortical mitochondria from rats in good, reasonably pure yield. These organelles, which heretofore have been unobtainable in isolated form from small laboratory animals, are now readily accessible. A high degree of mitochondrial purity is shown by the electron micrographs, as well as the structural integrity of each mitochondrion. That these organelles have retained their functional integrity is shown by their high respiratory control ratios. In general, the biochemical performance of these adrenal cortical mitochondria closely mirrors that of typical hepatic or cardiac mitochondria.

  4. Isolated Left Ventricular Apical Hypoplasia: Reporting a Case With Mild Manifestations and Different Echocardiography Features

    PubMed Central

    Mirdamadi, Ahmad; Ashrafi, Samira

    2016-01-01

    Introduction Isolated left ventricular apical hypoplasia is an unusual type of cardiomyopathy that presents with different clinical manifestations according to the age of the disease, ranging from no symptoms in children to congestive heart failure, pulmonary edema, or even malignant tachycardia in adults. To our knowledge, only a few cases of isolated left ventricular apical hypoplasia have been reported in Asian adults. Case Presentation Herein, we described an adult case of isolated left ventricular apical hypoplasia referred to our heart center in Isfahan, Iran in 2015 with a complaint of mild dyspnea with the absence of obvious fatty tissue in the heart’s apex and an absence of any shunt, which are common findings in patients with this phenomenon. Conclusions Patients faced with isolated left ventricular apical hypoplasia should be monitored by echocardiography because of this disease’s possible progressive trend to life-threatening consequences. PMID:27800175

  5. Isolating Lysosomes from Rat Liver.

    PubMed

    Pryor, Paul R

    2016-04-01

    This protocol describes the generation of a fraction enriched in lysosomes from rat liver. The lysosomes are rapidly isolated using density-gradient centrifugation with gradient media that retain the osmolarity of the lysosomes such that they are functional and can be used in in vitro assays.

  6. Current-Voltage Relationship for Late Na(+) Current in Adult Rat Ventricular Myocytes.

    PubMed

    Clark, R B; Giles, W R

    2016-01-01

    It is now well established that the slowly inactivating component of the Na(+) current (INa-L) in the mammalian heart is a significant regulator of the action potential waveform. This insight has led to detailed studies of the role of INa-L in a number of important and challenging pathophysiological settings. These include genetically based ventricular arrhythmias (LQT 1, 2, and 3), ventricular arrhythmias arising from progressive cardiomyopathies (including diabetic), and proarrhythmic abnormalities that develop during local or global ventricular ischemia. Inhibition of INa-L may also be a useful strategy for management of atrial flutter and fibrillation. Many important biophysical parameters that characterize INa-L have been identified; and INa-L as an antiarrhythmia drug target has been studied extensively. However, relatively little information is available regarding (1) the ion transfer or current-voltage relationship for INa-L or (2) the time course of its reactivation at membrane potentials similar to the resting or diastolic membrane potential in mammalian ventricle. This chapter is based on our preliminary findings concerning these two very important physiological/biophysical descriptors for INa-L. Our results were obtained using whole-cell voltage clamp methods applied to enzymatically isolated rat ventricular myocytes. A chemical agent, BDF 9148, which was once considered to be a drug candidate in the Na(+)-dependent inotropic agent category has been used to markedly enhance INa-L current. BDF acts in a potent, selective, and reversible fashion. These BDF 9148 effects are compared and contrasted with the prototypical activator of INa-L, a sea anemone toxin, ATX II. PMID:27586292

  7. Current-Voltage Relationship for Late Na(+) Current in Adult Rat Ventricular Myocytes.

    PubMed

    Clark, R B; Giles, W R

    2016-01-01

    It is now well established that the slowly inactivating component of the Na(+) current (INa-L) in the mammalian heart is a significant regulator of the action potential waveform. This insight has led to detailed studies of the role of INa-L in a number of important and challenging pathophysiological settings. These include genetically based ventricular arrhythmias (LQT 1, 2, and 3), ventricular arrhythmias arising from progressive cardiomyopathies (including diabetic), and proarrhythmic abnormalities that develop during local or global ventricular ischemia. Inhibition of INa-L may also be a useful strategy for management of atrial flutter and fibrillation. Many important biophysical parameters that characterize INa-L have been identified; and INa-L as an antiarrhythmia drug target has been studied extensively. However, relatively little information is available regarding (1) the ion transfer or current-voltage relationship for INa-L or (2) the time course of its reactivation at membrane potentials similar to the resting or diastolic membrane potential in mammalian ventricle. This chapter is based on our preliminary findings concerning these two very important physiological/biophysical descriptors for INa-L. Our results were obtained using whole-cell voltage clamp methods applied to enzymatically isolated rat ventricular myocytes. A chemical agent, BDF 9148, which was once considered to be a drug candidate in the Na(+)-dependent inotropic agent category has been used to markedly enhance INa-L current. BDF acts in a potent, selective, and reversible fashion. These BDF 9148 effects are compared and contrasted with the prototypical activator of INa-L, a sea anemone toxin, ATX II.

  8. Stimulation of isolated ventricular myocytes within an open architecture microarray.

    PubMed

    Klauke, Norbert; Smith, Godfrey L; Cooper, Jonathan M

    2005-03-01

    This paper is concerned with the physiological responses of single heart cells within microfluidic chambers, in response to stimulation by integrated microelectrodes. To enable these investigations, which included the measurement of action potential duration, intracellular Ca2+ and cell shortening, a series of microfluidic chambers (50 microm wide, 180 microm long, 400 microm high, 500 microm pitch) and connecting channels (200 microm wide, 5000 microm long, 50 microm high, 500 microm pitch) were replica-moulded into the silicone elastomer, polydimethylsiloxane (PDMS). The structures were formed against a master of posts and lines, photolithograhically patterned into the high aspect ratio photoresist SU-8. The chambers within the slab of PDMS were aligned against pairs of stimulating gold microelectrodes (50 microm long, 20 microm wide, 0.1-10 microm thick, 180 microm apart) patterned on a microscope coverslip base, thus defining cavities of approximately 4 nL volume. The assembly was filled with physiological saline and single isolated rabbit ventricular myocytes were introduced by micropipetting, thus creating limited volumes of saline above individual myocytes that could be varied between 4 nL and > or = 4 microL. The application of transient current pulses to the cells via the electrodes caused transient contractions with constant amplitude (recorded as changes in sarcomere length), confirming that excitation contraction coupling (EC coupling) remained functional in these limited volumes. Continuous monitoring of the intracellular Ca2+ (using calcium sensitive dyes) showed, that in the absence of bath perfusion, the amplitude of the transients remained constant for approximately 3 min in the 4-nL volume and approximately 20 min for the 4 microL volume. Beyond this time, the cells became unexcitable until the bath was renewed. The action potential duration (APD) was recorded at stimulation frequencies of 1 Hz and 0.5 Hz using potential sensitive dyes and was

  9. Aspirate from human stented saphenous vein grafts induces epicardial coronary vasoconstriction and impairs perfusion and left ventricular function in rat bioassay hearts with pharmacologically induced endothelial dysfunction.

    PubMed

    Lieder, Helmut R; Baars, Theodor; Kahlert, Philipp; Kleinbongard, Petra

    2016-08-01

    Stent implantation into aortocoronary saphenous vein grafts (SVG) releases particulate debris and soluble vasoactive mediators, for example, serotonin. We now analyzed effects of the soluble mediators released into the coronary arterial blood during stent implantation on vasomotion of isolated rat epicardial coronary artery segments and on coronary flow and left ventricular developed pressure in isolated perfused rat hearts. Coronary blood was retrieved during percutaneous SVG intervention using a distal occlusion/aspiration protection device in nine symptomatic patients with stable angina pectoris and a flow-limiting SVG stenosis. The blood was separated into particulate debris and plasma. Responses to coronary plasma were determined in isolated rat epicardial coronary arteries and in isolated, constant pressure-perfused rat hearts (±nitric oxide synthase [NOS] inhibition and ±serotonin receptor blockade, respectively). Coronary aspirate plasma taken after stent implantation induced a stronger vasoconstriction of rat epicardial coronary arteries (52 ± 8% of maximal potassium chloride induced vasoconstriction [% KClmax = 100%]) than plasma taken before stent implantation (12 ± 8% of KClmax); NOS inhibition augmented this vasoconstrictor response (to 110 ± 15% and 24 ± 9% of KClmax). Coronary aspirate plasma taken after stent implantation reduced in isolated perfused rat hearts only under NOS inhibition coronary flow by 17 ± 3% and left ventricular developed pressure by 25 ± 4%. Blockade of serotonin receptors abrogated these effects. Coronary aspirate plasma taken after stent implantation induces vasoconstriction in isolated rat epicardial coronary arteries and reduces coronary flow and left ventricular developed pressure in isolated perfused rat hearts with pharmacologically induced endothelial dysfunction. PMID:27482071

  10. Physiological pathway of magnesium influx in rat ventricular myocytes.

    PubMed

    Tashiro, Michiko; Inoue, Hana; Konishi, Masato

    2014-11-01

    Cytoplasmic free Mg(2+) concentration ([Mg(2+)]i) was measured in rat ventricular myocytes with a fluorescent indicator furaptra (mag-fura-2) introduced by AM-loading. By incubation of the cells in a high-K(+) (Ca(2+)- and Mg(2+)-free) solution, [Mg(2+)]i decreased from ? 0.9 mM to 0.2 to 0.5 mM. The lowered [Mg(2+)]i was recovered by perfusion with Ca(2+)-free Tyrode's solution containing 1 mM Mg(2+). The time course of the [Mg(2+)]i recovery was fitted by a single exponential function, and the first derivative at time 0 was analyzed as being proportional to the initial Mg(2+) influx rate. The Mg(2+) influx rate was inversely related to [Mg(2+)]i, being higher at low [Mg(2+)]i. The Mg(2+) influx rate was augmented by the high extracellular Mg(2+) concentration (5 mM), whereas it was greatly reduced by cell membrane depolarization caused by high K(+). Known inhibitors of TRPM7 channels, 2-aminoethoxydiphenyl borate (2-APB), NS8593, and spermine reduced the Mg(2+) influx rate with half inhibitory concentrations (IC50) of, respectively, 17 ?M, 2.0 ?M, and 22 ?M. We also studied Ni(2+) influx by fluorescence quenching of intracellular furaptra by Ni(2+). The Ni(2+) influx was activated by lowering intra- and extracellular Mg(2+) concentrations, and it was inhibited by 2-APB and NS8593 with IC50 values comparable with those for the Mg(2+) influx. Intracellular alkalization (caused by pulse application of NH4Cl) enhanced, whereas intracellular acidification (induced after the removal of NH4Cl) slowed the Mg(2+) influx. Under the whole-cell patch-clamp configuration, the removal of intracellular and extracellular divalent cations induced large inward and outward currents, MIC (Mg-inhibited cation) currents or IMIC, carried by monovalent cations likely via TRPM7 channels. IMIC measured at -120 mV was diminished to ? 50% by 100 ?M 2-APB or 10 ?M NS8593. These results suggest that TRPM7/MIC channels serve as a major physiological pathway of Mg(2+) influx in rat

  11. The effect of sildenafil on right ventricular remodeling in a rat model of monocrotaline-induced right ventricular failure

    PubMed Central

    Bae, Hyun Kyung; Lee, Hyeryon; Kim, Kwan Chang

    2016-01-01

    Purpose Pulmonary arterial hypertension (PAH) leads to right ventricular failure (RVF) as well as an increase in pulmonary vascular resistance. Our purpose was to study the effect of sildenafil on right ventricular remodeling in a rat model of monocrotaline (MCT)-induced RVF. Methods The rats were distributed randomly into 3 groups. The control (C) group, the monocrotaline (M) group (MCT 60 mg/kg) and the sildenafil (S) group (MCT 60 mg/kg+ sildenafil 30 mg/kg/day for 28 days). Masson Trichrome staining was used for heart tissues. Western blot analysis and immunohistochemical staining were performed. Results The mean right ventricular pressure (RVP) was significantly lower in the S group at weeks 1, 2, and 4. The number of intra-acinar arteries and the medial wall thickness of the pulmonary arterioles significantly lessened in the S group at week 4. The collagen content also decreased in heart tissues in the S group at week 4. Protein expression levels of B-cell lymphoma-2 (Bcl-2)-associated X, caspase-3, Bcl-2, interleukin (IL)-6, matrix metalloproteinase (MMP)-2, endothelial nitric oxide synthase (eNOS), endothelin (ET)-1 and ET receptor A (ERA) in lung tissues greatly decreased in the S group at week 4 according to immunohistochemical staining. According to Western blotting, protein expression levels of troponin I, brain natriuretic peptide, caspase-3, Bcl-2, tumor necrosis factor-α, IL-6, MMP-2, eNOS, ET-1, and ERA in heart tissues greatly diminished in the S group at week 4. Conclusion Sildenafil alleviated right ventricular hypertrophy and mean RVP. These data suggest that sildenafil improves right ventricular function. PMID:27462355

  12. Right Ventricular Outflow Tract Obstruction Caused by Isolated Sinus of Valsalva Aneurysm.

    PubMed

    Abu Saleh, Walid K; Lin, Chun Huie; Reardon, Michael J; Ramlawi, Basel

    2016-08-01

    Isolated sinus of Valsalva aneurysm is a rare occurrence, with an incidence of <1.5% among congenital heart disease repairs in the world. We recount the case of a 64-year-old man who presented with right-sided heart failure symptoms caused by a severely dilated right coronary sinus of Valsalva aneurysm that substantially obstructed the right ventricular outflow tract. Successful surgical repair involved right ventricular outflow tract resection and subcoronary patch repair. PMID:27547152

  13. The Effects of Puerarin on Rat Ventricular Myocytes and the Potential Mechanism

    PubMed Central

    Xu, Hao; Zhao, Manxi; Liang, Shenghui; Huang, Quanshu; Xiao, Yunchuan; Ye, Liang; Wang, Qinyi; He, Longmei; Ma, Lanxiang; Zhang, Hua; Zhang, Li; Jiang, Hui; Ke, Xiao; Gu, Yuchun

    2016-01-01

    Puerarin, a known isoflavone, is commonly found as a Chinese herb medicine. It is widely used in China to treat cardiac diseases such as angina, cardiac infarction and arrhythmia. However, its cardioprotective mechanism remains unclear. In this study, puerarin significantly prolonged ventricular action potential duration (APD) with a dosage dependent manner in the micromolar range on isolated rat ventricular myocytes. However, submicromolar puerarin had no effect on resting membrane potential (RMP), action potential amplitude (APA) and maximal velocity of depolarization (Vmax) of action potential. Only above the concentration of 10 mM, puerarin exhibited more aggressive effect on action potential, and shifted RMP to the positive direction. Millimolar concentrations of puerarin significantly inhibited inward rectified K+ channels in a dosage dependent manner, and exhibited bigger effects upon Kir2.1 vs Kir2.3 in transfected HEK293 cells. As low as micromolar range concentrations of puerarin significantly inhibited Kv7.1 and IKs. These inhibitory effects may due to the direct inhibition of puerarin upon channels not via the PKA-dependent pathway. These results provided direct preclinical evidence that puerarin prolonged APD via its inhibitory effect upon Kv7.1 and IKs, contributing to a better understanding the mechanism of puerarin cardioprotection in the treatment of cardiovascular diseases. PMID:27762288

  14. The complex regulation of tanshinone IIA in rats with hypertension-induced left ventricular hypertrophy.

    PubMed

    Pang, Hui; Han, Bing; Yu, Tao; Peng, Zhen

    2014-01-01

    Tanshinone IIA has definite protective effects on various cardiovascular diseases. However, in hypertension-induced left ventricular hypertrophy (H-LVH), the signaling pathways of tanshinone IIA in inhibition of remodeling and cardiac dysfunction remain unclear. Two-kidney, one-clip induced hypertensive rats (n = 32) were randomized to receive tanshinone IIA (5, 10, 15 mg/kg per day) or 5% glucose injection (GS). Sham-operated rats (n = 8) received 5%GS as control. Cardiac function and dimensions were assessed by using an echocardiography system. Histological determination of the fibrosis and apoptosis was performed using hematoxylin eosin, Masson's trichrome and TUNEL staining. Matrix metalloproteinase 2 (MMP2) and tissue inhibitor of matrix metalloproteinases type 2 (TIMP2) protein expressions in rat myocardial tissues were detected by immunohistochemistry. Rat cardiomyocytes were isolated by a Langendorff perfusion method. After 48 h culture, the supernatant and cardiomyocytes were collected to determine the potential related proteins impact on cardiac fibrosis and apoptosis. Compared with the sham rats, the heart tissues of H-LVH (5%GS) group suffered severely from the oxidative damage, apoptosis of cardiomyocytes and extracellular matrix (ECM) deposition. In the H-LVH group, tanshinone IIA treated decreased malondialdehyde (MDA) content and increased superoxide dismutase (SOD) activity. Tanshinone IIA inhibited cardiomyocytes apoptosis as confirmed by the reduction of TUNEL positive cardiomyocytes and the down-regulation of Caspase-3 activity and Bax/Bcl-2 ratio. Meanwhile, plasma apelin level increased with down-regulation of APJ receptor. Tanshinone IIA suppressed cardiac fibrosis through regulating the paracrine factors released by cardiomyocytes and the TGF-β/Smads signaling pathway activity. In conclusion, our in vivo study showed that tanshinone IIA could improve heart function by enhancing myocardial contractility, inhibiting ECM deposition

  15. [Permanent cardiac stimulation in a patient with isolated dextrocardia and ventricular septal defect].

    PubMed

    Słowiński, S; Derlaga, B; Kapusta, J

    A case of pacemaker implantation because of acquired atrioventricular block third degree in woman aged 39 years with rare isolated dextrocardia with inversion of cardiac ventricles, compensatory transposition of both aorta and pulmonary artery, and ventricular septal defect. The end of electrode has wedged in the apex of the arterial ventricle. Following pacemaker implantation, patients clinical course of gynaecological operation was uneventful.

  16. The relationship between contraction and intracellular sodium in rat and guinea-pig ventricular myocytes.

    PubMed Central

    Harrison, S M; McCall, E; Boyett, M R

    1992-01-01

    1. The contraction, measured optically, and the intracellular Na+ activity (aNai), measured with the Na(+)-sensitive fluorescent dye SBFI, have been recorded simultaneously in rat and guinea-pig ventricular myocytes. 2. In rat and guinea-pig ventricular myocytes at rest, aNai was 7.8 +/- 0.3 mM (n = 4) and 5.1 +/- 0.3 mM (n = 16), respectively. 3. When both rat and guinea-pig ventricular myocytes were stimulated at 1 Hz after a rest there was usually a gradual increase in twitch shortening (referred to as a 'staircase') over several minutes accompanied by an increase in aNai over a similar time course. Twitch shortening increased by 21 +/- 3% (n = 6) and 20 +/- 4% (n = 16) (of steady-state twitch shortening during 1 Hz stimulation) per millimolar rise in aNai in rat and guinea-pig ventricular myocytes, respectively. 4. When rat and guinea-pig ventricular myocytes were exposed to strophanthidin to block the Na(+)-K+ pump, there were increases in twitch shortening and aNai over similar time courses. Twitch shortening increased by 24 +/- 4% (n = 5) and 20 +/- 3% (n = 10) (of control twitch shortening) per millimolar rise in aNai in rat and guinea-pig ventricular myocytes respectively. 5. The inotropic effect of cardiac glycosides, such as strophanthidin, is widely regarded to be principally the result of the rise in aNai. The similarity of the relation between twitch shortening and aNai during the staircase and on application of strophanthidin suggests that the progressive increase in the strength of contraction during the staircase was also linked to the rise in aNai. 6. In guinea-pig, but not rat, ventricular myocytes there was hysteresis in the relation between twitch shortening and aNai on application and wash-off of strophanthidin. This indicates that strophanthidin has another inotropic action in guinea-pig ventricular myocytes. 7. A computer model of excitation-contraction coupling has been developed to simulate the staircase and the action of cardiac glycoside

  17. Outcome of prolonged ventricular fibrillation and CPR in a rat model of chronic ischemic left ventricular dysfunction.

    PubMed

    Fang, Xiangshao; Huang, Lei; Sun, Shijie; Weil, Max Harry; Tang, Wanchun

    2013-01-01

    Patients with chronic left ventricular (LV) dysfunction are assumed to have a lower chance of successful CPR and lower likelihood of ultimate survival. However, these assumptions have rarely been documented. Therefore, we investigated the outcome of prolonged ventricular fibrillation (VF) and CPR in a rat model of chronic LV dysfunction. Sprague-Dawley rats were randomized to (1) chronic LV dysfunction: animals underwent left coronary artery ligation; and (2) sham control. Echocardiography was used to measure cardiac performance before surgery and 4 weeks after surgery. Four weeks after surgical intervention, 8 min of VF was induced and defibrillation was delivered after 8 min of CPR. LV dilation and low ejection fraction were observed 4 weeks after coronary ligation. With optimal chest compressions, coronary perfusion pressure values during CPR were well maintained and indistinguishable between groups. There were no differences in resuscitability and numbers of shock required for successful resuscitation between groups. Despite the significantly decreased cardiac index in LV dysfunction animals before induction of VF, no differences in cardiac index were observed between groups following resuscitation, which was associated with the insignificant difference in postresuscitation survival. In conclusion, the outcomes of CPR were not compromised by the preexisting chronic LV dysfunction. PMID:24455704

  18. The effect of Ligustrum delavayanum on isolated perfused rat heart

    PubMed Central

    Stankovičová, Tatiana; Frýdl, Miroslav; Kubicová, Mária; Baróniková, Slávka; Nagy, Milan; Grančai, Daniel; Švec, Pavel

    2001-01-01

    BACKGROUND: Extract of ligustrum leaves (Ligustrum delavayanum Hariot [Oleaceae]) is well known in traditional Chinese medicine. One of the active components, oleuropein, displays vasodilating and hypotensive effects. OBJECTIVE: To analyze the effect of 0.008% lyophilized extract of ligustrum dissolved in 0.5% ethanol on heart function. ANIMALS AND METHODS: Experiments were done on isolated rat hearts perfused by the Langendorff method in control conditions and during ischemic-reperfusion injury. RESULTS: Application of ligustrum induced positive inotropic and vasodilating effects in spontaneously beating hearts. Pretreatment of the hearts with ligustrum reduced left ventricular diastolic pressure measured during reperfusion and improved left ventricular contraction compared with hearts without any pretreatment. Ligustrum significantly suppressed the incidence and duration of cardiac reperfusion arrhythmias, expressed as G-score, from 7.40±0.58 in nontreated rats to 1.97±0.50. DISCUSSION: Application of ligustrum or ethanol alone induced changes in coordination between atria and ventricles during ischemia-reperfusion injury. The ‘g-score’, a new parameter summing the incidence and duration of atrioventricular blocks, atrioventricular dissociation and cardiac arrest, is introduced. The g-scores with ligustrum pretreatment were higher during ischemia than during reperfusion. Ethanol significantly depressed myocardial contractility and coronary flow, and nonsignificantly decreased heart rate of isolated rat hearts. Electrical changes observed during coronary reperfusion in the presence of ethanol were accompanied by deterioration of contractile function. CONCLUSIONS: Ligustrum had a significant protective effect on rat myocardium against ischemic-reperfusion injury. Ethanol partially attenuated the protective effect of ligustrum. PMID:20428448

  19. Echocardiographic Evaluation of Left Ventricular Function, Mass and Wall Stress in Children with Isolated Ventricular Septal Defect

    PubMed Central

    Waggoner, Alan D.; Nouri, Soraya; Schaffer, Michael S.; Chen, Su-Chiung

    1985-01-01

    M-Mode echocardiography was performed in 22 normal children and 22 children with ventricular septal defects. Left ventricular and left atrial chamber dimensions and wall thicknesses were measured in all patients. Utilizing these data, indices of left ventricular function were derived: shortening fraction, velocity of fiber shortening, peak diastolic fiber lengthening, end-systolic wall stress, radius thickness ratio, and ventricular mass. The results showed that ventricular septal defect was associated with enlarged left ventricular and atrial dimensions and increased shortening fraction, but that velocity of shortening and early diastolic lengthening remained normal. Left ventricular mass was increased, thus maintaining normal wall stress and radius/thickness ratio. Cardiac failure complicating ventricular septal defect was associated with enlarged left ventricular and atrial dimensions (indexed for weight). Ventricular mass, wall stress and function, however, were similar in subjects with ventricular septal defect, with or without cardiac failure. Since left ventricular mass was adequate to maintain wall stress and function in subjects with heart failure, other factors were presumably responsible for heart failure complicating ventricular septal defect. PMID:15227026

  20. Sustained vortex-like waves in normal isolated ventricular muscle.

    PubMed Central

    Davidenko, J M; Kent, P F; Chialvo, D R; Michaels, D C; Jalife, J

    1990-01-01

    Sustained reentrant excitation may be initiated in small (20 x 20 x less than 0.6 mm) preparations of normal ventricular muscle. A single appropriately timed premature electrical stimulus applied perpendicularly to the wake of a propagating quasiplanar wavefront gives rise to circulation of self-sustaining excitation waves, which pivot at high frequency (5-7 Hz) around a relatively small "phaseless" region. Such a region develops only very low amplitude depolarizations. Once initiated, most episodes of reentrant activity last indefinitely but can be interrupted by the application of an appropriately timed electrical stimulus. The entire course of the electrical activity is visualized with high temporal and spatial resolution, as well as high signal-to-noise ratio, using voltage-sensitive dyes and optical mapping. Two- and three-dimensional graphics of the fluorescence changes recorded by a 10 x 10 photodiode array from a surface of 12 x 12 mm provide sequential images (every msec) of voltage distribution during a reentrant vortex. The results suggest that two-dimensional vortex-like reentry in cardiac muscle is analogous to spiral waves in other biological and chemical excitable media. Images PMID:2247448

  1. Cardioprotective effect of polydatin on ventricular remodeling after myocardial infarction in coronary artery ligation rats.

    PubMed

    Gao, Yan; Gao, Jianping; Chen, Changxun; Wang, Huilin; Guo, Juan; Wu, Rong

    2015-05-01

    The purpose of this study was to explore the effect of polydatin on ventricular remodeling after myocardial infarction in coronary artery ligation rats and to elucidate the underlying mechanisms. A rat model of ventricular remodeling after myocardial infarction was established by left coronary artery ligation. Rats with coronary artery ligation were randomly divided into five groups: control, plus 40 mg/kg captopril, plus 25 mg/kg polydatin, plus 50 mg/kg polydatin, and plus 100 mg/kg polydatin. The sham-operated group was used as a negative control. Rats were administered intragastrically with the corresponding drugs or drinking water for seven weeks. At the end of the treatment, the left ventricular weight index and heart weight index were assessed. The cross-sectional size of cardiomyocytes was measured by staining myocardium tissue with hematoxylin and eosin. Collagen content was counted by Sirius red in aqueous saturated picric acid. The concentrations of angiotensin I, angiotensin II, aldosterone, and endothelin 1 in myocardium or serum were determined by radioimmunoassay. Hydroxyproline and nitric oxide concentrations and glutathione peroxidase and catalase activities in serum were measured by ultraviolet spectrophotometry. Our results showed that seven weeks of polydatin treatment resulted in a significantly reduced left ventricular weight index, heart weight index, serum concentrations of hydroxyproline and aldosterone, an increased concentration of nitric oxide as well as enhanced activities of glutathione peroxidase and catalase. Myocardial angiotensin I, angiotensin II, and endothelin 1 levels were also reduced. The cardiomyocyte cross-sectional area and collagen deposition diminished. This study suggests that polydatin may attenuate ventricular remodeling after myocardial infarction in coronary artery ligation rats through restricting the excessive activation of the renin-angiotensin-aldosterone system and inhibiting peroxidation.

  2. Hydrogen sulfide improves left ventricular function in smoking rats via regulation of apoptosis and autophagy.

    PubMed

    Zhou, Xiang; An, Guoyin; Chen, Jianchang

    2014-06-01

    The present study was designed to investigate the protective effects of hydrogen sulfide (H2S) against cigarette smoking-induced left ventricular dysfunction in rats. Left ventricular structure and function were assessed using two-dimensional echocardiography. Cardiomyocyte apoptosis was determined by Annexin V/PI and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining. Cardiac autophagy was evaluated by detection of autophagy-related protein expression and observation of autophagosomes. Our results indicated that administration of NaHS (a donor of H2S) could protect against smoking-induced left ventricular systolic dysfunction. H2S was found to exert anti-apoptotic effects in the myocardium of smoking rats by inhibiting JNK and P38 mitogen-activated protein kinases pathways and activating PI3K/Akt signaling. Moreover, H2S could also reduce smoking-induced autophagic cell death via regulation of AMPK/mTOR signaling pathway. In conclusion, our study demonstrates that H2S can improve left ventricular systolic function in smoking rats via regulation of apoptosis and autophagy.

  3. The Actions of Lyophilized Apple Peel on the Electrical Activity and Organization of the Ventricular Syncytium of the Hearts of Diabetic Rats

    PubMed Central

    Martínez-Ladrón de Guevara, Elideth; Pérez-Hernández, Nury; Villalobos-López, Miguel Ángel; Pérez-Ishiwara, David Guillermo; Salas-Benito, Juan Santiago; Martínez Martínez, Alejandro; Hernández-García, Vicente

    2016-01-01

    This study was designed to examine the effects of lyophilized red delicious apple peel (RDP) on the action potentials (APs) and the input resistance-threshold current relationship. The experiments were performed on isolated papillary heart muscles from healthy male rats, healthy male rats treated with RDP, diabetic male rats, and diabetic male rats treated with RDP. The preparation was superfused with oxygenated Tyrode's solution at 37°C. The stimulation and the recording of the APs, the input resistance, and the threshold current were made using conventional electrophysiological methods. The RDP presented no significant effect in normal rats. Equivalent doses in diabetic rats reduced the APD and ARP. The relationship between input resistance and threshold current established an inverse correlation. The results indicate the following: (1) The functional structure of the cardiac ventricular syncytium in healthy rats is heterogeneous, in terms of input resistance and threshold current. Diabetes further accentuates the heterogeneity. (2) As a consequence, conduction block occurs and increases the possibility of reentrant arrhythmias. (3) These modifications in the ventricular syncytium, coupled with the increase in the ARP, are the adequate substrate so that, with diabetes, the heart becomes more arrhythmogenic. (4) RDP decreases the APD, the ARP, and most syncytium irregularity caused by diabetes. PMID:26839897

  4. Increased rat cardiac angiotensin converting enzyme activity and mRNA expression in pressure overload left ventricular hypertrophy. Effects on coronary resistance, contractility, and relaxation.

    PubMed Central

    Schunkert, H; Dzau, V J; Tang, S S; Hirsch, A T; Apstein, C S; Lorell, B H

    1990-01-01

    We compared the activity and physiologic effects of cardiac angiotensin converting enzyme (ACE) using isovolumic hearts from male Wistar rats with left ventricular hypertrophy due to chronic experimental aortic stenosis and from control rats. In response to the infusion of 3.5 X 10(-8) M angiotensin I in the isolated buffer perfused beating hearts, the intracardiac fractional conversion to angiotensin II was higher in the hypertrophied hearts compared with the controls (17.3 +/- 4.1% vs 6.8 +/- 1.3%, P less than 0.01). ACE activity was also significantly increased in the free wall, septum, and apex of the hypertrophied left ventricle, whereas ACE activity from the nonhypertrophied right ventricle of the aortic stenosis rats was not different from that of the control rats. Northern blot analyses of poly(A)+ purified RNA demonstrated the expression of ACE mRNA, which was increased fourfold in left ventricular tissue obtained from the hearts with left ventricular hypertrophy compared with the controls. In both groups, the intracardiac conversion of angiotensin I to angiotensin II caused a comparable dose-dependent increase in coronary resistance. In the control hearts, angiotensin II activation had no significant effect on systolic or diastolic function; however, it was associated with a dose-dependent depression of left ventricular diastolic relaxation in the hypertrophied hearts. These novel observations suggest that cardiac ACE is induced in hearts with left ventricular hypertrophy, and that the resultant intracardiac activation of angiotensin II may have differential effects on myocardial relaxation in hypertrophied hearts relative to controls. Images PMID:2174912

  5. Congenital isolated cleft mitral valve leaflet and apical muscular ventricular septal defect in a Holstein calf.

    PubMed

    Depenbrock, Sarah M; Visser, Lance C; Kohnken, Rebecca A; Russell, Duncan S; Simpson, Katharine M; Bonagura, John D

    2015-09-01

    A 5-week-old Holstein heifer calf presented for emergency treatment of signs referable to gastrointestinal disease and hypovolemic shock. Fluid resuscitation uncovered clinical signs of primary cardiac disease and echocardiography revealed multiple congenital cardiac defects. Malformations included a cleft anterior mitral valve leaflet resembling an isolated cleft mitral valve and an apically-located muscular ventricular septal defect. The echocardiographic and postmortem findings associated with these defects are presented and discussed in this report.

  6. Altered ventricular torsion and transmural patterns of myocyte relaxation precede heart failure in aging F344 rats.

    PubMed

    Campbell, Stuart G; Haynes, Premi; Kelsey Snapp, W; Nava, Kristofer E; Campbell, Kenneth S

    2013-09-01

    The purpose of this study was to identify and explain changes in ventricular and cellular function that contribute to aging-associated cardiovascular disease in aging F344 rats. Three groups of female F344 rats, aged 6, 18, and 22 mo, were studied. Echocardiographic measurements in isoflurane-anesthetized animals showed an increase in peak left ventricular torsion between the 6- and the 18-mo-old groups that was partially reversed in the 22-mo-old animals (P < 0.05). Epicardial, midmyocardial, and endocardial myocytes were subsequently isolated from the left ventricles of each group of rats. Unloaded sarcomere shortening and Ca(2+) transients were then measured in these cells (n = >75 cells for each of the nine age-region groups). The decay time of the Ca(2+) transient and the time required for 50% length relaxation both increased with age but not uniformly across the three regions (P < 0.02). Further analysis revealed a significant shift in the transmural distribution of these properties between 18 and 22 mo of age, with the largest changes occurring in epicardial myocytes. Computational modeling suggested that these changes were due in part to slower Ca(2+) dissociation from troponin in aging epicardial myocytes. Subsequent biochemical assays revealed a >50% reduction in troponin I phosphoprotein content in 22-mo-old epicardium relative to the other regions. These data suggest that between 18 and 22 mo of age (before the onset of heart failure), F344 rats display epicardial-specific myofilament-level modifications that 1) break from the progression observed between 6 and 18 mo and 2) coincide with aberrant patterns of cardiac torsion.

  7. Structural characterization of rat ventricular tissue exposed to the smoke of two types of waterpipe

    PubMed Central

    Al-Awaida, Wajdy; Najjar, Hossam; Shraideh, Ziad

    2015-01-01

    Objective(s): this study focused on the effect of waterpipe smoke exposure toxicity on the structure of albino rat’s ventricular tissue and their recovery. Materials and Methods: Albino rats were divided into three groups: control, flavored, and unflavored. The control group was exposed to normal air while the flavored and unflavored groups were exposed to waterpipe smoke for a period of 90 days. Each group was followed by a period of 90 days of fresh air exposure. Following each period, the ventricular tissue was removed for biochemical and histopathological studies. Results: The ventricular tissues of waterpipe exposed rats showed some degree of separation between cardiac muscle fibers, infiltration of lymphocytes, and congestion of blood vessel. Also, thin cross sections of ventricular cells revealed pleomorphic mitochondria with partially disrupted cristae, partial disruption of the myofibrils, and deposited toxic materials. The unflavored waterpipe has more deleterious effects on heart ventricular tissues than the flavored one. Waterpipe smoke didn’t induce apoptosis in the ventricular tissue. We also found very high levels of plasma thiocyanate after exposure to smoke in the flavored and unflavored groups, while the control group showed no increase. After the recovery period, those tissues showed partial recovery. Conclusion: Waterpipe smoke induces structural changes in the heart ventricle tissues, causing a negative impact on the capacity of the cardiac muscle for pumping blood and may lead to heart attack due to accumulation of free radicals and tissue inflammation. Cessation of smoking is important in returning most of these changes to their normal structure. PMID:26730327

  8. Prenatal ethanol exposure alters ventricular myocyte contractile function in the offspring of rats: influence of maternal Mg2+ supplementation.

    PubMed

    Wold, L E; Norby, F L; Hintz, K K; Colligan, P B; Epstein, P N; Ren, J

    2001-01-01

    Fetal alcohol syndrome (FAS) is often associated with cardiac hypertrophy and impaired ventricular function in a manner similar to postnatal chronic alcohol ingestion. Chronic alcoholism has been shown to lead to hypomagnesemia, and dietary Mg2+ supplementation was shown to ameliorate ethanol- induced cardiovascular dysfunction such as hypertension. However, the role of gestational Mg2+ supplementation on FAS-related cardiac dysfunction is unknown. This study was conducted to examine the influence of gestational dietary Mg2+ supplementation on prenatal ethanol exposure-induced cardiac contractile response at the ventricular myocyte level. Timed-pregnancy female rats were fed from gestation day 2 with liquid diets containing 0.13 g/L Mg2+ supplemented with ethanol (36%) or additional Mg2+ (0.52 g/L), or both. The pups were maintained on standard rat chow through adulthood, and ventricular myocytes were isolated and stimulated to contract at 0.5 Hz. Mechanical properties were evaluated using an IonOptix soft-edge system, and intracellular Ca2+ transients were measured as changes in fura-2 fluorescence intensity (Delta FFI). Offspring from all groups displayed similar growth curves. Myocytes from the ethanol group exhibited reduced cell length, enhanced peak shortening (PS), and shortened time to 90% relengthening (TR90) associated with a normal Delta FFI and time to PS (TPS). Mg2+ reverted the prenatal ethanol-induced alteration in PS and maximal velocity of relengthening. However, it shortened TPS and TR90, and altered the Delta FFI, as well as Ca2+ decay rate by itself. Additionally, myocytes from the ethanol group exhibited impaired responsiveness to increased extracellular Ca2+ or stimulating frequency, which were restored by gestational Mg2+ supplementation. These data suggest that although gestational Mg2+ supplementation may be beneficial to certain cardiac contractile dysfunctions in offspring of alcoholic mothers, caution must be taken, as Mg2

  9. Itraconazole decreases left ventricular contractility in isolated rabbit heart: Mechanism of action

    SciTech Connect

    Qu, Yusheng; Fang, Mei; Gao, BaoXi; Amouzadeh, Hamid R.; Li, Nianyu; Narayanan, Padma; Acton, Paul; Lawrence, Jeff; Vargas, Hugo M.

    2013-04-15

    Itraconazole (ITZ) is an approved antifungal agent that carries a “black box warning” in its label regarding a risk of negative cardiac inotropy based on clinical findings. Since the mechanism of the negative inotropic effect is unknown, we performed a variety of preclinical and mechanistic studies to explore the pharmacological profile of ITZ and understand the negative inotropic mechanism. ITZ was evaluated in: (1) an isolated rabbit heart (IRH) preparation using Langendorff retrograde perfusion; (2) ion channel studies; (3) a rat heart mitochondrial function profiling screen; (4) a mitochondrial membrane potential (MMP) assay; (5) in vitro pharmacology profiling assays (148 receptors, ion channels, transporters, and enzymes); and (6) a kinase selectivity panel (451 kinases). In the IRH, ITZ decreased cardiac contractility (> 30%) at 0.3 μM, with increasing effect at higher concentrations, which indicated a direct negative inotropic effect upon the heart. It also decreased heart rate and coronary flow (≥ 1 μM) and prolonged PR/QRS intervals (3 μM). In mechanistic studies, ITZ inhibited the cardiac NaV channel (IC{sub 50}: 4.2 μM) and was devoid of any functional inhibitory effect at the remaining pharmacological targets. Lastly, ITZ did not affect MMP, nor interfere with mitochondrial enzymes or processes involved with fuel substrate utilization or energy formation. Overall, the cardiovascular and mechanistic data suggest that ITZ-induced negative inotropy is a direct effect on the heart, in addition, the potential involvement of mitochondria function and L-type Ca{sup 2+} channels are eliminated. The exact mechanism underlying the negative inotropy is uncertain, and requires further study. - Highlights: ► Effect of itraconazole (ITZ) was assessed in the isolated rabbit heart (IRH) assay. ► ITZ decreased ventricular contractility in IRH, indicating a direct effect. ► IC{sub 50} of ITZ on L-type I{sub Ca} was greater than 30 μM, on I{sub Na} was 4

  10. Contribution of baroreceptors and chemoreceptors to ventricular hypertrophy produced by sino-aortic denervation in rats.

    PubMed

    Van Vliet, B N; Chafe, L L; Montani, J P

    1999-05-01

    1. To test whether sino-aortic denervation (SAD)-induced right ventricular hypertrophy (RVH) is a consequence of baroreceptor or chemoreceptor denervation, we compared the effects of aortic denervation (AD), carotid denervation (CD), SAD and a SAD procedure modified to spare the carotid chemoreceptors (mSAD), 6 weeks after denervation surgery in rats. A sham surgery group served as the control. 2. The blood pressure (BP) level was unaffected by AD, CD or SAD, but increased (9 %) following mSAD. The mean heart rate level was not affected. Short-term BP variability was elevated following AD (81 %), SAD (144 %) and mSAD (146 %), but not after CD. Baroreflex heart rate responses to phenylephrine were attenuated in all denervation groups. 3. Significant RVH occurred only following CD and SAD. These procedures also produced high mortality (CD and SAD) and significant increases in right ventricular pressures and haematocrit (CD). 4. Significant left ventricular hypertrophy occurred following CD, SAD and mSAD. Normalized left ventricular weight was significantly correlated with indices of BP variability. 5. These results suggest that SAD-induced RVH is a consequence of chemoreceptor, not baroreceptor, denervation. Our results also demonstrate that a mSAD procedure designed to spare the carotid chemoreceptors produced profound baroreflex dysfunction and significant left, but not right, ventricular hypertrophy.

  11. Dual effects of tetracaine on spontaneous calcium release in rat ventricular myocytes.

    PubMed Central

    Györke, S; Lukyanenko, V; Györke, I

    1997-01-01

    1. Confocal microfluorometry was used to study the effects of tetracaine on spontaneous Ca2+ release from the sarcoplasmic reticulum (SR) in isolated rat ventricular myocytes. 2. At low concentrations (0.25-1.25 mM), tetracaine caused an initial inhibition of spontaneous release events (Ca2+ sparks) and Ca2+ waves, which was followed by a gradual increase in Ca2+ release activity. The frequency and magnitude of sparks were first decreased and then increased with respect to control levels. At high concentrations (> 1.25 mM), tetracaine abolished all forms of spontaneous release. 3. Exposure of the myocytes to tetracaine resulted in a gradual increase in the SR Ca2+ load as indexed by changes in the magnitude of caffeine-induced Ca2+ transients. 4. In cardiac SR Ca(2+)-release channels incorporated into lipid bilayers, tetracaine (> 0.25 mM) induced a steady inhibition of channel activity. Addition of millimolar Ca2+ to the luminal side of the channel caused an increase in channel open probability under control conditions as well as in the presence of various concentrations of tetracaine. 5. We conclude that the primary effect of tetracaine on SR Ca(2+)-release channels is inhibition of channel activity both in vitro and in situ. The ability of tetracaine to reduce spark magnitude suggests that these events are not due to activation of single channels or non-reducible clusters of channels and, therefore, supports the multichannel origin of sparks. We propose that the paradoxical late potentiation of release by submaximal concentrations of tetracaine is caused by a gradual increase in SR Ca2+ load and subsequent activation of the Ca(2+)-release channels by Ca2+ inside the SR. Images Figure 1 Figure 2 Figure 4 PMID:9147318

  12. Activation of soluble guanylyl cyclase by YC-1 in aortic smooth muscle but not in ventricular myocardium from rat

    PubMed Central

    Wegener, Jörg W; Gath, Ingolf; Förstermann, Ulrich; Nawrath, Hermann

    1997-01-01

    The effects of YC-1 (3-(5′-hydroxymethyl-2′-furyl)-1-benzyl indazole), an activator of soluble guanylyl cyclase, on tension, levels of cyclic GMP and cyclic AMP, and cardiac L-type Ca2+-current (ICa(L)) were investigated in aortic smooth muscle and ventricular heart muscle from rat.YC-1 (0.1–30 μM) induced a concentration-dependent relaxation in aortic rings precontracted with phenylephrine (3 μM). The relaxant effects of YC-1 were reversed by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (30 μM; ODQ), potentiated by zaprinast (10 μM) and antagonized by Rp-8-Br-cGMPS (100 μM).In ventricular heart muscle strips, YC-1 (30 μM) exhibited no effects on force of contraction (Fc) in the absence or presence of either zaprinast (10 μM) or 3-isobutyl-1-methylxanthine (30 μM). Fc was slightly increased by YC-1 (30 μM) in the presence of isoprenaline (100 nM), but this effect was not influenced by ODQ (30 μM).Cardiac ICa(L) was not significantly affected by YC-1 (30 μM), either in the absence or presence of isoprenaline (30 nM).In aortic rings, cyclic GMP levels were increased almost 3 fold by YC-1 (30 μM); this effect was abolished by ODQ (30 μM). In isolated ventricular cardiomyocytes, cyclic GMP levels were not affected by YC-1 (30 μM) but almost doubled by activation of particular guanylyl cyclase with atriopeptin II (100 nM).YC-1 (30 μM) did not increase cyclic AMP levels either in aortic rings or in ventricular cardiomyocytes. In contrast, isoprenaline (3 μM) increased cyclic AMP levels about two fold in both tissues. In cardiomyocytes, the effect of isoprenaline (3 μM) was slightly enhanced by YC-1 (30 μM).It is concluded that relaxation of smooth muscle preparations by YC-1 is mediated mainly by activation of soluble guanylyl cyclase and subsequent increase in cyclic GMP levels. The failure of YC-1 to affect cardiac Fc, levels of cyclic GMP, and ICa(L) suggests that soluble guanylyl cyclase is not

  13. The Preventive Effects of Neural Stem Cells and Mesenchymal Stem Cells Intra-ventricular Injection on Brain Stroke in Rats

    PubMed Central

    Hosseini, Seyed Mojtaba; Samimi, Nastaran; Farahmandnia, Mohammad; Shakibajahromi, Benafshe; Sarvestani, Fatemeh Sabet; Sani, Mahsa; Mohamadpour, Masoomeh

    2015-01-01

    Introduction: Stroke is one of the most important causes of disability in developed countries and, unfortunately, there is no effective treatment for this major problem of central nervous system (CNS); cell therapy may be helpful to recover this disease. In some conditions such as cardiac surgeries and neurosurgeries, there are some possibilities of happening brain stroke. Inflammation of CNS plays an important role in stroke pathogenesis, in addition, apoptosis and neural death could be the other reasons of poor neurological out come after stroke. In this study, we examined the preventive effects of the neural stem cells (NSCs) and mesenchymal stem cells (MSCs) intra-ventricular injected on stroke in rats. Aim: The aim of this study was to investigate the preventive effects of neural and MSCs for stroke in rats. Materials and Methods: The MSCs were isolated by flashing the femurs and tibias of the male rats with appropriate media. The NSCs were isolated from rat embryo ganglion eminence and they cultured NSCs media till the neurospheres formed. Both NSCs and MSCs were labeled with PKH26-GL. One day before stroke, the cells were injected into lateral ventricle stereotactically. Results: During following for 28 days, the neurological scores indicated that there are better recoveries in the groups received stem cells and they had less lesion volume in their brain measured by hematoxylin and eosin staining. Furthermore, the activities of caspase-3 were lower in the stem cell received groups than control group and the florescent microscopy images showed that the stem cells migrated to various zones of the brains. Conclusion: Both NSCs and MSCs are capable of protecting the CNS against ischemia and they may be good ways to prevent brain stroke consequences situations. PMID:26605202

  14. Differential Expression Levels of Integrin α6 Enable the Selective Identification and Isolation of Atrial and Ventricular Cardiomyocytes

    PubMed Central

    Wiencierz, Anne Maria; Kernbach, Manuel; Ecklebe, Josephine; Monnerat, Gustavo; Tomiuk, Stefan; Raulf, Alexandra; Christalla, Peter; Malan, Daniela; Hesse, Michael; Bosio, Andreas; Fleischmann, Bernd K.; Eckardt, Dominik

    2015-01-01

    Rationale Central questions such as cardiomyocyte subtype emergence during cardiogenesis or the availability of cardiomyocyte subtypes for cell replacement therapy require selective identification and purification of atrial and ventricular cardiomyocytes. However, current methodologies do not allow for a transgene-free selective isolation of atrial or ventricular cardiomyocytes due to the lack of subtype specific cell surface markers. Methods and Results In order to develop cell surface marker-based isolation procedures for cardiomyocyte subtypes, we performed an antibody-based screening on embryonic mouse hearts. Our data indicate that atrial and ventricular cardiomyocytes are characterized by differential expression of integrin α6 (ITGA6) throughout development and in the adult heart. We discovered that the expression level of this surface marker correlates with the intracellular subtype-specific expression of MLC-2a and MLC-2v on the single cell level and thereby enables the discrimination of cardiomyocyte subtypes by flow cytometry. Based on the differential expression of ITGA6 in atria and ventricles during cardiogenesis, we developed purification protocols for atrial and ventricular cardiomyocytes from mouse hearts. Atrial and ventricular identities of sorted cells were confirmed by expression profiling and patch clamp analysis. Conclusion Here, we introduce a non-genetic, antibody-based approach to specifically isolate highly pure and viable atrial and ventricular cardiomyocytes from mouse hearts of various developmental stages. This will facilitate in-depth characterization of the individual cellular subsets and support translational research applications. PMID:26618511

  15. Estrogen fails to facilitate resuscitation from ventricular fibrillation in male rats

    PubMed Central

    Miao, Yang; Edelheit, Ari; Velmurugan, Sathya; Borovnik-Lesjak, Vesna; Radhakrishnan, Jeejabai; Gazmuri, Raúl J

    2015-01-01

    Administration of 17β-estradiol has been shown to exert myocardial protective effects in hemorrhagic shock. We hypothesized that similar protective effects could help improve resuscitation from cardiac arrest. Three series of 18, 40, and 12 rats each, underwent ventricular fibrillation for 8 minutes followed by 8 minutes of chest compression and delivery of electrical shocks. In series-1, rats were randomized 1:1 to receive a bolus dose of 17β-estradiol (1 mg/kg) or 0.9% NaCl before chest compression; in series-2, rats were randomized 1:1:1:1 to receive a continuous infusion of 0.9% NaCl or a 17β-estradiol solution designed to attain a plasma level of 100, 102, or 104 nM during chest compression; and in series-3, rats were randomized 1:1 to receive a continuous infusion of 17β-estradiol to attain a plasma level of 102 nM or 0.9% NaCl during chest compression, providing inotropic support during the post-resuscitation interval using dobutamine infusion. 17β-estradiol failed to facilitate resuscitation in each of the 3 series. In series-1 and series-2, resuscitability and short-term survival was reduced in 17β-estradiol groups attaining statistical significance in series-2 when the three 17β-estradiol groups were combined (p = 0.035). In series-3, all rats were resuscitated and survived for 180 minutes aided by dobutamine which partially reversed post-resuscitation myocardial dysfunction but without additional benefits on myocardial function in the 17β-estradiol group. The present study failed to support a beneficial effect of 17β-estradiol for resuscitation from cardiac arrest and raised the possibility of detrimental cardiac effects compromising initial resuscitability and subsequent survival in a male rat model of ventricular fibrillation and closed chest resuscitation. PMID:26045892

  16. Comparison of sarcolemmal calcium channel current in rabbit and rat ventricular myocytes.

    PubMed Central

    Yuan, W; Ginsburg, K S; Bers, D M

    1996-01-01

    1. Fundamental properties of Ca2+ channel currents in rat and rabbit ventricular myocytes were measured using whole cell voltage clamp. 2. In rat, as compared with rabbit myocytes, Ca2+ channel current (ICa) was half-activated at about 10 mV more negative potential, decayed slower, was half-inactivated (in steady state) at about 5 mV more positive potential, and recovered faster from inactivation. 3. These features result in a larger steady-state window current in rat, and also suggest that under comparable voltage clamp conditions, including action potential (AP) clamp, more Ca2+ influx would be expected in rat myocytes. 4. Ca2+ channel current carried by Na+ and Cs+ in the absence of divalent ions (Ins) also activated at more negative potential and decayed more slowly in rat. 5. The reversal potential for Ins was 6 mV more positive in rabbit, consistent with a larger permeability ratio (PNa/PCs) in rabbit than in rat. ICa also reversed at slightly more positive potentials in rabbit (such that PCa/PCs might also be higher). 6. Ca2+ influx was calculated by integration of ICa evoked by voltage clamp pulses (either square pulses or pulses based on recorded rabbit or rat APs). For a given clamp waveform, the Ca2+ influx was up to 25% greater in rat, as predicted from the fundamental properties of ICa and Ins. 7. However, the longer duration of the AP in rabbit myocytes compensated for the difference in influx, such that the integrated Ca2+ influx via ICa in response to the species-appropriate waveform was about twice as large as that seen in rat. PMID:8799895

  17. Functional diversity of electrogenic Na+–HCO3− cotransport in ventricular myocytes from rat, rabbit and guinea pig

    PubMed Central

    Yamamoto, Taku; Swietach, Pawel; Rossini, Alessandra; Loh, Shih-Hurng; Vaughan-Jones, Richard D; Spitzer, Kenneth W

    2005-01-01

    The Na+–HCO3− cotransporter (NBC) is an important sarcolemmal acid extruder in cardiac muscle. The characteristics of NBC expressed functionally in heart are controversial, with reports suggesting electroneutral (NBCn; 1HCO3− : 1Na+; coupling coefficient n = 1) or electrogenic forms of the transporter (NBCe; equivalent to 2HCO3− : 1Na+; n = 2). We have used voltage-clamp and epifluorescence techniques to compare NBC activity in isolated ventricular myocytes from rabbit, rat and guinea pig. Depolarization (by voltage clamp or hyperkalaemia) reversibly increased steady-state pHi while hyperpolarization decreased it, effects seen only in CO2/HCO3−-buffered solutions, and blocked by S0859 (cardiac NBC inhibitor). Species differences in amplitude of these pHi changes were rat > guinea pig ≈ rabbit. Tonic depolarization (−140 mV to −0 mV) accelerated NBC-mediated pHi recovery from an intracellular acid load. At 0 mV, NBC-mediated outward current at resting pHi was +0.52 ± 0.05 pA pF−1 (rat, n = 5), +0.26 ± 0.05 pA pF−1 (guinea pig, n = 5) and +0.10 ± 0.03 pA pF−1 (rabbit, n = 9), with reversal potentials near −100 mV, consistent with n = 2. The above results indicate a functionally active voltage-sensitive NBCe in these species. Voltage-clamp hyperpolarization negative to the reversal potential for NBCe failed, however, to terminate or reverse NBC-mediated pHi-recovery from an acid load although it was slowed significantly, suggesting electroneutral NBC may also be operational. NBC-mediated pHi recovery was associated with a rise of [Na+]i at a rate ∼25% of that mediated via NHE, and consistent with an apparent NBC stoichiometry between n = 1 and n = 2. In conclusion, NBCe in the ventricular myocyte displays considerable functional variation among the three species tested (greatest in rat, least in rabbit) and may coexist with some NBCn activity. PMID:15550467

  18. Streptozotocin-induced diabetes prolongs twitch duration without affecting the energetics of isolated ventricular trabeculae

    PubMed Central

    2014-01-01

    Background Diabetes induces numerous electrical, ionic and biochemical defects in the heart. A general feature of diabetic myocardium is its low rate of activity, commonly characterised by prolonged twitch duration. This diabetes-induced mechanical change, however, seems to have no effect on contractile performance (i.e., force production) at the tissue level. Hence, we hypothesise that diabetes has no effect on either myocardial work output or heat production and, consequently, the dependence of myocardial efficiency on afterload of diabetic tissue is the same as that of healthy tissue. Methods We used isolated left ventricular trabeculae (streptozotocin-induced diabetes versus control) as our experimental tissue preparations. We measured a number of indices of mechanical (stress production, twitch duration, extent of shortening, shortening velocity, shortening power, stiffness, and work output) and energetic (heat production, change of enthalpy, and efficiency) performance. We calculated efficiency as the ratio of work output to change of enthalpy (the sum of work and heat). Results Consistent with literature results, we showed that peak twitch stress of diabetic tissue was normal despite suffering prolonged duration. We report, for the first time, the effect of diabetes on mechanoenergetic performance. We found that the indices of performance listed above were unaffected by diabetes. Hence, since neither work output nor change of enthalpy was affected, the efficiency-afterload relation of diabetic tissue was unaffected, as hypothesised. Conclusions Diabetes prolongs twitch duration without having an effect on work output or heat production, and hence efficiency, of isolated ventricular trabeculae. Collectively, our results, arising from isolated trabeculae, reconcile the discrepancy between the mechanical performance of the whole heart and its tissues. PMID:24731754

  19. Protective effects of drag-reducing polymers on ischemic reperfusion injury of isolated rat heart.

    PubMed

    Hu, Feng; Wang, Yali; Gong, Kaizheng; Ge, Gaoyuan; Cao, Mingqiang; Zhao, Pei; Sun, Xiaoning; Zhang, Zhengang

    2016-01-01

    Drag-reducing polymers (DRPs) are blood-soluble macromolecules that can increase blood flow and reduce vascular resistance. The purpose of the present study was to observe the effect of DRPs on ischemic reperfusion (I/R) injury of isolated rat hearts. Experiments were performed on isolated rat hearts subjected to 30 min of ischemia followed by 90 min of reperfusion in Langendorff preparations. Adult Wistar rats were divided into the following five groups: control group, I/R group, group III (I/R and 2×10(-7)  g/ml PEO reperfusion), group IV (I/R and 1×10(-6)  g/ml PEO reperfusion), and group V (I/R and 5×10(-6)  g/ml PEO reperfusion). Left ventricular end-diastolic pressure (LVEDP), left ventricular systolic pressure (LVSP), maximum rate of ventricular pressure increase and decrease ( ± dp/dtmax), heart rate (HR) and coronary flow were measured. Lactate dehydrogenase (LDH) and creatine kinase (CK) activity and coronary flow, myocardial infarction size and cardiomyocytes apoptosis were also assayed. Our results showed that PEO decreased LVEDP and increased LVSP, ± dP/dtmax in group IV and group V compared with the I/R group (all P <  0.05). The coronary flow significantly increased and the activities of LDH and CK in the coronary flow significantly decreased in group IV and group V compared with those in the I/R group (all P <  0.05). Cell apoptosis and myocardial infarction size were reduced in group IV and group V compared with the I/R group (all P <  0.05). Collectively, these results suggested that DRPs had a protective effect on cardiac I/R injury of isolated rat hearts and it may offer a new potential approach for the treatment of acute ischemic heart diseases.

  20. Intramembrane charge movement in guinea-pig and rat ventricular myocytes.

    PubMed Central

    Hadley, R W; Lederer, W J

    1989-01-01

    1. Non-linear capacitative current (charge movement) was studied in isolated guinea-pig and rat ventricular myocytes. Linear capacitance was subtracted using standard procedures. Most of the experiments were done with guinea-pig myocytes, while rat myocytes were used for comparison. 2. When a myocyte was held at -100 mV, depolarizing clamp steps produced a rapid outward current transient, which was followed by an inward current transient upon repolarization. This current was identified as the movement of charged particles in the cell membrane, rather than ionic movement across the membrane, for the following reasons: (1) the current saturated at membrane potentials positive to +20 mV; (2) the current was capacitative in nature, having no reversal potential; (3) in general, the charge moved during depolarization (Qon) approximated the charge moved during repolarization (Qoff). 3. Qoff was significantly less than Qon for a depolarization from -100 mV to 0 mV. However, the Qoff/Qon ratio approached unity if the cell was instead repolarized to -140 mV. This was interpreted as being due to the immobilization of a fraction of the charge during the depolarization, which recovered rapidly enough to be measured at -140 mV, but recovered too slowly at -100 mV. 4. Charge movement in these cells had a sigmoidal dependence on the membrane potential, which could be empirically described by the two-state Boltzmann equation Q = Qmax/(1 + exp[-(V-V*)/kappa]), where Q is the charge movement at potential V, Qmax is the maximum charge, V* is the membrane potential at Q = Qmax/2, and kappa is a slope factor. Qmax was 11.7 nC/microF, V* was -18 mV and kappa was 16 mV in guinea-pig myocytes held at -100 mV, while the values in rat myocytes were 10.9 nC/microF, -32 mV and 13 mV. 5. The charge movement could be partially immobilized by a prior depolarization. This effect developed over a broad voltage range, from -120 to +20 mV. The fraction of charge that could be immobilized by a 10 s

  1. Effects of valsartan on ventricular arrhythmia induced by programmed electrical stimulation in rats with myocardial infarction

    PubMed Central

    Jiao, Kun-Li; Li, Yi-Gang; Zhang, Peng-Pai; Chen, Ren-Hua; Yu, Yi

    2012-01-01

    Abstract The impact of angiotensin II receptor blockers (ARBs) on electrical remodelling after myocardial infarction (MI) remains unclear. The purpose of the present study was to evaluate the effect of valsartan on incidence of ventricular arrhythmia induced by programmed electrical stimulation (PES) and potential link to changes of myocardial connexins (Cx) 43 expression and distribution in MI rats. Fifty-nine rats were randomly divided into three groups: Sham (n = 20), MI (n = 20) and MI + Val (20 mg/kg/day per gavage, n = 19). After eight weeks, the incidence of PES-induced ventricular tachycardia (VT) and fibrillation (VF) was compared among groups. mRNA and protein expressions of Cx43, angiotensin II type 1 receptor (AT1R) in the LV border zone (BZ) and non-infarct zone (NIZ) were determined by real-time PCR and Western blot, respectively. Connexins 43 protein and collagen distribution were examined by immunohistochemistry in BZ and NIZ sections from MI hearts. Valsartan effectively improved the cardiac function, reduced the prolonged QTc (163.7 ± 3.7 msec. versus 177.8 ± 4.5 msec., P < 0.05) after MI and the incidence of VT or VF evoked by PES (21.1% versus 55%, P < 0.05). Angiotensin II type 1 receptor expression was significantly increased in BZ and NIZ sections after MI, which was down-regulated by valsartan. The mRNA and protein expressions of Cx43 in BZ were significantly reduced after MI and up-regulated by valsartan. Increased collagen deposition and reduced Cx43 expression in BZ after MI could be partly attenuated by Valsartan. Valsartan reduced the incidence of PES-induced ventricular arrhythmia, this effect was possibly through modulating the myocardial AT1R and Cx43 expression. PMID:22128836

  2. Toluene and benzene inhalation influences on ventricular arrhythmias in the rat.

    PubMed

    Magos, G A; Lorenzana-Jiménez, M; Vidrio, H

    1990-01-01

    We have previously found that toluene did not share the capacity of benzene for increasing the arrhythmogenic action of epinephrine in the rat, but appeared to elicit the opposite effect. The present experiments were carried out to verify this observation in rats subjected to more severe ventricular arrhythmias. In animals previously inhaling either air, toluene or benzene and anesthetized with pentobarbital, arrhythmias were produced by coronary ligation or aconitine. In both models, toluene decreased and benzene increased the number of ectopic ventricular beats in the 30 min following induction of arrhythmia. Gas chromatographic measurement of toluene levels in the heart during and after inhalation revealed essentially constant concentrations at the time of arrhythmia evaluation, equivalent to approximately one-third the peak levels observed at the end of inhalation. Although the mechanism of the effect of toluene on arrhythmia could not be ascertained, nonspecific membrane stabilization or central serotonergic stimulation were considered as possible explanations. Since both mechanisms could be operant also in the case of benzene, the opposite effects of the solvents on arrhythmia could not be readily accounted for.

  3. Methanolic Extract of Ceplukan Leaf (Physalis minima L.) Attenuates Ventricular Fibrosis through Inhibition of TNF-α in Ovariectomized Rats

    PubMed Central

    Lestari, Bayu; Permatasari, Nur; Rohman, Mohammad Saifur

    2016-01-01

    The increase of heart failure prevalence on menopausal women was correlated with the decrease of estrogen level. The aim of this study is to investigate the effects of ceplukan leaf (Physalis minima L.), which contains phytoestrogen physalin and withanolides, on ventricular TNF-α level and fibrosis in ovariectomized rats. Wistar rats were divided into six groups (control (—); OVX 5: 5-week ovariectomy (OVX); OVX 9: 9-week ovariectomy; treatments I, II, and III: 9-weeks OVX + 4-week ceplukan leaf's methanolic extract doses 500, 1500, and 2500 mg/kgBW, resp.). TNF-α levels were measured with ELISA. Fibrosis was counted as blue colored tissues percentage using Masson's Trichrome staining. This study showed that prolonged hypoestrogen increases ventricular fibrosis (p < 0.05). Ceplukan leaf treatment also resulted in a decrease of ventricular fibrosis and TNF-α level in dose dependent manner compared to without treatment group (p < 0.05). Furthermore, the TNF-α level was normalized in 2500 mg/kgBW Physalis minima L. (p < 0.05) treatment. The reduction of fibrosis positively correlated with TNF-α level (p < 0.05, r = 0.873). Methanolic extract of ceplukan leaf decreases ventricular fibrosis through the inhibition of ventricular TNF-α level in ovariectomized rats. PMID:26941790

  4. Lown-Ganong-Levine syndrome in a 3-month-old infant with isolated left ventricular noncompaction.

    PubMed

    Shabanian, Reza; Kiani, Abdolrazagh; Rad, Elaheh Malakan; Eslamiyeh, Hosein

    2010-02-01

    This report describes a 3-month-old boy with isolated left ventricular noncompaction admitted to a medical facility due to heart failure and dysrhythmia. His electrocardiogram showed a short PR interval and a normal QRS complex after abortion of supraventricular tachycardia in favor of Lown-Ganong-Levine syndrome or enhanced atrioventricular nodal conduction.

  5. Effects of Dantrolene Treatment on Ventricular Electrophysiology and Arrhythmogenesis in Rats With Chronic β-Adrenergic Receptor Activation.

    PubMed

    Liu, Tao; Shi, Shao-bo; Qin, Mu; Huang, Cong-xin

    2015-07-01

    Dantrolene, which is primarily used to treat malignant hyperthermia, has recently been suggested for the prevention of arrhythmogenesis in various animal models. In this study, the effects of dantrolene treatment on electrophysiological properties and ventricular arrhythmias (VAs) in rats with chronic β-adrenergic receptor (β-AR) activation were investigated. Rats were randomized to treatment with saline (control group), isoproterenol (ISO; ISO group), or ISO + dantrolene (ID group) for 2 weeks. An electrophysiological study was performed to assess action potential duration restitution (APDR) and induce action potential duration (APD) alternans or VA in vitro. The protein levels of Cav1.2, sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2a), and ryanodine receptor 2 (RyR2) were detected by Western blot. Compared with the control group, chronic administration of ISO significantly increased APD, the maximum slope (Smax) of APDR curve, and the spatial dispersions of Smax and APD (all P < .01), and all effects were attenuated by dantrolene treatment (all P < .05). Additionally, chronic ISO administration significantly reduced the protein levels of SERCA2 and RyR2, but increased the Cav1.2 protein expression (all P < .05). However, compared with the ISO group, dantrolene treatment preserved SERCA2a and RyR2 protein levels and decreased Cav1.2 protein levels in the ID group (all P < .05). The intracellular Ca(2+) ([Ca(2+)]i) levels measured by incubating isolated cardiomyocytes with Fluo-3/alveolar macrophages were significantly increased in the ISO group compared with the control group (P < .01). Dantrolene treatment markedly reduced the rise of [Ca(2+)]i levels caused by chronic administration of ISO (P < .05). Dantrolene treatment also prevented the reductions in the APD alternans and VA thresholds induced by chronic ISO stimulation (all P < .05). These data suggest that dantrolene stabilizes ventricular electrophysiological characteristics and increases the expression

  6. Regional alterations of repolarizing K+ currents among the left ventricular free wall of rats with ascending aortic stenosis

    PubMed Central

    Volk, Tilmann; Nguyen, Thi Hong-Diep; Schultz, Jobst-Hendrik; Faulhaber, Jörg; Ehmke, Heimo

    2001-01-01

    The effect of cardiac hypertrophy on electrocardiogram (ECG), action potential duration (APD) and repolarizing K+ currents was investigated in epicardial, midmyocardial and endocardial myocytes isolated from the rat left ventricular free wall. Cardiac hypertrophy was induced by stenosis of the ascending aorta (AS), which led to an increased pressure load (+85 ± 10 mm) of the left ventricle; sham-operated animals served as controls. In ECG recordings from AS rats, the QTc interval was prolonged and the main vectors of the QRS complex and the T-wave pointed in opposite directions, indicating an abnormal sequence of repolarization. APD and K+ currents were recorded using the whole-cell patch-clamp technique. In the AS group, APD90 (90 % repolarization) was significantly prolonged in epicardial and midmyocardial, but not endocardial myocytes. Corresponding to the increase in APD, the magnitude of the transient outward K+ current (Ito1) was significantly smaller (-30 %) in epicardial and midmyocardial, but not endocardial myocytes. Inactivation and steady-state inactivation of Ito1 were not affected by hypertrophy. Recovery from inactivation was slightly prolonged in endocardial myocytes from AS rats. No differences in delayed rectifier currents (IK) or inwardly rectifying K+ currents (IK1) were detected between myocytes of the three regions of sham-operated or AS animals. However, both currents were reduced by AS. The present data show that cardiac hypertrophy caused by pressure overload leads to an increase in APD and a decrease in Ito1 primarily in epicardial and midmyocardial myocytes, which implies a major role of alterations in Ito1 for the reduced gradient in APD. The effects of AS on IK1 and IK may slightly counteract the decrease in APD gradient. The observed changes in APD and underlying ionic currents could well explain the alterations in repolarization observed in the ECG induced by cardiac hypertrophy. PMID:11158275

  7. Interventricular comparison of the energetics of contraction of trabeculae carneae isolated from the rat heart

    PubMed Central

    Han, June-Chiew; Taberner, Andrew J; Nielsen, Poul M F; Loiselle, Denis S

    2013-01-01

    We compare the energetics of right ventricular and left ventricular trabeculae carneae isolated from rat hearts. Using our work-loop calorimeter, we subjected trabeculae to stress-length work (W), designed to mimic the pressure–volume work of the heart. Simultaneous measurement of heat production (Q) allowed calculation of the accompanying change of enthalpy (ΔH=W+Q). From the mechanical measurements (i.e. stress and change of length), we calculated work, shortening velocity and power. In combination with heat measurements, we calculated activation heat (QA), crossbridge heat (Qxb) and two measures of cardiac efficiency: ‘mechanical efficiency’ (ɛmech=W/ΔH) and ‘crossbridge efficiency’ (ɛxb=W/(ΔH–QA)). With respect to their left ventricular counterparts, right venticular trabeculae have higher peak shortening velocity, and higher peak mechanical efficiency, but with no difference of stress development, twitch duration, work performance, shortening power or crossbridge efficiency. That is, the 35% greater maximum mechanical efficiency of right venticular than left ventricular trabeculae (13.6 vs. 10.2%) is offset by the greater metabolic cost of activation (QA) in the latter. When corrected for this difference, crossbridge efficiency does not differ between the ventricles. PMID:23184511

  8. Stimulation of single isolated adult ventricular myocytes within a low volume using a planar microelectrode array.

    PubMed

    Klauke, Norbert; Smith, Godfrey L; Cooper, Jon

    2003-09-01

    Microchannels (40- microm wide, 10- microm high, 10-mm long, 70- microm pitch) were patterned in the silicone elastomer, polydimethylsiloxane on a microscope coverslip base. Integrated within each microchamber were individually addressable stimulation electrodes (40- microm wide, 20- microm long, 100-nm thick) and a common central pseudo-reference electrode (60- microm wide, 500- microm long, 100-nm thick). Isolated rabbit ventricular myocytes were introduced into the chamber by micropipetting and subsequently capped with a layer of mineral oil, thus creating limited volumes of saline around individual myocytes that could be varied from 5 nL to 100 pL. Excitation contraction coupling was studied by monitoring myocyte shortening and intracellular Ca(2+) transients (using Fluo-3 fluorescence). The amplitude of stimulated myocyte shortening and Ca(2+) transients remained constant for 90 min in the larger volume (5 nL) configuration, although the shortening (but not the Ca(2+) transient) amplitude gradually decreased to 20% of control within 60 min in the low volume (100 pL) arrangement. These studies indicate a lower limit for the extracellular volume required to stimulate isolated adult cardiac myocytes. Whereas this arrangement could be used to create a screening assay for drugs, individual microchannels (100 pL) can also be used to study the effects of limited extracellular volume on the contractility of single cardiac myocytes.

  9. Stimulation of Single Isolated Adult Ventricular Myocytes within a Low Volume Using a Planar Microelectrode Array

    PubMed Central

    Klauke, Norbert; Smith, Godfrey L.; Cooper, Jon

    2003-01-01

    Microchannels (40-μm wide, 10-μm high, 10-mm long, 70-μm pitch) were patterned in the silicone elastomer, polydimethylsiloxane on a microscope coverslip base. Integrated within each microchamber were individually addressable stimulation electrodes (40-μm wide, 20-μm long, 100-nm thick) and a common central pseudo-reference electrode (60-μm wide, 500-μm long, 100-nm thick). Isolated rabbit ventricular myocytes were introduced into the chamber by micropipetting and subsequently capped with a layer of mineral oil, thus creating limited volumes of saline around individual myocytes that could be varied from 5 nL to 100 pL. Excitation contraction coupling was studied by monitoring myocyte shortening and intracellular Ca2+ transients (using Fluo-3 fluorescence) . The amplitude of stimulated myocyte shortening and Ca2+ transients remained constant for 90 min in the larger volume (5 nL) configuration, although the shortening (but not the Ca2+ transient) amplitude gradually decreased to 20% of control within 60 min in the low volume (100 pL) arrangement. These studies indicate a lower limit for the extracellular volume required to stimulate isolated adult cardiac myocytes. Whereas this arrangement could be used to create a screening assay for drugs, individual microchannels (100 pL) can also be used to study the effects of limited extracellular volume on the contractility of single cardiac myocytes. PMID:12944291

  10. ATP-sensitive K+ channels in rat ventricular myocytes are blocked and inactivated by internal divalent cations.

    PubMed

    Findlay, I

    1987-10-01

    K+ currents were recorded from ATP-sensitive channels in inside-out patches from isolated rat ventricular myocytes. In the absence of internal divalent cations the current voltage relationship could be described by constant-field assumptions with a permeability of 1.25 X 10(-13) cm2/s; outward currents saturated under a high driving force for K+ movement. Internal 0.1-5.0 mM Mg2+, 0.1 microM Ca2+ and 10 mM Na+ each depressed the flux of K+ ions moving outwards through open channels. Internal 0.1-5.0 mM Mg2+, 0.1-1.0 microM Ca2+ and 1-10 microM Ba2+ and Sr2+ blocked K+ channel activity in a dose- and voltage-dependent manner. Run-down channels could be reactivated by Mg-ATP, but not by AMP-PNP, ATP gamma S or Mg-free ATP which suggested that phosphorylation of the channels was involved in their activity. Ca2+ (greater than = 1 microM) and Sr2+ (1 mM) markedly inactivated K+ ATP channels, millimolar Ba2+ or Mg2+ were less effective. This suggested that the run down of the channels was a Ca2+-dependent dephosphorylation of the K+ channel protein.

  11. Effects of Sleep Deprivation on Action Potential and Transient Outward Potassium Current in Ventricular Myocytes in Rats

    PubMed Central

    Fang, Zhou; Ren, Yi-Peng; Lu, Cai-Yi; Li, Yang; Xu, Qiang; Peng, Li; Fan, Yong-Yan

    2015-01-01

    Background Sleep deprivation contributes to the development and recurrence of ventricular arrhythmias. However, the electrophysiological changes in ventricular myocytes in sleep deprivation are still unknown. Material/Methods Sleep deprivation was induced by modified multiple platform technique. Fifty rats were assigned to control and sleep deprivation 1, 3, 5, and 7 days groups, and single ventricular myocytes were enzymatically dissociated from rat hearts. Action potential duration (APD) and transient outward current (Ito) were recorded using whole-cell patch clamp technique. Results Compared with the control group, the phases of APD of ventricular myocytes in 3, 5, and 7 days groups were prolonged and APD at 20% and 50% level of repolarization (APD20 and APD50) was significantly elongated (The APD20 values of control, 1, 3, 5, and 7 days groups: 5.66±0.16 ms, 5.77±0.20 ms, 8.28±0.30 ms, 11.56±0.32 ms, 13.24±0.56 ms. The APD50 values: 50.66±2.16 ms, 52.77±3.20 ms, 65.28±5.30 ms, 83.56±7.32 ms, 89.24±5.56 ms. P<0.01, n=18). The current densities of Ito significantly decreased. The current density-voltage (I–V) curve of Ito was vitally suppressed downward. The steady-state inactivation curve and steady-state activation curve of Ito were shifted to left and right, respectively, in sleep deprivation rats. The inactivation recovery time of Ito was markedly retarded and the time of closed-state inactivation was markedly accelerated in 3, 5, and 7 days groups. Conclusions APD of ventricular myocytes in sleep deprivation rats was significantly prolonged, which could be attributed to decreased activation and accelerated inactivation of Ito. PMID:25694200

  12. An endogenous protectant effect of cardiac cyclic GMP against reperfusion-induced ventricular fibrillation in the rat heart.

    PubMed Central

    Pabla, R.; Bland-Ward, P.; Moore, P. K.; Curtis, M. J.

    1995-01-01

    1. After a period of myocardial ischaemia, reperfusion of the myocardium can elicit cardiac arrhythmias. Susceptibility to these arrhythmias declines with time, such that a preceding period of more than approximately 40 min ischaemia is associated with few reperfusion-induced arrhythmias. We have tested the hypothesis that this decline in susceptibility occurs, in part, because of protection by endogenous guanosine 3':5'-cyclic monophosphate (cyclic GMP). 2. Rat isolated hearts were subjected to 60 min left regional ischaemia followed by reperfusion (n = 10 per group). Methylene blue (20 microM), a soluble guanylate cyclase inhibitor, raised the incidence of reperfusion-induced ventricular fibrillation (VF) from 10% in control hearts to 80% (P < 0.05). This effect of methylene blue was abolished by co-perfusion with zaprinast (100 microM), a phosphodiesterase inhibitor which, in the rat heart, is cyclic GMP-specific (specific for the type-V phosphodiesterase isozyme). 3. Methylene blue reduced cyclic GMP levels in the ischaemic, non-ischaemic and reperfused myocardium (P < 0.05) to 50 +/- 10, 52 +/- 12 and 70 +/- 7 fmol mg-1 tissue wet weight, respectively from control values of 143 +/- 38, 147 +/- 43 and 156 +/- 15 fmol mg-1. Co-perfusion with zaprinast prevented this effect, and cyclic GMP levels were actually elevated (P < 0.05) to 366 +/- 102, 396 +/- 130 and 293 +/- 22 fmol mg-1 in ischaemic, non-ischaemic and reperfused myocardium, respectively. Zaprinast by itself also elevated cyclic GMP content. Cyclic AMP levels were not affected by zaprinast or methylene blue. 4. In conclusion, when endogenous cardiac cyclic GMP synthesis is reduced, susceptibility to reperfusion-induced VF after sustained ischaemia is substantially increased. The effect is prevented by inhibiting cyclic GMP degradation. Therefore cyclic GMP appears to be an endogenous intracellular cardioprotectant, and its actions may account for the low susceptibility to VF normally encountered in

  13. Simvastatin ameliorates ventricular remodeling via the TGF-β1 signaling pathway in rats following myocardial infarction

    PubMed Central

    XIAO, XIANGBIN; CHANG, GUANGLEI; LIU, JIAN; SUN, GUANGYUN; LIU, LI; QIN, SHU; ZHANG, DONGYING

    2016-01-01

    Statins are widely used in patients with cardiovascular diseases. A considerable number of previous studies revealed that the intracellular signaling of transforming growth factor (TGF)-β1 mediated the development of cardiomyocyte hypertrophy and interstitial fibrosis. However, whether statins can ameliorate ventricular remodeling in post-myocardial infarction via the TGF-β1 signaling pathway remains to be rigorously tested. The left anterior descending artery was ligated to induce a rat model of myocardial infarction. The rat model of myocardial infarction was treated with simvastatin through gastric gavage (10, 20 or 40 mg kg−1·d−1). All rats were sacrificed on day 28 after the myocardial infarction operation. The results revealed that simvastatin significantly improved the hemodynamic indexes, left ventricular mass index, the myocardial tissue structure, the cardiomyocyte cross-sectional area and the collagen volume fraction, and also showed that the levels of TGF-β1, TGF-activated kinase (TAK)1 and drosophila mothers against decapentaplegic (Smad)3 were significantly reduced following treatment with simvastatin, while the levels of Smad7 in the simvastatin treatment groups were markedly increased. The results of the present study suggested that statins ameliorated ventricular remodeling in post-myocardial infarction rats via the TGF-β1 signaling pathway, which provided a novel explanation for the pleiotropic effects of statins that benefit the cardiovascular system. PMID:27121011

  14. Tyrosine kinase inhibitor BIBF1000 does not hamper right ventricular pressure adaptation in rats.

    PubMed

    de Raaf, Michiel Alexander; Herrmann, Franziska Elena; Schalij, Ingrid; de Man, Frances S; Vonk-Noordegraaf, Anton; Guignabert, Christophe; Wollin, Lutz; Bogaard, Harm Jan

    2016-09-01

    BIBF1000 is a small molecule tyrosine kinase inhibitor targeting vascular endothelial growth factor receptor (VEGFR), fibroblast growth factor receptor (FGFR), and platelet-derived growth factor receptor (PDGFR) and is a powerful inhibitor of fibrogenesis. BIBF1000 is very similar to BIBF1120 (nintedanib), a drug recently approved for the treatment of idiopathic pulmonary fibrosis (IPF). A safety concern pertaining to VEGFR, FGFR, and PDGFR inhibition is the possible interference with right ventricular (RV) responses to an increased afterload, which could adversely affect clinical outcome in patients with IPF who developed pulmonary hypertension. We tested the effect of BIBF1000 on the adaptation of the RV in rats subjected to mechanical pressure overload. BIBF1000 was administered for 35 days in pulmonary artery-banded (PAB) rats. RV adaptation was assessed by echocardiography, pressure volume loop analysis, histology, and determination of atrial natriuretic peptide (ANP) expression. BIBF1000 treatment resulted in growth attenuation but had no effects on RV function after PAB, given absence of changes in cardiac index, end-systolic elastance, connective tissue disposition, and capillary density. We conclude that, in this experimental model of increased afterload, combined VEGFR, FGFR, and PDGFR inhibition does not hamper RV adaptation to pressure overload. PMID:27342880

  15. Asiatic acid inhibits left ventricular remodeling and improves cardiac function in a rat model of myocardial infarction

    PubMed Central

    HUO, LIANYING; SHI, WENBING; CHONG, LING; WANG, JINLONG; ZHANG, KAI; LI, YUFENG

    2016-01-01

    Left ventricular remodeling results in cardiac dysfunction and accounts for the majority of the morbidity and mortality following myocardial infarction (MI). The aim of the present study was to investigate the effect of asiatic acid (AA) on cardiac function and left ventricular remodeling in a rat model of MI and explore the underlying mechanisms. Rats were subjected to coronary artery ligation to model MI and orally treated with AA. After 4 weeks, cardiac function was assessed by echocardiography. Cardiomyocyte cross-sectional area was recorded, and the expression levels of a number of inflammatory cytokines were detected using ELISA. The degree of interstitial fibrosis was determined by evaluating the mRNA expression levels of collagen II and III. Western blot analysis was performed to detect the expression levels of total and phosphorylated p38 MAPK and ERK1/2, to investigate whether they are involved in the mechanism underlying the effect of AA on the heart. Rats subjected to MI displayed significantly impaired cardiac function compared with those subjected to a sham procedure, while this change was reversed by treatment with AA. Furthermore, AA markedly inhibited cardiac hypertrophy, reduced the mRNA expression levels of inflammatory cytokines and decreased interstitial fibrosis in the infarct border zone of MI model rats compared with those in vehicle-treated MI model rats. Furthermore, the phosphorylation of p38 MAPK and ERK1/2 was blocked by AA in the MI rats but not in the sham rats. In summary, AA treatment preserved cardiac function and inhibited left ventricular remodeling, potentially by blocking the phosphorylation of p38 MAPK and ERK1/2 in the infarct border zone of the ischemic myocardium, indicating that AA may be a novel candidate for development as a therapy for MI. PMID:26889217

  16. Differential metal content and gene expression in rat left ventricular hypertrophy due to hypertension and hyperactivity.

    PubMed

    Subramanian, Meenakumari; Hunt, Adam L; Petrucci, Giuseppe A; Chen, Zengyi; Hendley, Edith D; Palmer, Bradley M

    2014-07-01

    The spontaneously hypertensive rat (SHR) has been studied extensively as a model of left ventricular hypertrophy (LVH) and associated cardiac dysfunction due to hypertension (HT). The SHR also possesses a hyperactive trait (HA). Crossbreeding SHR with Wistar-Kyoto (WKY) control rats, which are nonHT and nonHA, followed by selected inbreeding produced two additional homozygous strains: WKHT and WKHA, in which the traits of HT and HA, respectively, are expressed separately. WKHT, WKHA and SHR all display LVH, but only the SHR exhibits cardiac dysfunction. We hypothesized that cardiac dysfunction in the SHR is uniquely characterized by calcium overload. We measured total cardiac Ca, Cu, Fe, K, Mg and Zn in the four strains. We found elevated Ca and depressed Cu, Mg and Zn with HT, but not unique to SHR. We surmise that HT promotes aberrant regulation of cardiac Ca(2+), Cu(2+), Mg(2+) and Zn(2+), which does not necessarily result in cardiac dysfunction. Interestingly, Cu was elevated in HA strains compared to nonHA counterparts. We then analyzed gene expression as mRNA of Cu-containing proteins, most notably mitochondrial-Cox, Dbh, Lox, Loxl1, Loxl2, Sod1 and Tyr. The gene expression profiles of Lox, Loxl1, Loxl2 and Sod1 were found especially high in the WKHA, which if reflective of protein content could account for the high Cu content in the WKHA. The mRNA of other genes, notably Mb, Fxyd1, Maoa and Maob were also examined. We found that Maoa gene expression and monoamine oxidase-A (MAO-A) protein content were low in the SHR compared to the other strains. The finding that MAO-A protein is low in the SHR and normal in the WKHT and WKHA strains is most consistent with the idea that MAO-A protects against the development of cardiac dysfunction in LVH but not against LVH in these rats.

  17. Prevention of airway hyperresponsiveness induced by left ventricular dysfunction in rats

    PubMed Central

    2012-01-01

    Background The effectiveness of strategies for treatment of the altered static lung volume and against the development of bronchial hyperreactivity (BHR) following a left ventricular dysfunction (LVD) induced by myocardial ischaemia was investigated in a rat model of sustained postcapillary pulmonary hypertension. Methods Airway resistance (Raw) was identified from the respiratory system input impedance (Zrs) in four groups of rats. End-expiratory lung volume (EELV) was determined plethysmographically, and Zrs was measured under baseline conditions and following iv infusions of 2, 6 or 18 μg/kg/min methacholine. Sham surgery was performed in the rats in Group C, while the left interventricular coronary artery was ligated and Zrs and its changes following identical methacholine challenges were reassessed in the same rats 8 weeks later, during which no treatment was applied (Group I), or the animals were treated daily with a combination of an angiotensin enzyme converter inhibitor and a diuretic (enalapril and furosemide, Group IE), or a calcium channel blocker (diltiazem, Group ID). The equivalent dose of methacholine causing a 100% increase in Raw (ED50) was determined in each group. Diastolic pulmonary arterial pressure (PapD) was assessed by introducing a catheter into the pulmonary artery. Results The sustained presence of a LVD increased PapD in all groups of rats, with variable but significant elevations in Groups I (p = 0.004), ID (p = 0.013) and IE (p = 0.006). A LVD for 8 weeks induced no changes in baseline Raw but elevated the EELV independently of the treatments. In Group I, BHR consistently developed following the LVD, with a significant decrease in ED50 from 10.0 ± 2.5 to 6.9 ± 2.5 μg/kg/min (p = 0.006). The BHR was completely abolished in both Groups ID and IE, with no changes in ED50 (9.5 ± 3.6 vs. 10.7 ± 4.7, p = 0.33 and 10.6 ± 2.1 vs. 9.8 ± 3.5 μg/kg/min p = 0.56, respectively). Conclusions

  18. Isolated congenital cardiac diverticulum originating from the left ventricular apex: Report of a pediatric case

    PubMed Central

    Uysal, Fahrettin; Bostan, Ozlem Mehtap; Toprak, Muhammed Hamza Halil; Signak, Isik Senkaya; Cil, Ergun

    2016-01-01

    Congenital ventricular diverticulum is a rare cardiac anomaly defined as a localized protrusion of the ventricular free wall. Although, it is usually asymptomatic, complications such as embolism, infective endocarditis, and arrhythmias can occur. The diagnosis can be made by echocardiography, cardiac magnetic resonance imaging, or catheter angiography. Surgical resection is the treatment of choice in symptomatic patients, whereas the management of asymptomatic patients often represents a therapeutic dilemma. We report here, a 9-month-old patient with asymptomatic congenital left ventricular (LV) diverticulum associated with epigastric hernia. PMID:27212863

  19. Stabilization of mitochondrial membrane potential prevents doxorubicin-induced cardiotoxicity in isolated rat heart

    SciTech Connect

    Montaigne, David; Marechal, Xavier; Baccouch, Riadh; Modine, Thomas; Preau, Sebastien; Zannis, Konstantinos; Marchetti, Philippe; Lancel, Steve; Neviere, Remi

    2010-05-01

    The present study was undertaken to examine the effects of doxorubicin on left ventricular function and cellular energy state in intact isolated hearts, and, to test whether inhibition of mitochondrial membrane potential dissipation would prevent doxorubicin-induced mitochondrial and myocardial dysfunction. Myocardial contractile performance and mitochondrial respiration were evaluated by left ventricular tension and its first derivatives and cardiac fiber respirometry, respectively. NADH levels, mitochondrial membrane potential and glucose uptake were monitored non-invasively via epicardial imaging of the left ventricular wall of Langendorff-perfused rat hearts. Heart performance was reduced in a time-dependent manner in isolated rat hearts perfused with Krebs-Henseleit solution containing 1 muM doxorubicin. Compared with controls, doxorubicin induced acute myocardial dysfunction (dF/dt{sub max} of 105 +- 8 mN/s in control hearts vs. 49 +- 7 mN/s in doxorubicin-treated hearts; *p < 0.05). In cardiac fibers prepared from perfused hearts, doxorubicin induced depression of mitochondrial respiration (respiratory control ratio of 4.0 +- 0.2 in control hearts vs. 2.2 +- 0.2 in doxorubicin-treated hearts; *p < 0.05) and cytochrome c oxidase kinetic activity (24 +- 1 muM cytochrome c/min/mg in control hearts vs. 14 +- 3 muM cytochrome c/min/mg in doxorubicin-treated hearts; *p < 0.05). Acute cardiotoxicity induced by doxorubicin was accompanied by NADH redox state, mitochondrial membrane potential, and glucose uptake reduction. Inhibition of mitochondrial permeability transition pore opening by cyclosporine A largely prevented mitochondrial membrane potential dissipation, cardiac energy state and dysfunction. These results suggest that in intact hearts an impairment of mitochondrial metabolism is involved in the development of doxorubicin cardiotoxicity.

  20. Characterization of a beta-adrenergically inhibited K+ current in rat cardiac ventricular cells.

    PubMed Central

    Scamps, F

    1996-01-01

    1. The electrophysiological properties and beta-adrenergic regulation of a non-inactivating K+ current were studied using the whole-cell patch-clamp technique (22 +/- 2 degrees C) in adult rat ventricular cells. 2. In the presence of 4-aminopyridine, an inhibitor of the rapidly inactivating current, the depolarization-activated current consisted only of a slowly decaying outward current (IK). The presence of a non-inactivating current (ISS) was revealed when analysing inactivation curves. 3. IK and ISS were both sensitive to 50 mM tetraethylammonium and 10 mM 4-aminopyridine inhibition. IK was totally blocked by 100 microM clofilium, while ISS was not inhibited but rather enhanced by this class III anti-arrhythmic agent. 4. Unlike IK, ISS was only slightly decreased by depolarizing prepulses and it did not show time-dependent inactivation when measured during 500 ms depolarizations. 5. ISS was decreased by the beta-adrenergic agonist isoprenaline (1 microM). Forskolin (10 microM) mimicked the effects of isoprenaline. The non-specific beta-adrenergic antagonist, propranolol (3 microM), and a specific beta 1-adrenergic antagonist, CGP 20712A (0.3 microM), both prevented the effects of isoprenaline. Cell perfusion with 100 microM PKI6-22, a peptide inhibitor of the cyclic AMP-dependent protein kinase, reduced or abolished the effects of isoprenaline. 6. The dose-response curve for the inhibition of ISS by isoprenaline was positioned to the left of that for the calcium current. The threshold dose and the dose giving 50% of the maximal effect were, respectively, 0.1 and 0.21 nM for ISS and 1 and 4.3 nM for ICa. 7. In view of the high sensitivity of ISS to isoprenaline, its possible physiological effect was evaluated on action potential duration during beta-adrenergic stimulation. At 1 nM, a concentration that did not increase ICa, isoprenaline induced a significant prolongation of action potential duration as a consequence of ISS inhibition. With 1 microM isoprenaline

  1. Evaluation of activity inotropic of a new steroid derivative using an isolated rat heart model

    PubMed Central

    Lauro, Figueroa-Valverde; Francisco, Díaz-Cedillo; Elodia, García-Cervera; Eduardo, Pool-Gómez; Maria, López-Ramos; Marcela, Rosas-Nexticapa; Lenin, Hau-Heredia; Bety, Sarabia-Alcocer; Landy, Campos-Ramos

    2014-01-01

    There are studies which indicate that some steroid derivatives have inotropic activity; nevertheless, the cellular site and mechanism of action at cardiovascular level is very confusing. In order, to clarify these phenomena in this study, a new estradiol derivative was synthesized with the objective of to evaluate its biological activity on left ventricular pressure and characterize their molecular mechanism. The Langendorff technique was used to measure changes on perfusion pressure and coronary resistance in an isolated rat heart model in absence or presence of the estradiol derivative. Additionally, to characterize the molecular mechanism involved in the inotropic activity induced by the OTBDS-estradiol-hexanoic acid derivative was evaluated by measuring left ventricular pressure in absence or presence of following compounds; tamoxifen, prazosin, metoprolol, indomethacin and nifedipine. The results showed that the OTBDS-estradiol-hexanoic acid derivative significantly increased the perfusion pressure and coronary resistance in comparison with the control conditions. Additionally, other data indicate that OTBDS-estradiol-hexanoic acid derivative increase left ventricular pressure in a dose-dependent manner (0.001 to 100 nM); nevertheless, this phenomenon was significantly inhibited only by nifedipine at a dose of 1 nM. These data suggest that positive inotropic activity induced by the OTBDS-estradiol-hexanoic acid derivative is via activation of L-type calcium channel. This phenomenon is a particularly interesting because the positive inotropic activity induced by this steroid derivative involves a molecular mechanism different in comparison with other positive inotropic drugs. PMID:24995077

  2. Evaluation of activity inotropic of a new steroid derivative using an isolated rat heart model.

    PubMed

    Lauro, Figueroa-Valverde; Francisco, Díaz-Cedillo; Elodia, García-Cervera; Eduardo, Pool-Gómez; Maria, López-Ramos; Marcela, Rosas-Nexticapa; Lenin, Hau-Heredia; Bety, Sarabia-Alcocer; Landy, Campos-Ramos

    2014-01-01

    There are studies which indicate that some steroid derivatives have inotropic activity; nevertheless, the cellular site and mechanism of action at cardiovascular level is very confusing. In order, to clarify these phenomena in this study, a new estradiol derivative was synthesized with the objective of to evaluate its biological activity on left ventricular pressure and characterize their molecular mechanism. The Langendorff technique was used to measure changes on perfusion pressure and coronary resistance in an isolated rat heart model in absence or presence of the estradiol derivative. Additionally, to characterize the molecular mechanism involved in the inotropic activity induced by the OTBDS-estradiol-hexanoic acid derivative was evaluated by measuring left ventricular pressure in absence or presence of following compounds; tamoxifen, prazosin, metoprolol, indomethacin and nifedipine. The results showed that the OTBDS-estradiol-hexanoic acid derivative significantly increased the perfusion pressure and coronary resistance in comparison with the control conditions. Additionally, other data indicate that OTBDS-estradiol-hexanoic acid derivative increase left ventricular pressure in a dose-dependent manner (0.001 to 100 nM); nevertheless, this phenomenon was significantly inhibited only by nifedipine at a dose of 1 nM. These data suggest that positive inotropic activity induced by the OTBDS-estradiol-hexanoic acid derivative is via activation of L-type calcium channel. This phenomenon is a particularly interesting because the positive inotropic activity induced by this steroid derivative involves a molecular mechanism different in comparison with other positive inotropic drugs.

  3. Effects of Rosiglitazone with Insulin Combination Therapy on Oxidative Stress and Lipid Profile in Left Ventricular Muscles of Diabetic Rats

    PubMed Central

    Kavak, Servet; Ayaz, Lokman; Emre, Mustafa

    2012-01-01

    Purpose. In this study, we tested the hypothesis that rosiglitazone (RSG) with insulin is able to quench oxidative stress initiated by high glucose through prevention of NAD(P)H oxidase activation. Methods and Materials. Male albino Wistar rats were randomly divided into an untreated control group (C), a diabetic group (D) that was treated with a single intraperitoneal injection of streptozotocin (45 mgkg−1), and rosiglitazone group that was treated with RSG twice daily by gavage and insulin once daily by subcutaneous injection (group B). HbA1c and blood glucose levels in the circulation and malondialdehyde and 3-nitrotyrosine levels in left ventricular muscle were measured. Result. Treatment of D rats with group B resulted in a time-dependent decrease in blood glucose. We found that the lipid profile and HbA1c levels in group B reached the control group D rat values at the end of the treatment period. There was an increase in 3-nitrotyrosine levels in group D compared to group C. Malondialdehyde and 3-nitrotyrosine levels were found to be decreased in group B compared to group D (P < 0.05). Conclusion. Our data suggests that the treatment of diabetic rats with group B for 8 weeks may decrease the oxidative/nitrosative stress in left ventricular tissue of rats. Thus, in diabetes-related vascular diseases, group B treatment may be cardioprotective. PMID:22829806

  4. Ventricular filling slows epicardial conduction and increases action potential duration in an optical mapping study of the isolated rabbit heart

    NASA Technical Reports Server (NTRS)

    Sung, Derrick; Mills, Robert W.; Schettler, Jan; Narayan, Sanjiv M.; Omens, Jeffrey H.; McCulloch, Andrew D.; McCullough, A. D. (Principal Investigator)

    2003-01-01

    INTRODUCTION: Mechanical stimulation can induce electrophysiologic changes in cardiac myocytes, but how mechanoelectric feedback in the intact heart affects action potential propagation remains unclear. METHODS AND RESULTS: Changes in action potential propagation and repolarization with increased left ventricular end-diastolic pressure from 0 to 30 mmHg were investigated using optical mapping in isolated perfused rabbit hearts. With respect to 0 mmHg, epicardial strain at 30 mmHg in the anterior left ventricle averaged 0.040 +/- 0.004 in the muscle fiber direction and 0.032 +/- 0.006 in the cross-fiber direction. An increase in ventricular loading increased average epicardial activation time by 25%+/- 3% (P < 0.0001) and correspondingly decreased average apparent surface conduction velocity by 16%+/- 7% (P = 0.007). Ventricular loading did not significantly alter action potential duration at 20% repolarization (APD20) but did at 80% repolarization (APD80), from 179 +/- 7 msec to 207 +/- 5 msec (P < 0.0001). The dispersion of APD20 was decreased with loading from 19 +/- 2 msec to 13 +/- 2 msec (P = 0.024), whereas the dispersion of APD80 was not significantly changed. These electrophysiologic changes with ventricular loading were not affected by the nonspecific stretch-activated channel blocker streptomycin (200 microM) and were not attributable to changes in myocardial perfusion or the presence of an electromechanical decoupling agent (butanedione monoxime) during optical mapping. CONCLUSION: Acute loading of the left ventricle of the isolated rabbit heart decreased apparent epicardial conduction velocity and increased action potential duration by a load-dependent mechanism that may not involve stretch-activated channels.

  5. Simultaneous recording of ATP-sensitive K+ current and intracellular Ca2+ in anoxic rat ventricular myocytes. Effects of glibenclamide.

    PubMed

    Russ, U; Englert, H; Schölkens, B A; Gögelein, H

    1996-05-01

    We investigated the temporal relationship between the adenosine triphosphate-sensitive K current (KATP current), hypoxic shortening and Ca accumulation in cardiomyocytes exposed to anoxia or metabolic inhibition. Whole-cell, patch-clamp experiments were performed with nonstimulated isolated rat heart ventricular muscle cells loaded with the Ca-sensitive fluorescent dye 1-[2-(5-carboxyoxazol-2-yl)-6-aminobenzofuran-5-oxy]-2-(2'- amino-5'-methylphenoxy) ethane-N,N,N',N'-tetraacetic acid (fura-2) via the patch pipette. After approximately 8 min anoxia, the KATP current started to rise and reached a maximum of 21.3 +/- 3.7 nA (n = 5, recorded at 0 mV clamp potential) within 1-3 min. At that time hypoxic contracture also occurred. Resting cytoplasmic free calcium (Cai) did not change significantly before hypoxic shortening. After hypoxic contracture, the KATP current decreased and Cai started to rise, reaching about 1 micromol/l. The presence of glibenclamide (10 micromol/l) in the bath reduced the anoxia-induced KATP current by more than 50%, but did not significantly influence the time dependence of current, hypoxic shortening and Cai, or the magnitude of Cai. Metabolic inhibition with 1.5 mmol/l CN resulted in KATP current increase and hypoxic shortening, occurring somewhat earlier than under anoxia, but all other parameters were comparable. In non-patch-clamped cells loaded with fura-2 AM ester and field-stimulated with 1 Hz, 1 micronol/l glibenclamide had no significant effect on the magnitude of the Cai increase caused by exposure of the cells to 1.5 mmol/l CN-. After CN- wash-out in non-patch-clamped cells, Cai declined, oscillated and finally returned to control values. It can be concluded that glibenclamide inhibits anoxia-induced KATP currents only partially and has no significant effect on anoxia-induced rise in resting Cai.

  6. Ultrastructural localization of calsequestrin in adult rat atrial and ventricular muscle cells

    PubMed Central

    1985-01-01

    The distribution of calsequestrin in rat atrial and ventricular myocardial cells was determined by indirect immunocolloidal gold labeling of ultrathin frozen sections. The results presented show that calsequestrin is confined to the sarcoplasmic reticulum where it is localized in the lumen of the peripheral and the interior junctional sarcoplasmic reticulum as well as in the lumen of the corbular sarcoplasmic reticulum, but absent from the lumen of the network sarcoplasmic reticulum. Comparison of these results with our previous studies on the distribution of the Ca2+ + Mg2+-dependent ATPase of the cardiac sarcoplasmic reticulum show directly that the Ca2+ + Mg2+- dependent ATPase and calsequestrin are confined to distinct regions within the continuous sarcoplasmic reticulum membrane. Assuming that calsequestrin provides the major site of Ca2+ sequestration in the lumen of the sarcoplasmic reticulum, the results presented support the idea that both junctional (interior and peripheral) and specialized nonjunctional (corbular) regions of the sarcoplasmic reticulum are involved in Ca2+ storage and possibly release. Furthermore, the structural differences between the junctional and the corbular sarcoplasmic reticulum support the possibility that Ca2+ storage and/or release from the lumen of the junctional and the corbular sarcoplasmic reticulum are regulated by different physiological signals. PMID:4008530

  7. Biphasic effects of hyposmotic challenge on excitation-contraction coupling in rat ventricular myocytes.

    PubMed

    Brette, F; Calaghan, S C; Lappin, S; White, E; Colyer, J; Le Guennec, J Y

    2000-10-01

    The effects of short (1 min) and long (7-10 min) exposure to hyposmotic solution on excitation-contraction coupling in rat ventricular myocytes were studied. After short exposure, the action potential duration at 90% repolarization (APD(90)), the intracellular Ca(2+) concentration ([Ca(2+)](i)) transient amplitude, and contraction increased, whereas the L-type Ca(2+) current (I(Ca, L)) amplitude decreased. Fractional sarcoplasmic reticulum (SR) Ca(2+) release increased but SR Ca(2+) load did not. After a long exposure, I(Ca,L), APD(90), [Ca(2+)](i) transient amplitude, and contraction decreased. The abbreviation of APD(90) was partially reversed by 50 microM DIDS, which is consistent with the participation of Cl(-) current activated by swelling. After 10-min exposure to hyposmotic solution in cells labeled with di-8-aminonaphthylethenylpyridinium, t-tubule patterning remained intact, suggesting the loss of de-t-tubulation was not responsible for the fall in I(Ca,L). After long exposure, Ca(2+) load of the SR was not increased, and swelling had no effect on the site-specific phosphorylation of phospholamban, but fractional SR Ca(2+) release was depressed. The initial positive inotropic response to hyposmotic challenge may be accounted for by enhanced coupling between Ca(2+) entry and release. The negative inotropic effect of prolonged exposure can be accounted for by shortening of the action potential duration and a fall in the I(Ca,L) amplitude. PMID:11009486

  8. A comparative assessment of fluo Ca2+ indicators in rat ventricular myocytes

    PubMed Central

    Hagen, Brian M.; Boyman, Liron; Kao, Joseph P.Y.; Lederer, W. Jonathan

    2012-01-01

    Summary The fluo family of indicators is frequently used in studying Ca2+ physiology; however, choosing which fluo indicator to use is not obvious. Indicator properties are typically determined in well-defined aqueous solutions. Inside cells, however, the properties can change markedly. We have characterized each of three fluo variants (fluo-2MA, fluo-3 and fluo-4) in two forms—the acetoxymethyl (AM) ester and the K+ salt. We loaded indicators into rat ventricular myocytes and used confocal microscopy to monitor depolarization-induced fluorescence changes and fractional shortening. Myocytes loaded with the indicator AM esters showed significantly different Ca2+ transients and fractional shortening kinetics. Loading the K+ salts via whole-cell patch-pipette eliminated differences between fluo-3 and fluo-4, but not fluo-2. Cells loaded with different indicator AM esters showed different staining patterns—suggesting differential loading into organelles. Ca2+ dissociation constants (Kd,Ca), measured in protein-rich buffers mimicking the cytosol were significantly higher than values determined in simple buffers. This increase in Kd,Ca (decrease in Ca2+ affinity) was greatest for fluo-3 and fluo-4, and least for fluo-2. We conclude that the structurally-similar fluo variants differ with respect to cellular loading, subcellular compartmentalization, and intracellular Ca2+ affinity. Therefore, judicious choice of fluo indicator and loading procedure is advisable when designing experiments. PMID:22721780

  9. Effects of cannabidiol on contractions and calcium signaling in rat ventricular myocytes.

    PubMed

    Ali, Ramez M; Al Kury, Lina T; Yang, Keun-Hang Susan; Qureshi, Anwar; Rajesh, Mohanraj; Galadari, Sehamuddin; Shuba, Yaroslav M; Howarth, Frank Christopher; Oz, Murat

    2015-04-01

    Cannabidiol (CBD), a major nonpsychotropic cannabinoid found in Cannabis plant, has been shown to influence cardiovascular functions under various physiological and pathological conditions. In the present study, the effects of CBD on contractility and electrophysiological properties of rat ventricular myocytes were investigated. Video edge detection was used to measure myocyte shortening. Intracellular Ca(2+) was measured in cells loaded with the Ca(2+) sensitive fluorescent indicator fura-2 AM. Whole-cell patch clamp was used to measure action potential and Ca(2+) currents. Radioligand binding was employed to study pharmacological characteristics of CBD binding. CBD (1μM) caused a significant decrease in the amplitudes of electrically evoked myocyte shortening and Ca(2+) transients. However, the amplitudes of caffeine-evoked Ca(2+) transients and the rate of recovery of electrically evoked Ca(2+) transients following caffeine application were not altered. CBD (1μM) significantly decreased the duration of APs. Further studies on L-type Ca(2+) channels indicated that CBD inhibits these channels with IC50 of 0.1μM in a voltage-independent manner. Radioligand studies indicated that the specific binding of [(3)H]Isradipine, was not altered significantly by CBD. The results suggest that CBD depresses myocyte contractility by suppressing L-type Ca(2+) channels at a site different than dihydropyridine binding site and inhibits excitation-contraction coupling in cardiomyocytes.

  10. Effects of cannabidiol on contractions and calcium signaling in rat ventricular myocytes.

    PubMed

    Ali, Ramez M; Al Kury, Lina T; Yang, Keun-Hang Susan; Qureshi, Anwar; Rajesh, Mohanraj; Galadari, Sehamuddin; Shuba, Yaroslav M; Howarth, Frank Christopher; Oz, Murat

    2015-04-01

    Cannabidiol (CBD), a major nonpsychotropic cannabinoid found in Cannabis plant, has been shown to influence cardiovascular functions under various physiological and pathological conditions. In the present study, the effects of CBD on contractility and electrophysiological properties of rat ventricular myocytes were investigated. Video edge detection was used to measure myocyte shortening. Intracellular Ca(2+) was measured in cells loaded with the Ca(2+) sensitive fluorescent indicator fura-2 AM. Whole-cell patch clamp was used to measure action potential and Ca(2+) currents. Radioligand binding was employed to study pharmacological characteristics of CBD binding. CBD (1μM) caused a significant decrease in the amplitudes of electrically evoked myocyte shortening and Ca(2+) transients. However, the amplitudes of caffeine-evoked Ca(2+) transients and the rate of recovery of electrically evoked Ca(2+) transients following caffeine application were not altered. CBD (1μM) significantly decreased the duration of APs. Further studies on L-type Ca(2+) channels indicated that CBD inhibits these channels with IC50 of 0.1μM in a voltage-independent manner. Radioligand studies indicated that the specific binding of [(3)H]Isradipine, was not altered significantly by CBD. The results suggest that CBD depresses myocyte contractility by suppressing L-type Ca(2+) channels at a site different than dihydropyridine binding site and inhibits excitation-contraction coupling in cardiomyocytes. PMID:25711828

  11. Heat stress activates AKT via focal adhesion kinase-mediated pathway in neonatal rat ventricular myocytes.

    PubMed

    Wei, Hongguang; Vander Heide, Richard S

    2008-08-01

    Heat stress (HS)-induced cardioprotection is associated with increased paxillin localization to the membrane fraction of neonatal rat ventricular myocytes (NRVM). The purpose of this study was 1) to examine the subcellular signaling pathways activated by HS; 2) to determine whether myocardial stress organizes and activates an integrated survival pathway; and 3) to investigate potential downstream cytoprotective proteins activated by HS. After HS, NRVM were subjected to chemical inhibitors (CI) designed to simulate ischemia by inhibiting both glycolysis and mitochondrial respiration. Protein kinase B (AKT) expression (wild type) was increased selectively with an adenoviral vector. Cell signaling was analyzed with Western blot analysis, while oncosis/apoptosis was assayed by measuring Trypan blue exclusion and/or terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) staining, respectively. HS increased phosphorylation of focal adhesion kinase (FAK) at tyrosine 397 but did not adversely affect the viability of NRVM before CI. HS increased association between FAK and phosphatidylinositol 3-kinase as well as causing a significant increase in AKT activity. Increased expression of wild-type AKT protected myocytes from both oncotic and apoptotic cell death. Increased expression of a FAK inhibitor, FRNK, reduced AKT phosphorylation in response to HS both at time 0 and after 10 min of CI compared with myocytes expressing empty virus. We conclude that myocardial stress activates cytoskeleton-based signaling pathways that are associated with protection from lethal cell injury.

  12. Effects of an early treatment with lisinopril and isosorbide-5-mononitrate on hemodynamics and late ventricular remodelling in rats with 9-week myocardial infarction.

    PubMed

    Riva, E; Kurosaki, M; Porzio, S; Latini, R; Lagrasta, C; Olivetti, G

    1995-06-01

    This study was undertaken to assess whether the converting enzyme inhibitor lisinopril, and the long-acting nitrate, isosorbide-5-mononitrate, affect left ventricle dysfunction and anatomical remodelling in rats with myocardial infarction. Lisinopril, isosorbide-5-mononitrate or vehicle were given to rats (n = 10-14 per group) immediately after coronary artery occlusion (by an intravenous bolus) and then for nine weeks (in drinking water). At the end of the study, left ventricular pressures were measured, the heart arrested in diastole, and infarct size, left ventricular chamber volume and wall thicknesses measured. Lisinopril significantly lowered systemic blood pressure and left ventricular systolic pressure in rats with small (< 15% scarred tissue of the left ventricle) and large (> 15%) infarcts; the weight of the left ventricle (including the septum) was reduced by 24% and 28% in animals with small and large infarcts, respectively. Lisinopril lowered left ventricular end-diastolic pressure (by 33% and 39%) and chamber volume (by 4% and 34%) in rats with small and large infarcts, respectively, compared with controls (NS). The combined anatomical and hemodynamic changes led to a reduction of the circumferential wall stress by 20% and 44% in lisinopril-treated rats with small and large infarcts, respectively (NS). No significant changes were seen in the nitrate-treated hearts compared with controls. Lisinopril, given early after myocardial infarction and continued for nine weeks, significantly affected cardiac hemodynamics and ventricular weights in rats with infarcts of different sizes.(ABSTRACT TRUNCATED AT 250 WORDS)

  13. Insulin internalization in isolated rat hepatocytes

    SciTech Connect

    Galan, J.; Trankina, M.; Noel, R.; Ward, W. )

    1990-02-26

    This project was designed to determine whether neomycin, an aminoglycoside antibiotic, has a significant effect upon the pathways of ligand endocytosis in isolated rat hepatocytes. The pathways studied include receptor-mediated endocytosis and fluid-phase endocytosis. Neomycin causes a dose-dependent acceleration of {sup 125}I-insulin internalization. Since fluid-phase endocytosis can also be a significant factor in {sup 125}I-insulin internalization, lucifer yellow (LY), a marker for fluid-phase endocytosis, was incorporated into an assay similar to the {sup 125}I-insulin internalization procedure. In the presence of 5 mM neomycin, a significant increase in LY uptake was evident at 0.2 and 0.4 mg/ml of LY. At 0.8 mg/ml, a decrease in LY uptake was observed. The increased rate of {sup 125}I-insulin internalization in the presence of neomycin was intriguing. Since one action of neomycin is to inhibit phosphoinositidase C, it suggests that the phosphotidylinositol cycle may be involved in ligand internalization by hepatocytes. At low insulin concentrations, receptor-mediated uptake predominates. Fluid-phase uptake can become an important uptake route as insulin concentrations are increased. Since neomycin stimulates fluid-phase endocytosis, it must also be taken into account when measuring ligand internalization.

  14. Heat production of quiescent ventricular trabeculae isolated from guinea-pig heart.

    PubMed Central

    Daut, J; Elzinga, G

    1988-01-01

    1. A new calorimetric technique has been developed which allows continuous measurement of the rate of energy expenditure in superfused preparations of cardiac muscle. Thin trabeculae of guinea-pig ventricular muscle were mounted in a Perspex tube of 0.8 mm inner diameter and the temperature difference of the perfusate upstream and downstream of the preparation was measured. 2. The resting heat rate of trabeculae of 240-575 microns diameter from guinea-pig heart was determined repeatedly for up to 6 h after cardiectomy. It did not vary with time during the course of the experiment. 3. The average resting heat rate measured in HEPES-buffered Tyrode solution containing 20 mM-glucose and 2 mM-pyruvate as substrates was 130 +/- 29 mW/g dry weight or 36 +/- 8 mW/cm3 of tissue (n = 15). This is an order of magnitude larger than the resting heat rate reported in the literature for isolated cardiac preparations. 4. After omitting the pyruvate from the superfusate the resting heat rate decreased to 60-70% of its steady value within 4 min. After readmission of pyruvate this effect was reversed. The average resting heat rate with glucose as sole substrate was 23 +/- 4 mW/cm3. 5. Uncoupling of the mitochondria by 50 microM-2,4-dinitrophenol (DNP) increased the heat rate up to 170 mW/cm3. This effect could be maintained for several minutes and was fully reversible. Raising the external K+ concentration to 150 mM (NaCl replaced by KCl) induced a transient rise in the rate of heat production up to 115 mW/cm3. 6. The heat production during uncoupling of the mitochondria and during potassium contractures was inversely related to the diameter of the preparation. Calculation based on Hill's equation (Hill, 1928) indicated that this was caused by the development of anoxia at the core of the preparation. 7. In contrast, the rate of heat production of quiescent preparations was not correlated with diameter and calculation indicated that at rest there was no anoxic core. The high value of

  15. Chronic hydrogen-rich saline treatment reduces oxidative stress and attenuates left ventricular hypertrophy in spontaneous hypertensive rats.

    PubMed

    Yu, Yong-Sheng; Zheng, Hao

    2012-06-01

    In hypertensive animals and patients, oxidative stress represents the primary risk factor for progression of left ventricular hypertrophy. Recently, it has been demonstrated that hydrogen, as a novel antioxidant, can selectively reduce hydroxyl radicals and peroxynitrite anion to exert therapeutic antioxidant activity. In the current study, we explored the effect of chronic treatment with hydrogen-rich saline (HRS) on left ventricular hypertrophy in spontaneously hypertensive rats (SHR). The 8-week-old male SHR and age-matched Wistar-Kyoto rats (WKY) were randomized into HRS-treated (6 ml/kg/day for 3 months, i.p.) and vehicle-treated groups. HRS treatment had no significant effect on blood pressure, but it effectively attenuated left ventricular hypertrophy in SHR. HRS treatment abated oxidative stress, restored the activity of antioxidant enzymes including GPx, GST, catalase, and SOD, suppressed NADPH oxidase activity and downregulated Nox2 and Nox4 expression in left ventricles of SHR. HRS treatment suppressed pro-inflammatory cytokines including IL-1β, IL-6, TNF-α, and MCP-1, and inhibited NF-κB activation through preventing IκBα degradation in left ventricles of SHR. HRS treatment preserved mitochondrial function through restoring electron transport chain enzyme activity, repressing ROS formation, and enhancing ATP production in left ventricles of SHR. Moreover, HRS treatment suppressed ACE expression and locally reduced angiotensin II generation in left ventricles of SHR. In conclusion, HRS treatment attenuates left ventricular hypertrophy through abating oxidative stress, suppressing inflammatory process, preserving mitochondrial function, in which suppression of HRS on angiotensin II in left ventricles locally might be involved.

  16. [Effect of allitridum on remodeling of the transient outward potassium current of ventricular myocytes of spontaneously hypertensive rats].

    PubMed

    Dan, Qing; Zhao, Ying; Wu, Zhi-juan; Zhu, Chao; Liu, Li; Xu, Bin; Liu, Yu-qi; Chen, Qi; Li, Yang

    2015-01-01

    We aimed to study the effect of allitridum (All) on the transient outward potassium current (Ito) of ventricular myocytes of spontaneously hypertensive rats (SHR). Totally 30 male SHRs were randomly divided into three groups: low-dose All group (7.5 mg·kg(-1)), high-dose All group (15.0 mg·kg(-1)) and normal saline group. The other 10 sex and age matched Wistar-kyoto rats (WKY) were also taken as control group (WKY group). All animals received i.p. administration for 8 weeks. The dual enzymatic method was used to separate single ventricular myocyte from animals. Patch-clamp technique was used to record Ito and analyze the effect of All on the current. It was shown that the left ventricular hypertrophy of SHR was reversed significantly by All. Furthermore, the density of Ito was recovered in both high and low dose All groups. The peak current densities of Ito were enhanced from 18.23±3.64 to 25.17±2.86 pA/pF (P<0.01) and 36.47±5.42 pA/pF (P<0.01) at +50 mV by All 7.5 mg·kg(-1) and 15.0 mg·kg(-1), respectively, which was not significantly different with WKY group. The effect was associated with positive shift of the steady-state, close-state inactivation, and shortened recovery from inactivation of Ito. It is concluded that All decreases the remodeling of Ito of ventricular hypertrophic myocytes of SHR. PMID:25924473

  17. Overexpression of VEGF-C attenuates chronic high salt intake-induced left ventricular maladaptive remodeling in spontaneously hypertensive rats.

    PubMed

    Yang, Guo-Hong; Zhou, Xin; Ji, Wen-Jie; Zeng, Shan; Dong, Yan; Tian, Lu; Bi, Ying; Guo, Zhao-Zeng; Gao, Fei; Chen, Hong; Jiang, Tie-Min; Li, Yu-Ming

    2014-02-15

    Recent studies have shown that the tonicity-responsive enhancer binding protein (TonEBP)/vascular endothelial growth factor-C (VEGF-C) signaling pathway-induced lymphangiogenesis provides a buffering mechanism for high salt (HS) intake-induced elevation of blood pressure (BP). Moreover, blocking of TonEBP/VEGF-C signaling by mononuclear phagocyte depletion can induce salt-sensitive hypertension in rats. We hypothesized that HS intake could have an impact on cardiac lymphangiogenesis, and regulation of VEGF-C bioactivity, which is largely through the main receptor for VEGFR-3, may modulate HS intake-induced left ventricular remodeling. We demonstrated upregulation of TonEBP, increased macrophage infiltration, and enhanced lymphangiogenesis in the left ventricles of spontaneously hypertensive rats (SHR) that were fed a HS diet (8.0% NaCl). Then, retrovirus vectors capable of overexpression (ΔNΔC/VEGF-C/Cys152Ser, used for overexpressing VEGF-C) and blocking (VEGFR-3-Rg, used for trapping of bioactive VEGF-C) of VEGF-C and control vector (pLPCX) were intravenously administered to SHR from week 9 of a 12-wk HS loading period. At the end of the HS challenge, overexpression of VEGF-C led to enhanced cardiac lymphangiogenesis, decreased myocardial fibrosis, and macrophage infiltration, preserved left ventricular functions, as well as decreased blood pressure level compared with the HS group and the control vector-treated HS group. In contrast, systemic blocking of VEGF-C was associated with elevation of blood pressure level and an exacerbation of hypertensive left ventricular remodeling, as indicated by increased fibrosis and macrophage infiltration, and diminished lymphangiogenesis. Hence, our findings highlight that VEGF-C/VEGFR-3 is a promising therapeutic target to attenuate hypertensive left ventricular remodeling induced by HS intake, presumably via blood pressure-dependent and -independent mechanisms. PMID:24337460

  18. Dehydroepiandrosterone reverses chronic hypoxia/reoxygenation-induced right ventricular dysfunction in rats.

    PubMed

    Dumas de La Roque, Eric; Bellance, Nadège; Rossignol, Rodrigue; Begueret, Hugues; Billaud, Marie; dos Santos, Pierre; Ducret, Thomas; Marthan, Roger; Dahan, Diana; Ramos-Barbón, David; Amor-Carro, Óscar; Savineau, Jean-Pierre; Fayon, Michael

    2012-12-01

    Dehydroepiandrosterone (DHEA) prevents chronic hypoxia-induced pulmonary hypertension and associated right ventricle dysfunction in rats. In this animal model, reoxygenation following hypoxia reverses pulmonary hypertension but not right ventricle dysfunction. We thus studied the effect of DHEA on the right ventricle after reoxygenation, i.e. after a normoxic recovery phase secondary to chronic hypoxia in rats. Right ventricle function was assessed in vivo by Doppler echocardiography and in vitro by the isolated perfused heart technique in three groups of animals: control, recovery (21 days of hypoxia followed by 21 days of normoxia) and recovery DHEA (30 mg · kg(-1) every 2 days during the recovery phase). Right ventricle tissue was assessed by optical and electron microscopy. DHEA abolished right ventricle diastolic dysfunction, as the echographic E wave remained close to that of controls (mean ± SD 76.5 ± 2.4 and 79.7 ± 1.7 cm · s(-1), respectively), whereas it was diminished to 40.3 ± 3.7 in the recovery group. DHEA also abolished right ventricle systolic dysfunction, as shown by the inhibition of the increase in the slope of the pressure-volume curve in isolated heart. The DHEA effect was related to cardiac myocytes proliferation. In conclusion, DHEA prevents right ventricle dysfunction in this animal model by preventing cardiomyocyte alteration.

  19. CyPA-CD147-ERK1/2-cyclin D2 signaling pathway is upregulated during rat left ventricular hypertrophy.

    PubMed

    Tang, Fu-Cai; Wang, Hong-Yan; Ma, Ming-Ming; Guan, Tian-Wang; Pan, Long; Yao, Dun-Chen; Chen, Ya-Lan; Chen, Wei-Bei; Tu, Yong-Sheng; Fu, Xiao-Dong

    2015-08-25

    The changes of serum cyclophilin A (CyPA), its receptor CD147 and the downstream signaling pathway during the process of cardiac hypertrophy remain unknown. The present study aims to investigate the relationships between CyPA-CD147-ERK1/2-cyclin D2 signaling pathway and the development of cardiac hypertrophy. Left ventricular hypertrophy was prepared by 2-kidney, 2-clip in Sprague-Dawley rats and observed for 1 week, 4 and 8 weeks. Left ventricular hypertrophy was evaluated by ratio of left ventricular heart weight to body weight (LVW/BW) and cardiomyocyte cross sectional area (CSA). CyPA levels in serum were determined with a rat CyPA ELISA kit. Expressions of CyPA, CD147, phospho-ERK1/2 and cyclin D2 in left ventricular myocytes were determined by Western blot and immunostaining. Compared with sham groups, systolic blood pressure reached hypertensive levels at 4 weeks in 2K2C groups. LVW/BW and CSA in 2K2C groups were significantly increased at 4 and 8 weeks after clipping. ELISA results indicated a prominent increase in serum CyPA level associated with the degree of left ventricular hypertrophy. Western blot revealed that the expressions of CyPA, CD147, phospho-ERK1/2 and cyclin D2 in left ventricular tissues were also remarkably increased as the cardiac hypertrophy developed. The results of the present study demonstrates that serum CyPA and CyPA-CD147-ERK1/2-cyclin D2 signaling pathway in ventricular tissues are time-dependently upregulated and activated with the process of left ventricular hypertrophy. These data suggest that CyPA-CD147 signaling cascade might play a role in the pathogenesis of left ventricular hypertrophy, and CyPA might be a prognosticator of the degree of left ventricular hypertrophy. PMID:26300251

  20. Analysis of Cav1.2 and Ryanodine Receptor Clusters in Rat Ventricular Myocytes

    PubMed Central

    Scriven, David R.L.; Asghari, Parisa; Schulson, Meredith N.; Moore, Edwin D.W.

    2010-01-01

    We analyzed the distribution of ryanodine receptor (RyR) and Cav1.2 clusters in adult rat ventricular myocytes using three-dimensional object-based colocalization metrics. We found that ∼75% of the Cav1.2 clusters and 65% of the RyR clusters were within couplons, and both were roughly two and a half times larger than their extradyadic counterparts. Within a couplon, Cav1.2 was concentrated near the center of the underlying RyR cluster and accounted for ∼67% of its size. These data, together with previous findings from binding studies, enable us to estimate that a couplon contains 74 RyR tetramers and 10 copies of the α-subunit of Cav1.2. Extradyadic clusters of RyR contained ∼30 tetramers, whereas the extradyadic Cav1.2 clusters contained, on average, only four channels. Between 80% and 85% of both RyR and Cav1.2 molecules are within couplons. RyR clusters were in the closest proximity, with a median nearest-neighbor distance of 552 nm; comparable values for Cav1.2 clusters and couplons were 619 nm and 735 nm, respectively. Extradyadic RyR clusters were significantly closer together (624 nm) and closer to the couplons (674 nm) than the couplons were to each other. In contrast, the extradyadic clusters of Cav1.2 showed no preferential localization and were broadly distributed. These results provide a wealth of morphometric data that are essential for understanding intracellular Ca2+ regulation and modeling Ca2+ dynamics. PMID:21156134

  1. Pentaerythritol Tetranitrate Targeting Myocardial Reactive Oxygen Species Production Improves Left Ventricular Remodeling and Function in Rats With Ischemic Heart Failure.

    PubMed

    Fraccarollo, Daniela; Galuppo, Paolo; Neuser, Jonas; Bauersachs, Johann; Widder, Julian D

    2015-11-01

    Reduced nitric oxide bioavailability contributes to progression of cardiac dysfunction and remodeling in ischemic heart failure. Clinical use of organic nitrates as nitric oxide donors is limited by development of nitrate tolerance and reactive oxygen species formation. We investigated the effects of long-term therapy with pentaerythritol tetranitrate (PETN), an organic nitrate devoid of tolerance, in rats with congestive heart failure after extensive myocardial infarction. Seven days after coronary artery ligation, rats were randomly allocated to treatment with PETN (80 mg/kg BID) or placebo for 9 weeks. Long-term PETN therapy prevented the progressive left ventricular dilatation and improved left ventricular contractile function and relaxation in rats with congestive heart failure. Mitochondrial superoxide anion production was markedly increased in the failing left ventricular myocardium and nearly normalized by PETN treatment. Gene set enrichment analysis revealed that PETN beneficially modulated the dysregulation of mitochondrial genes involved in energy metabolism, paralleled by prevention of uncoupling protein-3, thioredoxin-2, and superoxide dismutase-2 downregulation. Moreover, PETN provided a remarkable protective effect against reactive fibrosis in chronically failing hearts. Mechanistically, induction of heme oxygenase-1 by PETN prevented mitochondrial superoxide generation, NOX4 upregulation, and ensuing formation of extracellular matrix proteins in fibroblasts from failing hearts. In summary, PETN targeting reactive oxygen species generation prevented the changes of mitochondrial antioxidant enzymes and progressive fibrotic remodeling, leading to amelioration of cardiac functional performance. Therefore, PETN might be a promising therapeutic option in the treatment of ischemic heart diseases involving oxidative stress and impairment in nitric oxide bioactivity.

  2. A high-resolution thermoelectric module-based calorimeter for measuring the energetics of isolated ventricular trabeculae at body temperature.

    PubMed

    Johnston, Callum M; Han, June-Chiew; Ruddy, Bryan P; Nielsen, Poul M F; Taberner, Andrew J

    2015-07-15

    Isolated ventricular trabeculae are the most common experimental preparations used in the study of cardiac energetics. However, the experiments have been conducted at subphysiological temperatures. We have overcome this limitation by designing and constructing a novel calorimeter with sufficiently high thermal resolution for simultaneously measuring the heat output and force production of isolated, contracting, ventricular trabeculae at body temperature. This development was largely motivated by the need to better understand cardiac energetics by performing such measurements at body temperature to relate tissue performance to whole heart behavior in vivo. Our approach uses solid-state thermoelectric modules, tailored for both temperature sensing and temperature control. The thermoelectric modules have high sensitivity and low noise, which, when coupled with a multilevel temperature control system, enable an exceptionally high temperature resolution with a noise-equivalent power an order of magnitude greater than those of other existing muscle calorimeters. Our system allows us to rapidly and easily change the experimental temperature without disturbing the state of the muscle. Our calorimeter is useful in many experiments that explore the energetics of normal physiology as well as pathophysiology of cardiac muscle.

  3. [Left-ventricular function and physical exertion tolerance in patients with myocardial infarction with isolated lesion of the coronary arteries].

    PubMed

    Golikov, A P; Levshunov, S P; Belozerov, G E

    1989-01-01

    Myocardial infarction area and left-ventricular myocardial contractility, determined by sectoral scanning, and exercise tolerance were assessed in 47 myocardial infarction patients with isolated coronary arterial lesions. The area under myocardial infarction was shown to be dependent on the site of the atherosclerotic process rather than the degree of stenosis in patients with isolated coronary arterial lesions. A relationship was established between the incidence of complications developing in the acute phase of infarction and the degree of stenosis. The disease was complicated more frequently in patients with coronary arterial occlusion as compared to those with severe coronary-arterial stenosis. High stress tolerance, irrespective of the site of myocardial infarction, is an evidence of great functional potentials in this category of patients.

  4. [Isolated left ventricular muscular diverticulum in an adult. Value of non-invasive examinations].

    PubMed

    Holeman, A; Bellorini, M; Lefevre, T; Lévy, M; Loiret, J; Huerta, F; Thébault, B; Funck, F

    1997-10-01

    The authors report a case of ventriculum in a 45 year old women investigated for chest pain. This was a congenital muscular left ventricular diverticulum confirmed by a complete imaging series including echocardiography, magnetic resonance imaging, angio-scintigraphy and conventional angiography. This diverticulum was unusual due to the fact that there was no associated congenital disease and that it was discovered in an adult. The authors review the literature and discuss the value of non-invasive imaging procedures.

  5. Prolonged asystole in a patient with an isolated left ventricular assist device.

    PubMed

    Javed, Wasim; Chaggar, Parminder S; Venkateswaran, Rajamiyer; Shaw, Steven M

    2016-09-01

    Left ventricular assist devices (LVADs) are well established in the management of end-stage heart failure as either destination therapy, a bridge prior to cardiac transplantation or during myocardial recovery. Despite LVADs requiring adequate left ventricular preload to effectively augment systemic circulation, there have been rare cases of patients with LVADs surviving sustained, normally fatal arrhythmias, such as ventricular fibrillation and asystole. Whilst current reports describe an LVAD patient surviving 15 days with such an arrhythmia, we describe the case of a patient with an LVAD surviving 104 days of asystole via a Fontan mechanism of circulation, which we believe is the longest known survival of a sustained fatal arrhythmia. This case highlights the physiology of circulations supported by LVADs and the unique challenges that may arise in managing ambulant LVAD patients, such as predicting prognosis. Given the increasing use of LVADs to treat end-stage heart failure, these issues are likely to become more frequently encountered in the future. PMID:27539188

  6. Ionic mechanism of the effects of hydrogen peroxide in rat ventricular myocytes.

    PubMed

    Ward, C A; Giles, W R

    1997-05-01

    1. Whole-cell and amphotericin-perforated patch-clamp techniques have been used to study the effects of hydrogen peroxide (H2O2) on action potentials and underlying ionic currents in single myocytes from the ventricles of adult rat hearts. 2. The results obtained differed markedly depending on the recording method utilized. Conventional whole-cell recordings, in which the myoplasm is dialysed with the contents of the pipette, failed to show any significant effects of H2O2 on the action potential or cell shortening. In contrast, when action potentials were recorded with the amphotericin-perforated patch method, H2O2 (50-200 microM) produced a marked prolongation of the action potential and an increase in cell shortening. 3. Voltage-clamp recordings with the amphotericin-perforated patch method showed that H2O2 caused no significant changes in either the Ca(2+)-independent transient outward K+ current (Ito) or the inwardly rectifying K+ current (IK1). 4. Application of tetrodotoxin (TTX; 8 x 10(-6) M), a Na+ channel blocker, largely inhibited the effects of H2O2 on the action potential. Moreover, anthopleurin A (4 x 10 (-7) M), which augments Na+ current (INa) by slowing its inactivation, mimicked the effects of H2O2 on the action potential of ventricular myocytes. These effects on INa were also blocked almost completely by TTX. 5. The hypothesis that H2O2 can augment INa by slowing its kinetics of inactivation was tested directly using ensemble recordings from cell-attached macropatches. These results demonstrated a significant enhancement of late opening events when H2O2 (200 microM) was included in the recording pipette. A corresponding slowing of inactivation of the ensemble INa was observed. 6. The possibility that protein kinase C (PKC) is an intracellular second messenger for the observed effects of H2O2 was examined using the blocker bisindolylmaelimide (BIS; 10(-7) M). Bath application of BIS prior to H2O2 exposure significantly delayed and also attenuated

  7. Sitagliptin decreases ventricular arrhythmias by attenuated glucose-dependent insulinotropic polypeptide (GIP)-dependent resistin signalling in infarcted rats

    PubMed Central

    Lee, Tsung-Ming; Chen, Wei-Ting; Chang, Nen-Chung

    2016-01-01

    Myocardial infarction (MI) was associated with insulin resistance, in which resistin acts as a critical mediator. We aimed to determine whether sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, can attenuate arrhythmias by regulating resistin-dependent nerve growth factor (NGF) expression in postinfarcted rats. Normoglycaemic male Wistar rats after ligating coronary artery were randomized to either vehicle or sitagliptin for 4 weeks starting 24 h after operation. Post-infarction was associated with increased myocardial noradrenaline [norepinephrine (NE)] levels and sympathetic hyperinnervation. Compared with vehicle, sympathetic innervation was blunted after administering sitagliptin, as assessed by immunofluorescent analysis of tyrosine hydroxylase, growth-associated factor 43 and neurofilament and western blotting and real-time quantitative RT-PCR of NGF. Arrhythmic scores in the sitagliptin-treated infarcted rats were significantly lower than those in vehicle. Furthermore, sitagliptin was associated with reduced resistin expression and increased Akt activity. Ex vivo studies showed that glucose-dependent insulinotropic polypeptide (GIP) infusion, but not glucagon-like peptide-1 (GLP-1), produced similar reduction in resistin levels to sitagliptin in postinfarcted rats. Furthermore, the attenuated effects of sitagliptin on NGF levels can be reversed by wortmannin (a phosphatidylinositol 3-kinase antagonist) and exogenous resistin infusion. Sitagliptin protects ventricular arrhythmias by attenuating sympathetic innervation in the non-diabetic infarcted rats. Sitagliptin attenuated resistin expression via the GIP-dependent pathway, which inhibited sympathetic innervation through a signalling pathway involving phosphatidylinositol 3-kinase (PI3K) and Akt protein. PMID:26811539

  8. Sitagliptin decreases ventricular arrhythmias by attenuated glucose-dependent insulinotropic polypeptide (GIP)-dependent resistin signalling in infarcted rats.

    PubMed

    Lee, Tsung-Ming; Chen, Wei-Ting; Chang, Nen-Chung

    2016-01-01

    Myocardial infarction (MI) was associated with insulin resistance, in which resistin acts as a critical mediator. We aimed to determine whether sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, can attenuate arrhythmias by regulating resistin-dependent nerve growth factor (NGF) expression in postinfarcted rats. Normoglycaemic male Wistar rats after ligating coronary artery were randomized to either vehicle or sitagliptin for 4 weeks starting 24 h after operation. Post-infarction was associated with increased myocardial noradrenaline [norepinephrine (NE)] levels and sympathetic hyperinnervation. Compared with vehicle, sympathetic innervation was blunted after administering sitagliptin, as assessed by immunofluorescent analysis of tyrosine hydroxylase, growth-associated factor 43 and neurofilament and western blotting and real-time quantitative RT-PCR of NGF. Arrhythmic scores in the sitagliptin-treated infarcted rats were significantly lower than those in vehicle. Furthermore, sitagliptin was associated with reduced resistin expression and increased Akt activity. Ex vivo studies showed that glucose-dependent insulinotropic polypeptide (GIP) infusion, but not glucagon-like peptide-1 (GLP-1), produced similar reduction in resistin levels to sitagliptin in postinfarcted rats. Furthermore, the attenuated effects of sitagliptin on NGF levels can be reversed by wortmannin (a phosphatidylinositol 3-kinase antagonist) and exogenous resistin infusion. Sitagliptin protects ventricular arrhythmias by attenuating sympathetic innervation in the non-diabetic infarcted rats. Sitagliptin attenuated resistin expression via the GIP-dependent pathway, which inhibited sympathetic innervation through a signalling pathway involving phosphatidylinositol 3-kinase (PI3K) and Akt protein. PMID:26811539

  9. Mechanical effects of liriodenine on the left ventricular-arterial coupling in Wistar rats: pressure-stroke volume analysis

    PubMed Central

    Chang, Kuo-Chu; Su, Ming-Jai; Peng, Ying-I; Shao, Ching-Chih; Wu, Yang-Chang; Tseng, Yung-Zu

    2001-01-01

    In a recent in vivo study, liriodenine, an aporphine alkaloid, has been identified as a prominent anti-arrhythmic agent that can prevent rats' sudden deaths, even at the dose as low as 10−7 g kg−1. The aim of this study was to determine whether liriodenine at its effective anti-arrhythmic dose of 10−7 g kg−1 had effects on the left ventricular (LV)-arterial coupling in Wistar rats. LV pressure and ascending aortic flow signals were recorded to construct the ventricular and arterial end-systolic pressure-stroke volume relationships to calculate LV end-systolic elastance (Ees) and effective arterial volume elastance (Ea), respectively. The optimal afterload (Qload) determined by the ratio of Ea to Ees was used to measure the optimality of energy transmission from the left ventricle to the arterial system. Liriodenine at the dose of 10−7 g kg−1 showed no significant changes in basal heart rate (HR), cardiac output (CO), LV end-systolic pressure (Pes), Ea, Ees, and Qload. By contrast, liriodenine at the dose of 10−6 g kg−1 produced a significant fall of 2.0% in HR and a significant rise of 5.8% in CO, but no significant change in Pes. Moreover, liriodenine administration of 10−6 g kg−1 to rats significantly decreased Ees by 8.5% and Ea by 10.6%, but did not change Qload. We conclude that liriodenine at the dose of 10−7 g kg−1 has no effects on the mechanical properties of the heart and the vasculature and the matching condition for the left ventricle coupled to its vasculature in rats. Even at 10 times the effective anti-arrhythmic dose, liriodenine shows no effects on the efficiency of energy transferred from the left ventricle to the arterial system. PMID:11325791

  10. Ca exchange under non-perfusion-limited conditions in rat ventricular cells: Identification of subcellular compartments

    SciTech Connect

    Langer, G.A.; Rich, T.L.; Orner, F.B. )

    1990-08-01

    Freshly prepared ventricular myocytes from rat hearts, aliquots of which were tested for sarcolemmal integrity by La exposure, were labeled at high 45Ca specific activity. Isotope was subsequently washed out at a perfusion rate of 2.8 ml/s with washout solution sampled each 1 s. No initial unrecorded period of washout was imposed. Four compartments were distinguishable: (1) a rapid compartment (RC) containing 2.6 mmol Ca/kg dry wt of La-displaceable Ca, half time (t1/2) less than 1 s; (2) an intermediate compartment(s) (IC) containing 2.1 mmol, t1/2 = 3 and 19 s; (3) a slow compartment (SC) containing 1.6 mmol, t1/2 = 3.6 min; (4) an inexchangeable compartment that demonstrated no 45Ca uptake after 60-min labeling containing 1.2 mmol. Introduction of 10 mM caffeine as a probe for sarcoplasmic reticulum (SR) content at various times during the washouts caused an increased release of 45Ca. The net increased 45Ca release plotted as a function of time at which caffeine was introduced produced a biexponential curve with t1/2s of 2 and 22 s, very similar to the t1/2s of the IC. Ryanodine (1 microM) significantly reduced the caffeine-induced 45Ca release, confirming the SR locus of the IC. Cells were perfused with 10 mM NaH2PO4 to specifically increase mitochondrial 45Ca labeling. Subsequent removal of PO4 at various times during washouts produced large increases in effluent 45Ca. A plot of the net peak release of 45Ca vs. time of PO4 removal was monoexponential with t1/2 = 3.3 min, very similar to the SC t1/2. The large La-accessible RC remains unlocalized, but the rapidity of its exchange places it in the sarcolemma and/or at sites in rapid equilibrium with the sarcolemma.

  11. The protective role of neocuproine against cardiac damage in isolated perfused rat hearts.

    PubMed

    Applebaum, Y J; Kuvin, J; Borman, J B; Uretzky, G; Chevion, M

    1990-01-01

    The effect of neocuproine on cardiac injury was studied using retrogradely perfused isolated rat hearts in two experimental systems. In the first system, where hydrogen peroxide-induced damage was studied, neocuproine at the range of 40-175 microM provided protection at the level of 70-85%, as demonstrated by the reduced loss in the peak systolic pressure (P), in +dP/dt and in -dP/dt. In the second system, where ischemia/reperfusion-induced arrhythmias were studied, neocuproine (42 microM) provided a marked protection against cardiac injury as demonstrated by the lowering of the incidence in irreversible ventricular fibrillation, by decreasing the duration of ventricular fibrillation and by the concomitant increase of the duration of normal sinus rhythm, and by improving the post-ischemic recovery of P, +dP/dt and -dP/dt. Free radicals have already been implicated as causative agents in cardiac injury resulting from either hydrogen peroxide or ischemia followed by reperfusion. Additionally, iron and copper have already been shown to drastically exacerbate the injurious effects of free radicals. Thus, the results reported here with neocuproine, a highly effective chelator for both iron and copper, as well as with adventitious copper and with the combination of neocuproine and copper, are in accord with the mediatory role of transition metals in enhancing the deleterious effects induced by free radicals.

  12. Positive inotropic activity induced by a dehydroisoandrosterone derivative in isolated rat heart model.

    PubMed

    Figueroa-Valverde, L; Díaz-Cedillo, F; García-Cervera, E; Pool Gómez, E; López-Ramos, M; Rosas-Nexticapa, M; Martinez-Camacho, R

    2013-10-01

    Experimental studies indicate that some steroid derivatives have inotropic activity; nevertheless, there is scarce information about the effects of the dehydroisoandrosterone and its derivatives at cardiovascular level. In addition, to date the cellular site and mechanism of action of dehydroisoandrosterone at cardiovascular level is very confusing. In order, to clarify those phenomena in this study, a dehydroisoandrosterone derivative was synthesized with the objective of to evaluate its activity on perfusion pressure and coronary resistance and compare this phenomenon with the effect exerted by dehydroisoandrosterone. The Langendorff technique was used to measure changes on perfusion pressure and coronary resistance in an isolated rat heart model in absence or presence of dehydroisoandrosterone and its derivative. Additionally, to characterize the molecular mechanism involved in the inotropic activity induced by dehydroisoandrosterone derivative was evaluated by measuring left ventricular pressure in absence or presence of following compounds; flutamide, prazosin, metoprolol and nifedipine. The results showed that dehydroisoandrosterone derivative significantly increased the perfusion pressure and coronary resistance in comparison with the control conditions and dehydroisoandrosterone. Additionally, other data indicate that dehydroisoandrosterone derivative increase left ventricular pressure in a dose-dependent manner [1 × 10(-9)-1 × 10(-4) mmol]; nevertheless, this phenomenon was significantly inhibited by nifedipine at a dose of 1 × 10(-6) mmol. In conclusion, these data suggest that dehydroisoandrosterone derivative induces positive inotropic activity through of activation the L-type calcium channel.

  13. Low vagally-mediated heart rate variability and increased susceptibility to ventricular arrhythmias in rats bred for high anxiety.

    PubMed

    Carnevali, Luca; Trombini, Mimosa; Graiani, Gallia; Madeddu, Denise; Quaini, Federico; Landgraf, Rainer; Neumann, Inga D; Nalivaiko, Eugene; Sgoifo, Andrea

    2014-04-10

    In humans, there is a documented association between anxiety disorders and cardiovascular disease. Putative underlying mechanisms may include an impairment of the autonomic nervous system control of cardiac function. The primary objective of the present study was to characterize cardiac autonomic modulation and susceptibility to arrhythmias in genetic lines of rats that differ largely in their anxiety level. To reach this goal, electrocardiographic recordings were performed in high-anxiety behavior (HAB, n=10) and low-anxiety behavior (LAB, n=10) rats at rest, during stressful stimuli and under autonomic pharmacological manipulations, and analyzed by means of time- and frequency-domain indexes of heart rate variability. During resting conditions, HAB rats displayed a reduced heart rate variability, mostly in terms of lower parasympathetic (vagal) modulation compared to LAB rats. In HAB rats, this relatively low cardiac vagal control was associated with smaller heart rate responsiveness to acute stressors compared to LAB counterparts. In addition, beta-adrenergic pharmacological stimulation induced a larger incidence of ventricular tachyarrhythmias in HABs compared to LABs. At sacrifice, a moderate increase in heart-body weight ratio was observed in HAB rats. We conclude that high levels of anxiety-related behavior in rats are associated with signs of i) impaired autonomic modulation of heart rate (low vagally-mediated heart rate variability), ii) poor adaptive heart rate responsiveness to stressful stimuli, iii) increased arrhythmia susceptibility, and iv) cardiac hypertrophy. These results highlight the utility of the HAB/LAB model for investigating the mechanistic basis of the comorbidity between anxiety disorders and cardiovascular disease.

  14. Isolation and perfusion of rat inner medullary vasa recta.

    PubMed

    Evans, Kristen K; Nawata, C Michele; Pannabecker, Thomas L

    2015-08-15

    Outer medullary isolated descending vasa recta have proven to be experimentally tractable, and consequently much has been learned about outer medullary vasa recta endothelial transport, pericyte contractile mechanisms, and tubulovascular interactions. In contrast, inner medullary vasa recta have never been isolated from any species, and therefore isolated vasa recta function has never been subjected to in vitro quantitative evaluation. As we teased out inner medullary thin limbs of Henle's loops from the Munich-Wistar rat, we found that vasa recta could be isolated using similar protocols. We isolated ∼30 inner medullary vasa recta from 23 adult male Munich-Wistar rats and prepared them for brightfield or electron microscopy, gene expression analysis by RT-PCR, or isolated tubule microperfusion. Morphological characteristics include branching and nonbranching segments exhibiting a thin endothelium, axial surface filaments radiating outward giving vessels a hairy appearance, and attached interstitial cells. Electron microscopy shows multiple cells, tight junctions, and either continuous or fenestrated endothelia. Isolated vasa recta express genes encoding the urea transporter UT-B and/or the fenestral protein PV-1, genes expressed in descending or ascending vasa recta, respectively. The transepithelial NaCl permeability (383.3 ± 60.0 × 10(-5) cm/s, mean ± SE, n = 4) was determined in isolated perfused vasa recta. Future quantitative analyses of isolated inner medullary vasa recta should provide structural and functional details important for more fully understanding fluid and solute flows through the inner medulla and their associated regulatory pathways. PMID:26062876

  15. Comparison of Macitentan and Bosentan on Right Ventricular Remodeling in a Rat Model of Non-vasoreactive Pulmonary Hypertension

    PubMed Central

    Landskroner, Kyle; Bauer, Yasmina; Vercauteren, Magali; Rey, Markus; Renault, Berengère; Studer, Rolf; Vezzali, Enrico; Freti, Diego; Hadana, Hakim; Schläpfer, Manuela; Cattaneo, Christophe; Bortolamiol, Céline; Weber, Edgar; Whitby, Brian R.; Delahaye, Stéphane; Wanner, Daniel; Steiner, Pauline; Nayler, Oliver; Hess, Patrick; Clozel, Martine

    2015-01-01

    Aims: We compared the efficacy of macitentan, a novel dual endothelin A/endothelin B receptor antagonist, with that of another dual endothelin receptor antagonist, bosentan, in a rat model of non-vasoreactive pulmonary hypertension (PH) with particular emphasis on right ventricular (RV) remodeling. Methods and Results: Unlike monocrotaline or hypoxic/sugen rats, bleomycin-treated rats presented a non-vasoreactive PH characterized by the absence of pulmonary dilatation to adenosine. We therefore chose the bleomycin rat model to compare the effects of the maximally effective doses of macitentan and bosentan on pulmonary vascular and RV remodeling. Macitentan (100 mg·kg−1·d−1), but not bosentan (300 mg·kg−1·d−1), significantly prevented pulmonary vascular remodeling, RV hypertrophy, and cardiomyocyte diameter increase. Cardiac protection by macitentan was associated with a significant attenuation of genes related to cell hypertrophy and extracellular matrix remodeling. Microautoradiography and high performance liquid chromatography analysis showed greater distribution of macitentan than bosentan in the RV and pulmonary tissue. Conclusions: Macitentan was more efficacious than bosentan in preventing the development of pulmonary and RV hypertrophies in a model of non-vasoreactive PH. Greater ability to distribute into the tissue could contribute to the greater structural improvement by macitentan compared with bosentan. PMID:26230396

  16. Intrauterine endotoxin-induced impairs pulmonary vascular function and right ventricular performance in infant rats and improvement with early vitamin D therapy.

    PubMed

    Mandell, Erica; Powers, Kyle N; Harral, Julie W; Seedorf, Gregory J; Hunter, Kendall S; Abman, Steven H; Dodson, R Blair

    2015-12-15

    High pulmonary vascular resistance (PVR), proximal pulmonary artery (PA) impedance, and right ventricular (RV) afterload due to remodeling contribute to the pathogenesis and severity of pulmonary hypertension (PH). Intra-amniotic exposure to endotoxin (ETX) causes sustained PH and high mortality in rat pups at birth, which are associated with impaired vascular growth and RV hypertrophy in survivors. Treatment of ETX-exposed pups with antenatal vitamin D (vit D) improves survival and lung growth, but the effects of ETX exposure on RV-PA coupling in the neonatal lung are unknown. We hypothesized that intrauterine ETX impairs RV-PA coupling through sustained abnormalities of PA stiffening and RV performance that are attenuated with vit D therapy. Fetal rats were exposed to intra-amniotic injections of ETX, ETX+vit D, or saline at 20 days gestation (term = 22 days). At postnatal day 14, pups had pressure-volume measurements of the RV and isolated proximal PA, respectively. Lung homogenates were assayed for extracellular matrix (ECM) composition by Western blot. We found that ETX lungs contain decreased α-elastin, lysyl oxidase, collagen I, and collagen III proteins (P < 0.05) compared control and ETX+vit D lungs. ETX-exposed animals have increased RV mechanical stroke work (P < 0.05 vs. control and ETX+vit D) and elastic potential energy (P < 0.05 vs. control and ETX+vit D). Mechanical stiffness and ECM remodeling are increased in the PA (P < 0.05 vs. control and ETX+vit D). We conclude that intrauterine exposure of fetal rats to ETX during late gestation causes persistent impairment of RV-PA coupling throughout infancy that can be prevented with early vit D treatment.

  17. Intrauterine endotoxin-induced impairs pulmonary vascular function and right ventricular performance in infant rats and improvement with early vitamin D therapy.

    PubMed

    Mandell, Erica; Powers, Kyle N; Harral, Julie W; Seedorf, Gregory J; Hunter, Kendall S; Abman, Steven H; Dodson, R Blair

    2015-12-15

    High pulmonary vascular resistance (PVR), proximal pulmonary artery (PA) impedance, and right ventricular (RV) afterload due to remodeling contribute to the pathogenesis and severity of pulmonary hypertension (PH). Intra-amniotic exposure to endotoxin (ETX) causes sustained PH and high mortality in rat pups at birth, which are associated with impaired vascular growth and RV hypertrophy in survivors. Treatment of ETX-exposed pups with antenatal vitamin D (vit D) improves survival and lung growth, but the effects of ETX exposure on RV-PA coupling in the neonatal lung are unknown. We hypothesized that intrauterine ETX impairs RV-PA coupling through sustained abnormalities of PA stiffening and RV performance that are attenuated with vit D therapy. Fetal rats were exposed to intra-amniotic injections of ETX, ETX+vit D, or saline at 20 days gestation (term = 22 days). At postnatal day 14, pups had pressure-volume measurements of the RV and isolated proximal PA, respectively. Lung homogenates were assayed for extracellular matrix (ECM) composition by Western blot. We found that ETX lungs contain decreased α-elastin, lysyl oxidase, collagen I, and collagen III proteins (P < 0.05) compared control and ETX+vit D lungs. ETX-exposed animals have increased RV mechanical stroke work (P < 0.05 vs. control and ETX+vit D) and elastic potential energy (P < 0.05 vs. control and ETX+vit D). Mechanical stiffness and ECM remodeling are increased in the PA (P < 0.05 vs. control and ETX+vit D). We conclude that intrauterine exposure of fetal rats to ETX during late gestation causes persistent impairment of RV-PA coupling throughout infancy that can be prevented with early vit D treatment. PMID:26475735

  18. PDE2 activity differs in right and left rat ventricular myocardium and differentially regulates β2 adrenoceptor-mediated effects

    PubMed Central

    Soler, Fernando; Fernández-Belda, Francisco; Pérez-Schindler, Joaquín; Handschin, Christoph; Fuente, Teodomiro

    2015-01-01

    The important regulator of cardiac function, cAMP, is hydrolyzed by different cyclic nucleotide phosphodiesterases (PDEs), whose expression and activity are not uniform throughout the heart. Of these enzymes, PDE2 shapes β1 adrenoceptor-dependent cardiac cAMP signaling, both in the right and left ventricular myocardium, but its role in regulating β2 adrenoceptor-mediated responses is less well known. Our aim was to investigate possible differences in PDE2 transcription and activity between right (RV) and left (LV) rat ventricular myocardium, as well as its role in regulating β2 adrenoceptor effects. The free walls of the RV and the LV were obtained from Sprague–Dawley rat hearts. Relative mRNA for PDE2 (quantified by qPCR) and PDE2 activity (evaluated by a colorimetric procedure and using the PDE2 inhibitor EHNA) were determined in RV and LV. Also, β2 adrenoceptor-mediated effects (β2-adrenoceptor agonist salbutamol + β1 adrenoceptor antagonist CGP-20712A) on contractility and cAMP concentrations, in the absence or presence of EHNA, were studied in the RV and LV. PDE2 transcript levels were less abundant in RV than in LV and the contribution of PDE2 to the total PDE activity was around 25% lower in the microsomal fraction of the RV compared with the LV. β2 adrenoceptor activation increased inotropy and cAMP levels in the LV when measured in the presence of EHNA, but no such effects were observed in the RV, either in the presence or absence of EHNA. These results indicate interventricular differences in PDE2 transcript and activity levels, which may distinctly regulate β2 adrenoceptor-mediated contractility and cAMP concentrations in the RV and in the LV of the rat heart. PMID:25432985

  19. Repeated sauna therapy attenuates ventricular remodeling after myocardial infarction in rats by increasing coronary vascularity of noninfarcted myocardium.

    PubMed

    Sobajima, Mitsuo; Nozawa, Takashi; Shida, Takuya; Ohori, Takashi; Suzuki, Takayuki; Matsuki, Akira; Inoue, Hiroshi

    2011-08-01

    Repeated sauna therapy (ST) increases endothelial nitric oxide synthase (eNOS) activity and improves cardiac function in heart failure as well as peripheral blood flow in ischemic limbs. The present study investigates whether ST can increase coronary vascularity and thus attenuate cardiac remodeling after myocardial infarction (MI). We induced MI by ligating the left coronary artery of Wistar rats. The rats were placed in a far-infrared dry sauna at 41°C for 15 min and then at 34°C for 20 min once daily for 4 wk. Cardiac hemodynamic, histopathological, and gene analyses were performed. Despite the similar sizes of MI between the ST and non-ST groups (51.4 ± 0.3 vs. 51.1 ± 0.2%), ST reduced left ventricular (LV) end-diastolic (9.7 ± 0.4 vs. 10.7 ± 0.5 mm, P < 0.01) and end-systolic (8.6 ± 0.5 vs. 9.6 ± 0.6 mm, P < 0.01) dimensions and attenuated MI-induced increases in LV end-diastolic pressure. Cross-sectional areas of cardiomyocytes were smaller in ST rats and associated with a significant reduction in myocardial atrial natriuretic peptide mRNA levels. Vascular density was reduced in the noninfarcted myocardium of non-ST rats, and the density of cells positive for CD31 and for α-smooth muscle actin was decreased. These decreases were attenuated in ST rats compared with non-ST rats and associated with increases in myocardial eNOS and vascular endothelial growth factor mRNA levels. In conclusion, ST attenuates cardiac remodeling after MI, at least in part, through improving coronary vascularity in the noninfarcted myocardium. Repeated ST might serve as a novel noninvasive therapy for patients with MI.

  20. Cardioprotective mechanisms of Prunus cerasus (sour cherry) seed extract against ischemia-reperfusion-induced damage in isolated rat hearts.

    PubMed

    Bak, Istvan; Lekli, Istvan; Juhasz, Bela; Nagy, Norbert; Varga, Edit; Varadi, Judit; Gesztelyi, Rudolf; Szabo, Gergo; Szendrei, Levente; Bacskay, Ildiko; Vecsernyes, Miklos; Antal, Miklos; Fesus, Laszlo; Boucher, Francois; de Leiris, Joel; Tosaki, Arpad

    2006-09-01

    The effects of kernel extract obtained from sour cherry (Prunus cerasus) seed on the postischemic cardiac recovery were studied in isolated working rat hearts. Rats were treated with various daily doses of the extract for 14 days, and hearts were then isolated and subjected to 30 min of global ischemia followed by 120 min of reperfusion. The incidence of ventricular fibrillation (VF) and tachycardia (VT) fell from their control values of 92% and 100% to 50% (not significant) and 58% (not significant), 17% (P<0.05), and 25% (P<0.05) with the doses of 10 mg/kg and 30 mg/kg of the extract, respectively. Lower concentrations of the extract (1 and 5 mg/kg) failed to significantly reduce the incidence of VF and VT during reperfusion. Sour cherry seed kernel extract (10 and 30 mg/kg) significantly improved the postischemic recovery of cardiac function (coronary flow, aortic flow, and left ventricular developed pressure) during reperfusion. We have also demonstrated that the extract-induced protection in cardiac function significantly reflected in a reduction of infarct size. Immunohistochemistry indicates that a reduction in caspase-3 activity and apoptotic cells by the extract, beside other potential action mechanisms of proanthocyanidin, trans-resveratrol, and flavonoid components of the extract, could be responsible for the cardioprotection in ischemic-reperfused myocardium. PMID:16617126

  1. Genetic diversity among Borrelia burgdorferi isolates from wood rats and kangaroo rats in California.

    PubMed Central

    Zingg, B C; Brown, R N; Lane, R S; LeFebvre, R B

    1993-01-01

    Twenty-nine Borrelia burgdorferi isolates, obtained from dusky-footed wood rats (Neotoma fuscipes) and California kangaroo rats (Dipodomys californicus) in California, were analyzed genetically. Chromosomal DNA was examined by restriction endonuclease analysis (REA) and gene probe restriction fragment length polymorphism. Pulsed-field gel electrophoresis was used to analyze the plasmid profiles of the isolates. REA, the method with the greatest discrimination, disclosed 24 distinct restriction patterns among the 29 isolates. These restriction patterns were sorted into four restriction fragment length polymorphism groups on the basis of their gene hybridization patterns. Results of the REA and plasmid profile analysis supported this grouping. The degree of genetic diversity among Californian isolates demonstrated by our findings is greater than that previously reported among other groups of North American isolates and is similar or greater than the diversity reported among European isolates. Images PMID:7905880

  2. Metabolic Inhibition Strongly Inhibits Na+-Dependent Mg2+ Efflux in Rat Ventricular Myocytes

    PubMed Central

    Tashiro, Michiko; Inoue, Hana; Konishi, Masato

    2009-01-01

    Abstract We measured intracellular Mg2+ concentration ([Mg2+]i) in rat ventricular myocytes using the fluorescent indicator furaptra (25°C). In normally energized cells loaded with Mg2+, the introduction of extracellular Na+ induced a rapid decrease in [Mg2+]i: the initial rate of decrease in [Mg2+]i (initial Δ[Mg2+]i/Δt) is thought to represent the rate of Na+-dependent Mg2+ efflux (putative Na+/Mg2+ exchange). To determine whether Mg2+ efflux depends directly on energy derived from cellular metabolism, in addition to the transmembrane Na+ gradient, we estimated the initial Δ[Mg2+]i/Δt after metabolic inhibition. In the absence of extracellular Na+ and Ca2+, treatment of the cells with 1 μM carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone, an uncoupler of mitochondria, caused a large increase in [Mg2+]i from ∼0.9 mM to ∼2.5 mM in a period of 5–8 min (probably because of breakdown of MgATP and release of Mg2+) and cell shortening to ∼50% of the initial length (probably because of formation of rigor cross-bridges). Similar increases in [Mg2+]i and cell shortening were observed after application of 5 mM potassium cyanide (KCN) (an inhibitor of respiration) for ≥90 min. The initial Δ[Mg2+]i/Δt was diminished, on average, by 90% in carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone-treated cells and 92% in KCN-treated cells. When the cells were treated with 5 mM KCN for shorter times (59–85 min), a significant decrease in the initial Δ[Mg2+]i/Δt (on average by 59%) was observed with only a slight shortening of the cell length. Intracellular Na+ concentration ([Na+]i) estimated with a Na+ indicator sodium-binding benzofuran isophthalate was, on average, 5.0–10.5 mM during the time required for the initial Δ[Mg2+]i/Δt measurements, which is well below the [Na+]i level for half inhibition of the Mg2+ efflux (∼40 mM). Normalization of intracellular pH using 10 μM nigericin, a H+ ionophore, did not reverse the inhibition of the Mg2+ efflux

  3. Islands of spatially discordant APD alternans underlie arrhythmogenesis by promoting electrotonic dyssynchrony in models of fibrotic rat ventricular myocardium.

    PubMed

    Majumder, Rupamanjari; Engels, Marc C; de Vries, Antoine A F; Panfilov, Alexander V; Pijnappels, Daniël A

    2016-01-01

    Fibrosis and altered gap junctional coupling are key features of ventricular remodelling and are associated with abnormal electrical impulse generation and propagation. Such abnormalities predispose to reentrant electrical activity in the heart. In the absence of tissue heterogeneity, high-frequency impulse generation can also induce dynamic electrical instabilities leading to reentrant arrhythmias. However, because of the complexity and stochastic nature of such arrhythmias, the combined effects of tissue heterogeneity and dynamical instabilities in these arrhythmias have not been explored in detail. Here, arrhythmogenesis was studied using in vitro and in silico monolayer models of neonatal rat ventricular tissue with 30% randomly distributed cardiac myofibroblasts and systematically lowered intercellular coupling achieved in vitro through graded knockdown of connexin43 expression. Arrhythmia incidence and complexity increased with decreasing intercellular coupling efficiency. This coincided with the onset of a specialized type of spatially discordant action potential duration alternans characterized by island-like areas of opposite alternans phase, which positively correlated with the degree of connexinx43 knockdown and arrhythmia complexity. At higher myofibroblast densities, more of these islands were formed and reentrant arrhythmias were more easily induced. This is the first study exploring the combinatorial effects of myocardial fibrosis and dynamic electrical instabilities on reentrant arrhythmia initiation and complexity. PMID:27072041

  4. Islands of spatially discordant APD alternans underlie arrhythmogenesis by promoting electrotonic dyssynchrony in models of fibrotic rat ventricular myocardium

    NASA Astrophysics Data System (ADS)

    Majumder, Rupamanjari; Engels, Marc C.; de Vries, Antoine A. F.; Panfilov, Alexander V.; Pijnappels, Daniël A.

    2016-04-01

    Fibrosis and altered gap junctional coupling are key features of ventricular remodelling and are associated with abnormal electrical impulse generation and propagation. Such abnormalities predispose to reentrant electrical activity in the heart. In the absence of tissue heterogeneity, high-frequency impulse generation can also induce dynamic electrical instabilities leading to reentrant arrhythmias. However, because of the complexity and stochastic nature of such arrhythmias, the combined effects of tissue heterogeneity and dynamical instabilities in these arrhythmias have not been explored in detail. Here, arrhythmogenesis was studied using in vitro and in silico monolayer models of neonatal rat ventricular tissue with 30% randomly distributed cardiac myofibroblasts and systematically lowered intercellular coupling achieved in vitro through graded knockdown of connexin43 expression. Arrhythmia incidence and complexity increased with decreasing intercellular coupling efficiency. This coincided with the onset of a specialized type of spatially discordant action potential duration alternans characterized by island-like areas of opposite alternans phase, which positively correlated with the degree of connexinx43 knockdown and arrhythmia complexity. At higher myofibroblast densities, more of these islands were formed and reentrant arrhythmias were more easily induced. This is the first study exploring the combinatorial effects of myocardial fibrosis and dynamic electrical instabilities on reentrant arrhythmia initiation and complexity.

  5. Islands of spatially discordant APD alternans underlie arrhythmogenesis by promoting electrotonic dyssynchrony in models of fibrotic rat ventricular myocardium

    PubMed Central

    Majumder, Rupamanjari; Engels, Marc C.; de Vries, Antoine A. F.; Panfilov, Alexander V.; Pijnappels, Daniël A.

    2016-01-01

    Fibrosis and altered gap junctional coupling are key features of ventricular remodelling and are associated with abnormal electrical impulse generation and propagation. Such abnormalities predispose to reentrant electrical activity in the heart. In the absence of tissue heterogeneity, high-frequency impulse generation can also induce dynamic electrical instabilities leading to reentrant arrhythmias. However, because of the complexity and stochastic nature of such arrhythmias, the combined effects of tissue heterogeneity and dynamical instabilities in these arrhythmias have not been explored in detail. Here, arrhythmogenesis was studied using in vitro and in silico monolayer models of neonatal rat ventricular tissue with 30% randomly distributed cardiac myofibroblasts and systematically lowered intercellular coupling achieved in vitro through graded knockdown of connexin43 expression. Arrhythmia incidence and complexity increased with decreasing intercellular coupling efficiency. This coincided with the onset of a specialized type of spatially discordant action potential duration alternans characterized by island-like areas of opposite alternans phase, which positively correlated with the degree of connexinx43 knockdown and arrhythmia complexity. At higher myofibroblast densities, more of these islands were formed and reentrant arrhythmias were more easily induced. This is the first study exploring the combinatorial effects of myocardial fibrosis and dynamic electrical instabilities on reentrant arrhythmia initiation and complexity. PMID:27072041

  6. Effects of antiarrhythmic drugs on ventricular fibrillation thresholds of normal and ischaemic myocardium in the anaesthetized rat.

    PubMed Central

    Marshall, R. J.; Muir, A. W.; Winslow, E.

    1983-01-01

    1 The effects of agents which produce membrane stabilization (class I), beta 1-adrenoceptor blockade (class II), prolongation of the cardiac action potential (class III) or inhibition of the slow inward current (class IV) were investigated for their ability to increase the ventricular fibrillation threshold (VFT) or to modify the fall in VFT consequent upon coronary artery ligation in the anaesthetized rat. 2 The class I agent, Org6001, increased VFT of normal myocardium and in lower doses reduced the postligation fall in VFT. 3 The class II agent, metoprolol, failed to increase VFT of normal myocardium but reduced the postligation fall. 4 The class III agent, melperone, increased VFT of both normal and ischaemic myocardium whereas the class IV agent, nifedipine failed to influence VFT in either region. 5 Bepridil (class I and IV) was similar to Org6001 and sotalol (class II and III) in that it increased VFT of normal myocardium and in lower doses reduced the postligation fall in VFT. 6 Measurement of VFT before and after coronary artery ligation in the rat constitutes a rapid and reproducible screen to detect antifibrillatory activity. 7 The results also suggest that in the rat, the low currents used (approximately 400 microA) do not release substantial quantities of catecholamines whereas these may be released by coronary artery ligation. PMID:6824812

  7. Non-targeted metabolomics identified a common metabolic signature of lethal ventricular tachyarrhythmia (LVTA) in two rat models.

    PubMed

    Wang, Xingxing; Wang, Dian; Yu, Xiaojun; Zhang, Guohong; Wu, Jiayan; Zhu, Guanghui; Su, Ruibing; Lv, Junyao

    2016-06-21

    Lethal ventricular tachyarrhythmia (LVTA) is the predominant underlying mechanism of sudden cardiac death (SCD). The aim of this study is to characterize the metabolic features of myocardia following LVTA, and identify potential biomarkers to diagnose LVTA. We developed two LVTA rat models induced by aconitine injection or coronary artery ligation, which represent cardiac ion channel disease-related and cardiac ischemia-related SCD, respectively. The myocardial metabolic profile was investigated by gas chromatography-mass spectrometry and proton nuclear magnetic resonance-based metabolomics. Twenty-three aconitine-injected and 14 coronary artery ligation-treated rats developed LVTA SCD. A total of 38 differential metabolites of myocardia were identified in aconitine-induced LVTA rats, of which 31 metabolites showed a similar change in coronary artery ligation-related LVTA rats. Fatty acids (stearic, palmitic, linoleic, elaidic, and myristic) and branched-chain amino acids (valine, leucine, and isoleucine) were the most down-regulated metabolites. Furthermore, elevated ADP, phosphate, lactate, glutamate, aspartate, threonine, choline and arginine were also observed. Major pathways regarding these dysregulated metabolites post LVTA are energy excessive consumption and deficit, ionic imbalance, oxidative stress, cardiac cytotoxicity and membrane injury. Valine, stearic acid and leucine collectively enable a precision of 92.9% to distinguish LVTA from its control, and are correlated with several arrhythmia indices. Our results uncovered a common metabolic feature of LVTA in myocardia in two rat models, which represent cardiac ion channel disease and cardiac ischemia, respectively. l-Valine, l-leucine and stearic acid jointly confer good potential for distinguishing LVTA, which might be potential biomarkers of LVTA-related SCD. PMID:27138062

  8. Cardiac actions of phencyclidine in isolated guinea pig and rat heart: possible involvement of slow channels

    SciTech Connect

    Temma, K.; Akera, T.; Ng, Y.C.

    1985-03-01

    The mechanisms responsible for the positive inotropic effect of phencyclidine were studied in isolated preparations of guinea pig and rat heart. In electrically paced left atrial muscle preparations, phencyclidine increased the force of contraction; rat heart muscle preparations were more sensitive than guinea pig heart muscle preparations. The positive inotropic effect of phencyclidine was not significantly reduced by a combination of phentolamine and nadolol; however, the effect was competitively blocked by verapamil in the presence of phentolamine and nadolol. Inhibition of the outward K+ current by tetraethylammonium chloride also produced a positive inotropic effect; however, the effect of tetraethylammonium was reduced by phentolamine and nadolol, and was almost insensitive to verapamil. The inotropic effect of phencyclidine was associated with a marked prolongation of the action potential duration and a decrease in maximal upstroke velocity of the action potential, with no change in the resting membrane potential. The specific (/sup 3/H)phencyclidine binding observed with membrane preparations from guinea pig ventricular muscle was saturable with a single class of high-affinity binding site. This binding was inhibited by verapamil, diltiazem, or nitrendipine, but not by ryanodine or tetrodotoxin. These results suggest that the positive inotropic effect of phencyclidine results from enhanced Ca/sup 2 +/ influx via slow channels, either by stimulation of the channels or secondary to inhibition of outward K/sup +/ currents.

  9. The length-dependent activation of contraction is equally impaired in impuberal male and female rats in monocrotaline-induced right ventricular failure.

    PubMed

    Lookin, Oleg; Balakin, Alexander; Kuznetsov, Daniil; Protsenko, Yuri

    2015-11-01

    The length-dependent activation of contraction is attenuated in the failing myocardium of adult male rats. This pathological change is not seen in adult female rats, possibly because of a protective effect of sex hormones. The present study evaluated length-dependent changes in isometric twitch, Ca(2+) transient (CaT) and action potential (AP) in the right ventricular myocardium of impuberal healthy male and female rats (control) and in rats treated with a single injection of 50 mg/kg monocrotaline (MCT). Compared with sex-matched control rats, MCT-treated male and female rats exhibited increased right ventricular weight (134% and 142% of control, respectively), decreased left ventricular weight (72% and 79%), twitch attenuation (48.8 ± 2.7% and 57.5 ± 1.2%) and prolongation (125 ± 3% and 127 ± 2%), CaT attenuation (37.8 ± 0.4% and 39.1 ± 1.1%) and prolongation (114 ± 1% and 116 ± 1%) and AP prolongation at 90% repolarization (195 ± 2% and 203 ± 1%). The MCT-treated male rats exhibited a 50% lower integral magnitude and an approximately 25% larger time-to-peak 'bump' compared with control male rats. These parameters in MCT-treated female rats tended to show similar changes to those seen in the control female rats, with no significant difference between the two groups. In all groups, integral magnitude and time-to-peak 'bump' increased with length. In conclusion, the length-dependent activation of contraction was equally blunted in the failing right ventricular myocardium of impuberal male and female rats. This was related to changes in CaT and AP, which were similar between male and female rats. Therefore, puberty is necessary for manifestation of the protective effects of sex hormones on this remodelling.

  10. Prilocaine elimination by isolated perfused rat lung and liver.

    PubMed

    Geng, W P; Ebke, M; Foth, H

    1995-01-01

    Prilocaine is assumed to undergo significant elimination by extrahepatic organs and to differ in this respect from other commonly used local anaesthetics. In order to clarify whether the lung may play an important role as a site of elimination of prilocaine, the kinetic parameters were studied in isolated perfused rat lungs and were compared to those of isolated livers. Furthermore, the structurally related compounds bupivacaine and mepivacaine were also investigated in this system. Prilocaine was dispersed into a relatively large apparent distribution volume in perfused rat lung (139 ml versus 97 ml in controls). In single-pass perfused lungs the observed maximum of concentration was decreased by about 60% compared to controls. The mean residence time was prolonged by about 40%. These observations suggest that prilocaine is substantially retained by rat lung and that this effect occurs particularly during first-pass. However, the ability of rat lung to degrade prilocaine was relatively low. The clearance values were about 0.3 ml/min equal to about 20% of the hepatic capacity calculated per g of tissue. Thus it must be assumed that prilocaine is only transiently retained by the lung and will gain systemic availability later on. In rat lungs the kinetics of prilocaine elimination were not substantially different from those of bupivacaine and mepivacaine (16 and 12%). These observations do not support the assumption that especially prilocaine undergoes extrahepatic elimination.

  11. Mechanical effects of liriodenine on the left ventricular-arterial coupling in Wistar rats: pressure-stroke volume analysis.

    PubMed

    Chang, K C; Su, M J; Peng, Y I; Shao, C C; Wu, Y C; Tseng, Y Z

    2001-05-01

    1. In a recent in vivo study, liriodenine, an aporphine alkaloid, has been identified as a prominent anti-arrhythmic agent that can prevent rats' sudden deaths, even at the dose as low as 10(-7) g kg(-1). The aim of this study was to determine whether liriodenine at its effective anti-arrhythmic dose of 10(-7) g kg(-1) had effects on the left ventricular (LV)-arterial coupling in Wistar rats. 2. LV pressure and ascending aortic flow signals were recorded to construct the ventricular and arterial end-systolic pressure-stroke volume relationships to calculate LV end-systolic elastance (E(es)) and effective arterial volume elastance (E(a)), respectively. The optimal afterload (Q(load)) determined by the ratio of E(a) to E(es) was used to measure the optimality of energy transmission from the left ventricle to the arterial system. 3. Liriodenine at the dose of 10(-7) g kg(-1) showed no significant changes in basal heart rate (HR), cardiac output (CO), LV end-systolic pressure (P(es)), E(a), E(es), and Q(load). 4. By contrast, liriodenine at the dose of 10(-6) g kg(-1) produced a significant fall of 2.0% in HR and a significant rise of 5.8% in CO, but no significant change in P(es). Moreover, liriodenine administration of 10(-6) g kg(-1) to rats significantly decreased E(es) by 8.5% and E(a) by 10.6%, but did not change Q(load). 5. We conclude that liriodenine at the dose of 10(-7) g kg(-1) has no effects on the mechanical properties of the heart and the vasculature and the matching condition for the left ventricle coupled to its vasculature in rats. Even at 10 times the effective anti-arrhythmic dose, liriodenine shows no effects on the efficiency of energy transferred from the left ventricle to the arterial system. PMID:11325791

  12. Early social isolation augments alcohol consumption in rats.

    PubMed

    Lesscher, Heidi M B; Spoelder, Marcia; Rotte, Marthe D; Janssen, Martijn J; Hesseling, Peter; Lozeman-van't Klooster, José G; Baars, Annemarie M; Vanderschuren, Louk J M J

    2015-10-01

    There is a considerable degree of individual vulnerability for alcohol use disorder (AUD) as only a subpopulation of individuals who regularly consume alcohol develop AUD. It is therefore very important to understand the factors and mechanisms that contribute towards the individual risk for AUD. In this respect, social influences, in particular during development, may be relevant for AUD as disruptions in early social experiences are associated with an increased risk for AUD. Social play, the most prominent form of social behaviour shown by young mammals, is rewarding and considered to be important for social, emotional and cognitive development. Recent studies suggest that early social isolation, effectively depriving animals from social play, increases the risk for addictive behaviour. The aim of this study was therefore to explore the long-term consequences of early social isolation on alcohol consumption and motivation for alcohol. To this end, rats were socially isolated from postnatal days 21-42, followed by 4 weeks of social housing, and voluntary alcohol consumption and operant responding for alcohol were determined in adulthood. We observed enhanced levels of alcohol consumption in adulthood in previously isolated rats, whereas operant responding for alcohol was not altered. The impact of early social isolation was independent of the individual variation in alcohol consumption. These data indicate that social isolation, during a developmental period when social play is highly abundant, enhances the propensity to consume alcohol in adulthood. This implies that early social experience may be a protective factor against excessive alcohol use.

  13. Depressive behavior induced by social isolation of predisposed female rats.

    PubMed

    Zanier-Gomes, Patrícia Helena; de Abreu Silva, Tomaz Eugênio; Zanetti, Guilherme Cia; Benati, Évelyn Raquel; Pinheiro, Nanci Mendes; Murta, Beatriz Martins Tavares; Crema, Virgínia Oliveira

    2015-11-01

    Depression is a mood disorder that is more prevalent in women and has been closely associated with chronic stress. Many models of depression have been suggested that consider different forms of stress. In fact, stress is present in the life of every human being, but only a few develop depression. Accordingly, it seems wrong to consider all stressed animals to be depressed, emphasizing the importance of predisposition for this mood disorder. Based on this finding, we evaluated a predisposition to depressive behavior of female rats on the forced swim test (FST), and the more immobile the animal was during the FST, the more predisposed to depression it was considered to be. Then, animals were subjected to the stress of social isolation for 21 days and were re-evaluated by the FST. The Predisposed/Isolated rats presented higher immobility times. Once all the rats had prior experience in the FST, we calculated an Index of Increase by Isolation, confirming the previous results. Based on this result, we considered the Predisposed/Isolated group as presenting depressive behavior ('Depressed') and the Nonpredisposed/Nonisolated group as the control group ('Nondepressed'). The animals were distributed into 4 new groups: Nondepressed/Vehicle, Nondepressed/Amitriptyline, Depressed/Vehicle, Depressed/Amitriptyline. After 21 days of treatment, only the Depressed/Vehicle group differed from the other 3 groups, demonstrating the efficacy of amitriptyline in treating the depressive behavior of the Depressed animals, validating the model. This study shows that conducting an FST prior to any manipulation can predict predisposition to depressive behavior in female rats and that the social isolation of predisposed animals for 21 days is effective in inducing depressive behavior. This behavior can be considered real depressive behavior because it takes into account predisposition, chronic mild stress, and the prevalent gender.

  14. Unidirectional block between isolated rabbit ventricular cells coupled by a variable resistance.

    PubMed Central

    Joyner, R W; Sugiura, H; Tan, R C

    1991-01-01

    We have used pairs of electrically coupled cardiac cells to investigate the dependence of successful conduction of an action potential on three components of the conduction process: (a) the amount of depolarization required to be produced in the nonstimulated cell (the "sink" for current flow) to initiate an action potential in the nonstimulated cell, (b) the intercellular resistance as the path for intercellular current flow, and (c) the ability of the stimulated cell to maintain a high membrane potential to serve as the "source" of current during the conduction process. We present data from eight pairs of simultaneously recorded rabbit ventricular cells, with the two cells of each pair physically separated from each other. We used an electronic circuit to pass currents into and out of each cell such that these currents produced the effects of any desired level of intercellular resistance. The cells of equal size (as assessed by their current threshold and their input resistance for small depolarizations) show bidirectional failure of conduction at very high values of intercellular resistance which then converts to successful bidirectional conduction at lower values of intercellular resistance. For cell pairs with asymmetrical cell sizes, there is a large range of values of intercellular resistance over which unidirectional block occurs with conduction successful from the larger cell to the smaller cell but with conduction block from the smaller cell to the larger cell. We then further show that one important component which limits the conduction process is the large early repolarization which occurs in the stimulated cell during the process of conduction, a process that we term "source loading." PMID:1760503

  15. Effects of aged garlic extract on left ventricular diastolic function and fibrosis in a rat hypertension model.

    PubMed

    Hara, Yuki; Noda, Akiko; Miyata, Seiko; Minoshima, Makoto; Sugiura, Mari; Kojima, Jun; Otake, Masafumi; Furukawa, Mayuko; Cheng, Xian Wu; Nagata, Kohzo; Murohara, Toyoaki

    2013-01-01

    Daily consumption of garlic is known to lower the risk of hypertension and ischemic heart disease. In this study, we examined whether aged garlic extract (AGE) prevents hypertension and the progression of compensated left ventricular (LV) hypertrophy in Dahl salt-sensitive (DS) rats. DS rats were randomly divided into three groups: those fed an 8% NaCl diet until 18 weeks of age (8% NaCl group), those additionally treated with AGE (8% NaCl + AGE group), and control rats maintained on a diet containing 0.3% NaCl until 18 weeks of age (0.3% NaCl group). AGE was administered orally by gastric gavage once a day until 18 weeks of age. LV mass was significantly higher in the 8% NaCl + AGE group than in the 0.3% NaCl group at 18 weeks of age, but significantly lower in the 8% NaCl + AGE group than in the 8% NaCl group. No significant differences were observed in systolic blood pressure (SBP) between the 8% NaCl and 8% NaCl + AGE groups at 12 and 18 weeks of age. LV end-diastolic pressure and pressure half-time at 12 and 18 weeks of age were significantly lower in the 8% NaCl + AGE group compared with the 8% NaCl group. AGE significantly reduced LV interstitial fibrosis at 12 and 18 weeks of age. Chronic AGE intake attenuated LV diastolic dysfunction and fibrosis without significantly decreasing SBP in hypertensive DS rats.

  16. Reduced subcommissural organ glycoprotein immunoreactivity precedes aqueduct closure and ventricular dilatation in H-Tx rat hydrocephalus.

    PubMed

    Somera, K C; Jones, H C

    2004-03-01

    The H-Tx rat has fetal-onset hydrocephalus associated with closure of the cerebral aqueduct and a reduction in the secretory cells of the subcommissural organ (SCO), a circumventricular organ situated in the dorsal wall of the cerebral aqueduct. The objective of this study was to determine the role of the SCO in hydrocephalus pathogenesis. Serial brain sections through aqueduct regions containing the SCO from H-Tx rats, together with non-hydrocephalic Fischer F344 rats, were studied at E16, before hydrocephalus onset, at E17, the beginning of onset, and at P0 when the hydrocephalus was overt. Tissues were immunostained by AFRU, an antibody against the SCO glycoprotein, and for the intermediate filament nestin. The area of SCO cells with AFRU immunostaining and the severity of lateral ventricle dilatation were quantified by image analysis. At E16 all fetuses had distinct SCO ependymal cells, open aqueducts and normal lateral ventricles. The H-Tx fetuses fell into two groups with large areas and small areas of AFRU immunoreactivity, all with a full complement of SCO cells. By E17, fetuses with small areas of immunoreactivity had reduced numbers of tall SCO secretory cells, and most had aqueducts closed posteriorly and dilated ventricles. Three additional fetuses with small areas of immunoreactivity had narrow but patent aqueducts and normal ventricles, and another had an open aqueduct and dilated ventricles. At P0, pups previously identified as hydrocephalic had small areas of AFRU immunoreactivity, an aqueduct that was closed anteriorly but open posteriorly, ventricular dilatation, and an absence of SCO secretory cells. The aqueduct even when closed was lined by typical ependymal cells throughout. Decreased nestin immunostaining accompanied the SCO changes. It is concluded that reduced SCO glycoprotein immunoreactivity precedes both aqueduct closure and expansion of the lateral ventricles in the H-Tx rat.

  17. Estradiol improves right ventricular function in rats with severe angioproliferative pulmonary hypertension: effects of endogenous and exogenous sex hormones

    PubMed Central

    Frump, Andrea L.; Goss, Kara N.; Vayl, Alexandra; Albrecht, Marjorie; Fisher, Amanda; Tursunova, Roziya; Fierst, John; Whitson, Jordan; Cucci, Anthony R.; Brown, M. Beth

    2015-01-01

    Estrogens are disease modifiers in PAH. Even though female patients exhibit better right ventricular (RV) function than men, estrogen effects on RV function (a major determinant of survival in PAH) are incompletely characterized. We sought to determine whether sex differences exist in RV function in the SuHx model of PAH, whether hormone depletion in females worsens RV function, and whether E2 repletion improves RV adaptation. Furthermore, we studied the contribution of ERs in mediating E2’s RV effects. SuHx-induced pulmonary hypertension (SuHx-PH) was induced in male and female Sprague-Dawley rats as well as OVX females with or without concomitant E2 repletion (75 μg·kg−1·day−1). Female SuHx rats exhibited superior CI than SuHx males. OVX worsened SuHx-induced decreases in CI and SuHx-induced increases in RVH and inflammation (MCP-1 and IL-6). E2 repletion in OVX rats attenuated SuHx-induced increases in RV systolic pressure (RVSP), RVH, and pulmonary artery remodeling and improved CI and exercise capacity (V̇o2max). Furthermore, E2 repletion ameliorated SuHx-induced alterations in RV glutathione activation, proapoptotic signaling, cytoplasmic glycolysis, and proinflammatory cytokine expression. Expression of ERα in RV was decreased in SuHx-OVX but was restored upon E2 repletion. RV ERα expression was inversely correlated with RVSP and RVH and positively correlated with CO and apelin RNA levels. RV-protective E2 effects observed in females were recapitulated in male SuHx rats treated with E2 or with pharmacological ERα or ERβ agonists. Our data suggest significant RV-protective ER-mediated effects of E2 in a model of severe PH. PMID:25713318

  18. Effects of aged garlic extract on left ventricular diastolic function and fibrosis in a rat hypertension model.

    PubMed

    Hara, Yuki; Noda, Akiko; Miyata, Seiko; Minoshima, Makoto; Sugiura, Mari; Kojima, Jun; Otake, Masafumi; Furukawa, Mayuko; Cheng, Xian Wu; Nagata, Kohzo; Murohara, Toyoaki

    2013-01-01

    Daily consumption of garlic is known to lower the risk of hypertension and ischemic heart disease. In this study, we examined whether aged garlic extract (AGE) prevents hypertension and the progression of compensated left ventricular (LV) hypertrophy in Dahl salt-sensitive (DS) rats. DS rats were randomly divided into three groups: those fed an 8% NaCl diet until 18 weeks of age (8% NaCl group), those additionally treated with AGE (8% NaCl + AGE group), and control rats maintained on a diet containing 0.3% NaCl until 18 weeks of age (0.3% NaCl group). AGE was administered orally by gastric gavage once a day until 18 weeks of age. LV mass was significantly higher in the 8% NaCl + AGE group than in the 0.3% NaCl group at 18 weeks of age, but significantly lower in the 8% NaCl + AGE group than in the 8% NaCl group. No significant differences were observed in systolic blood pressure (SBP) between the 8% NaCl and 8% NaCl + AGE groups at 12 and 18 weeks of age. LV end-diastolic pressure and pressure half-time at 12 and 18 weeks of age were significantly lower in the 8% NaCl + AGE group compared with the 8% NaCl group. AGE significantly reduced LV interstitial fibrosis at 12 and 18 weeks of age. Chronic AGE intake attenuated LV diastolic dysfunction and fibrosis without significantly decreasing SBP in hypertensive DS rats. PMID:24172194

  19. Altered Left Ventricular Ion Channel Transcriptome in a High-Fat-Fed Rat Model of Obesity: Insight into Obesity-Induced Arrhythmogenesis

    PubMed Central

    Yon, Marianne; Pickavance, Lucy; Yanni Gerges, Joseph; Davis, Gershan; Wilding, John; Jian, Kun; Hart, George; Boyett, Mark

    2016-01-01

    Introduction. Obesity is increasingly common and is associated with an increased prevalence of cardiac arrhythmias. The aim of this study was to see whether in obesity there is proarrhythmic gene expression of ventricular ion channels and related molecules. Methods and Results. Rats were fed on a high-fat diet and compared to control rats on a normal diet (n = 8). After 8 weeks, rats on the high-fat diet showed significantly greater weight gain and higher adiposity. Left ventricle samples were removed at 8 weeks and mRNA expression of ion channels and other molecules was measured using qPCR. Obese rats had significant upregulation of Cav1.2, HCN4, Kir2.1, RYR2, NCX1, SERCA2a, and RYR2 mRNA and downregulation of ERG mRNA. In the case of HCN4, it was confirmed that there was a significant increase in protein expression. The potential effects of the mRNA changes on the ventricular action potential and intracellular Ca2+ transient were predicted using computer modelling. Modelling predicted prolongation of the ventricular action potential and an increase in the intracellular Ca2+ transient, both of which would be expected to be arrhythmogenic. Conclusion. High-fat diet causing obesity results in arrhythmogenic cardiac gene expression of ion channels and related molecules. PMID:27747100

  20. Cardioprotective effect of aqueous extract of Chichorium intybus on ischemia-reperfusion injury in isolated rat heart

    PubMed Central

    Sadeghi, Najmeh; Dianat, Mahin; Badavi, Mohammad; Malekzadeh, Ahad

    2015-01-01

    Objective: Several studies have shown that Chichorium intybus (C. intybus) which possesses flavonoid compounds has an effective role in treatment of cardiovascular diseases. Contractile dysfunction mostly occurs after acute myocardial infarction, cardiac bypass surgery, heart transplantation and coronary angioplasty. The aim of the present study was to investigate the effect of aqueous extract of C. intybus on ischemia- reperfusion injury in isolated rat heart. Materials and Methods: The animals were divided into four groups (Sham, Control, 1 mg/ml and 3 mg/ml of extract) of 8 rats. The aorta was cannulated, and then the heart was mounted on a Langendorff apparatus. Next, a balloon was inserted into the left ventricle (LV) and peak positive value of time derivate of LV pressure (+dp/dt), coronary flow (CF), and left ventricular systolic pressure (LVSP) in pre-ischemia and reperfusion period were calculated by a Power Lab system. All groups underwent a 30-minute global ischemia followed by a 60-minute reperfusion. Results: The results showed that heart rate (HR), coronary flow, and left ventricular developed pressure (LVDP) and rate of pressure product (RPP) significantly decreased in the control group during reperfusion, while these values in the groups receiving the extract (3mg/ml) improved significantly during reperfusion (p<0.001). Conclusion: It seems that flavonoid compounds of aqueous extract of C. intybus reduce ischemia - reperfusion injuries, suggesting its protective effect on heart function after ischemia. PMID:26693414

  1. Electrical and mechanical effects of new aminosteroids on guinea-pig isolated ventricular muscle.

    PubMed Central

    Adamantidis, M. M.; Honoré, E. R.; Dupuis, B. A.

    1988-01-01

    1. LND 623 and LND 796 are two aminosteroid derivatives which exert similar positive inotropic effects to digitalis. Their electrophysiological, toxic and inotropic effects were investigated in both normal and partially K+-depolarized ventricular muscle. 2. In guinea-pig myocardial fibres, LND 623 and LND 796 required tenfold higher concentrations than digoxin to induce the same signs of toxicity; e.g. triggered activities generated from delayed afterdepolarizations, leading to the marked depression of action potential characteristics and inexcitability. These abnormal rhythms and delayed afterdepolarizations were abolished by 1 mM caffeine. The toxic effects were reversed by washout, particularly in the case of LND 796. 3. In normal-K+ solution, LND 623 and LND 796 exhibited concentration-dependent positive inotropic effects on guinea-pig papillary muscle and increased concomitantly resting membrane potential and action potential amplitude. The range of active concentrations (0.1 to 1 microM) of LND 623 was larger than that of digoxin (0.3 to 1 microM). Like digoxin, LND 796 exerted negative inotropic effects at the lowest concentrations (0.01 to 0.03 microM) and positive inotropic effects at high concentrations (1 and 3 microM). 4. In partially K+-depolarized papillary muscle, in the presence of 2 microM histamine, LND 623 (3 and 10 microM) and LND 796 (10 and 30 microM) enhanced the two components P1 and P2 of the contraction and increased slow action potential amplitude, resting potential and maximal rate of depolarization. Low concentrations (0.03 to 0.3 microM) of LND 796 induced negative inotropic effects. beta-Adrenoceptor blockade with atenolol (1 microM) did not modify the activity of LND 623 but significantly enhanced the negative inotropic effect on P2 induced by 1 and 3 microM LND 796 and reduced the positive inotropic effect on P1 and P2 of the highest concentration (30 microM) studied. 5. In the presence of either caffeine (1 mM) or Ca2+-free, Sr2

  2. (/sup 3/H)-8-cyclopentyl-1,3-dipropylxanthine binding to A1 adenosine receptors of intact rat ventricular myocytes

    SciTech Connect

    Martens, D.; Lohse, M.J.; Schwabe, U.

    1988-09-01

    The purpose of the present study was the identification of A1 adenosine receptors in intact rat ventricular myocytes, which are thought to mediate the negative inotropic effects of adenosine. The adenosine receptor antagonist (/sup 3/H)-8-cyclopentyl-1,3-dipropylxanthine was used as radioligand. Binding of the radioligand to intact myocytes was rapid, reversible, and saturable with a binding capacity of 40,000 binding sites per cell. The dissociation constant of the radioligand was 0.48 nM. The adenosine receptor antagonists 8-cyclopentyl-1,3-dipropylxanthine, xanthine amine congener, and theophylline were competitive inhibitors with affinities in agreement with results obtained for A1 receptors in other tissues. Competition experiments using the adenosine receptor agonists R-N(6)-phenylisopropyladenosine, 5'-N-ethylcarboxamidoadenosine, and S-N(6)-phenylisopropyladenosine gave monophasic displacement curves with Ki values of 50 nM, 440 nM, and 4,300 nM, which agreed well with the GTP-inducible low affinity state in cardiac membranes. The low affinity for agonists was not due to agonist-induced desensitization, and correlated well with the corresponding IC50 values for the inhibition of cyclic AMP accumulation by isoprenaline. It is suggested that only a low affinity state of A1 receptors can be detected in intact rat myocytes due to the presence of high concentrations of guanine nucleotides in intact cells.

  3. Computational analysis of the regulation of Ca2+ dynamics in rat ventricular myocytes

    NASA Astrophysics Data System (ADS)

    Bugenhagen, Scott M.; Beard, Daniel A.

    2015-10-01

    Force-frequency relationships of isolated cardiac myocytes show complex behaviors that are thought to be specific to both the species and the conditions associated with the experimental preparation. Ca2+ signaling plays an important role in shaping the force-frequency relationship, and understanding the properties of the force-frequency relationship in vivo requires an understanding of Ca2+ dynamics under physiologically relevant conditions. Ca2+ signaling is itself a complicated process that is best understood on a quantitative level via biophysically based computational simulation. Although a large number of models are available in the literature, the models are often a conglomeration of components parameterized to data of incompatible species and/or experimental conditions. In addition, few models account for modulation of Ca2+ dynamics via β-adrenergic and calmodulin-dependent protein kinase II (CaMKII) signaling pathways even though they are hypothesized to play an important regulatory role in vivo. Both protein-kinase-A and CaMKII are known to phosphorylate a variety of targets known to be involved in Ca2+ signaling, but the effects of these pathways on the frequency- and inotrope-dependence of Ca2+ dynamics are not currently well understood. In order to better understand Ca2+ dynamics under physiological conditions relevant to rat, a previous computational model is adapted and re-parameterized to a self-consistent dataset obtained under physiological temperature and pacing frequency and updated to include β-adrenergic and CaMKII regulatory pathways. The necessity of specific effector mechanisms of these pathways in capturing inotrope- and frequency-dependence of the data is tested by attempting to fit the data while including and/or excluding those effector components. We find that: (1) β-adrenergic-mediated phosphorylation of the L-type calcium channel (LCC) (and not of phospholamban (PLB)) is sufficient to explain the inotrope-dependence; and (2) that

  4. Myocardial impulse propagation is impaired in right ventricular tissue of Zucker Diabetic Fatty (ZDF) rats

    PubMed Central

    2013-01-01

    Background Diabetes increases the risk of cardiovascular complications including arrhythmias, but the underlying mechanisms remain to be established. Decreased conduction velocity (CV), which is an independent risk factor for re-entry arrhythmias, is present in models with streptozotocin (STZ) induced type 1 diabetes. Whether CV is also disturbed in models of type 2 diabetes is currently unknown. Methods We used Zucker Diabetic Fatty (ZDF) rats, as a model of type 2 diabetes, and their lean controls Zucker Diabetic Lean (ZDL) rats to investigate CV and its response to the anti-arrhythmic peptide analogue AAP10. Gap junction remodeling was examined by immunofluorescence and western blotting. Cardiac histomorphometry was examined by Masson`s Trichrome staining and intracellular lipid accumulation was analyzed by Bodipy staining. Results CV was significantly slower in ZDF rats (56±1.9 cm/s) compared to non-diabetic controls (ZDL, 66±1.6 cm/s), but AAP10 did not affect CV in either group. The total amount of Connexin43 (C×43) was identical between ZDF and ZDL rats, but the amount of lateralized C×43 was significantly increased in ZDF rats (42±12 %) compared to ZDL rats (30±8%), p<0.04. Judged by electrophoretic mobility, C×43 phosphorylation was unchanged between ZDF and ZDL rats. Also, no differences in cardiomyocyte size or histomorphometry including fibrosis were observed between groups, but the volume of intracellular lipid droplets was 4.2 times higher in ZDF compared to ZDL rats (p<0.01). Conclusion CV is reduced in type 2 diabetic ZDF rats. The CV disturbance may be partly explained by increased lateralization of C×43, but other factors are likely also involved. Our data indicates that lipotoxicity potentially may play a role in development of conduction disturbances and arrhythmias in type 2 diabetes. PMID:23327647

  5. Isolation and characterization of endosomes from rat liver

    SciTech Connect

    Kennedy, G.C.

    1987-01-01

    Three fractions of rat liver endosomes, called 50 Kg Light, 50 Kg Heavy, and 150 Kg have been isolated on 16% Percoll gradients. The 50 Kg Heavy fraction accumulates ligand as a function of time after injection, using either /sup 125/I-asialoorosomucoid (/sup 125/I-ASOR) or /sup 125/I-immunoglobulin A (/sup 125/I-IgA) as ligands. A pulse-chase protocol was also used to study the kinetics of ligand entry into the endosomal compartments. A double-label, 3,3'-diaminobenzidine (DAB)-induced density shift protocol was used to study the internalization of two ligands with different destinations in the hepatocyte. Rats were injected intraportally with /sup 125/I-ASOR-HRP and /sup 131/I-IgA and the liver was fractionated at various times post-injection. The three ligand-containing endosomal fractions were isolated and each subjected to the DAB shift procedure. This treatment causes organelles containing /sup 125/I-ASOR-HRP and another ligand occupying the same compartment to shift to a higher density. Thus, information on whether the /sup 131/I-IgA is colocalized or segregated from the /sup 125/I-ASOR-HRP can be obtained. The authors have used an instantaneous pulse, temperature shift protocol to study the heterogeneity of these three endosomal fractions isolated from rat liver.

  6. Right aortic arch with isolation of the left innominate artery in a case of double chamber right ventricle and ventricular septal defect

    PubMed Central

    Mangukia, Chirantan; Sethi, Sonali; Agarwal, Saket; Mishra, Smita; Satsangi, Deepak kumar

    2014-01-01

    Herein, we report an unusual case of right aortic arch with isolation of the left innominate artery in a case of double chamber right ventricle with ventricular septal defect. The blood supply to the innominate artery was by a collateral arising from the descending aorta. The embryological development of this anomaly can be explained by the hypothetical double aortic arch model proposed by Edwards with interruption of the arch at two levels. PMID:24987265

  7. Endogenous triacylglycerol utilization by the isolated rat atria.

    PubMed

    Varela, A; Savino, E A

    1988-03-01

    The isolated atria from 24 h fasted rats, either in the presence of glucose or in a substrate-free medium containing 2-deoxyglucose, mobilized the endogenous triacylglycerol (TG) to a greater extent than those from fed rats. The TG of the fasted atria had almost disappeared at the end of the 90 min incubation in the substrate-free plus 2-deoxyglucose medium, whereas in those from fed rats a mobilization-resistant portion of about 40% of the TG pool remained. This finding coincided with a lower decay of the contractile and pacemaker activities in the atria from fasted rats. Insulin abolished the TG mobilization in the atria from fed rats in the presence of glucose, but it was ineffective in the fasted atria. These data suggest that the endogenous-TG and glucose share in supporting the atrial functions, that insulin is involved in the control of TG consumption only in the fed state and that the greater TG mobilization in the fasted atria, at least partly, meets the energy requirements of the tissue.

  8. Effects of the venom of the spider Ornithoctonus hainana on neonatal rat ventricular myocytes cellular and ionic electrophysiology.

    PubMed

    Zhang, Yiya; Liu, Jinyan; Liu, Zhonghua; Wang, Meichi; Wang, Jing; Lu, Shanshan; Zhu, Li; Zeng, Xiongzhi; Liang, Songping

    2014-09-01

    Cardiac ion channels are membrane-spanning proteins that allow the passive movement of ions across the cell membrane along its electrochemical gradient, which regulates the resting membrane potential as well as the shape and duration of the cardiac action potential. Additionally, they have been recognized as potential targets for the actions of neurotransmitters, hormones and drugs of cardiac diseases. Spider venoms contain high abundant of toxins that target diverse ion channels and have been considered as a potential resource of new constituents with specific pharmacological properties. However, few peptides from spider venoms were detected as cardiac channel antagonists. In order to explore the effects of the venom of Ornithoctonus hainana on the action potential and ionic currents of neonatal rat ventricular myocytes (NRVMs), whole cell patch clamp technique was used to record action potential duration (APD), sodium current (INa), L calcium current (ICaL), rapidly activating and inactivating transient outward currents (Ito1), rapid (IKr) and slow (IKs) components of the delayed rectifier currents and the inward rectifier currents (IK1). Our results showed that 100 μg/mL venom obviously prolonged APDs. Significantly, the venom could inhibit INa and ICaL effectively, while no evident inhibitory effects on cardiac K(+) channels (Ito1, Iks, Ikr and Ik1) were observed, suggesting that the venom represented a multifaceted pharmacological profile. The effect of venom on Na(+) and Ca(2+) currents of ventricular myocytes revealed that the hainan venom as a rich resource of cardiac channel antagonists might be valuable tools for the investigation of both channels and drug development.

  9. Tickling during adolescence alters fear-related and cognitive behaviors in rats after prolonged isolation.

    PubMed

    Hori, Miyo; Yamada, Kazuo; Ohnishi, Junji; Sakamoto, Shigeko; Furuie, Hiroki; Murakami, Kazuo; Ichitani, Yukio

    2014-05-28

    Social interactions during adolescence are important especially for neuronal development and behavior. We recently showed that positive emotions induced by repeated tickling could modulate fear-related behaviors and sympatho-adrenal stress responses. In the present study, we examined whether tickling during early to late adolescence stage could reverse stress vulnerability induced by socially isolated rearing. Ninety-five male Fischer rats were reared under different conditions from postnatal day (PND) 21 to 53: group-housed (three rats/cage), isolated-nontickled (one rat/cage) and isolated-tickled (received tickling stimulation for 5min a day). Auditory fear conditioning was then performed on the rats at PND 54. Isolated-tickled rats exhibited significantly lower freezing compared with group-housed rats in the first retention test performed 48h after conditioning and compared with isolated-nontickled rats in the second retention test performed 96h after conditioning. Moreover, group-housed and isolated-tickled rats tended to show a significant decrease in freezing responses in the second retention test; however, isolated-nontickled rats did not. In the Morris water maze task that was trained in adulthood (PND 88), but not in adolescence (PND 56), isolated-nontickled rats showed slower decrease of escape latency compared to group-housed rats; however, tickling treatment significantly improved this deficit. These results suggest that tickling stimulation can alleviate the detrimental effects of isolated rearing during adolescence on fear responses and spatial learning. PMID:24727339

  10. Tickling during adolescence alters fear-related and cognitive behaviors in rats after prolonged isolation.

    PubMed

    Hori, Miyo; Yamada, Kazuo; Ohnishi, Junji; Sakamoto, Shigeko; Furuie, Hiroki; Murakami, Kazuo; Ichitani, Yukio

    2014-05-28

    Social interactions during adolescence are important especially for neuronal development and behavior. We recently showed that positive emotions induced by repeated tickling could modulate fear-related behaviors and sympatho-adrenal stress responses. In the present study, we examined whether tickling during early to late adolescence stage could reverse stress vulnerability induced by socially isolated rearing. Ninety-five male Fischer rats were reared under different conditions from postnatal day (PND) 21 to 53: group-housed (three rats/cage), isolated-nontickled (one rat/cage) and isolated-tickled (received tickling stimulation for 5min a day). Auditory fear conditioning was then performed on the rats at PND 54. Isolated-tickled rats exhibited significantly lower freezing compared with group-housed rats in the first retention test performed 48h after conditioning and compared with isolated-nontickled rats in the second retention test performed 96h after conditioning. Moreover, group-housed and isolated-tickled rats tended to show a significant decrease in freezing responses in the second retention test; however, isolated-nontickled rats did not. In the Morris water maze task that was trained in adulthood (PND 88), but not in adolescence (PND 56), isolated-nontickled rats showed slower decrease of escape latency compared to group-housed rats; however, tickling treatment significantly improved this deficit. These results suggest that tickling stimulation can alleviate the detrimental effects of isolated rearing during adolescence on fear responses and spatial learning.

  11. [Relations of the duration of pre-existing angina pectoris, collateral circulation and left ventricular function after isolated coronary occlusion with or without myocardial infarction].

    PubMed

    Juillière, Y; Danchin, N; Grentzinger, A; Suty-Selton, C; Perrin, O; Guenoun, P; Pernot, C; Cherrier, F

    1990-10-01

    The aim of this retrospective study was to determine the relationship between the duration of preceding angina pectoris, collateral circulation and left ventricular function after isolated coronary occlusion with or without myocardial infarction. Coronary angiography of 138 consecutive patients showed isolated and complete occlusions of the left anterior descending (58 patients) or right coronary artery (80 patients). One hundred and four patients had myocardial infarction with (Group A, n = 21) or without (Group B, n = 83) preceding angina pectoris and 34 had angina without myocardial infarction (Group C). The left ventricular ejection fraction was measured by ventriculography in the 30 degrees right anterior oblique projection. The collateral circulation was assessed by coronary angiography and evaluated as follows: no flow or flow limited to collateral branches (subgroup 1) and partial or complete filling of the epicardial arterial segment (subgroup 2). In the global population the left ventricular ejection fraction was higher and the duration of preceding angina pectoris was longer in the subgroups with a well developed collateral circulation. There was no difference in ejection fraction between Groups A and B (presence of myocardial infarction), on the other hand, within each of the groups, a good collateral circulation (subgroup 2) was associated with a significantly higher ejection fraction. Group C (without infarction) patients had better ejection fractions than Groups A or B, especially when the collateral circulation was poorly developed. Within Group C, the quality of the collateral circulation did not seem to affect the ejection fraction. The left ventricular ejection fraction is lower in patients with isolated coronary occlusion and myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. Nicotine and carbon monoxide: effects on the isolated rat heart.

    PubMed

    McGrath, J J

    1986-01-01

    We studied the combined effects of carbon monoxide (CO) and nicotine on the performance of the isolated rat heart. Hearts were removed from laboratory rats and perfused through the aorta with 95% O2-5% CO2 (oxygenated) Krebs-Henseleit solution (KHs). After 30 min, the perfusate was switched rapidly to one of three solutions: KHs containing 10% CO-85% O2-5% CO2 (CO), 10 micrograms/ml nicotine (Nic), or CO combined with nicotine (CO + Nic). KHs containing CO increased coronary flow by 41% without affecting heart rate or pulse pressure. Coronary flow returned to control values during recovery in oxygenated KHs. KHs containing Nic decreased heart rate by 20% and coronary flow by 28%. Pulse pressure was unaffected. Both heart rate and coronary flow returned towards control values during recovery in oxygenated KHs. KHs containing CO + Nic decreased heart rate 16% but stimulated coronary flow 13%. Heart rate returned towards control values during recovery; however, coronary flow, which declined to control values after 8 min, continued to decrease during recovery. These results indicate that the separate effects of CO and Nic on coronary flow in the isolated rat heart are opposing and reversible, but that the decrease they produce in combination is irreversible.

  13. Protein phosphorylation in isolated hepatocytes of septic and endotoxemic rats

    SciTech Connect

    Deaciuc, I.V.; Spitzer, J.A. )

    1989-11-01

    The purpose of this study was to investigate possible alterations induced by sepsis and endotoxicosis in the late phase of Ca2+-dependent signaling in rat liver. Hepatocytes isolated from septic or chronically endotoxin (ET)-treated rats were labeled with (32P)H3PO4 and stimulated with various agents. Proteins were resolved by one-dimensional polyacrylamide gel electrophoresis and autoradiographed. Vasopressin (VP)- and phenylephrine (PE)-induced responses were attenuated in both septic and ET-treated rats for cytosolic and membrane proteins compared with their respective controls. Glucagon and 12-O-myristate phorbol-13-acetate (TPA) affected only the phosphorylation of membrane proteins. Glucagon-induced changes in the phosphorylation of membrane proteins were affected by both sepsis and endotoxicosis, whereas TPA-stimulated phosphorylation was lowered only in endotoxicosis. Response to the Ca2+ ionophore A23187 was depressed in septic rats for cytosolic proteins. The phosphorylation of two cytosolic proteins, i.e., 93 and 61 kDa (previously identified as glycogen phosphorylase and pyruvate kinase, respectively), in response to VP, PE, and A23187 was severely impaired by endotoxicosis and sepsis. TPA did not affect the phosphorylation state of these two proteins. The results show that sepsis and endotoxicosis produce perturbations of the phosphorylation step in Ca2+ transmembrane signaling. Such changes can explain alterations of glycogenolysis and gluconeogenesis associated with sepsis and endotoxicosis.

  14. Acute reversal of phospholamban inhibition facilitates the rhythmic whole-cell propagating calcium waves in isolated ventricular myocytes.

    PubMed

    Chan, Yi-Hsin; Tsai, Wei-Chung; Song, Zhen; Ko, Christopher Y; Qu, Zhilin; Weiss, James N; Lin, Shien-Fong; Chen, Peng-Sheng; Jones, Larry R; Chen, Zhenhui

    2015-03-01

    Phospholamban (PLB) inhibits the activity of cardiac sarcoplasmic reticulum (SR) Ca(2+)-ATPase (SERCA2a). Phosphorylation of PLB during sympathetic activation reverses SERCA2a inhibition, increasing SR Ca(2+) uptake. However, sympathetic activation also modulates multiple other intracellular targets in ventricular myocytes (VMs), making it impossible to determine the specific effects of the reversal of PLB inhibition on the spontaneous SR Ca(2+) release. Therefore, it remains unclear how PLB regulates rhythmic activity in VMs. Here, we used the Fab fragment of 2D12, a monoclonal anti-PLB antibody, to test how acute reversal of PLB inhibition affects the spontaneous SR Ca(2+) release in normal VMs. Ca(2+) sparks and spontaneous Ca(2+) waves (SCWs) were recorded in the line-scan mode of confocal microscopy using the Ca(2+) fluorescent dye Fluo-4 in isolated permeabilized mouse VMs. Fab, which reverses PLB inhibition, significantly increased the frequency, amplitude, and spatial/temporal spread of Ca(2+) sparks in VMs exposed to 50 nM free [Ca(2+)]. At physiological diastolic free [Ca(2+)] (100-200 nM), Fab facilitated the formation of whole-cell propagating SCWs. At higher free [Ca(2+)], Fab increased the frequency and velocity, but decreased the decay time of the SCWs. cAMP had little additional effect on the frequency or morphology of Ca(2+) sparks or SCWs after Fab addition. These findings were complemented by computer simulations. In conclusion, acute reversal of PLB inhibition alone significantly increased the spontaneous SR Ca(2+) release, leading to the facilitation and organization of whole-cell propagating SCWs in normal VMs. PLB thus plays a key role in subcellular Ca(2+) dynamics and rhythmic activity of VMs.

  15. Structural and functional effects of social isolation on the hippocampus of rats with traumatic brain injury.

    PubMed

    Khodaie, Babak; Lotfinia, Ahmad Ali; Ahmadi, Milad; Lotfinia, Mahmoud; Jafarian, Maryam; Karimzadeh, Fariba; Coulon, Philippe; Gorji, Ali

    2015-02-01

    Social isolation has significant long-term psychological and physiological consequences. Both social isolation and traumatic brain injury (TBI) alter normal brain function and structure. However, the influence of social isolation on recovery from TBI is unclear. This study aims to evaluate if social isolation exacerbates the anatomical and functional deficits after TBI in young rats. Juvenile male rats were divided into four groups; sham operated control with social contacts, sham control with social isolation, TBI with social contacts, and TBI with social isolation. During four weeks after brain injury in juvenile rats, we evaluated the animal behaviors by T-maze and open-field tests, recorded brain activity with electrocorticograms and assessed structural changes by histological procedures in the hippocampal dentate gyrus, CA1, and CA3 areas. Our findings revealed significant memory impairments and hyperactivity conditions in rats with TBI and social isolation compared to the other groups. Histological assessments showed an increase of the mean number of dark neurons, apoptotic cells, and caspase-3 positive cells in all tested areas of the hippocampus in TBI rats with and without social isolation compared to sham rats. Furthermore, social isolation significantly increased the number of dark cells, apoptotic neurons, and caspase-3 positive cells in the hippocampal CA3 region in rats with TBI. This study indicates the harmful effect of social isolation on anatomical and functional deficits induced by TBI in juvenile rats. Prevention of social isolation may improve the outcome of TBI.

  16. Complete inhibition of creatine kinase in isolated perfused rat hearts

    SciTech Connect

    Fossel, E.T.; Hoefeler, H.

    1987-01-01

    Transient exposure of an isolated isovolumic perfused rat heart to low concentrations (0.5 mM) of perfusate-born iodoacetamide resulted in complete inhibition of creatine kinase and partial inhibition of glyceraldehyde-3-phosphate dehydrogenase in the heart. At low levels of developed pressure, hearts maintained mechanical function, ATP, and creatine phosphate levels at control values. However, iodoacetamide-inhibited hearts were unable to maintain control values of end diastolic pressure or peak systolic pressure as work load increased. Global ischemia resulted in loss of all ATP without loss of creatine phosphate, indicating lack of active creatine kinase. These results indicate that isovolumic perfused rat hearts are able to maintain normal function and normal levels of high-energy phosphates without active creatine kinase at low levels of developed pressure. /sup 31/P-NMR of the heart was carried out.

  17. Mechanisms of the statins cytotoxicity in freshly isolated rat hepatocytes.

    PubMed

    Abdoli, Narges; Heidari, Reza; Azarmi, Yadollah; Eghbal, Mohammad Ali

    2013-06-01

    Statins are potent drugs, used as lipid-lowering agents in cardiovascular diseases. Hepatotoxicity is one of the serious adverse effects of statins, and the exact mechanism of hepatotoxicity is not yet clear. In this study, the cytotoxic effects of the most commonly used statins, that is, atorvastatin, lovastatin, and simvastatin toward isolated rat hepatocytes, were evaluated. Markers, such as cell death, reactive oxygen species (ROS) formation, lipid peroxidation, mitochondrial membrane potential, and the amount of reduced and oxidized glutathione in the statin-treated hepatocytes, were investigated. It was found that the statins caused cytotoxicity toward rat hepatocytes dose dependently. An elevation in ROS formation, accompanied by a significant amount of lipid peroxidation and mitochondrial depolarization, was observed. Cellular glutathione reservoirs were decreased, and a significant amount of oxidized glutathione was formed. This study suggests that the adverse effect of statins toward hepatocytes is mediated through oxidative stress and the hepatocytes mitochondria play an important role in the statin-induced toxicity.

  18. Optimal dose-setting study of curcumin for improvement of left ventricular systolic function after myocardial infarction in rats.

    PubMed

    Sunagawa, Yoichi; Sono, Shogo; Katanasaka, Yasufumi; Funamoto, Masafumi; Hirano, Sae; Miyazaki, Yusuke; Hojo, Yuya; Suzuki, Hidetoshi; Morimoto, Eriko; Marui, Akira; Sakata, Ryuzo; Ueno, Morio; Kakeya, Hideaki; Wada, Hiromichi; Hasegawa, Koji; Morimoto, Tatsuya

    2014-01-01

    A natural p300-specific histone acetyltransferase inhibitor, curcumin, may have a therapeutic potential for heart failure. However, a study of curcumin to identify an appropriate dose for heart failure has yet to be performed. Rats were subjected to a left coronary artery ligation. One week later, rats with a moderate severity of myocardial infarction (MI) were randomly assigned to 4 groups receiving the following: a solvent as a control, a low dose of curcumin (0.5 mg∙kg(-1)∙day(-1)), a medium dose of curcumin (5 mg∙kg(-1)∙day(-1)), or a high dose of curcumin (50 mg∙kg(-1)∙day(-1)). Daily oral treatment was continued for 6 weeks. After treatment, left ventricular (LV) fractional shortening was dose-dependently improved in the high-dose (25.2% ± 1.6%, P < 0.001 vs. vehicle) and medium-dose (19.6% ± 2.4%) groups, but not in the low-dose group (15.5% ± 1.4%) compared with the vehicle group (15.1% ± 0.8%). The histological cardiomyocyte diameter and perivascular fibrosis as well as echocardiographic LV posterior wall thickness dose-dependently decreased in the groups receiving high and medium doses. The beneficial effects of oral curcumin on the post-MI LV systolic function are lower at 5 compared to 50 mg∙kg(-1)∙day(-1) and disappear at 0.5 mg∙kg(-1)∙day(-1). To clinically apply curcumin therapy for heart failure patients, a precise, optimal dose-setting study is required.

  19. IMPACT OF ISOPRENALINE AND CAFFEINE ON DEVELOPMENT OF LEFT VENTRICULAR HYPERTROPHY AND RENAL HEMODYNAMIC IN WISTAR KYOTO RATS.

    PubMed

    Ahmad, Ashfaq; Sattar, Munavvar Z A; Rathore, Hassaan A; Khan, Safia Akhtar; Lazhari, Mohammed A; Hashmi, Fayaz; Abdullah, Nor A; Johns, Edward J

    2015-01-01

    Left ventricular hypertrophy (LVH) is a compensatory mechanism in response to an increased work load on the heart. This study investigated the impact of chronic isoprenaline and caffeine (I/C model) administration on cardiac geometry, systemic hemodynamic and physiological data in rats as LVH develops. LVH was induced by administering isoprenaline (5 mg/kg s.c. every 72 h) and caffeine (62 mg/L) in drinking water for 14 days to Wistar Kyoto (WKY) rats. Mean arterial pressure (MAP), systolic blood pressure (SBP), heart weight, LV weight, LV chamber diameter and thickness of myocardium were observed as LVH indicators. MAP was significantly higher (142 ± 13 vs. 119 ± 2 mmHg, respectively) while heart rate (HR) in LVH was lower (314 ± 9 vs. 264 ± 18 BPM) compared to control WKY. Heart weight, LV weight and kidney weight were 31%, 38% and 7%, respectively, greater in the LVH group as compared to the control WKY (all p < 0.05).The myocardium thickness was 101% greater while LV chamber diameter was 44% smaller in the LVH group as compared to the control WKY (p < 0.05). The superoxide dismutase (SOD), glutathione reductase (GSH) and total antioxidant capacity (T-AOC) levels were significantly reduced while malonodialdehyde (MDA) level increased in LVH as compared to control WKY (all p < 0.05). In conclusion, isoprenaline and caffeine (I/C) induces LVH and cardiac hypertrophy with increases in blood pressure, fluid excretion and reduced renal hemodynamics. Prooxidant mechanism of the body and arterial stiffness are dominant in this disease model. This model of LVH is easily generated and associated with low mortality. PMID:26665409

  20. IMPACT OF ISOPRENALINE AND CAFFEINE ON DEVELOPMENT OF LEFT VENTRICULAR HYPERTROPHY AND RENAL HEMODYNAMIC IN WISTAR KYOTO RATS.

    PubMed

    Ahmad, Ashfaq; Sattar, Munavvar Z A; Rathore, Hassaan A; Khan, Safia Akhtar; Lazhari, Mohammed A; Hashmi, Fayaz; Abdullah, Nor A; Johns, Edward J

    2015-01-01

    Left ventricular hypertrophy (LVH) is a compensatory mechanism in response to an increased work load on the heart. This study investigated the impact of chronic isoprenaline and caffeine (I/C model) administration on cardiac geometry, systemic hemodynamic and physiological data in rats as LVH develops. LVH was induced by administering isoprenaline (5 mg/kg s.c. every 72 h) and caffeine (62 mg/L) in drinking water for 14 days to Wistar Kyoto (WKY) rats. Mean arterial pressure (MAP), systolic blood pressure (SBP), heart weight, LV weight, LV chamber diameter and thickness of myocardium were observed as LVH indicators. MAP was significantly higher (142 ± 13 vs. 119 ± 2 mmHg, respectively) while heart rate (HR) in LVH was lower (314 ± 9 vs. 264 ± 18 BPM) compared to control WKY. Heart weight, LV weight and kidney weight were 31%, 38% and 7%, respectively, greater in the LVH group as compared to the control WKY (all p < 0.05).The myocardium thickness was 101% greater while LV chamber diameter was 44% smaller in the LVH group as compared to the control WKY (p < 0.05). The superoxide dismutase (SOD), glutathione reductase (GSH) and total antioxidant capacity (T-AOC) levels were significantly reduced while malonodialdehyde (MDA) level increased in LVH as compared to control WKY (all p < 0.05). In conclusion, isoprenaline and caffeine (I/C) induces LVH and cardiac hypertrophy with increases in blood pressure, fluid excretion and reduced renal hemodynamics. Prooxidant mechanism of the body and arterial stiffness are dominant in this disease model. This model of LVH is easily generated and associated with low mortality.

  1. Cardio-protecteffect of qiliqiangxin capsule on left ventricular remodeling, dysfunction and apoptosis in heart failure rats after chronic myocardial infarction

    PubMed Central

    Liang, Tuo; Zhang, Yuhui; Yin, Shijie; Gan, Tianyi; An, Tao; Zhang, Rongcheng; Wang, Yunhong; Huang, Yan; Zhou, Qiong; Zhang, Jian

    2016-01-01

    Background: Qiliqiangxin (QL) capsule is a traditional Chinese medicine which has been approved for the treatment of chronic heart failure. Evidences proved that QL capsules further reduced the NT-proBNP levels and improved left ventricular ejection fraction in CHF patients but the evidence supporting its underlying mechanism is still unclear. Methods and Results: Myocardial infarction (MI) -Heart failure (HF) Sprague-Dawley ratsmodel and neonatal rat cardiac myocytes (NRCMs) were used. Animals were assigned into 4 groups, normal group (n=6), shame-operation group (n=6), MI rats 4 weeks after left anterior descending coronary artery ligation were randomized into vehicle group (n=8), QL group (n=8). QL significantly attenuated cardiac dysfunction and ventricle remodeling as echocardiography and hemodynamic measurements showed improvement in left ventricular ejection fraction, fractional shortening, ±dp/dt and left ventricular end diastolic and systolic diameters in QL treated group compared with the vehicle group. Improvements ininterstitial fibrosisand mitochondrial structures were also exhibited by Sirius Red staining, RT-PCR and electron microscopy. QL treatment improved apoptosis and VEGF expression in rats marginal infract area. Complementary experiments analyzed the improved apoptosis and up-regulate of VEGF in ischemia-hypoxia cultivated NRCMs is in an Akt dependent manner and can be reversed by Akt inhibitor. Conclusion: QL capsule can improve cardiac dysfunction and ventricular remodeling in MI-HF ratsmodel, this cardiac protective efficacy may be concerned with attenuated apoptosis and cardiac fibrosis. Up-regulated VEGF expression and Akt phosphorylation may take part in this availability. PMID:27347313

  2. Acute third ventricular administration of leptin decreases protein and fat in self-selecting rats.

    PubMed

    Wetzler, Sandrine; Jean-Joseph, Gwladys; Even, Patrick; Tomé, Daniel; Larue-Achagiotis, Christiane

    2005-04-15

    The peripheral administration of leptin reduces food intake (FI) body weight gain (BWG) and modifies food choice. The aim of this study was to examine the effect of acute cerebral injections of leptin on food selection in rats. Male rats were first adapted to the food choice paradigm (protein, carbohydrate, fat) for 3 weeks. They were then implanted with a cannula in the third ventricle. Leptin (leptin group=L) or saline (control group=C) injections were performed at either the beginning or the end of the night at 4-day intervals. FI was recorded continuously, 3 days before, during and then after injections. Rats were sacrificed 86 h after the second injection. After both injections, BWG and FI were reduced. The reduction in FI concerned only nocturnal intake, whatever the timing of the injection. When the injection was given at the beginning of the night, the reductions after a 1-h latency period were -45% and -27.5% during the first and second days, respectively. Following the second injection, the same effects were observed immediately (-16% and -41%, respectively). Only the fat and protein intakes were significantly reduced. This lower FI was due to a reduction in meal size and duration. The reduction resulted in a lower BWG and total white adipose tissue mass. At the time of sacrifice, 6 h after food deprivation, leptinemia and insulinemia were reduced in leptin-treated rats. Glycemia values were identical. It was thus demonstrated that central leptin was a satiation factor rather than a satiety factor.

  3. Traditional formula, modern application: chinese medicine formula sini tang improves early ventricular remodeling and cardiac function after myocardial infarction in rats.

    PubMed

    Liu, Jiangang; Peter, Karoline; Shi, Dazhuo; Zhang, Lei; Dong, Guoju; Zhang, Dawu; Breiteneder, Heimo; Jakowitsch, Johannes; Ma, Yan

    2014-01-01

    SINI TANG (SNT) IS A TRADITIONAL CHINESE HERBAL FORMULA CONSISTING OF FOUR DIFFERENT HERBS: the root of Aconitum carmichaelii, the bark of Cinnamomum cassia, the rhizome of Zingiber officinale, and the root of Glycyrrhiza uralensis. This study aims to evaluate the improvement of early ventricular remodeling and cardiac function in myocardial infarction (MI) rats by SNT. A MI model was established by ligation of the left anterior descending coronary artery. Following treatment for 4 weeks, ultrasonic echocardiography was performed. Myocardial histopathological changes were observed using haematoxylin and eosin staining. Collagens (type I and type III), transforming growth factor- β 1 (TGF- β 1), and Toll-like receptors (TLR-2 and TLR-4) were measured in plasma, serum, and myocardial tissue. SNT treatment decreased the infarct size, the left ventricular cavity area/heart cavity area ratio, and the left ventricle dimension at end systole and increased the left ventricular ejection fraction. SNT reduced the levels of TLR-2 and TLR-4 in myocardial tissue significantly and decreased the collagens content in serum and in myocardial tissue. SNT could partially reduce the level of TGF- β 1 in serum and in myocardial tissue. Our data suggest that the Chinese medicine formula SNT has the potential to improve early ventricular remodeling and cardiac function after MI.

  4. Effects of Single Drug and Combined Short-term Administration of Sildenafil, Pimobendan, and Nicorandil on Right Ventricular Function in Rats With Monocrotaline-induced Pulmonary Hypertension

    PubMed Central

    Tanaka, Ryou; Yoshiyuki, Rieko; Fukayama, Toshiharu; Goya, Seijiro; Fukushima, Ryuji

    2015-01-01

    Abstract: This study was designed to assess the progression of pulmonary arterial hypertension (PAH) and the effectiveness of therapy using recently investigated echocardiographic parameters. PAH is characterized by the progressive elevation of pulmonary artery pressure and right ventricular hypertrophy and dysfunction, which ultimately results in right-sided heart failure and death. Echocardiography results and invasive measurements of right and left ventricular systolic pressures were compared after 3-week administrations of sildenafil (S group), pimobendan (P group), nicorandil (N group), and their combinations (SP and SPN groups) in male rats with monocrotaline (MCT)-induced pulmonary hypertension (M group) and without this condition (C group). The groups that received pimobendan alone and in combinations (SP and SPN groups) showed improvement in their echocardiographic parameters of systolic function. A significant improvement of diastolic function was achieved in the SPN group. Invasive measurements showed the most significant decreases of right ventricular systolic pressure in the N and SPN groups, and the use of pimobendan resulted in a comparatively low risk of adverse hemodynamic effects (left ventricular systolic pressure). Although our results suggested the attenuation of PAH severity in all treatment groups, PAH could not be reversed. PMID:25806612

  5. Effects of Single Drug and Combined Short-term Administration of Sildenafil, Pimobendan, and Nicorandil on Right Ventricular Function in Rats With Monocrotaline-induced Pulmonary Hypertension.

    PubMed

    Nakata, Telma M; Tanaka, Ryou; Yoshiyuki, Rieko; Fukayama, Toshiharu; Goya, Seijiro; Fukushima, Ryuji

    2015-06-01

    This study was designed to assess the progression of pulmonary arterial hypertension (PAH) and the effectiveness of therapy using recently investigated echocardiographic parameters. PAH is characterized by the progressive elevation of pulmonary artery pressure and right ventricular hypertrophy and dysfunction, which ultimately results in right-sided heart failure and death. Echocardiography results and invasive measurements of right and left ventricular systolic pressures were compared after 3-week administrations of sildenafil (S group), pimobendan (P group), nicorandil (N group), and their combinations (SP and SPN groups) in male rats with monocrotaline (MCT)-induced pulmonary hypertension (M group) and without this condition (C group). The groups that received pimobendan alone and in combinations (SP and SPN groups) showed improvement in their echocardiographic parameters of systolic function. A significant improvement of diastolic function was achieved in the SPN group. Invasive measurements showed the most significant decreases of right ventricular systolic pressure in the N and SPN groups, and the use of pimobendan resulted in a comparatively low risk of adverse hemodynamic effects (left ventricular systolic pressure). Although our results suggested the attenuation of PAH severity in all treatment groups, PAH could not be reversed.

  6. Ramipril attenuates left ventricular remodeling by regulating the expression of activin A-follistatin in a rat model of heart failure

    PubMed Central

    Wei, Qun; Liu, Haiyan; Liu, Miao; Yang, Chunyan; Yang, Jie; Liu, Zhonghui; Yang, Ping

    2016-01-01

    Prior studies have shown that overexpression of ACT A can lead to ventricular remodeling in rat models of heart failure. Furthermore, recently work studying demonstrated that stimulation of activin An expression in rat aortic smooth muscle (RASM) cells by angiotensin II (Ang II). Ramipril is a recently developed angiotensin converting enzyme (ACE) inhibitor. To investigate the effects of Ramipril on expression of ACT A-FS, we established the rat model of heart failure after myocardial infarction (MI), and divided into either a sham operation (SO), MI, or MI-Ramipril group. We found that Ramipril significantly attenuates collagen-I and III deposition (col-I and III). Notably, we determined that expression of ACT A and II activin receptor (ActRII) were significantly down-regulated in the non-infarcted area of the left ventricle in the Ramipril group, whereas the mRNA and protein levels of FS were markedly up-regulated. Our data suggested that Ramipril benefited left ventricular remodeling by reducing fibrosis and collagen accumulation in the left ventricle of rats after myocardial infarction. This observation was also associated with down-regulation of ACT A expression. This study elucidated a new protective mechanism of Ramipril and suggests a novel strategy for treatment of post-infarct remodeling and subsequent heart failure. PMID:27642098

  7. Ramipril attenuates left ventricular remodeling by regulating the expression of activin A-follistatin in a rat model of heart failure.

    PubMed

    Wei, Qun; Liu, Haiyan; Liu, Miao; Yang, Chunyan; Yang, Jie; Liu, Zhonghui; Yang, Ping

    2016-01-01

    Prior studies have shown that overexpression of ACT A can lead to ventricular remodeling in rat models of heart failure. Furthermore, recently work studying demonstrated that stimulation of activin An expression in rat aortic smooth muscle (RASM) cells by angiotensin II (Ang II). Ramipril is a recently developed angiotensin converting enzyme (ACE) inhibitor. To investigate the effects of Ramipril on expression of ACT A-FS, we established the rat model of heart failure after myocardial infarction (MI), and divided into either a sham operation (SO), MI, or MI-Ramipril group. We found that Ramipril significantly attenuates collagen-I and III deposition (col-I and III). Notably, we determined that expression of ACT A and II activin receptor (ActRII) were significantly down-regulated in the non-infarcted area of the left ventricle in the Ramipril group, whereas the mRNA and protein levels of FS were markedly up-regulated. Our data suggested that Ramipril benefited left ventricular remodeling by reducing fibrosis and collagen accumulation in the left ventricle of rats after myocardial infarction. This observation was also associated with down-regulation of ACT A expression. This study elucidated a new protective mechanism of Ramipril and suggests a novel strategy for treatment of post-infarct remodeling and subsequent heart failure. PMID:27642098

  8. Isolation and purification of rat liver morphine UDP-glucuronosyltransferase

    SciTech Connect

    Puig, J.F.; Tephly, T.R.

    1986-03-05

    The enhancement of rat liver microsomal morphine (M) and 4-hydroxybiphenyl (4-HBP) UDP-glucuronyltransferase (UDPGT) activities by phenobarbital treatment has been proposed to represent increased activity of a single enzyme form, GT-2. They have separated M and 4-HBP UDPGT activities from Emulgen 911-solubilized microsomes obtained from livers of phenobarbital-treated Wistar rats. A sensitive assay procedure was developed to quantify M-UDPGT and 4-HBP-UDPGT activities using /sup 14/C-UDP-glucuronic acid (UDPGA) and reversed phase C-18 minicolumns whereby the radioactive glucuronides were differentially eluted from labeled UDPGA. Trisacryl DEAE, and chromatofocusing procedures were employed to separate M-UDPGT and 4-HBP-UDPGT in the presence of exogenous phosphatidylcholine (PC). The PC is necessary to stabilize UDPGT activities. M-UDPGT was isolated to apparent homogeneity and displayed a monomeric molecular weight of 56,000 daltons on SDS-PAGE. It reacted with M but not with 4-HBP, bilirubin, p-nitrophenol, testosterone, androsterone, estrone, 4-aminobiphenyl or ..cap alpha..-naphthylamine. 4-HBP-UDPGT did not react with M. Therefore, M and 4-HBP glucuronidations are catalyzed by separate enzymes in rat liver microsomes.

  9. Experimental studies on islets isolation, purification and function in rats.

    PubMed

    Pang, Xinlu; Xue, Wujun; Feng, Xinshun; Tian, Xiaohui; Teng, Yan; Ding, Xiaoming; Pan, Xiaoming; Guo, Qi; He, Xiaoli

    2015-01-01

    To develop a simple and effective method of islet isolation and purification in rats. Collagenase P was injected into pancreatic duct followed by incubation in water bath to digest the pancreas and isolate islet, then discontinuous gravity gradient purification was used to purify the islet. The purified islets were identified by dithizone staining. The viability of islets was assessed by fluorescence staining of acridine orange (AO) and propidium iodide (PI). The function of purified islets was determined by glucose-stimulated insulin release test and transplantation of rat with streptozocin-induced diabetes. 738±193 islets were recovered after purification. The average purity was 77±13%, the viability of islets was more than 95%. When inspected by glucose stimulation, the secreted insulin concentration was 24.31±5.47 mIU/L when stimulated by low concentration glucose and 37.62±4.29 mIU/L by high concentration glucose. There was significant difference between the two phases (P<0.05). The blood sugar concentration recovered to normal level after two days in the animals with islet transplantation. In conclusion, islets can be procured with good function and shape by using the method of injecting collagenase into pancreatic duct followed by incubation in water bath and purification using discontinuous gravity gradient. PMID:26885021

  10. Experimental studies on islets isolation, purification and function in rats

    PubMed Central

    Pang, Xinlu; Xue, Wujun; Feng, Xinshun; Tian, Xiaohui; Teng, Yan; Ding, Xiaoming; Pan, Xiaoming; Guo, Qi; He, Xiaoli

    2015-01-01

    To develop a simple and effective method of islet isolation and purification in rats. Collagenase P was injected into pancreatic duct followed by incubation in water bath to digest the pancreas and isolate islet, then discontinuous gravity gradient purification was used to purify the islet. The purified islets were identified by dithizone staining. The viability of islets was assessed by fluorescence staining of acridine orange (AO) and propidium iodide (PI). The function of purified islets was determined by glucose-stimulated insulin release test and transplantation of rat with streptozocin-induced diabetes. 738±193 islets were recovered after purification. The average purity was 77±13%, the viability of islets was more than 95%. When inspected by glucose stimulation, the secreted insulin concentration was 24.31±5.47 mIU/L when stimulated by low concentration glucose and 37.62±4.29 mIU/L by high concentration glucose. There was significant difference between the two phases (P<0.05). The blood sugar concentration recovered to normal level after two days in the animals with islet transplantation. In conclusion, islets can be procured with good function and shape by using the method of injecting collagenase into pancreatic duct followed by incubation in water bath and purification using discontinuous gravity gradient. PMID:26885021

  11. The effect of cinnamon extract on isolated rat uterine strips.

    PubMed

    Alotaibi, Mohammed

    2016-03-01

    Cinnamon is a spice used by some populations as a traditional remedy to control blood pressure and thus hypertension. Cinnamon extract decreases contractility in some smooth muscles, but its effect on uterine smooth muscle is unknown. The aim of this study was to determine the physiological and pharmacological effects of cinnamon extract (CE) on the contractions of isolated rat uterine strips and to investigate its possible mechanism of action. Isolated longitudinal uterine strips were dissected from non-pregnant rats, mounted vertically in an organ bath chamber, and exposed to different concentrations of CE (10-20mg/mL). The effect of CE was investigated in the presence of each of the following solutions: 60mM KCl, 5nM oxytocin, and 1μM Bay K8644. CE significantly decreased the force of uterine contraction in a concentration-dependent manner and significantly attenuated the uterine contractions elicited by KCl and oxytocin. In addition, CE significantly decreased the contractile force elicited when L-type Ca(2+) channels were activated by Bay K8644. CE's major mechanism may be inhibition of L-type Ca(2+) channels, which limits calcium influx. These data demonstrate that CE can be a potent tocolytic that can decrease uterine activity regardless of how the force was produced, even when the uterus was stimulated by agonists. As a result, cinnamon may be used to alleviate menstrual pain associated with dysmenorrhoea or prevent unwanted uterine activity in early pregnancy. PMID:26952750

  12. Protective effects of remote ischemic preconditioning in isolated rat hearts

    PubMed Central

    Teng, Xiao; Yuan, Xin; Tang, Yue; Shi, Jingqian

    2015-01-01

    To use Langendorff model to investigate whether remote ischemic preconditioning (RIPC) attenuates post-ischemic mechanical dysfunction on isolated rat heart and to explore possible mechanisms. SD rats were randomly divided into RIPC group, RIPC + norepinephrine (NE) depletion group, RIPC + pertussis toxin (PTX) pretreatment group, ischemia/reperfusion group without treatment (ischemia group) and time control (TC) group. RIPC was achieved through interrupted occlusion of anterior mesenteric artery. Then, Langendorff model was established using routine methods. Heart function was tested; immunohistochemistry and ELISA methods were used to detect various indices related to myocardial injury. Compared with ischemia group in which the hemodynamic parameters deteriorated significantly, heart function recovered to a certain degree among the RIPC, RIPC + NE depletion, and RIPC + PTX groups (P<0.05). More apoptotic nuclei were observed in ischemia group than in the other three groups (P<0.05); more apoptotic nuclei were detected in NE depletion and PTX groups than in RIPC group (P<0.05). While, there was no significant difference between NE depletion and PTX groups. In conclusion, RIPC protection on I/R myocardium extends to the period after hearts are isolated. NE and PTX-sensitive inhibitory G protein might have a role in the protection process. PMID:26550168

  13. Experimental studies on islets isolation, purification and function in rats.

    PubMed

    Pang, Xinlu; Xue, Wujun; Feng, Xinshun; Tian, Xiaohui; Teng, Yan; Ding, Xiaoming; Pan, Xiaoming; Guo, Qi; He, Xiaoli

    2015-01-01

    To develop a simple and effective method of islet isolation and purification in rats. Collagenase P was injected into pancreatic duct followed by incubation in water bath to digest the pancreas and isolate islet, then discontinuous gravity gradient purification was used to purify the islet. The purified islets were identified by dithizone staining. The viability of islets was assessed by fluorescence staining of acridine orange (AO) and propidium iodide (PI). The function of purified islets was determined by glucose-stimulated insulin release test and transplantation of rat with streptozocin-induced diabetes. 738±193 islets were recovered after purification. The average purity was 77±13%, the viability of islets was more than 95%. When inspected by glucose stimulation, the secreted insulin concentration was 24.31±5.47 mIU/L when stimulated by low concentration glucose and 37.62±4.29 mIU/L by high concentration glucose. There was significant difference between the two phases (P<0.05). The blood sugar concentration recovered to normal level after two days in the animals with islet transplantation. In conclusion, islets can be procured with good function and shape by using the method of injecting collagenase into pancreatic duct followed by incubation in water bath and purification using discontinuous gravity gradient.

  14. Activation of Akt and cardioprotection against reperfusion injury are maximal with only five minutes of sevoflurane postconditioning in isolated rat hearts.

    PubMed

    Yao, Yuan-yuan; Zhu, Man-hua; Zhang, Feng-jiang; Wen, Chuan-yun; Ma, Lei-lei; Wang, Wen-na; Wang, Can-can; Liu, Xian-bao; Yu, Li-na; Qian, Ling-bo; Wang, Jian-an; Yan, Min

    2013-06-01

    It had been proved that administration of sevoflurane for the first two minutes of reperfusion effectively protects the heart against reperfusion injury in rats in vivo. Our aim was to investigate the duration of effective sevoflurane administration and its underlying mechanism in isolated rat hearts exposed to global ischemia/reperfusion (I/R) injury. Adult male Sprague-Dawley rats were randomly divided into six groups (n=12): a sham-operation group, an I/R group, and four sevoflurane postconditioning groups (S2, S5, S10, and S15). In the S2, S5, S10, and S15 groups, the duration times of sevoflurane administration were 2, 5, 10, and 15 min after the onset of reperfusion, respectively. The isolated rat hearts were mounted on the Langendorff system, and after a period of equilibrium were subjected to 40 min global ischemia and 120 min reperfusion. Left ventricular (LV) hemodynamic parameters were monitored throughout each experiment and the data at 30 min of equilibrium and 30, 60, 90, and 120 min of reperfusion were analyzed. Myocardial infarct size at the end of reperfusion (n=7 in each group) and the expression of myocardial phosphorylated Akt (p-Akt) after 15-min reperfusion were determined in a duplicate set of six groups of rat hearts (n=5 in each group). Compared with the I/R group, the S5, S10, and S15 groups had significantly improved left ventricular end-diastolic pressure (LVEDP), left ventricular developed pressure (LVDP), and the maximal rate of rise or fall of the LV pressure (±dP/dtmax), and decreased myocardial infarct size (P<0.05), but not the S2 group. After 15 min of reperfusion, the expression of p-Akt was markedly up-regulated in the S5, S10, and S15 groups compared with that in the I/R group (P<0.05), but not in the S2 group. Sevoflurane postconditioning for 5 min was sufficient to activate Akt and exert maximal cardioprotection against I/R injury in isolated rat hearts.

  15. The H{sub 1}–H{sub 2} domain of the α{sub 1} isoform of Na{sup +}–K{sup +}–ATPase is involved in ouabain toxicity in rat ventricular myocytes

    SciTech Connect

    Xiong, Chen; Li, Jun-xia; Guo, Hui-cai; Zhang, Li-nan; Guo, Wei; Meng, Jing; Wang, Yong-li

    2012-07-01

    The composition of different isoforms of Na{sup +}-K{sup +}-ATPase (NKA, Na/K pump) in ventricular myocytes is an important factor in determining the therapeutic effect and toxicity of cardiac glycosides (CGs) on heart failure. The mechanism whereby CGs cause these effects is still not completely clear. In the present study, we prepared two site-specific antibodies (SSA78 and WJS) against the H{sub 1}–H{sub 2} domain of α{sub 1} and α{sub 2} isoforms of NKA in rat heart, respectively, and compared their influences on the effect of ouabain (OUA) in isolated rat ventricular myocytes. SSA78 or WJS, which can specifically bind with the α{sub 1} or α{sub 2} isoform, were assessed with enzyme linked immunosorbent assay (ELISA), Western blot and immunofluorescent staining methods. Preincubation of myocytes with SSA78 inhibited low OUA affinity pump current but not high OUA affinity pump current, reduced the rise in cytosolic calcium concentration ([Ca{sup 2+}]{sub i}), attenuated mitochondrial Ca{sup 2+} overload, restored mitochondrial membrane potential reduction, and delayed the decrease of the myocardial contractile force as well as the occurrence of arrhythmic contraction induced by high concentrations (1 mM) but not low concentrations (1 μM) of OUA. Similarly, preincubation of myocytes with WJS inhibited high OUA affinity pump current, reduced the increase of [Ca{sup 2+}]{sub i} and the contractility induced by 1 μM but not that induced by 1 mM OUA. These results indicate that the H{sub 1}–H{sub 2} domain of the NKA α{sub 1} isoform mediates OUA-induced cardiac toxicity in rat ventricular myocytes, and inhibitors for this binding site may be used as an adjunct to CGs treatment for cardiovascular disease. -- Highlights: ► We prepared two antibodies against the H{sub 1}-H{sub 2} domain of α{sub 1} and α{sub 2} isoforms of NKA. ► The H{sub 1}-H{sub 2} domain of the NKA α{sub 1} isoform mediates OUA-induced cardiac toxicity. ► The H{sub 1}-H{sub 2

  16. Exposure to nitrous oxide stimulates a nitric oxide-dependent neuronal release of beta-endorphin in ventricular-cisternally-perfused rats.

    PubMed

    Zelinski, Lisa M; Ohgami, Yusuke; Quock, Raymond M

    2009-12-01

    We have previously shown that the antinociceptive effect of nitrous oxide (N(2)O) in the rat hot plate test is sensitive to antagonism by antisera against the endogenous opioid peptide beta-endorphin. Moreover, N(2)O-induced antinociception is reduced by inhibition of nitric oxide (NO) production in the brain. To test the hypothesis that N(2)O might stimulate an NO-dependent neuronal release of beta-endorphin, we conducted a ventricular-cisternal perfusion with artificial cerebrospinal fluid (aCSF) in urethane-anesthetized Sprague-Dawley rats. Ten-minute fractions of aCSF perfusate were collected from separate groups of room air-exposed rats, N(2)O-exposed rats, and L-NAME-pretreated, N(2)O-exposed rats; they were then analyzed for their content of NO metabolites and beta-endorphin. Compared to room air control, exposure to 70% N(2)O increased perfusate levels of the NO metabolites nitrite and nitrate as well as beta-endorphin. Pretreatment of rats with L-N(G)-nitro arginine methyl ester, an inhibitor of NO synthase, prevented the N(2)O-induced increases in nitrite, nitrate and beta-endorphin. These findings demonstrate in an in vivo rat model that N(2)O may stimulate an NO-dependent neuronal release of beta-endorphin. PMID:19747467

  17. Enhancement of contraction and L-type Ca(2+) current by murrayafoline-A via protein kinase C in rat ventricular myocytes.

    PubMed

    Chidipi, Bojjibabu; Son, Min-Jeong; Kim, Joon-Chul; Lee, Jeong Hyun; Toan, Tran Quoc; Cuong, Nguyen Manh; Lee, Byung Ho; Woo, Sun-Hee

    2016-08-01

    We previously reported that murrayafoline-A (1-methoxy-3-methyl-9H-carbazole, Mu-A) increases the contractility of ventricular myocytes, in part, via enhancing Ca(2+) influx through L-type Ca(2+) channels, and that it increases the Ca(2+) transients by activation of protein kinase C (PKC). In the present study, we further examined the cellular mechanisms for the enhancement of contractility and L-type Ca(2+) current (ICa,L) by Mu-A. Cell shortening and ICa,L were measured in rat ventricular myocytes using a video edge detection method and perforated patch-clamp technique, respectively. We found that the positive inotropic effect of Mu-A was not affected by pre-exposure to the β-adrenoceptor antagonist propranolol, the protein kinase A (PKA) inhibitors KT5720 or H-89, or the phospholipase C inhibitor U73122. Interestingly, the Mu-A-mediated increases in cell shortening and in the rate of contraction were completely suppressed by pre-treatment with the PKC inhibitor GF109203X. The stimulatory effect of Mu-A on ICa,L was not altered by inhibition of PKA (KT5720), G-protein coupled receptors (suramin), or α1-adrenoceptor (prazosin). However, pre-exposure to the PKC inhibitor, GF109203X or chelerythrine, abolished the Mu-A-induced increase in ICa,L. Pre-exposure to the Ca(2+)-calmodulin-dependent protein kinase II (CaMKII) inhibitor KN93 slightly reduced the stimulatory effects on contraction and ICa,L by Mu-A. Phosphorylation of PKC was enhanced by Mu-A in ventricular myocytes. These data suggest that Mu-A increases contraction and ICa,L via PKC in rat ventricular myocytes, and that the PKC-mediated responses in the presence of Mu-A may be partly mediated by CaMKII.

  18. Are there gender differences in left ventricular remodeling after myocardial infarction in rats?

    PubMed Central

    Antonio, Ednei Luiz; Serra, Andrey Jorge; dos Santos, Alexandra Alberta; Vieira, Stella Sousa; Silva, Jairo Montemor Augusto; Yoshizaki, Amanda; Sofia, Renato Rodrigues; Tucci, Paulo José Ferreira

    2015-01-01

    Objective An unclear issue is whether gender may influence at cardiac remodeling after myocardial infarction (MI). We evaluated left ventricle remodeling in female and male rats post-MI. Methods Rats were submitted to anterior descending coronary occlusion. Echocardiographic evaluations were performed on the first and sixth week post-occlusion to determine myocardial infarction size and left ventricle systolic function (FAC, fractional area change). Pulsed Doppler was applied to analyze left ventricle diastolic function using the following parameters: E wave, A wave, E/A ratio. Two-way ANOVA was applied for comparisons, complemented by the Bonferroni test. A P≤=0.05 was considered significant. Results There were no significant differences between genders for morphometric parameters on first (MI [Female (FE): 44.0±5.0 vs. Male (MA): 42.0±3.0%]; diastolic [FE: 0.04±0.003 vs. MA: 0.037±0.005, mm/g] and systolic [FE: 0.03±0.0004 vs. MA: 0.028±0.005, mm/g] diameters of left ventricle) and sixth (MI [FE: 44.0±5.0 vs. MA: 42.0±3.0, %]; diastolic [FE: 0.043±0.01 vs. MA: 0.034±0.005, mm/g] and systolic [FE: 0.035±0.01 vs. MA: 0.027±0.005, mm/g] of LV) week. Similar findings were reported for left ventricle functional parameters on first (FAC [FE: 34.0±6.0 vs. MA: 32.0±4.0, %]; wave E [FE: 70.0±18.0 vs. MA: 73.0±14.0, cm/s]; wave A [FE: 20.0±12.0 vs. MA: 28.0±13.0, cm/s]; E/A [FE: 4.9±3.4 vs. MA: 3.3±1.8]) and sixth (FAC [FE: 29.0±7.0 vs. MA: 31.0±7.0, %]; wave E [FE: 85.0±18.0 vs. MA: 87.0±20.0, cm/s]; wave A [FE: 20.0±11.0 vs. MA: 28.0±17.0, cm/s]; E/A [FE: 6.2±4.0 vs. MA: 4.6±3.4]) week. Conclusion Gender does not influence left ventricle remodeling post-MI in rats. PMID:25859870

  19. Exogenous superoxide dismutase and catalase promote recovery of function in isolated rat heart after regional ischemia and may be transported from capillaries into myocytes.

    PubMed

    Koke, J R; Christodoulides, N J; Chudej, L L; Bittar, N

    1990-08-10

    The effects of infusing superoxide dismutase (SOD) and catalase (CAT) into the coronary circulation were investigated in isolated, working rat hearts prior to and during a 15 minute episode of regional ischemia followed by 30 minutes reperfusion. Aortic output, left ventricular pressure and dP/dT were recorded. Compared to untreated hearts, SOD and CAT significantly improved function during reperfusion, but had no effect during the pre-ischemic or the ischemic period. To investigate possible transport of SOD and CAT into rat myocytes, cryotome sections of isolated, Langendorff perfused rat hearts were exposed to rabbit antibody prepared against the exogenous SOD and CAT. Bound antibody was detected by the indirect-fluorescent antibody test. The interior of myocytes from rat hearts exposed to SOD and CAT bound antibodies prepared against these enzymes, whereas myocytes from rat hearts not exposed to exogenous SOD and CAT only bound the CAT antibodies. This indicates the anti-SOD we prepared is specific for exogenous SOD, and also suggests exogenous SOD can gain access to the cytoplasm of myocytes from the coronary circulation. PMID:2274050

  20. Water and nonelectrolyte permeability of isolated rat hepatocytes

    SciTech Connect

    Alpini, G.; Garrick, R.A.; Jones, M.J.; Nunes, R.; Tavoloni, N.

    1986-12-01

    We have measured the diffusive permeability coefficients of isolated rat hepatocytes to /sup 3/H/sub 2/O, (/sup 14/C)urea, (/sup 14/C)erythritol, (/sup 14/C)mannitol, (/sup 3/H)sucrose, and (/sup 3/H)inulin, employing a technique previously developed for erythrocytes (Redwood et al., J. Gen. Physiol 64:706-729, 1974). Diffusion coefficients for the tracer molecules were measured in packed hepatocytes, supernatant fluid, and intracellular medium (lysed hepatocytes) and were calculated assuming one-dimensional semi-infinite diffusion through a homogeneous medium. By applying the series-parallel pathway model, the following permeability coefficients (10(-5) cm/sec) for the hepatocyte plasma membrane were obtained. /sup 3/H/sub 2/O, 98.6 +/- 18.4; (/sup 14/C)urea, 18.2 +/- 5.3; (/sup 14/C)erythritol, 4.8 +/- 1.6; (/sup 14/C)mannitol, 3.1 +/- 1.4; (/sup 3/H)sucrose, 0; (/sup 3/H)inulin, 0. These results indicate that isolated rat hepatocytes are highly permeable to water and polar nonelectrolytes, when compared with other transporting epithelia. This relatively high cellular permeability is consistent with a model in which nonelectrolyte permeation is via an aqueous pathway of equivalent pore diameter of 8-12 A. The finding that (/sup 14/C)erythritol and (/sup 14/C)mannitol cross the hepatocyte plasma membrane indicates that these molecules enter the bile canaliculus through the transcellular route. Conversely, the failure of (/sup 3/H)sucrose and (/sup 3/H)inulin to permeate the hepatocyte in the isolated condition supports the concept that biliary entry of these large carbohydrates, at least that fraction which cannot be accounted for by a vesicular mechanism, must occur via the transjunctional shunt pathway.

  1. Complete Genome Sequence of a Rat Hepatitis E Virus Strain Isolated in the United States

    PubMed Central

    Debing, Yannick; Emerson, Suzanne U.; Purcell, Robert H.; Dallmeier, Kai

    2014-01-01

    Hepatitis E virus is a common cause of acute hepatitis in humans. Related viruses have been isolated from multiple animal species, including rats, but their impact on human health is unclear. We present the first full-length genome sequence of a rat hepatitis E virus strain isolated in the United States (LA-B350). PMID:25377700

  2. The GSTM2 C-Terminal Domain Depresses Contractility and Ca2+ Transients in Neonatal Rat Ventricular Cardiomyocytes.

    PubMed

    Hewawasam, Ruwani P; Liu, Dan; Casarotto, Marco G; Board, Philip G; Dulhunty, Angela F

    2016-01-01

    The cardiac ryanodine receptor (RyR2) is an intracellular ion channel that regulates Ca2+ release from the sarcoplasmic reticulum (SR) during excitation-contraction coupling in the heart. The glutathione transferases (GSTs) are a family of phase II detoxification enzymes with additional functions including the selective inhibition of RyR2, with therapeutic implications. The C-terminal half of GSTM2 (GSTM2C) is essential for RyR2 inhibition, and mutations F157A and Y160A within GSTM2C prevent the inhibitory action. Our objective in this investigation was to determine whether GSTM2C can enter cultured rat neonatal ventricular cardiomyocytes and influence contractility. We show that oregon green-tagged GSTM2C (at 1 μM) is internalized into the myocytes and it reduces spontaneous contraction frequency and myocyte shortening. Field stimulation of myocytes evoked contraction in the same percentage of myocytes treated either with media alone or media plus 15 μM GSTM2C. Myocyte shortening during contraction was significantly reduced by exposure to 15 μM GSTM2C, but not 5 and 10 μM GSTM2C and was unaffected by exposure to 15 μM of the mutants Y160A or F157A. The amplitude of the Ca2+ transient in the 15 μM GSTM2C - treated myocytes was significantly decreased, the rise time was significantly longer and the decay time was significantly shorter than in control myocytes. The Ca2+ transient was not altered by exposure to Y160A or F157A. The results are consistent with GSTM2C entering the myocytes and inhibiting RyR2, in a manner that indicates a possible therapeutic potential for treatment of arrhythmia in the neonatal heart. PMID:27612301

  3. Role of inositol-1,4,5-trisphosphate receptor in the regulation of calcium transients in neonatal rat ventricular myocytes.

    PubMed

    Zeng, Zheng; Zhang, Heping; Lin, Na; Kang, Man; Zheng, Yuanyuan; Li, Chen; Xu, Pingxiang; Wu, Yongquan; Luo, Dali

    2014-01-01

    This study determined the regulatory effect of inositol 1,4,5-trisphosphate receptors (IP3Rs) on the basal Ca(2+) transients in cardiomyocytes. In cultured neonatal rat ventricular myocytes (NRVMs) at different densities, we used confocal microscopy to assess the effect of IP3Rs on the endogenous spontaneous Ca(2+) oscillations through specific activation of IP3Rs with myo-IP3 hexakis (butyryloxymethyl) ester (IP3BM), a membrane permeable IP3, and interference of IP3R expression with shRNA. We found that NRVMs at the monolayer state displayed coordinated Ca(2+) transients with less rate, shorter duration, and higher amplitude compared to single NRVMs. In addition, monolayer NRVMs exhibited 4 or 10 times more increased Ca(2+) transients in response to phenylephrine, an α-adrenergic receptor agonist, or IP3BM than single NRVMs did, while the transient pattern remained unaltered, suggesting that the sensitivity of intracellular Ca(2+) response to IP3R activation is different between single and monolayer NRVMs. However, interference of IP3R expression with shRNA reduced the frequency and amplitude of the spontaneous Ca(2+) fluctuates similarly in both densities of NRVMs, resembling the effects of ryanodine receptor inhibition by ryanodine or tetracaine. Our findings suggest that IP3Rs are involved, in part, in the regulation of native Ca(2+) transients, in profiles of their initiation and Ca(2+) release extent, in developing cardiomyocytes. In addition, caution should be paid in evaluating the behavior of Ca(2+) signaling in primary cultured cardiomyocytes at different densities. PMID:25242084

  4. Cardiotoxic Electrophysiological Effects of the Herbicide Roundup(®) in Rat and Rabbit Ventricular Myocardium In Vitro.

    PubMed

    Gress, Steeve; Lemoine, Sandrine; Puddu, Paolo-Emilio; Séralini, Gilles-Eric; Rouet, René

    2015-10-01

    Roundup (R), a glyphosate (G)-based herbicide (GBH), containing unknown adjuvants is widely dispersed around the world. Used principally by farmers, intoxications have increasingly been reported. We have studied R effects (containing 36 % of G) on right ventricular tissues (male Sprague-Dawley rats, up to 20,000 ppm and female New Zealand rabbits, at 25 and 50 ppm), to investigate R cardiac electrophysiological actions in vitro. We tested the reduced Ca(++) intracellular uptake mechanism as one potential cause of the electrical abnormalities after GBH superfusion, using the Na(+)/K(+)-ATPase inhibitor ouabain or the 1,4-dihydropyridine L-type calcium channel agonist BAY K 8644 which increases I Ca. R concentrations were selected based on human blood ranges found after acute intoxication. The study showed dose-dependent V max, APD50 and APD90 variations during 45 min of R superfusion. At the highest concentrations tested, there was a high incidence of conduction blocks, and 30-min washout with normal Tyrode solution did not restore excitability. We also observed an increased incidence of arrhythmias at different doses of R. Ouabain and BAY K 8644 prevented V max decrease, APD90 increase and the cardiac inexcitability induced by R 50 ppm. Glyphosate alone (18 and 180 ppm) had no significant electrophysiological effects. Thus, the action potential prolonging effect of R pointing to I Ca interference might explain both conduction blocks and proarrhythmia in vitro. These mechanisms may well be causative of QT prolongation, atrioventricular conduction blocks and arrhythmias in man after GBH acute intoxications as reported in retrospective hospital records.

  5. The GSTM2 C-Terminal Domain Depresses Contractility and Ca2+ Transients in Neonatal Rat Ventricular Cardiomyocytes

    PubMed Central

    Hewawasam, Ruwani P.; Liu, Dan; Casarotto, Marco G.; Board, Philip G.; Dulhunty, Angela F.

    2016-01-01

    The cardiac ryanodine receptor (RyR2) is an intracellular ion channel that regulates Ca2+ release from the sarcoplasmic reticulum (SR) during excitation–contraction coupling in the heart. The glutathione transferases (GSTs) are a family of phase II detoxification enzymes with additional functions including the selective inhibition of RyR2, with therapeutic implications. The C-terminal half of GSTM2 (GSTM2C) is essential for RyR2 inhibition, and mutations F157A and Y160A within GSTM2C prevent the inhibitory action. Our objective in this investigation was to determine whether GSTM2C can enter cultured rat neonatal ventricular cardiomyocytes and influence contractility. We show that oregon green-tagged GSTM2C (at 1 μM) is internalized into the myocytes and it reduces spontaneous contraction frequency and myocyte shortening. Field stimulation of myocytes evoked contraction in the same percentage of myocytes treated either with media alone or media plus 15 μM GSTM2C. Myocyte shortening during contraction was significantly reduced by exposure to 15 μM GSTM2C, but not 5 and 10 μM GSTM2C and was unaffected by exposure to 15 μM of the mutants Y160A or F157A. The amplitude of the Ca2+ transient in the 15 μM GSTM2C - treated myocytes was significantly decreased, the rise time was significantly longer and the decay time was significantly shorter than in control myocytes. The Ca2+ transient was not altered by exposure to Y160A or F157A. The results are consistent with GSTM2C entering the myocytes and inhibiting RyR2, in a manner that indicates a possible therapeutic potential for treatment of arrhythmia in the neonatal heart. PMID:27612301

  6. Changes of SERCA activity have only modest effects on sarcoplasmic reticulum Ca2+ content in rat ventricular myocytes.

    PubMed

    Bode, E F; Briston, S J; Overend, C L; O'Neill, S C; Trafford, A W; Eisner, D A

    2011-10-01

    Changes of the activity of the sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA) affect the amplitude of the systolic Ca(2+) transient and thence cardiac contractility. This is thought to be due to alterations of SR Ca(2+) content. Recent work on mice in which the expression of SERCA is decreased found that a large reduction of SERCA expression resulted in a proportionately much smaller decrease of SR Ca(2+) content. The aim of the current work was to investigate the quantitative nature of the dependence of both the amplitude of the systolic Ca(2+) transient and SR Ca(2+) content on SERCA activity during acute partial inhibition of SERCA. Experiments were performed on rat ventricular myocytes. Brief application of thapsigargin (1 μm) resulted in a decrease of SERCA activity as measured from the rate of decay of the systolic Ca(2+) transient. This was accompanied by a decrease in the amplitude of the systolic Ca(2+) transient which was linearly related to that of SERCA activity. However, the fractional decrease in the SR Ca(2+) content was much less than that of SERCA activity. On average SR Ca(2+) content was proportional to SERCA activity raised to the 0.38 ± 0.07 power. This shallow dependence of SR content on SERCA activity arises because Ca(2+) release is a steep function of SR Ca(2+) content. In contrast SR Ca(2+) content was increased 4.59 ± 0.40 (n = 8)-fold by decreasing ryanodine receptor opening with tetracaine (1 mm). Therefore a modest decrease of SR Ca(2+) content results in a proportionately larger fall of Ca(2+) release from the SR which can balance a larger initiating decrease of SERCA. In conclusion, the shallow dependence of SR Ca(2+) content on SERCA activity is expected for a system in which small changes of SR Ca(2+) content produce larger effects on the amplitude of the systolic Ca(2+) transient.

  7. Rat model of exercise-induced cardiac hypertrophy: hemodynamic characterization using left ventricular pressure-volume analysis.

    PubMed

    Radovits, Tamás; Oláh, Attila; Lux, Árpád; Németh, Balázs Tamás; Hidi, László; Birtalan, Ede; Kellermayer, Dalma; Mátyás, Csaba; Szabó, Gábor; Merkely, Béla

    2013-07-01

    Long-term exercise training is associated with characteristic structural and functional changes of the myocardium, termed athlete's heart. Several research groups investigated exercise training-induced left ventricular (LV) hypertrophy in animal models; however, only sporadic data exist about detailed hemodynamics. We aimed to provide functional characterization of exercise-induced cardiac hypertrophy in a rat model using the in vivo method of LV pressure-volume (P-V) analysis. After inducing LV hypertrophy by swim training, we assessed LV morphometry by echocardiography and performed LV P-V analysis using a pressure-conductance microcatheter to investigate in vivo cardiac function. Echocardiography showed LV hypertrophy (LV mass index: 2.41 ± 0.09 vs. 2.03 ± 0.08 g/kg, P < 0.01), which was confirmed by heart weight data and histomorphometry. Invasive hemodynamic measurements showed unaltered heart rate, arterial pressure, and LV end-diastolic volume along with decreased LV end-systolic volume, thus increased stroke volume and ejection fraction (73.7 ± 0.8 vs. 64.1 ± 1.5%, P < 0.01) in trained versus untrained control rats. The P-V loop-derived sensitive, load-independent contractility indexes, such as slope of end-systolic P-V relationship or preload recruitable stroke work (77.0 ± 6.8 vs. 54.3 ± 4.8 mmHg, P = 0.01) were found to be significantly increased. The observed improvement of ventriculoarterial coupling (0.37 ± 0.02 vs. 0.65 ± 0.08, P < 0.01), along with increased LV stroke work and mechanical efficiency, reflects improved mechanoenergetics of exercise-induced cardiac hypertrophy. Despite the significant hypertrophy, we observed unaltered LV stiffness (slope of end-diastolic P-V relationship: 0.043 ± 0.007 vs. 0.040 ± 0.006 mmHg/μl) and improved LV active relaxation (τ: 10.1 ± 0.6 vs. 11.9 ± 0.2 ms, P < 0.01). According to our knowledge, this is the first study that provides characterization of functional changes and hemodynamic relations in

  8. Intravenous Glial Growth Factor 2 (GGF2) Isoform of Neuregulin-1β Improves Left Ventricular Function, Gene and Protein Expression in Rats after Myocardial Infarction

    PubMed Central

    Murphy, Abigail; Smith, Holly M.; Galindo, Cristi L.; Pentassuglia, Laura; Peng, Xuyang; Lenneman, Carrie G.; Odiete, Oghenerukevwe; Friedman, David B.; Kronenberg, Marvin W.; Zheng, Siyuen; Zhao, Zhongming; Song, Yanna; Harrell, Frank E.; Srinivas, Maya; Ganguly, Anindita; Iaci, Jennifer; Parry, Tom J.; Caggiano, Anthony O.; Sawyer, Douglas B.

    2013-01-01

    Aims Recombinant Neuregulin (NRG)-1β has multiple beneficial effects on cardiac myocytes in culture, and has potential as a clinical therapy for heart failure (HF). A number of factors may influence the effect of NRG-1β on cardiac function via ErbB receptor coupling and expression. We examined the effect of the NRG-1β isoform, glial growth factor 2 (GGF2), in rats with myocardial infarction (MI) and determined the impact of high-fat diet as well as chronicity of disease on GGF2 induced improvement in left ventricular systolic function. Potential mechanisms for GGF2 effects on the remote myocardium were explored using microarray and proteomic analysis. Methods and Results Rats with MI were randomized to receive vehicle, 0.625 mg/kg, or 3.25 mg/kg GGF2 in the presence and absence of high-fat feeding beginning at day 7 post-MI and continuing for 4 weeks. Residual left ventricular (LV) function was improved in both of the GGF2 treatment groups compared with the vehicle treated MI group at 4 weeks of treatment as assessed by echocardiography. High-fat diet did not prevent the effects of high dose GGF2. In experiments where treatment was delayed until 8 weeks after MI, high but not low dose GGF2 treatment was associated with improved systolic function. mRNA and protein expression analysis of remote left ventricular tissue revealed a number of changes in myocardial gene and protein expression altered by MI that were normalized by GGF2 treatment, many of which are involved in energy production. Conclusions This study demonstrates that in rats with MI induced systolic dysfunction, GGF2 treatment improves cardiac function. There are differences in sensitivity of the myocardium to GGF2 effects when administered early vs. late post-MI that may be important to consider in the development of GGF2 in humans. PMID:23437060

  9. Ventricular assist device

    MedlinePlus

    VAD; RVAD; LVAD; BVAD; Right ventricular assist device; Left ventricular assist device; Biventricular assist device; Heart pump; Left ventricular assist system; LVAS; Implantable ventricular assist device

  10. Isolation and molecular characterization of Leptospira interrogans and Leptospira borgpetersenii isolates from the urban rat populations of Kuala Lumpur, Malaysia.

    PubMed

    Benacer, Douadi; Mohd Zain, Siti Nursheena; Amran, Fairuz; Galloway, Renee L; Thong, Kwai Lin

    2013-04-01

    Rats are considered the principal maintenance hosts of Leptospira. The objectives of this study were isolation and identification of Leptospira serovars circulating among urban rat populations in Kuala Lumpur. Three hundred urban rats (73% Rattus rattus and 27% R. norvegicus) from three different sites were trapped. Twenty cultures were positive for Leptospira using dark-field microscopy. R. rattus was the dominant carrier (70%). Polymerase chain reaction (PCR) confirmed that all isolates were pathogenic Leptospira species. Two Leptospira serogroups, Javanica and Bataviae, were identified using microscopic agglutination test (MAT). Pulsed-field gel electrophoresis (PFGE) identified two serovars in the urban rat populations: L. borgpetersenii serovar Javanica (85%) and L. interrogans serovar Bataviae (15%). We conclude that these two serovars are the major serovars circulating among the urban rat populations in Kuala Lumpur. Despite the low infection rate reported, the high pathogenicity of these serovars raises concern of public health risks caused by rodent transmission of leptospirosis.

  11. Transthoracic echocardiography in rats. Evalution of commonly used indices of left ventricular dimensions, contractile performance, and hypertrophy in a genetic model of hypertrophic heart failure (SHHF-Mcc-facp-Rats) in comparison with Wistar rats during aging.

    PubMed

    Reffelmann, Thorsten; Kloner, Robert A

    2003-09-01

    Two-weekly echocardiographic examinations were conducted in nine SHHF-Mc-fa(cp) rats in comparison with eight age-matched Wistar rats. In the SHHF-rats, characterized by progressive LV-dilation and decreasing contractile function between 77-87 weeks of age, left ventricular (LV) hypertrophy was most sensitively demonstrated by increased LV-mass-index (p < 0.001). LV-areas and area-ejection fraction (EF) (2D-images) discriminated more sensitively in the early stages than M-mode-derived diameters and fractional shortening (FS); midwall shortening was the most sensitive parameter of reduced systolic function. Post-mortem measurements showed an excellent correlation with calculated LV-mass (r = 0.91). Post-mortem LV-volumes correlated significantly with diastolic LV-diameters, LV-areas, and calculated LV-volumes (r = 0.56-0.59). Mean within-subject standard deviations in controls were 0.5-0.6 mm (LV-diameters), 3.1-4.6 mm(2) (LV-areas), approximately 10% of the mean for FS, area-EF and midwall shortening, and approximately 20% for wall thickness and LV-mass. The data might be used to choose the most sensitive parameters, and to estimate sample size for echocardiographic investigations in rats.

  12. Inhibition of phosphatidylethanolamine synthesis by glucagon in isolated rat hepatocytes.

    PubMed Central

    Tijburg, L B; Houweling, M; Geelen, M J; Van Golde, L M

    1989-01-01

    Exposure of isolated rat hepatocytes to glucagon or chlorophenylthio cyclic AMP led to an inhibition of the incorporation of [1,2-14C]ethanolamine into phosphatidylethanolamine. Pulse-chase experiments and measurement of the activities of the enzymes involved in the CDP-ethanolamine pathway provided evidence that the inhibitory effect of glucagon on the synthesis de novo of phosphatidylethanolamine was not caused by a diminished conversion of ethanolamine phosphate into CDP-ethanolamine. The observations suggested that the glucagon-induced inhibition of the biosynthesis of phosphatidylethanolamine is probably due to a decreased supply of diacylglycerols, resulting in a decreased formation of phosphatidylethanolamine from CDP-ethanolamine and diacylglycerols. PMID:2539092

  13. -Adrenergic receptors on rat ventricular myocytes: characteristics and linkage to cAMP metabolism

    SciTech Connect

    Buxton, I.L.O.; Brunton, L.L.

    1986-08-01

    When incubated with purified cardiomyocytes from adult rat ventricle, the 1-antagonist (TH)prazosin binds to a single class of sites with high affinity. Competition for (TH)prazosin binding by the 2-selective antagonist yohimbine and the nonselective -antagonist phentolamine demonstrates that these receptors are of the 1-subtype. In addition, incubation of myocyte membranes with (TH)yohimbine results in no measurable specific binding. Agonist competition for (TH)prazosin binding to membranes prepared from purified myocytes demonstrates the presence of two components of binding: 28% of 1-receptors interact with norepinephrine with high affinity (K/sub D/ = 36 nM), whereas the majority of receptors (72%) have a low affinity for agonist (K/sub D/ = 2.2 M). After addition of 10 M GTP, norepinephrine competes for (TH)prazosin binding to a single class of sites with lower affinity (K/sub D/ = 2.2 M). Incubation of intact myocytes for 2 min with 1 M norepinephrine leads to significantly less cyclic AMP (cAMP) accumulation than stimulation with either norepinephrine plus prazosin or isoproterenol. Likewise, incubation of intact myocytes with 10 W M norepinephrine leads to significantly less activation of cAMP-dependent protein kinase than when myocytes are stimulated by both norepinephrine and the 1-adrenergic antagonist, prazosin or the US -adrenergic agonist, isoproterenol. They conclude that the cardiomyocyte 1 receptor is coupled to a guanine nucleotide-binding protein, that 1-receptors are functionally linked to decreased intracellular cAMP content, and that this change in cellular cAMP is expressed as described activation of cAMP-dependent protein kinase.

  14. Sodium alterations in isolated rat heart during cardioplegic arrest

    SciTech Connect

    Schepkin, V.D.; Choy, I.O.; Budinger, T.F.

    1996-12-01

    Triple-quantum-filtered (TQF) Na nuclear magnetic resonance (NMR) without chemical shift reagent is used to investigate Na derangement in isolated crystalloid perfused rat hearts during St. Thomas cardioplegic (CP) arrest. The extracellular Na contribution to the NMR TQF signal of a rat heart is found to be 73 {+-} 5%, as determined by wash-out experiments at different moments of ischemia and reperfusion. With the use of this contribution factor, the estimated intracellular Na ([Na{sup +}]{sub i}) TQF signal is 222 {+-} 13% of preischemic level after 40 min of CP arrest and 30 min of reperfusion, and the heart rate pressure product recovery is 71 {+-} 8%. These parameters are significantly better than for stop-flow ischemia: 340 {+-} 20% and 6 {+-} 3%, respectively. At 37{degrees}C, the initial delay of 15 min in [Na{sup +}]{sub i} growth occurs during CP arrest along with reduced growth later ({approximately}4.0%/min) in comparison with stop-flow ischemia ({approximately}6.7%/min). The hypothermia (21{degrees}C, 40 min) for the stop-flow ischemia and CP dramatically decreases the [Na{sup +}]{sub i} gain with the highest heart recovery for CP ({approximately}100%). These studies confirm the enhanced sensitivity of TQF NMR to [Na{sup +}]{sub i} and demonstrate the potential of NMR without chemical shift reagent to monitor [Na{sup +}]{sub i} derangements. 48 refs., 7 figs., 1 tab.

  15. Degradation of bradykinin by isolated perfused rat lung

    SciTech Connect

    Churchill, M.; Orawski, A.T.; AchutaMurthy, P.N.; Simmons, W.H.

    1986-03-01

    Several studies have suggested that the essentially complete degradation of circulating bradykinin (BK) in lung is mediated in part by peptidase(s) other than the well-characterized angiotensin converting enzyme (ACE). The authors report here that the isolated perfused rat lung can inactivate BK by sequential N-terminal cleavage. (/sup 3/H-2, 3-Pro) BK was perfused through the lung and the products in the perfusate identified by HPLC. In the absence of inhibitors, BK was 89-100% degraded with /sup 3/H-Pro/sup 2/-Pro/sup 3/ and /sup 3/H-Pro as the major products. The dipeptidylaminopeptidase IV (DAP IV) inhibitor, diprotein A (Ile-Pro-Ile), greatly reduced the Pro-Pro and Pro peaks and produced a prominent BK/sub 2-7/ peak (or BK/sub 2-9/ peak if the ACE inhibitor, captopril, was also present). 2-Mercapto-ethanol, a rather specific inhibitor of aminopeptidase P (AP-P), prevented the release of Arg/sup 1/, producing major BK and/or BK/sub 1-7/ peaks. The neutral metalloendopeptidase inhibitor, phosphoramidon, had no effect on the pattern of degradation of BK by the perfused rat lung by the release of Arg/sup 1/ by AP-P followed by release of Pro/sup 2/-Pro/sup 3/ by DAP IV.

  16. Agmatine Modulation of Noradrenergic Neurotransmission in Isolated Rat Blood Vessels.

    PubMed

    Török, Jozef; Zemančíková, Anna

    2016-06-30

    Agmatine, a vasoactive metabolite of L-arginine, is widely distributed in mammalian tissues including blood vessels. Agmatine binding to imidazoline and α₂-adrenoceptors induces a variety of physiological and pharmacological effects. We investigated the effect of agmatine on contractile responses of the rat pulmonary artery and portal vein induced by electrical stimulation of perivascular nerves and by exogenous adrenergic substances. Experiments were performed on isolated segments of rat main pulmonary artery and its extralobular branches, and portal vein suspended in organ bath containing modified Krebs bicarbonate solution and connected to a force-displacement transducer for isometric tension recording. Electrical field stimulation (EFS) produced tetrodotoxin-sensitive contractile responses of pulmonary artery and portal vein. Besides the well known vasorelaxant actions, we found that agmatine also produced a concentration-dependent inhibition of neurogenic contractions induced by EFS in pulmonary arteries; however, the agmatine treatment did not influence the responses to exogenous noradrenaline. The inhibitory effect on EFS-induced contractions was not abolished by the α₂-adrenoceptor antagonist rauwolscine. In portal vein, in contrast, agmatine increased spontaneous mechanical contractions and enhanced the contractions induced by EFS. The results suggest that agmatine can significantly influence vascular function of pulmonary arteries and portal veins by modulating sympathetically mediated vascular contractions by pre- and postsynaptic mechanisms.

  17. Localization of Kv4.2 and KChIP2 in lipid rafts and modulation of outward K+ currents by membrane cholesterol content in rat left ventricular myocytes.

    PubMed

    Rudakova, Elena; Wagner, Michael; Frank, Magdalena; Volk, Tilmann

    2015-02-01

    Lipid rafts are cholesterol-enriched microdomains of the cell membrane. Here we investigate the localization of the pore forming K(+)-channel α-subunit Kv4.2 and the β-subunit KChIP2, underlying the transient outward K(+) current (I to), in lipid rafts in left ventricular myocytes. Furthermore, we explored the impact of membrane cholesterol depletion (using 20 mM methyl-beta-cyclodextrin (MBCD)) on K(+) outward currents. Cholesterol-saturated MBCD (20 mM) served as control. Myocytes were isolated from the left ventricular free wall of Wistar rats. The Triton X-100 (4 °C) insoluble fraction of whole cell protein was analyzed by sucrose density gradient centrifugation followed by Western blot. Kv4.2 and KChIP2 were partially detected in low-density fractions (lipid rafts). MBCD treatment (5 min) resulted in a shift of Kv4.2 and KChIP2 towards high-density fractions. K(+) currents were assessed by whole-cell patch-clamp. MBCD treatment resulted in a 29 ± 3 % decrease in I to (20.0 ± 1.6pApF(-1) vs. 28.5 ± 2.0pApF(-1), n = 15, p < 0.001, V Pip = 40 mV) within 5 min. Control solution resulted in a significantly smaller reduction in I to (17 ± 3 %, p < 0.001, p < 0.01 compared with MBCD). MBCD induced a 38 ± 9 % increase in the non-inactivating current component (I sus) (10.1 ± 0.6pApF(-1) vs. 7.6 ± 0.4pApF(-1), n = 15, p < 0.001). This effect was absent in control solution. The increase in I sus was not sensitive to 100 μM 4-aminopyridine or 20 mM tetraethylammonium, making a contribution of Kv1.5 or Kv2.1 unlikely. In conclusion, in rat ventricular cardiomyocytes, a fraction of Kv4.2 and KChIP2 is localized in lipid rafts. Membrane cholesterol depletion results in ~12 % net reduction of I to, a redistribution of the channel proteins Kv4.2 and KChIP2 and an increased delayed rectifier current.

  18. Effects of prenatal exposure to ethanol on neocortical development: II. Cell proliferation in the ventricular and subventricular zones of the rat.

    PubMed

    Miller, M W

    1989-09-15

    Prenatal exposure to ethanol alters the generation of neocortical neurons; ethanol reduces the numbers of neurons generated between gestational day (G) 12 and G19 but paradoxically increases neuronogenesis after G19. The present study used [3H]thymidine autoradiography to examine the effects of ethanol on the proliferation of cells in the two cortical germinal zones, the ventricular and subventricular zones. Pregnant rats were fed one of three diets: a liquid ethanol-containing (6.7% v/v) diet (Et), a nutritionally matched isocaloric liquid diet (Ct), or chow and water (Ch). Fetuses were administered with [3H]thymidine on G13, G17, or G20 and killed 45-60 minutes later. Autoradiographs were prepared to identify radiolabeled and mitotic cells. Additional brains from 13-23-day-old fetuses were processed for cytoarchitectonic analyses. The size of the lateral ventricles in the fetuses was not significantly affected by the prenatal exposure. Both the ventricular and subventricular zones were evident throughout the period from G13 to G23. In all three groups, the ventricular zone was thickest from G13 to G17, but from G15 on, the ventricular zone of Et-treated fetuses was significantly thinner than those of either controls. On G13, G17, and G20, the labeling index (the ratio of radiolabeled cells to the total population) was significantly less in Et-treated fetuses. The mitotic index was similar in Et-, Ch-, and Ct-treated fetuses. The subventricular zone of all fetuses was most prominent during later fetal ages and it was thicker in Et-treated fetuses than in controls. Moreover, the labeling and mitotic indices for the subventricular zone of Et-treated rats were significantly greater than for controls. Thus, ethanol had different effects on the two neocortical germinal zones: the proliferation of ventricular cells was inhibited, whereas the proliferation of subventricular cells was stimulated. These data suggest that ethanol-induced changes in neuronogenesis result

  19. Isolation, propagation, and characterization of rat liver serosal mesothelial cells.

    PubMed Central

    Faris, R. A.; McBride, A.; Yang, L.; Affigne, S.; Walker, C.; Cha, C. J.

    1994-01-01

    Although rat liver epithelial cell (RLEC) lines have been developed by a number of laboratories, the identity of the clonogenic nonparenchymal progenitors is unknown. To provide insight into the derivation of RLEC, we immunoisolated serosal liver mesothelial cells (LMC) and bile duct epithelial cells and attempted to propagate each epithelial cell population using culture conditions routinely employed to establish RLEC lines. Briefly, the selective reactivity of LMC with two bile duct cell surface markers, OC.2 and BD.2, was exploited to develop an immunocytochemical technique to isolate LMC. Livers were collagenase dissociated, the mesothelial capsule was "peeled" and digested with pronase to destroy contaminating hepatocytes, and rare biliary ductal epithelial cells were immunodepleted using OC.2. LMC were subsequently isolated by selective binding to magnetic beads adsorbed with BD.2 and cultured in supplemented Waymouths 752/1 media containing 10% fetal calf serum. Proliferating BD.2+ LMC rapidly formed epithelial-like monolayers that could be continuously subcultured after trypsinization. In contrast, attempts to establish cell lines from purified OC.2+ bile duct epithelial cells were unsuccessful. Results from reverse transcriptase polymerase chain reaction analysis confirmed that LMC expressed Wilms' tumor transcripts, a lineage marker for mesodermally-derived cells. In summary, our findings clearly demonstrate that LMC can be continuously propagated using culture conditions routinely employed to establish RLEC lines, an observation that supports the contention that some RLEC lines may be derived from LMC. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:7992846

  20. Preparation of plasma-membrane subfractions from isolated rat hepatocytes.

    PubMed Central

    Wisher, M H; Evans, W H

    1977-01-01

    1. Rat livers were dissociated into their constituent cells by perfusion through the portal vein with a medium containing collagenase, and hepatocytes separated from non-parenchymal cells. 2. It is shown that the procedure described by Wisher & Evans [(1975) Biochem. J. 146, 375-388] for preparation of plasma membranes from liver tissue when applied to isolated hepatocytes also yielded subfractions of similar morphology and marker-enzyme distribution. 3. Thus the distribution of alkaline phosphodiesterase, 5'-nucleotidase and the basal and glucagon-stimulated adenylate cyclase among two 'light' vesicular and one 'heavy' junction-containing plasma-membrane subfractions paralleled that reported for tissue-derived plasma-membrane subfractions. 4. Increased recoveries and specific activities of plasma-membrane marker enzymes were obtained when soya-bean trypsin inhibitor was included in the collagenase-containing perfusion media used to dissociate the liver. 5. Polyacrylamide-gel-electrophoretic analysis of the corresponding plasma-membrane subfractions prepared from liver tissue and isolated hepatocytes were generally similar. 6. The results indicate that the functional polarity of the hepatocyte's plasma membrane is retained after tissue dissociation. The damage occurring to plasma-membrane ectoenzymes by the collagenase-perfusion procedure is discussed. Images PLATE 1 PLATE 2 PLATE 3 PMID:880246

  1. Effects of Aronia melanocarpa Fruit Juice on Isolated Rat Hepatocytes

    PubMed Central

    Kondeva-Burdina, Magdalena; Valcheva-Kuzmanova, Stefka; Markova, Tsvetelina; Mitcheva, Mitka; Belcheva, Anna

    2015-01-01

    Background: Aronia melanocarpa (Michx.) Elliot fruits are very rich in polyphenols – procyanidins, flavonoids, and phenolic acids. Objective: On rat hepatocytes, isolated by two-stepped collagenase perfusion, we investigated the effect of A. melanocarpa fruit juice (AMFJ) in two models of liver toxicity caused by (i) metabolic bioactivation of carbon tetrachloride (CCl4), and (ii) tert-butyl hydroperoxide (t-BuOOH)-induced oxidative stress. Materials and Methods: Isolated rat hepatocytes are a suitable model for hepatotoxicity studies. We determined the main parameters of the functional and metabolic status of rat hepatocytes: Cell viability (measured by trypan blue exclusion) and the levels of lactate dehydrogenase (LDH), reduced glutathione (GSH), and malondialdehyde (MDA). These parameters were used to investigate the protective effects of AMFJ in the two toxicity models. The effects of AMFJ were compared with those of silymarin. The cells were treated either with AMFJ or silymarin at increasing concentrations of 5 μg/ml, 10 μg/ml, 30 μg/ml, 50 μg/ml, and 100 μg/ml which were used for measuring of IC50. Results: In both toxicity models – CCl4 and t-BuOOH, AMFJ showed statistically significant cytoprotective and antioxidant activities. AMFJ prevented the loss of cell viability and GSH depletion, decreased LDH leakage and MDA production. The effects of AMFJ at the concentrations of 5, 10, 30, and 50 μg/ml were similar to those of the same concentrations of silymarin, while the effect of the highest AMFJ concentration of 100 μg/ml was higher than that of the same silymarin concentration. The effects were concentration-dependent and more prominent in the t-BuOOH model, compared to those in the CCl4 model. Conclusion: The cytoprotective and antioxidant effects of AMFJ established in this study might be due to its polyphenolic ingredients, which could influence the cytochrome P450-mediated metabolism of the experimental hepatotoxic substances (CCl4 and t

  2. Effects of bepridil on ventricular depolarization and repolarization of rabbit isolated hearts with particular reference to its possible proarrhythmic properties.

    PubMed Central

    Osaka, T.; Kodama, I.; Toyama, J.; Yamada, K.

    1988-01-01

    1. Effects of bepridil on ventricular depolarization and repolarization sequences were examined in rabbit Langendorff-perfused hearts. 2. In distant bipolar electrograms (DBEs), bepridil, 10(-6) M, caused a significant prolongation of QT intervals. At 10(-5) M, the QT prolongation was further enhanced, and a significant prolongation of QRS duration was also observed. Polymorphous ventricular tachycardia was frequently induced by a single premature stimulus at the higher concentration. 3. In epicardial electrograms recorded through modified bipolar electrodes, bepridil, 10(-6) M, prolonged the interval from the peak negative deflection of the QRS complex to the apex of the T wave (Q-aT), which corresponded to the intracellular action potential duration at 90% repolarization (APD90). The Q-aT prolongation was larger in the base than in the apex, resulting in a marked distortion and dispersion of repolarization. The epicardial activation sequence was unaffected. 4. At 10(-5) M bepridil, the dispersion of repolarization was much more enhanced by activation delay in the epicardial surface. 5. These findings suggest that bepridil causes regionally different lengthening of APD in ventricular muscle leading to an increase in temporal dispersion of repolarization, and that this dispersion may be inducive for re-entrant arrhythmias when accompanied by slow conduction at toxic doses. PMID:3260528

  3. Effects of salicylic acid on post-ischaemic ventricular function and purine efflux in isolated mouse hearts.

    PubMed

    Farthing, Don; Gehr, Lynne; Karnes, H Thomas; Sica, Domenic; Gehr, Todd; Larus, Terri; Farthing, Christine; Xi, Lei

    2007-01-01

    Acetyl salicylic acid (aspirin) is one of the most widely used drugs in the world. Various plasma concentrations of aspirin and its predominant metabolite, salicylic acid, are required for its antiarthritic (1.5-2.5 mM), anti-inflammatory (0.5-5.0 mM) or antiplatelet (0.18-0.36 mM) actions. A recent study demonstrated the inhibitory effects of both aspirin and salicylic acid on oxidative phosphorylation and ATP synthesis in isolated rat cardiac mitochondria in a dose-dependent manner (0-10 mM concentration range). In this context, the present study was conducted to determine the effects of salicylic acid on inosine efflux (a potential biomarker of acute cardiac ischaemia) as well as cardiac contractile function in the isolated mouse heart following 20 min of zero-flow global ischaemia. Inosine efflux was found at significantly higher concentrations in ischaemic hearts perfused with Krebs buffer fortified with 1.0 mM salicylic acid compared with those without salicylic acid (12575+/-3319 vs. 1437+/-348 ng ml(-1) min(-1), mean+/-SEM, n=6 per group, p<0.01). These results indicate that 1.0 mM salicylic acid potentiates 8.8-fold ATP nucleotide purine catabolism into its metabolites (e.g. inosine, hypoxanthine). Salicylic acid (0.1 or 1.0 mM) did not appreciably inhibit purine nucleoside phosphorylase (the enzyme converts inosine to hypoxanthine) suggesting the augmented inosine efflux was due to the salicylic acid effect on upstream elements of cellular respiration. Whereas post-ischaemic cardiac function was further depressed by 1.0 mM salicylic acid, perfusion with 0.1 mM salicylic acid led to a remarkable functional improvement despite moderately increased inosine efflux (2.7-fold). We conclude that inosine is a sensitive biomarker for detecting cardiac ischaemia and salicylic acid-induced effects on cellular respiration. However, the inosine efflux level appears to be a poor predictor of the individual post-ischaemic cardiac functional recovery in this ex vivo

  4. Effects of salicylic acid on post-ischaemic ventricular function and purine efflux in isolated mouse hearts.

    PubMed

    Farthing, Don; Gehr, Lynne; Karnes, H Thomas; Sica, Domenic; Gehr, Todd; Larus, Terri; Farthing, Christine; Xi, Lei

    2007-01-01

    Acetyl salicylic acid (aspirin) is one of the most widely used drugs in the world. Various plasma concentrations of aspirin and its predominant metabolite, salicylic acid, are required for its antiarthritic (1.5-2.5 mM), anti-inflammatory (0.5-5.0 mM) or antiplatelet (0.18-0.36 mM) actions. A recent study demonstrated the inhibitory effects of both aspirin and salicylic acid on oxidative phosphorylation and ATP synthesis in isolated rat cardiac mitochondria in a dose-dependent manner (0-10 mM concentration range). In this context, the present study was conducted to determine the effects of salicylic acid on inosine efflux (a potential biomarker of acute cardiac ischaemia) as well as cardiac contractile function in the isolated mouse heart following 20 min of zero-flow global ischaemia. Inosine efflux was found at significantly higher concentrations in ischaemic hearts perfused with Krebs buffer fortified with 1.0 mM salicylic acid compared with those without salicylic acid (12575+/-3319 vs. 1437+/-348 ng ml(-1) min(-1), mean+/-SEM, n=6 per group, p<0.01). These results indicate that 1.0 mM salicylic acid potentiates 8.8-fold ATP nucleotide purine catabolism into its metabolites (e.g. inosine, hypoxanthine). Salicylic acid (0.1 or 1.0 mM) did not appreciably inhibit purine nucleoside phosphorylase (the enzyme converts inosine to hypoxanthine) suggesting the augmented inosine efflux was due to the salicylic acid effect on upstream elements of cellular respiration. Whereas post-ischaemic cardiac function was further depressed by 1.0 mM salicylic acid, perfusion with 0.1 mM salicylic acid led to a remarkable functional improvement despite moderately increased inosine efflux (2.7-fold). We conclude that inosine is a sensitive biomarker for detecting cardiac ischaemia and salicylic acid-induced effects on cellular respiration. However, the inosine efflux level appears to be a poor predictor of the individual post-ischaemic cardiac functional recovery in this ex vivo

  5. Effects of prolonged application of isoprenaline on intracellular free magnesium concentration in isolated heart of rat.

    PubMed Central

    Nishimura, H.; Matsubara, T.; Ikoma, Y.; Nakayama, S.; Sakamoto, N.

    1993-01-01

    1. The effect of prolonged application of isoprenaline on intracellular free-Mg2+ concentration ([Mg2+]i) was examined by use of 31P-nuclear magnetic resonance (31P-n.m.r.) in rat isolated hearts. Left ventricular pressure (LVP) was simultaneously measured. 2. [Mg2+]i was estimated from the separation of the alpha- and beta-ATP peaks, using the dissociation constant of MgATP 38 microM (established previously). In normal (phosphate-free, Krebs-Henseleit) solution, [Mg2+]i was approximately 0.4 mM. 3. When isoprenaline was applied for 100 min, a transient increase in [Mg2+]i was observed during the initial 25 min, whilst concentrations of ATP ([ATP]) and phosphocreatine ([PCr]) decreased and [Pi] correspondingly increased. During the subsequent 75 min of isoprenaline application, [Mg2+]i decreased below its resting levels. Washout of isoprenaline restored [Mg2+]i and [PCr], but [ATP] remained low. These changes elicited by isoprenaline were not observed in the presence of propranolol, a typical alpha-adrenoceptor blocker. 4. Isoprenaline increased both LVP and heart rate. The increased LVP and heart rate slowly returned to lower values during prolonged application of isoprenaline, but remained higher than those before application. 5. The transient rise in [Mg2+]i elicited by isoprenaline could be attributed to the decrease in [ATP] resulting in a release of Mg2+. The subsequent decrease in [Mg2+]i during the prolonged applications suggests that beta-adrenoceptor stimulation itself facilitates Mg(2+)-extruding mechanism(s). PMID:8358545

  6. Differential effects of furnidipine and its active metabolites in rat isolated working heart.

    PubMed

    Krzemiński, Tadeusz F; Hudziak, Damian; Sielańczyk, Andrzej W; Porc, Maurycy; Kedzia, Agnieszka

    2008-01-01

    1,4,-dihydropyridines, belonging to the class of "privileged structures", are known to protect the heart from stunning, ischemia and ventricular arrhythmias and mainly used in hypertension. The aim of this study was to compare the continuous infusion of parent drug, furnidipine, with its two active metabolites (M-2; M-3) in rat isolated working heart model, where the following parameters were measured and calculated: heart rate, preload pressure, aortic systolic and diastolic pressures (AoD), as well as +/-dP/dt, aortic (AF) and coronary flow (CF), oxygen and carbon dioxide partial pressures and pH values in pulmonary effluent, myocardial oxygen consumption. At first, the optimal vasodilatatory dose of M-2 was estimated and afterwards it was compared with equivalent doses of both remaining substances. The strongest vasodilatatory effects were observed after the lowest dose of M-2 was used (10(-7) M), at the same time being without marked influence on pressure parameters. The pro-drug evoked significantly weaker influence on both flows. Furthermore, furnidipine significantly reduced AoD and AF in comparison to control as well as +dP/dt in comparison to the initial values, while M-2 did not. Both metabolites caused a significant CF increase, but M-3 additionally the AoS and AoD decrease in comparison to the control. Regarding clear differences in the measured parameters between the pro-drug and its metabolites found, the obtained results allow to claim that the metabolites vs. furnidipine possess a beneficial influence. The distinct flow shift from aorta into the coronaries was observed only after M-2 and to a lesser extent--M-3. The cardio-depressant potency of both metabolites is overcome by advantageous vasodilatatory effect. M-2, being a final product, easier to control and at the same time a precursor of the new chemical class of therapeutics, is promising as a cardio-protective agent.

  7. Role of transiently altered sarcolemmal membrane permeability and basic fibroblast growth factor release in the hypertrophic response of adult rat ventricular myocytes to increased mechanical activity in vitro.

    PubMed Central

    Kaye, D; Pimental, D; Prasad, S; Mäki, T; Berger, H J; McNeil, P L; Smith, T W; Kelly, R A

    1996-01-01

    One of the trophic factors that has been implicated in initiating or facilitating growth in response to increased mechanical stress in several tissues and cell types is basic fibroblast growth factor (bFGF; FGF-2). Although mammalian cardiac muscle cells express bFGF, it is not known whether it plays a role in mediating cardiac adaptation to increased load, nor how release of the cytosolic 18-kD isoform of bFGF would be regulated in response to increased mechanical stress. To test the hypothesis that increased mechanical activity induces transient alterations in sarcolemmal permeability that allow cytosolic bFGF to be released and subsequently to act as an autocrine and paracrine growth stimulus, we examined primary isolates of adult rat ventricular myocytes maintained in serum-free, defined medium that were continually paced at 3 Hz for up to 5 d. Paced myocytes, but not nonpaced control cells, exhibited a "hypertrophic" response, which was characterized by increases in the rate of phenylalanine incorporation, total cellular protein content, and cell size. These changes could be mimicked in control cells by exogenous recombinant bFGF and could be blocked in continually paced cells by a specific neutralizing anti-bFGF antibody. In addition, medium conditioned by continually paced myocytes contained significantly more bFGF measured by ELISA and more mitogenic activity for 3T3 cells, activity that could be reduced by a neutralizing anti-bFGF antibody. The hypothesis that transient membrane disruptions sufficient to allow release of cytosolic bFGF occur in paced myocytes was examined by monitoring the rate of uptake into myocytes from the medium of 10-kD dextran linked to fluorescein. Paced myocytes exhibited a significantly higher rate of fluoresceinlabeled dextran uptake. These data are consistent with the hypothesis that nonlethal, transient alterations in sarcolemmal membrane permeability with release of cytosolic bFGF is one mechanism by which increased

  8. Ventricular arrhythmias.

    PubMed Central

    Kavanagh, K M; Wyse, D G

    1988-01-01

    Sudden cardiac death claims thousands of Canadians annually. Ventricular tachycardia and fibrillation account for up to 85% of these deaths. Identifying the patients at risk remains a major challenge. Those who have recurrent ventricular tachycardia or have been resuscitated from ventricular fibrillation are generally considered to be at highest risk. Although ventricular premature beats in the absence of previous ventricular tachycardia or fibrillation are not helpful in identifying such patients in most cases, they can indicate increased risk for sudden cardiac death in the presence of a structural cardiac abnormality, particularly recent myocardial infarction; however, the need for treatment in such cases is speculative and is being investigated. Treatment is mandatory for survivors of an episode of ventricular fibrillation and those with recurrent sustained ventricular tachycardia or torsade de pointes ventricular tachycardia. The approach to management is either invasive or noninvasive. Selection of an antiarrhythmic agent is facilitated by knowledge of some basic electrophysiologic features of the heart and of the classification of antiarrhythmic drugs. However, drug therapy has to be individualized on the basis of efficacy, left ventricular function and adverse effects or potential adverse effects of the drug. Amiodarone therapy or nonpharmacologic therapy should be considered if a suitable antiarrhythmic agent cannot be found. PMID:3284626

  9. Effect of overexpressed adenylyl cyclase VI on β1- and β2-adrenoceptor responses in adult rat ventricular myocytes

    PubMed Central

    Stark, Joalice C C; Haydock, Stephen F; Foo, Roger; Brown, Morris J; Harding, Sian E

    2004-01-01

    Adenylyl cyclase VI (ACVI) is one of the most abundantly expressed β adrenergic receptor (βAR)-coupled cyclases responsible for cyclic AMP (cAMP) production within the mammalian myocardium. We investigated the role of ACVI in the regulation of cardiomyocyte contractility and whether it is functionally coupled with β1 adrenergic receptor (β1AR). Recombinant adenoviruses were generated for ACVI and for antisense to ACVI (AS). Adult rat ventricular myocytes were transfected with ACVI virus, AS or both (SAS). Adenovirus for green fluorescent protein (GFP) served as control. Myocyte contraction amplitudes (% shortening) and relaxation times (R50) were analysed. ACVI function was determined using cAMP assays. ACVI-transfected cells demonstrated a strong 139 kDa ACVI protein band compared to controls. ACVI myocytes had higher steady-state intracellular cAMP levels than GFP myocytes when unstimulated (GFP vs ACVI=6.60±0.98 vs 14.2±2.1 fmol cAMP/viable cell, n=4, P<0.05) and in the presence of 1 μM isoprenaline or 10 μM forskolin. ACVI myocytes had increased basal contraction (% shortening: GFP vs ACVI: 1.90±1.36 vs 3.91±2.29, P<0.0001) and decreased basal R50 (GFP vs ACVI: 62.6±24.2 ms (n=50) vs 45.0±17.2 ms (n=248), P<0.0001). ACVI myocyte responses were increased for forskolin (Emax: GFP=6.70±1.59 (n=6); ACVI=9.06±0.69 (n=14), P<0.01) but not isoprenaline. ACVI myocyte responses were increased (Emax: GFP vs ACVI=3.16±0.77 vs 5.10±0.60, P<0.0001) to xamoterol (a partial β1AR-selective agonist) under β2AR blockade (+50 nM ICI 118, 551). AS decreased both control and ACVI-stimulated xamoterol responses (Emax: AS=2.59±1.42, SAS=1.38±0.5). ACVI response was not mimicked by IBMX. Conversely, response through β2 adrenergic receptor (β2AR) was decreased in ACVI myocytes. In conclusion, ACVI overexpression constitutively increases myocyte contraction amplitudes by raising cAMP levels. Native ACVI did not contribute to basal cAMP production or contraction

  10. Role of Na(+)-H(+) exchange in the modulation of L-type Ca(2+) current during fluid pressure in rat ventricular myocytes.

    PubMed

    Kim, Joon-Chul; Woo, Sun-Hee

    2013-02-01

    Application of fluid pressure (FP) using pressurized fluid flow suppresses the L-type Ca(2+) current through both enhancement of Ca(2+) release and intracellular acidosis in ventricular myocytes. As FP-induced intracellular acidosis is more severe during the inhibition of Na(+)-H(+) exchange (NHE), we examined the possible role of NHE in the regulation of I(Ca) during FP exposure using HOE642 (cariporide), a specific NHE inhibitor. A flow of pressurized (~16 dyn/cm(2)) fluid was applied onto single rat ventricular myocytes, and the I(Ca) was monitored using a whole-cell patch-clamp under HEPES-buffered conditions. In cells pre-exposed to FP, additional treatment with HOE642 dose-dependently suppressed the I(Ca) (IC(50) = 0.97 ± 0.12 μM) without altering current-voltage relationships and inactivation time constants. In contrast, the I(Ca) in control cells was not altered by HOE642. The HOE642 induced a left shift in the steady-state inactivation curve. The suppressive effect of HOE642 on the I(Ca) under FP was not altered by intracellular high Ca(2+) buffering. Replacement of external Cl(-) with aspartate to inhibit the Cl(-)-dependent acid loader eliminated the inhibitory effect of HOE642 on I(Ca). These results suggest that NHE may attenuate FP-induced I(Ca) suppression by preventing intracellular H(+) accumulation in rat ventricular myocytes and that NHE activity may not be involved in the Ca(2+)-dependent inhibition of the I(Ca) during FP exposure. PMID:23313474

  11. Impaired visual memory in rats reared in isolation is reversed by D-cycloserine in the adult rat.

    PubMed

    Strømme Johannesen, Tone; Myhrer, Trond

    2002-02-15

    Previous studies have shown that environmental factors can influence cholinergic and glutamatergic activity in the developing brain, and that the variations in neurochemistry are accompanied by behavioral changes in later life. Rats reared in isolated, social, or enriched environments were tested with a visual discrimination task in adulthood. The results show that saline-treated rats reared in isolation exhibited impaired retention of the discrimination task compared to rats raised in social or enriched environments. However, systemic administration of the NMDA receptor agonist, D-cycloserine (3 mg/kg), restored normal memory function in cognitively impoverished rats. Acquisition of the task was not affected by the rearing conditions. D-Cycloserine is considered to be an efficient cognitive enhancer probably able to compensate for assumed loss of NMDA receptors during isolated rearing. PMID:11864642

  12. Effects of total flavones from Acanthopanax senticosus on L-type calcium channels, calcium transient and contractility in rat ventricular myocytes.

    PubMed

    Guan, Shengjiang; Ma, Juanjuan; Chu, Xi; Gao, Yonggang; Zhang, Ying; Zhang, Xuan; Zhang, Fenghua; Liu, Zhenyi; Zhang, Jianping; Chu, Li

    2015-04-01

    Acanthopanax senticosus (Rupr. et Maxim.) Harms (AS), a traditional herbal medicine, has been widely used to treat ischemic heart disease. However, the underlying cellular mechanisms of its benefits to cardiac function remain unclear. The present study examined the effects of total flavones from AS (TFAS) on L-type Ca(2+) channel currents (ICa-L ) using the whole cell patch-clamp technique and on intracellular calcium ([Ca(2+) ]i ) handling and cell contractility in rat ventricular myocytes with the aid of a video-based edge-detection system. Exposure to TFAS resulted in a concentration- and voltage-dependent blockade of ICa-L , with the half-maximal inhibitory concentration (IC50 ) of 283.12 µg/mL and the maximal inhibitory effect of 36.49 ± 1.95%. Moreover, TFAS not only increased the maximum current in the current-voltage relationship but also shifted the activation and inactivation curves of ICa-L toward the hyperpolarizing direction. Meanwhile, TFAS significantly reduced amplitudes of myocyte shortening and [Ca(2+) ]i with an increase in the time to 10% of the peak (Tp) and a decrease in the time to 10% of the baseline (Tr). Thus, the cardioprotective effects of TFAS may be attributed mainly to the attenuation of [Ca(2+) ]i through the direct inhibition of ICa-L in rat ventricular myocytes and consequent negative effect on myocardial contractility. PMID:25586009

  13. Prostanoids inhibit release of endogenous norepinephrine from rat isolated trachea.

    PubMed

    Racké, K; Bähring, J; Langer, C; Bräutigam, M; Wessler, I

    1992-11-01

    Prostanoids, of epithelial origin, are known as modulators of several processes in the airways. The present study examined whether prostanoids are involved in the local control of sympathetic neurotransmission. The release of endogenous norepinephrine from rat isolated tracheae was evoked by electrical field stimulation (3 Hz, 540 pulses) in the presence of yohimbine, desipramine, and tyrosine. In different series of experiments, indomethacin (3 mumol/L) increased the evoked release of endogenous norepinephrine by 70 to 80%. In the presence of indomethacin, prostaglandin E2 (PGE2) and several prostanoid receptor agonists inhibited the evoked release of norepinephrine in a concentration-dependent manner, maximally by 60 to 70%. According to the concentration producing 35% inhibition of norepinephrine release (half-maximal effect), the following rank order of potencies was observed (EC35): nocloprost (8 nmol/L), sulprostone (30 nmol/L), PGE2 (308 nmol/L), iloprost (2 mumol/L), and U46619 (> 10 mumol/L). The EP1 receptor antagonist AH 6809 (3 mumol/L) had no effect on the evoked norepinephrine release and did not affect the inhibitory effect of 1 mumol/L of sulprostone. In the absence of indomethacin, the inhibitory effect of PGE2 was similar to that observed in the presence of indomethacin. After removal of the epithelium, the evoked norepinephrine release was markedly reduced. However, no significant effect of indomethacin was observed in epithelium-denuded tracheae. In conclusion, norepinephrine release in the rat trachea is inhibited via prostaglandin receptors that have the pharmacologic characteristics of the EP3 subtype. Endogenous eicosanoids, most likely of epithelial origin, are involved in the local control of the release of norepinephrine. PMID:1443867

  14. Effects of oxymetazoline on isolated rat's tracheal smooth muscle.

    PubMed

    Wang, Hsing-Won; Wu, Chi-Chung

    2008-06-01

    Oxymetazoline is often used as a decongestant in rhinitis patients who are suffering from nasal obstruction. It is used as a nasal drop or spray solution. The effect on nasal mucosa in vitro or in vivo is well known. However, the effect of the drug on tracheal smooth muscle has rarely been explored. During administration of the drug to the nose, it might affect the trachea via inhalation. We used our preparation to test the effectiveness of oxymetazoline on isolated rat's tracheal smooth muscle. A 5 mm long portion of rat trachea was submersed in 30 ml Kreb's solution in a muscle bath at 37 degrees C. Changes in tracheal contractility in response to the application of parasympathetic mimetic agents were measured using a transducer connected to a Pentium III computer equipped with polygraphy software. The following assessments were performed: (1) effect on tracheal smooth muscle resting tension; (2) effect on contraction caused by 10(-6)M methacholine as a parasympathetic mimetic; (3) effect of oxymetazoline on electrically induced tracheal smooth muscle contractions. Addition of parasympathetic mimetics to the incubation medium caused the trachea to contract in a dose-dependent manner. Addition of oxymetazoline induced a significant relaxation response when the preparation was up to 10(-4) M. At the same concentration, the drug also could inhibit EFS induced spike contraction. Oxymetazoline had negligible effect on the basal tension of trachea as the concentration increased. The degree of drug-induced tracheal contraction or relaxation was dose-dependent. The study indicated that high concentrations of oxymetazoline might actually antagonize cholinergic receptors of the trachea.

  15. Noninvasive Blood Perfusion Measurements of an Isolated Rat Liver and an Anesthetized Rat Kidney

    PubMed Central

    Mudaliar, Ashvinikumar V.; Ellis, Brent E.; Ricketts, Patricia L.; Lanz, Otto I.; Lee, Charles Y.; Diller, Thomas E.; Scott, Elaine P.

    2008-01-01

    A simple, cost effective, and noninvasive blood perfusion system is tested in animal models. The system uses a small sensor to measure the heat transfer response to a thermal event (convective cooling) imposed on the tissue surface. Heat flux data are compared with a mathematical model of the tissue to estimate both blood perfusion and thermal contact resistance between the tissue and the probe. The perfusion system was evaluated for repeatability and sensitivity using isolated rat liver and exposed rat kidney tests. Perfusion in the isolated liver tests was varied by controlling the flow of the perfusate into the liver, and the perfusion in the exposed kidney tests was varied by temporarily occluding blood flow through the renal artery and vein. The perfusion estimated by the convective perfusion probe was in good agreement with that of the metered flow of the perfusate into the liver model. The liver tests indicated that the probe can be used to detect small changes in perfusion (0.005 ml/ml/s). The probe qualitatively tracked the changes in the perfusion in the kidney model due to occlusion of the renal artery and vein. PMID:19045542

  16. Upregulation of the kappa opioidergic system in left ventricular rat myocardium in response to volume overload: Adaptive changes of the cardiac kappa opioid system in heart failure.

    PubMed

    Treskatsch, Sascha; Shaqura, Mohammed; Dehe, Lukas; Feldheiser, Aarne; Roepke, Torsten K; Shakibaei, Mehdi; Spies, Claudia D; Schäfer, Michael; Mousa, Shaaban A

    2015-12-01

    Opioids have long been known for their analgesic effects and are therefore widely used in anesthesia and intensive care medicine. However, in the last decade research has focused on the opioidergic influence on cardiovascular function. This project thus aimed to detect the precise cellular localization of kappa opioid receptors (KOR) in left ventricular cardiomyocytes and to investigate putative changes in KOR and its endogenous ligand precursor peptide prodynorphin (PDYN) in response to heart failure. After IRB approval, heart failure was induced using a modified infrarenal aortocaval fistula (ACF) in male Wistar rats. All rats of the control and ACF group were characterized by their morphometrics and hemodynamics. In addition, the existence and localization as well as adaptive changes of KOR and PDYN were investigated using radioligand binding, double immunofluorescence confocal analysis, RT-PCR and Western blot. Similar to the brain and spinal cord, [(3)H]U-69593 KOR selective binding sites were detected the left ventricle (LV). KOR colocalized with Cav1.2 of the outer plasma membrane and invaginated T-tubules and intracellular with the ryanodine receptor of the sarcoplasmatic reticulum. Interestingly, KOR could also be detected in mitochondria of rat LV cardiomyocytes. As a consequence of heart failure, KOR and PDYN were up-regulated on the mRNA and protein level in the LV. These findings suggest that the cardiac kappa opioidergic system might modulate rat cardiomyocyte function during heart failure.

  17. Axial Stretch of Rat Single Ventricular Cardiomyocytes Causes an Acute and Transient Increase in Ca2+ Spark Rate

    PubMed Central

    Iribe, Gentaro; Ward, Christopher W.; Camelliti, Patrizia; Bollensdorff, Christian; Mason, Fleur; Burton, Rebecca A.B.; Garny, Alan; Morphew, Mary K.; Hoenger, Andreas; Lederer, W. Jonathan; Kohl, Peter

    2010-01-01

    We investigate acute effects of axial stretch, applied by carbon fibers (CFs), on diastolic Ca2± spark rate in rat isolated cardiomyocytes. CFs were attached either to both cell ends (to maximize the stretched region), or to the center and one end of the cell (to compare responses in stretched and nonstretched half-cells). Sarcomere length was increased by 8.01 ± 0.94% in the stretched cell fraction, and time series of XY confocal images were recorded to monitor diastolic Ca2± spark frequency and dynamics. Whole-cell stretch causes an acute increase of Ca2± spark rate (to 130.7 ± 6.4%) within 5 seconds, followed by a return to near background levels (to 104.4±5.1%) within 1 minute of sustained distension. Spark rate increased only in the stretched cell region, without significant differences in spark amplitude, time to peak, and decay time constants of sparks in stretched and nonstretched areas. Block of stretch-activated ion channels (2 gmol/L GsMTx-4), perfusion with Na±/Ca2±-free solution, and block of nitric oxide synthesis (1 mmol/L L-NAME) all had no effect on the stretch-induced acute increase in Ca2± spark rate. Conversely, interference with cytoskeletal integrity (2 hours of 10 gmol/L colchicine) abolished the response. Subsequent electron microscopic tomography confirmed the close approximation of microtubules with the T-tubular–sarcoplasmic reticulum complex (to within · 10−8m). In conclusion, axial stretch of rat cardiomyocytes acutely and transiently increases sarcoplasmic reticulum Ca2± spark rate via a mechanism that is independent of sarcolemmal stretch-activated ion channels, nitric oxide synthesis, or availability of extracellular calcium but that requires cytoskeletal integrity. The potential of microtubule-mediated modulation of ryanodine receptor function warrants further investigation. PMID:19197074

  18. [Reperfusion injury in the isolated rat liver after hypothermic preservation].

    PubMed

    Kopecký, M; Balás, P; Semecký, V; Tilser, I; Rouchalová, E

    2002-03-01

    Histological changes which appear as a result of reperfusion injury of cold-preserved rat liver were studied at intervals of 0 hr, 3 hr, 24 hr and 48 hr of cold storage. The isolated livers were stored in a UW solution (University of Wisconsin), which is used in human liver transplantations. Computer image analysis of light microscopic sections (methyl green-pyronin stained) was used for the study and quantification of injured cells. The method of TUNEL was performed to prove possible apoptosis of sinusoidal endothelial cells and heptocytes. Bile production during reperfusion and ALT, AST, LDH and ACP were measured in the reperfusion medium at the end of the 90 min reperfusion. It has been confirmed that prolongation of the cold storage of liver results in extensive changes in the liver structure and increased injury of liver cells. Sinusoidal endothelial cells were damaged more and earlier than hepatocytes. It has been shown that methyl green-pyronin stained sections are advantageous for the study of these morphological changes, allowing the strongest view of these changes. The appearance of TUNEL positive cells and an increase in the levels of biochemical parameters, e.g. AST or ALT, indicate earlier cell injury. The methodology described in this article can be used for the study of reperfusion injury of the liver and for the study of this phenomenon in other experiments. PMID:11928282

  19. Regulation of atriopeptin release from the isolated rat heart

    SciTech Connect

    Currie, M.G.; Newman, W.H.

    1986-03-05

    Recent studies have demonstrated that the mammalian atria possess an endocrine function which appears to play a role in the regulation of systemic arterial pressure, fluid balance, and electrolyte homeostasis. They have begun to study the regulation of atriopeptin (atrial natriuretic factor) release into the coronary effluent of the isolated perfused rat heart. Characterization by high pressure liquid chromatography of the form of the hormone released indicates that the predominant form is the active low MW circulating hormone not the pro-hormone. The release of immunoreactive atriopeptin (iAP) was stimulated by infusion of norepinephrine (1 ..mu..M) or epinephrine (1 ..mu..M) 3.0 and 2.6-fold, respectively. The ..beta..-adrenergic agonist isoproterenol and the ..cap alpha..-2 adrenergic agonist BHT-920 lacked effects on iAP release. On the other hand, the ..cap alpha..-1 adrenergic agonist phenylephrine caused a dose-dependent increase in release of iAP. Release of iAP stimulated by phenylephrine was inhibited by the ..cap alpha.. antagonist phentolamine. Further, iAP release was stimulated 4.2-fold by phorbol ester (1 ..mu..M) but was not affected by 4-..beta.. phorbol (1 ..mu..M). From these collective data they conclude that the release of atriopeptin is stimulated by ..cap alpha..-1 receptor activation and that protein kinase C participates in the regulation of secretion. The data suggests that the sympathetic nervous system may play a physiologic role in the regulation of atriopeptin secretion.

  20. Nickel chloride inhibits metabolic coronary vasodilatation in isolated rat hearts

    SciTech Connect

    Edoute, Y.; Rubanyi, G.M.; Vanhoutte, P.M.

    1986-03-01

    Nickel is a potent coronary vasoconstrictor and it is released from ischemic myocardium. To determine whether or not nickel ions cause coronary vasoconstriction when local vasodilator mechanisms are stimulated the authors studied the inter-relation between exogenous nickel chloride (NiCl/sub 2/) and metabolic coronary vasodilatation in isolated rat hearts perfused by a modified Langendorff technique. NiCl/sub 2/ induced dose-dependent (10/sup -7/-10/sup -5/M) increases in coronary vascular resistance in spontaneously beating hearts. Pacing of the hearts (380/min) and infusing adenosine (10/sup -6/M) evoked comparable increases in coronary flow but did not affect the coronary vasoconstriction caused by NiCl/sub 2/. At concentrations (> 10/sup -7/M) which evoked vasoconstriction, NiCl/sub 2/ significantly reduced vasodilator responses evoked by pacing, transient coronary occlusion and adenosine. Lower concentrations, which did not cause vasoconstriction, had no effect on these vasodilator responses. Thus, at relative low concentrations NiCl/sub 2/ inhibits metabolic dilatation of the coronary vessels which may contribute to the increased vascular resistance caused by the trace metal under ischemic/hypoxic conditions.

  1. Phosphorus nuclear magnetic resonance in isolated perfused rat pancreas

    SciTech Connect

    Matsumoto, Takehisa; Kanno, Tomio; Seo, Yoshiteru; Murakami, Masataka; Watari, Hiroshi National Institute for Physiological Sciences, Okazaki )

    1988-04-01

    Phosphorus nuclear magnetic resonance spectroscopy was applied to measure phosphorus energy metabolites in isolated perfused rat pancreas. The gland was perfused with a modified Krebs-Henseleit solution at room temperature (25{degree}C). {sup 31}P resonances of creatine phosphate (PCr), ATP, ADP, inorganic phosphate (P{sub i}) and phosphomonoesters (PMEs) were observed in all the preparations of pancreas. In different individual preparations, the resonance of PCr varied, but those of ATP were almost the same. The initial levels of PCr and ATP in individual preparations, however, remained almost unchanged during perfusion with the standard solution for 2 h. When the perfusion was stopped, the levels of ATP and PCr decreased, while the levels of PME and P{sub i} increased. At that time, the P{sub i} resonance shfted to a higher magnetic field, indicating that the tissue pH decreased. On reperfusion, the tissue levels of phosphorus compounds and the tissue pH were restored to their initial resting levels. Continuous infusion of 0.1 {mu}M acetylcholine caused marked and sustained increases in the flow of pancreatic juice and protein output. During the stimulation the tissue levels of phosphorus compounds remained unchanged, while the tissue pH was decreased slightly.

  2. Electron microscopic morphometry of isolated rat brain porosome complex.

    PubMed

    Zhvania, Mzia G; Japaridze, Nadezhda J; Qsovreli, Mariam G; Okuneva, Vera G; Surmava, Arkadi G; Lordkipanidze, Tamar G

    2015-11-01

    Porosomes are the universal secretory portals at the cell plasma membrane where secretory vesicles dock and transiently fuse via the kiss-and-run mechanism of cellular secretion, to release intravesicular cargo to the outside of the cell. During last two decades discovery of porosome and a great volume of work from different laboratories provide molecular insights on the structure, function, and composition of the porosome complex, especially the neuronal porosome. In rat neurons 12-17 nm cup-shaped lipoprotein porosomes present at presynaptic membrane. They possess a central plug and sometimes are with docked synaptic vesicles. Although earlier studies have greatly progressed our understanding of the morphology and the proteome and limited lipidome of the neuronal porosome complex, the current study was carried out to determine the morphology of the bare protein backbone of the neuronal porosome complex. Results from our study demonstrate that although the eight-fold symmetry of the immunoisolated porosome is maintained, and the central plug is preserved in the isolated structures, there is a loss in the average size of the porosome complex, possibly due to a loss of lipids from the complex. PMID:26119463

  3. Passive viscoelastic work of isolated rat, Rattus norvegicus, diaphragm muscle.

    PubMed

    Syme, D A

    1990-05-01

    1. The passive elastic and viscous properties of isolated rat diaphragm muscle were studied, under various strains and strain rates similar to those in the animal, to measure their effects on the storage and release of mechanical potential energy. 2. Increasing the muscle length or amplitude of the displacement increased energy loss per stretch/shorten cycle, and increased the relative recovery of potential energy from the stretch during subsequent shortening. 3. Increasing strain rates increased energy loss per cycle and decreased the relative recovery of energy put into the stretch. 4. These effects were due to increased viscous resistance and increased elastic tension with increased length, and increased viscous resistance with increased strain rates. 5. The effects of increasing strain rate alone (1-4 Hz) were small relative to the effects of a 10% increase in muscle length or the amplitude of the length cycle. 6. Diaphragm muscle movements involving low velocity, small amplitude displacements at long muscle lengths are most effective at conserving net passive mechanical energy, while short muscle lengths minimize gross energy loss. PMID:2391652

  4. Molecular cytotoxic mechanisms of chlorpromazine in isolated rat hepatocytes.

    PubMed

    MacAllister, Stephanie L; Young, Cheryl; Guzdek, Anna; Zhidkov, Nickholas; O'Brien, Peter J

    2013-01-01

    Chlorpromazine (CPZ), a member of the largest class of first-generation antipsychotic agents, is known to cause hepatotoxicity in the form of cholestasis and hepatocellular necrosis in some patients. The mechanism of CPZ hepatotoxicity is unclear, but is thought to result from reactive metabolite formation. The goal of this research was to assess potential cytotoxic mechanisms of CPZ using the accelerated cytotoxicity mechanism screening (ACMS) technique with freshly isolated rat hepatocytes. This study identified CPZ cytotoxicity and inhibition of mitochondrial membrane potential (MMP) to be concentration-dependent. Furthermore, inhibition of cytochrome P450s (CYPs), including CYP2D1 and 1A2, delayed CPZ cytotoxicity, suggesting a role for CYP activation of CPZ to a toxic metabolite(s) in this model. Metabolism studies also demonstrated glucuronide and glutathione (GSH) requirement for CPZ detoxification in hepatocytes. Inactivating the 2-electron reduction pathway, NAD(P)H quinone oxidoreductase (NQO1), caused a significant increase in hepatocyte susceptibility to CPZ, indicating quinoneimine contribution to CPZ cytotoxicity. Nontoxic concentrations of peroxidase/H(2)O(2) (inflammatory model) increased cytotoxicity in CPZ-treated hepatocytes and caused additional mitochondrial toxicity. Inflammation further depleted GSH and increased oxidized glutathione (GSSG) levels. Results suggest activation of CPZ to reactive metabolites by 2 pathways in hepatocytes: (i) a CYP-catalyzed quinoneimine pathway, and (ii) a peroxidase-catalyzed oxidation of CPZ to CPZ radicals.

  5. Organization of connexons in isolated rat liver gap junctions.

    PubMed

    Gogol, E; Unwin, N

    1988-07-01

    Gap junction plaques from rat liver plasma membranes have been subjected to a range of detergent treatments in order to evaluate systematically the influence of different isolation procedures on their structure. The separation of the connexons was found to vary depending on the conditions used. In the absence of detergent the center-to-center separation of the connexons is, on average, approximately 90 A, and they are arranged on a hexagonal lattice so that the symmetry of the double-layered structure approximates to p6m in projection (or p622 in three-dimensions). Exposure to increasing concentration of detergent reduces the connexon separation to values below 80 A. More severe detergent treatment leads to disintegration of the gap junction plaques. Specimens with center-to-center separations smaller than 86 A show progressively larger deviation from p6m symmetry, seen as apparent rotations of the connexon assemblies within the crystal lattice. This reorganization occurs with both ice-embedded and negatively-stained specimens, using ionic or nonionic detergents, and therefore is probably a packing readjustment caused by depletion of intervening lipid molecules. PMID:3416022

  6. Repeated Cocaine Experience Facilitates Sucrose-Reinforced Operant Responding in Enriched and Isolated Rats

    ERIC Educational Resources Information Center

    Klein, Emily D.; Gehrke, Brenda J.; Green, Thomas A.; Zentall, Thomas R.; Bardo, Michael T.

    2007-01-01

    The purpose of the present experiment was to determine whether repeated cocaine exposure differentially affects sucrose-reinforced operant responding in rats raised in an enriched condition (EC) or an isolated condition (IC). Specifically, the performance of EC and IC rats pressing a lever for sucrose under a high fixed-ratio schedule (FR 30)…

  7. Effects of REM sleep deprivation on sensorimotor gating and startle habituation in rats: role of social isolation in early development.

    PubMed

    Chang, Hsin-An; Liu, Yia-Ping; Tung, Che-Se; Chang, Chuan-Chia; Tzeng, Nian-Sheng; Huang, San-Yuan

    2014-07-11

    The present study examined the role of rapid eye movement (REM) sleep on sensorimotor gating function in a developmentally rodent model of schizophrenic-spectrum disorders. Startle magnitude, prepulse inhibition (PPI) and startle habituation in an acoustic startle test were measured after 72-h of REM sleep deprivation (REMSD) in 14-week-old rats that were reared in one of the following conditions: control social interaction, 2-week isolation, and continuous isolation, since weaning. The results showed that REMSD significantly inhibited rats' PPI in socially controlled rats, and rats in two isolation groups appeared less sensitive to REMSD. After REMSD, startle habituation was significantly reduced in continuous-isolated rats but not in 2-week-isolated rats. These data indicate that REM sleep is essential for PPI; REMSD inhibits startle habituation in rats with continuous social isolation. In addition, social interaction, in early life or for the whole life, functions differently to the sensorimotor gating.

  8. Isoflavones isolated from red clover (Trifolium pratense) inhibit smooth muscle contraction of the isolated rat prostate gland.

    PubMed

    Brandli, A; Simpson, J S; Ventura, S

    2010-09-01

    This study investigated whether red clover contains any bioactive constituents which may affect contractility of rat prostatic smooth muscle in an attempt to determine whether its medicinal use in the treatment of benign prostatic hyperplasia is supported by pharmacological effects. A commercially available red clover extract was chemically fractionated and various isoflavones (genistein, formononetin and biochanin A) were isolated from these fractions and their effects on contractility were examined on preparations of the isolated rat prostate gland. Contractile effects of the isolated fractions were compared with commercially available isoflavones (genistein, formononetin and biochanin A). Pharmacological tools were used to investigate the mechanism of action modifying smooth muscle contraction. Crude red clover extract (Trinovin) inhibited electrical field stimulation induced contractions of the rat prostate across a range of frequencies with an IC(50) of approximately 68 microg/ml. Contractions of the rat prostate elicited by exogenous administration of acetylcholine, noradrenaline or adenosine 5'-triphosphate (ATP) were also inhibited. Chromatographic separation, and final purification by high performance liquid chromatography (HPLC) permitted the isolation of the isoflavones: daidzein, calycosin, formononetin, prunetin, pratensin, biochanin A and genistein. Genistein, formononetin and biochanin A (100 microM) from either commercial sources or isolated from red clover extract inhibited electrical field stimulation induced contractions of the isolated rat prostate. It is concluded that isoflavones contained in red clover are able to inhibit prostatic smooth muscle contractions in addition to their antiproliferative effects. However, the high concentrations required to observe these smooth muscle relaxant effects mean that a therapeutic benefit from this mechanism is unlikely at doses used clinically.

  9. Regulation of the frequency-dependent facilitation of L-type Ca2+ currents in rat ventricular myocytes.

    PubMed Central

    Tiaho, F; Piot, C; Nargeot, J; Richard, S

    1994-01-01

    1. An increase in the rate of stimulation induces an augmentation of L-type Ca2+ currents (ICa) and concomitant slowing of current decay in rat ventricular cells. This facilitation is quasi immediate (1-3 s), graded with the rate of stimulation, and occurs only from negative holding potentials. We investigated this effect using trains of stimulation at 1 Hz and the whole-cell patch-clamp technique (18-22 degrees C). 2. The decay of ICa is normally bi-exponential and comprises fast and slow current components (ICa,fc and ICa,sc, respectively). Facilitation of ICa was observed only when ICa,fc was predominant. 3. Facilitation developed during the run-up of ICa with the interconversion of ICa,sc into ICa,fc, and vanished during the run-down of ICa with the loss of ICa,fc.Ni2+ (300 microM) and nifedipine (1 microM) suppressed facilitation owing to the preferential inhibition of ICa,fc. 4. Facilitation of ICa was not altered (when present) or favoured (when absent) by the cAMP-dependent phosphorylation of Ca2+ channels promoted by isoprenaline or by intracellular application of cAMP or of the catalytic subunit of protein kinase A (C-sub). A similar effect was observed when the dihydropyridine agonist Bay K 8644 was applied. In both cases, facilitation was linked to a preferential increase of ICa,fc. 5. Following intracellular application of inhibitors of protein kinase A in combination with a non-hydrolysable ATP analogue, ICa consisted predominantly of ICa,sc and no facilitation was observed. The calmodulin antagonist naphthalenesulphonamide had no effect on facilitation. 6. When Bay K 8644 was applied in combination with isoprenaline, cAMP or C-sub, the decay of ICa was slowed with the predominant development of ICa,sc, and facilitation of ICa was nearly abolished. Facilitation also depended on extracellular Ca2+, and was suppressed when Ba2+ replaced Ca2+ as the permeating ion. 7. When no EGTA was included in the patch pipette, facilitation was not further enhanced

  10. Quantification of Coupled Stiffness and Fiber Orientation Remodeling in Hypertensive Rat Right-Ventricular Myocardium Using 3D Ultrasound Speckle Tracking with Biaxial Testing

    PubMed Central

    Park, Dae Woo; Sebastiani, Andrea; Yap, Choon Hwai; Simon, Marc A.; Kim, Kang

    2016-01-01

    Mechanical and structural changes of right ventricular (RV) in response to pulmonary hypertension (PH) are inadequately understood. While current standard biaxial testing provides information on the mechanical behavior of RV tissues using surface markers, it is unable to fully assess structural and mechanical properties across the full tissue thickness. In this study, the mechanical and structural properties of normotensive and pulmonary hypertension right ventricular (PHRV) myocardium through its full thickness were examined using mechanical testing combined with 3D ultrasound speckle tracking (3D-UST). RV pressure overload was induced in Sprague–Dawley rats by pulmonary artery (PA) banding. The second Piola–Kirchhoff stress tensors and Green-Lagrangian strain tensors were computed in the RV myocardium using the biaxial testing combined with 3D-UST. A previously established non-linear curve-fitting algorithm was applied to fit experimental data to a Strain Energy Function (SEF) for computation of myofiber orientation. The fiber orientations obtained by the biaxial testing with 3D-UST compared well with the fiber orientations computed from the histology. In addition, the re-orientation of myofiber in the right ventricular free wall (RVFW) along longitudinal direction (apex-to-outflow-tract direction) was noticeable in response to PH. For normotensive RVFW samples, the average fiber orientation angles obtained by 3D-UST with biaxial test spiraled from 20° at the endo-cardium to -42° at the epi-cardium (Δ = 62°). For PHRV samples, the average fiber orientation angles obtained by 3D-UST with biaxial test had much less spiral across tissue thickness: 3° at endo-cardium to -7° at epi-cardium (Δ = 10°, P<0.005 compared to normotensive). PMID:27780271

  11. Sex-related differences in intrinsic myocardial properties influence cardiac function in middle-aged rats during infarction-induced left ventricular remodeling.

    PubMed

    Dedkov, Eduard I; Bogatyryov, Yevgen; Pavliak, Kristina; Santos, Adora T; Chen, Yue-Feng; Zhang, Youhua; Pingitore, Alessandro

    2016-06-01

    We previously determined that residual left ventricular (LV) myocardium of middle-aged rats had sex-related differences in regional tissue properties 4 weeks after a large myocardial infarction (MI). However, the impact of such differences on cardiac performance remained unclear. Therefore, our current study aimed to elucidate whether sex-related changes in MI-induced myocardial remodeling can influence cardiac function. A similar-sized MI was induced in 12-month-old male (M-MI) and female (F-MI) Sprague-Dawley rats by ligation of the left coronary artery. The cardiac function was monitored for 2 months after MI and then various LV parameters were compared between sexes. We found that although two sex groups had a similar pattern of MI-induced decline in LV function, F-MI rats had greater cardiac performance compared to M-MI rats, considering the higher values of EF (39.9 ± 3.4% vs. 26.7 ± 7.7%, P < 0.05), SW index (40.4 ± 2.1 mmHg • mL/kg vs. 20.2 ± 3.3 mmHg • mL/kg, P < 0.001), and CI (139.2 ± 7.9 mL/min/kg vs. 74.9 ± 14.7 mL/min/kg, P < 0.01). The poorer pumping capacity in M-MI hearts was associated with markedly reduced LV compliance and prolonged relaxation. On the tissue level, F-MI rats revealed a higher, than in M-MI rats, density of cardiac myocytes in the LV free wall (2383.8 ± 242.6 cells/mm(2) vs. 1785.7 ± 55.9 cells/mm(2), P < 0.05). The latter finding correlated with a lower density of apoptotic cardiac myocytes in residual LV myocardium of F-MI rats (0.18 ± 0.08 cells/mm(2) vs. 0.91 ± 0.30 cells/mm(2) in males, P < 0.01). Thus, our data suggested that F-MI rats had markedly attenuated decline in cardiac performance compared to males due to ability of female rats to better retain functionally favorable intrinsic myocardial properties.

  12. Beta-Adrenoceptor Stimulation Reveals Ca2+ Waves and Sarcoplasmic Reticulum Ca2+ Depletion in Left Ventricular Cardiomyocytes from Post-Infarction Rats with and without Heart Failure.

    PubMed

    Sadredini, Mani; Danielsen, Tore Kristian; Aronsen, Jan Magnus; Manotheepan, Ravinea; Hougen, Karina; Sjaastad, Ivar; Stokke, Mathis Korseberg

    2016-01-01

    Abnormal cellular Ca2+ handling contributes to both contractile dysfunction and arrhythmias in heart failure. Reduced Ca2+ transient amplitude due to decreased sarcoplasmic reticulum Ca2+ content is a common finding in heart failure models. However, heart failure models also show increased propensity for diastolic Ca2+ release events which occur when sarcoplasmic reticulum Ca2+ content exceeds a certain threshold level. Such Ca2+ release events can initiate arrhythmias. In this study we aimed to investigate if both of these aspects of altered Ca2+ homeostasis could be found in left ventricular cardiomyocytes from rats with different states of cardiac function six weeks after myocardial infarction when compared to sham-operated controls. Video edge-detection, whole-cell Ca2+ imaging and confocal line-scan imaging were used to investigate cardiomyocyte contractile properties, Ca2+ transients and Ca2+ waves. In baseline conditions, i.e. without beta-adrenoceptor stimulation, cardiomyocytes from rats with large myocardial infarction, but without heart failure, did not differ from sham-operated animals in any of these aspects of cellular function. However, when exposed to beta-adrenoceptor stimulation, cardiomyocytes from both non-failing and failing rat hearts showed decreased sarcoplasmic reticulum Ca2+ content, decreased Ca2+ transient amplitude, and increased frequency of Ca2+ waves. These results are in line with a decreased threshold for diastolic Ca2+ release established by other studies. In the present study, factors that might contribute to a lower threshold for diastolic Ca2+ release were increased THR286 phosphorylation of Ca2+/calmodulin-dependent protein kinase II and increased protein phosphatase 1 abundance. In conclusion, this study demonstrates both decreased sarcoplasmic reticulum Ca2+ content and increased propensity for diastolic Ca2+ release events in ventricular cardiomyocytes from rats with heart failure after myocardial infarction, and that these

  13. Beta-Adrenoceptor Stimulation Reveals Ca2+ Waves and Sarcoplasmic Reticulum Ca2+ Depletion in Left Ventricular Cardiomyocytes from Post-Infarction Rats with and without Heart Failure.

    PubMed

    Sadredini, Mani; Danielsen, Tore Kristian; Aronsen, Jan Magnus; Manotheepan, Ravinea; Hougen, Karina; Sjaastad, Ivar; Stokke, Mathis Korseberg

    2016-01-01

    Abnormal cellular Ca2+ handling contributes to both contractile dysfunction and arrhythmias in heart failure. Reduced Ca2+ transient amplitude due to decreased sarcoplasmic reticulum Ca2+ content is a common finding in heart failure models. However, heart failure models also show increased propensity for diastolic Ca2+ release events which occur when sarcoplasmic reticulum Ca2+ content exceeds a certain threshold level. Such Ca2+ release events can initiate arrhythmias. In this study we aimed to investigate if both of these aspects of altered Ca2+ homeostasis could be found in left ventricular cardiomyocytes from rats with different states of cardiac function six weeks after myocardial infarction when compared to sham-operated controls. Video edge-detection, whole-cell Ca2+ imaging and confocal line-scan imaging were used to investigate cardiomyocyte contractile properties, Ca2+ transients and Ca2+ waves. In baseline conditions, i.e. without beta-adrenoceptor stimulation, cardiomyocytes from rats with large myocardial infarction, but without heart failure, did not differ from sham-operated animals in any of these aspects of cellular function. However, when exposed to beta-adrenoceptor stimulation, cardiomyocytes from both non-failing and failing rat hearts showed decreased sarcoplasmic reticulum Ca2+ content, decreased Ca2+ transient amplitude, and increased frequency of Ca2+ waves. These results are in line with a decreased threshold for diastolic Ca2+ release established by other studies. In the present study, factors that might contribute to a lower threshold for diastolic Ca2+ release were increased THR286 phosphorylation of Ca2+/calmodulin-dependent protein kinase II and increased protein phosphatase 1 abundance. In conclusion, this study demonstrates both decreased sarcoplasmic reticulum Ca2+ content and increased propensity for diastolic Ca2+ release events in ventricular cardiomyocytes from rats with heart failure after myocardial infarction, and that these

  14. Beta-Adrenoceptor Stimulation Reveals Ca2+ Waves and Sarcoplasmic Reticulum Ca2+ Depletion in Left Ventricular Cardiomyocytes from Post-Infarction Rats with and without Heart Failure

    PubMed Central

    Danielsen, Tore Kristian; Aronsen, Jan Magnus; Manotheepan, Ravinea; Hougen, Karina; Sjaastad, Ivar; Stokke, Mathis Korseberg

    2016-01-01

    Abnormal cellular Ca2+ handling contributes to both contractile dysfunction and arrhythmias in heart failure. Reduced Ca2+ transient amplitude due to decreased sarcoplasmic reticulum Ca2+ content is a common finding in heart failure models. However, heart failure models also show increased propensity for diastolic Ca2+ release events which occur when sarcoplasmic reticulum Ca2+ content exceeds a certain threshold level. Such Ca2+ release events can initiate arrhythmias. In this study we aimed to investigate if both of these aspects of altered Ca2+ homeostasis could be found in left ventricular cardiomyocytes from rats with different states of cardiac function six weeks after myocardial infarction when compared to sham-operated controls. Video edge-detection, whole-cell Ca2+ imaging and confocal line-scan imaging were used to investigate cardiomyocyte contractile properties, Ca2+ transients and Ca2+ waves. In baseline conditions, i.e. without beta-adrenoceptor stimulation, cardiomyocytes from rats with large myocardial infarction, but without heart failure, did not differ from sham-operated animals in any of these aspects of cellular function. However, when exposed to beta-adrenoceptor stimulation, cardiomyocytes from both non-failing and failing rat hearts showed decreased sarcoplasmic reticulum Ca2+ content, decreased Ca2+ transient amplitude, and increased frequency of Ca2+ waves. These results are in line with a decreased threshold for diastolic Ca2+ release established by other studies. In the present study, factors that might contribute to a lower threshold for diastolic Ca2+ release were increased THR286 phosphorylation of Ca2+/calmodulin-dependent protein kinase II and increased protein phosphatase 1 abundance. In conclusion, this study demonstrates both decreased sarcoplasmic reticulum Ca2+ content and increased propensity for diastolic Ca2+ release events in ventricular cardiomyocytes from rats with heart failure after myocardial infarction, and that these

  15. Behavioral effects of repeated handling differ in rats reared in social isolation and environmental enrichment.

    PubMed

    Pritchard, L M; Van Kempen, T A; Zimmerberg, B

    2013-03-01

    The post-weaning social environment has profound effects on behavior and physiology in rodents. Social isolation increases anxiety-like behaviors and novelty-induced locomotor activity, while environmental enrichment decreases these behaviors. In some cases, the effects of social isolation are ameliorated by repeated handling. The goal of the present study was to determine whether the effects of handling differ in rats reared in social isolation and those reared in an enriched environment. After weaning, male Long-Evans rats were housed individually (ISO)(3) or in groups in an enriched environment (EE). During adulthood, rats from each housing condition received four, once-daily, brief handling sessions or remained undisturbed in the home cage. All rats were then tested in the open field, elevated plus maze, and for behavioral responses to d-amphetamine (1.0mg/kg). EE rats spent more time on the open arms of the elevated plus maze and were more likely than ISO rats to emerge from the start box in the open field, suggesting lower anxiety. Handling significantly decreased open arm time in EE rats and marginally increased open arm time in ISO rats. Housing condition did not affect amphetamine-stimulated locomotor activity, but handling altered the time course of the amphetamine response. ISO rats exhibited significantly fewer stereotyped behaviors than did EE rats, but repeated handling eliminated this difference. These findings support previously published studies that suggest brief handling of adult rats may at least partially ameliorate the effects of post-weaning social isolation on anxiety-like behaviors and psychostimulant sensitivity. Furthermore, there are complex interactions between the effects of housing environment and handling, suggesting that handling may be perceived and/or processed differently, depending on the animal's housing environment.

  16. Specific binding of /sup 3/H-naloxone with isolated rat enterocytes

    SciTech Connect

    Yarygin, K.N.; Shitin, A.G.; Suiridov, D.D.; Titov, M.I.; Vinogradov, V.A.

    1985-12-01

    This paper presents data on the specific binding of naloxone with isolated rat enterocytes. Naloxone was bound with the cells in medium 199 containing 1 mg/ml of BSA. The incubation mixture contained 5 x 100 mM /sup 3/H-naloxone and, if indicated, other substances also. Dose dependence of binding of naloxone with rat enterocytes is shown. The kinetics of specific binding of naloxone with enterocytes at different temperatures is also shown, as is the irreversibility of binding of /sup 3/H-naloxone with isolated rat enterocytes. It was found that different ligands of opioid receptors can inhibit binding of naloxone competitively.

  17. Rapid Responses and Mechanism of Action for Low-Dose Bisphenol S on ex Vivo Rat Hearts and Isolated Myocytes: Evidence of Female-Specific Proarrhythmic Effects

    PubMed Central

    Gao, Xiaoqian; Ma, Jianyong; Chen, Yamei

    2015-01-01

    Background Bisphenol S (BPS) has increasingly been used as a substitute for bisphenol A (BPA) in some “BPA-free” consumer goods and in thermal papers. Wide human exposure to BPS has been reported; however, the biological and potential toxic effects of BPS are poorly understood. Objective In this study, we sought to elucidate the sex-specific rapid effect of BPS in rat hearts and its underlying mechanism. Methods We examined the rapid effects of BPS in rat hearts using electrophysiology, confocal and conventional fluorescence imaging, and immunoblotting. Treatment was administered via acute perfusion of excised hearts or isolated cardiac myocytes. Results In female rat hearts acutely exposed to 10–9 M BPS, the heart rate was increased; in the presence of catecholamine-induced stress, the frequency of ventricular arrhythmia events was markedly increased. BPS-exposed hearts showed increased incidence of arrhythmogenic-triggered activities in female ventricular myocytes and altered myocyte Ca2+ handling, particularly spontaneous Ca2+ release from the sarcoplasmic reticulum. The dose responses of BPS actions were inverted U-shaped. The impact of BPS on myocyte Ca2+ handling was mediated by estrogen receptor β signaling and by rapid increases in the phosphorylation of key Ca2+ handling proteins, including ryanodine receptor and phospholamban. The proarrhythmic effects of BPS were female specific; male rat hearts were not affected by BPS at the organ, myocyte, or protein levels. Conclusion Rapid exposure to low-dose BPS showed proarrhythmic impact on female rat hearts; these effects at the organ, cellular, and molecular levels are remarkably similar to those reported for BPA. Evaluation of the bioactivity and safety of BPS and other BPA analogs is necessary before they are used as BPA alternatives in consumer products. Citation Gao X, Ma J, Chen Y, Wang HS. 2015. Rapid responses and mechanism of action for low-dose bisphenol S on ex vivo rat hearts and isolated

  18. Hormone release from isolated nerve endings of the rat neurohypophysis.

    PubMed Central

    Cazalis, M; Dayanithi, G; Nordmann, J J

    1987-01-01

    1. Isolated neurosecretory nerve endings were prepared from rat neurohypophyses. The amount of vasopressin (AVP) and oxytocin released was measured by radioimmunoassay. 2. The amount of hormone release under resting conditions was not affected by external calcium (Ca2+o). Secretion decreased by ca. 50% when external sodium (Na+o) was replaced by choline or sucrose. 3. Ouabain did not modify the basal AVP release. 4. The Na+ ionophore monensin increased the release of AVP only in the presence of Na+o. This increase was maintained during prolonged exposure to the ionophore and occurred in the presence of Ca2+o only. 5. In the presence of Ca2+o, the amount of evoked hormone release was dependent on the external K+ concentration. Half-maximal activation was achieved with ca. 40 mM-K+. The K+-induced secretion was potentiated in Na+-free solution. 6. Prolonged 100 mM-K+-induced depolarization in the presence of Ca2+o gave rise to a large increase in hormone secretion which decreased with time (t1/2 = 2.5 min). The release could be reactivated after permeabilization of the nerve terminals in the presence of micromolar concentrations of Ca2+. 7. A stepwise paradigm in which Ko+ is incrementally increased to 25, 50, 75 and then 100 mM released more AVP than a prolonged exposure to 100 mM-K+. 8. Veratridine increased the amount of AVP released. This effect was considerably reduced in the absence of Nao+ and abolished in the presence of D600. 9. The depolarization-induced AVP release was blocked by different Ca2+-antagonists. Their effectiveness was nitrendipine = nicardipine greater than Cd2+ greater than Gd3+ greater than Co2+ = Mn2+. 10. The dihydropyridine Bay K 8644 potentiated both the basal and the K+-evoked AVP release. Its maximal effect was obtained with 25-50 mM-Ko+. 11. In conclusion, the isolated neurohypophysial terminals which have both Na+ and Ca2+ channels and release AVP and oxytocin upon depolarization might be an excellent system to study further the

  19. Dynamic expression profiles of MMPs/TIMPs and collagen deposition in mechanically unloaded rat heart: implications for left ventricular assist device support-induced cardiac alterations.

    PubMed

    Wang, Lu; Xu, Yu-Xian; Du, Xiao-Jie; Sun, Quan-Ge; Tian, Ying-Jun

    2013-09-01

    Left ventricular assist devices (LVADs) ameliorate heart failure by reducing preload and afterload. However, extracellular matrix (ECM) deposition after application of LVADs is not clearly defined. The purpose of the present study was to investigate ECM remodeling after mechanical unloading in a rat heart transplant model. Sixty male Lewis rats were subjected to abdominal heterotopic heart transplantation, and the transplanted hearts were pressure- and volume-unloaded. The age- and weight- matched male Lewis rats who had undergone open thoracic surgeries were used as the control. Left ventricle ECM accumulation and the expression/activity of matrix metalloproteinases (MMPs) and tissue inhibitor of matrix metalloproteinases (TIMPs) were measured on the third, seventh, and fourteenth days after transplantation/sham surgery. Compared with the control group, myocardial ECM deposition significantly increased on the seventh and fourteenth days after heart transplantation (P < 0.05) and peaked on the 14th day. The gelatinase activity as well as mRNA expression of MMP-2 and MMP-9 significantly increased after transplantation (P < 0.05). Both mRNA and protein levels of TIMP-1 and TIMP-2 significantly increased compared with those of the control group. Mechanical unloading may lead to adverse remodeling of the ECM of the left ventricle. The underlying mechanism may due to the imbalance of the MMP/TIMP system, especially the remarkable upregulation of TIMPs in the pressure and volume unloaded heart.

  20. K+ transport and membrane potentials in isolated rat parotid acini

    SciTech Connect

    Nauntofte, B.; Dissing, S.

    1988-10-01

    42K+ transport properties of isolated rat parotid acini were characterized concomitant with measurements of membrane potentials (Em) by means of the fluorescent dye diSC3-(5). In unstimulated acini suspended in a 5 mM K+ buffer, Em was governed by the K+ and Cl- gradients and amounted to about -59 mV, a value that remained unaffected on cholinergic stimulation. In unstimulated acini, 42K+ influx was largely mediated by the Na+-K+ pump, and the residual influxes were mediated by a bumetanide-sensitive component (cotransport system) and by K+ channels. Efflux of 42K+ was largely mediated by a bumetanide-sensitive component and by K+ channels. In the unstimulated state, the cotransport system was mediating K+-K+ exchange without contributing to the net uptake of K+. Within 10 s after stimulation, a approximately 10-fold increase in the acinar K+ conductance (gK) occurred, resulting in a rapid net efflux of K+ that amounted to approximately 3.8 mmol.l cells-1.s-1. Measurements of 42K+ fluxes as a function of the external K+ concentration revealed that in the stimulated state gK increases when external K+ is raised from 0.7 to 10 mM, consistent with an activation of acinar gK by the binding of external K+ to the channel. 42K+ flux ratios as well as the effect of the K+ channel inhibitor from scorpion venom (LQV) suggest that approximately 90% of K+ transport in the stimulated state is mediated by ''maxi'' K+ channels.

  1. Histo-anatomical structure of the living isolated rat heart in two contraction states assessed by diffusion tensor MRI

    PubMed Central

    Hales, Patrick W.; Schneider, Jürgen E.; Burton, Rebecca A.B.; Wright, Benjamin J.; Bollensdorff, Christian; Kohl, Peter

    2012-01-01

    Deformation and wall-thickening of ventricular myocardium are essential for cardiac pump function. However, insight into the histo-anatomical basis for cardiac tissue re-arrangement during contraction is limited. In this report, we describe dynamic changes in regionally prevailing cardiomyocyte (fibre) and myolaminar (sheet) orientations, using Diffusion Tensor Imaging (DTI) of ventricles in the same living heart in two different mechanical states. Hearts, isolated from Sprague–Dawley rats, were Langendorff-perfused and imaged, initially in their slack state during cardioplegic arrest, then during lithium-induced contracture. Regional fibre- and sheet-orientations were derived from DTI-data on a voxel-wise basis. Contraction was accompanied with a decrease in left-handed helical fibres (handedness relative to the baso-apical direction) in basal, equatorial, and apical sub-epicardium (by 14.0%, 17.3%, 15.8% respectively; p < 0.001), and an increase in right-handed helical fibres of the sub-endocardium (by 11.0%, 12.1% and 16.1%, respectively; p < 0.001). Two predominant sheet-populations were observed, with sheet-angles of either positive (β+) or negative (β−) polarity relative to a ‘chamber-horizontal plane’ (defined as normal to the left ventricular long-axis). In contracture, mean ‘intersection’-angle (geometrically quantifiable intersection of sheet-angle projections) between β+ and β− sheet-populations increased from 86.2 ± 5.5° (slack) to 108.3 ± 5.4° (p < 0.001). Subsequent high-resolution DTI of fixed myocardium, and histological sectioning, reconfirmed the existence of alternating sheet-plane populations. Our results suggest that myocardial tissue layers in alternating sheet-populations align into a more chamber-horizontal orientation during contraction. This re-arrangement occurs via an accordion-like mechanism that, combined with inter-sheet slippage, can significantly contribute to ventricular deformation, including wall

  2. Histo-anatomical structure of the living isolated rat heart in two contraction states assessed by diffusion tensor MRI.

    PubMed

    Hales, Patrick W; Schneider, Jürgen E; Burton, Rebecca A B; Wright, Benjamin J; Bollensdorff, Christian; Kohl, Peter

    2012-01-01

    Deformation and wall-thickening of ventricular myocardium are essential for cardiac pump function. However, insight into the histo-anatomical basis for cardiac tissue re-arrangement during contraction is limited. In this report, we describe dynamic changes in regionally prevailing cardiomyocyte (fibre) and myolaminar (sheet) orientations, using Diffusion Tensor Imaging (DTI) of ventricles in the same living heart in two different mechanical states. Hearts, isolated from Sprague-Dawley rats, were Langendorff-perfused and imaged, initially in their slack state during cardioplegic arrest, then during lithium-induced contracture. Regional fibre- and sheet-orientations were derived from DTI-data on a voxel-wise basis. Contraction was accompanied with a decrease in left-handed helical fibres (handedness relative to the baso-apical direction) in basal, equatorial, and apical sub-epicardium (by 14.0%, 17.3%, 15.8% respectively; p < 0.001), and an increase in right-handed helical fibres of the sub-endocardium (by 11.0%, 12.1% and 16.1%, respectively; p < 0.001). Two predominant sheet-populations were observed, with sheet-angles of either positive (β+) or negative (β-) polarity relative to a 'chamber-horizontal plane' (defined as normal to the left ventricular long-axis). In contracture, mean 'intersection'-angle (geometrically quantifiable intersection of sheet-angle projections) between β+ and β- sheet-populations increased from 86.2 ± 5.5° (slack) to 108.3 ± 5.4° (p < 0.001). Subsequent high-resolution DTI of fixed myocardium, and histological sectioning, reconfirmed the existence of alternating sheet-plane populations. Our results suggest that myocardial tissue layers in alternating sheet-populations align into a more chamber-horizontal orientation during contraction. This re-arrangement occurs via an accordion-like mechanism that, combined with inter-sheet slippage, can significantly contribute to ventricular deformation, including wall-thickening in a

  3. The effect of epigallocatechin gallate on hepatocytes isolated from normal and partially hepatectomized rats.

    PubMed

    Mezera, Vojtech; Kucera, Otto; Moravcova, Alena; Peterova, Eva; Cervinkova, Zuzana

    2014-06-01

    Epigallocatechin gallate (EGCG) is an antioxidant found in green tea. In this study, male Wistar rats were subjected either to partial hepatectomy (PHx), or a sham operation (LAP). Twenty-four hours after surgery, hepatocytes were isolated and treated with various concentrations of EGCG for up to 72 h. We then measured markers of cell viability, oxidative stress, DNA synthesis, and caspase activity. Morphological criteria, cell viability tests, and albumin synthesis revealed toxicity starting at 10 μmol/L. DNA synthesis was higher in hepatocytes isolated from rats after PHx and inhibited by EGCG. Furthermore, EGCG increased the activity of caspases 3 and 7, seen more in hepatocytes from PHx rats. In conclusion, EGCG at a concentration of 10 μmol/L was toxic for hepatocytes isolated from both PHx and LAP rats. PMID:24853265

  4. Early Adolescent Emergence of Reversal Learning Impairments in Isolation-Reared Rats

    PubMed Central

    Powell, Susan B.; Khan, Asma; Young, Jared W.; Scott, Christine N.; Buell, Mahalah R.; Caldwell, Sorana; Tsan, Elisa; de Jong, Loek A.W.; Acheson, Dean T.; Lucero, Jacinta; Geyer, Mark A.; Behrens, M. Margarita

    2015-01-01

    Cognitive impairments appear early in the progression of schizophrenia, often preceding the symptoms of psychosis. Thus, the systems subserving these functions may be more vulnerable to, and mechanistically linked with, the initial pathology. Understanding the trajectory of behavioral and anatomical abnormalities relevant to the schizophrenia prodrome and their sensitivity to interventions in relevant models will be critical to identifying early therapeutic strategies. Isolation rearing of rats is an environmental perturbation that deprives rodents of social contact from weaning through adulthood and produces behavioral and neuronal abnormalities that mirror some pathophysiology associated with schizophrenia, e.g. frontal cortex abnormalities and prepulse inhibition (PPI) of startle deficits. Previously, we showed that PPI deficits in isolation-reared rats emerge in mid-adolescence (4 weeks after weaning; approx. postnatal day 52) but are not present when tested at 2 weeks after weaning (approx. postnatal day 38). Because cognitive deficits are reported during early adolescence, are relevant to the prodrome, and are linked to functional outcome, we examined the putative time course of reversal learning deficits in isolation-reared rats. Separate groups of male Sprague Dawley rats were tested in a two-choice discrimination task at 2 and 8 weeks after weaning, on postnatal day 38 and 80, respectively. The isolation-reared rats displayed impaired reversal learning at both time points. Isolation rearing was also associated with deficits in PPI at 4 and 10 weeks after weaning. The reversal learning deficits in the isolated rats were accompanied by reductions in parvalbumin immunoreactivity, a marker for specific subpopulations of GABAergic neurons, in the hippocampus. Hence, isolation rearing of rats may offer a unique model to examine the ontogeny of behavioral and neurobiological alterations that may be relevant to preclinical models of prodromal psychosis. PMID

  5. MicroRNA-214 Inhibits Left Ventricular Remodeling in an Acute Myocardial Infarction Rat Model by Suppressing Cellular Apoptosis via the Phosphatase and Tensin Homolog (PTEN).

    PubMed

    Yang, Xingwei; Qin, Yanjun; Shao, Suxia; Yu, Yueqing; Zhang, Chongyang; Dong, Hua; Lv, Guangwei; Dong, Shimin

    2016-01-01

    The aims of the present study were to determine the role of miR-214 on left ventricular remodeling of rat heart with acute myocardial infarction (AMI) and to further investigate the underlying mechanism of miR-214-mediated myocardial protection. AMI was induced in which adenovirus-expressing miR-214 (Ad-miR-214), anti-miR-214, or Ad-GFP had been delivered into rats hearts 4 days prior, while a phosphatase and tensin homolog (PTEN) inhibitor was administered via intra-peritoneal injection 30 minutes prior to AMI. Changes in hemodynamic parameters were detected and recorded. Left ventricular (LV) dimensions and LV/BW were measured. Quantitative RT-PCR was used to determine the miR-214 expression levels of the myocytes in the infarcted, border, and non-infarcted areas of the LV. Myocardial infarct size was also measured. Flow cytometry analysis was performed to examine cellular apoptosis. Western blot analysis was performed to examine PTEN expression. The results showed that miR-214 was upregulated in both border and infarcted areas. Myocardial cell apoptosis was decreased in the Ad-miR-214 group, but was increased in the anti-miR-214 group, while there were no differences among the Ad-GFP-group, PTEN-ad-miR-214 group, or PTEN-anti-miR-214 group. Myocardial infarct size, LV dimensions, heart rate (HR), and LV end-diastolic pressure (LVEDP) were decreased while the maximal rates of rise or decline in blood pressure in the ventricular chamber (± dp/dt) and LV systolic pressure (LVSP) were increased in the Ad-miR-214 group, all of which exhibited opposite changes in the anti-miR-214 group. PTEN was downregulated in the Ad-miR-214 group and upregulated in the anti-miR-214 group. PTEN was decreased in both the border and infarcted areas compared with non-infarcted areas. The study results suggest that Ad-miR-214 improves LV remodeling and decreases the apoptosis of myocardial cells through PTEN, suggesting a possible mechanism by which Ad-miR-214 functions in protecting

  6. Sex differences in the outcome of juvenile social isolation on HPA axis function in rats.

    PubMed

    Pisu, M G; Garau, A; Boero, G; Biggio, F; Pibiri, V; Dore, R; Locci, V; Paci, E; Porcu, P; Serra, M

    2016-04-21

    Women are more likely than men to suffer from anxiety disorders and major depression. These disorders share hyperresponsiveness to stress as an etiological factor. Thus, sex differences in brain arousal systems and their regulation by chronic stress may account for the increased vulnerability to these disorders in women. Social isolation is a model of early life stress that results in neurobiological alterations leading to increased anxiety-like and depressive-like behaviors. Here we investigated the sex difference in the effects of post-weaning social isolation on acute stress sensitivity and behavior in rats. In both sexes, social isolation at weaning reduced basal levels of the neuroactive steroid allopregnanolone in the brain and of corticosterone in plasma. Moreover, acute stress increased plasma corticosterone levels in both group-housed and socially isolated male and female rats; however this effect was greater in male than female rats subjected to social isolation. Intriguingly, group-housed female rats showed no change in plasma and brain levels of allopregnanolone after acute foot-shock stress. The absence of stress-induced effects on allopregnanolone synthesis might be due to the physiologically higher levels of this hormone in females vs. males. Accordingly, increasing allopregnanolone levels in male rats blunted the response to foot-shock stress in these animals. Socially isolated male, but not female, rats also display depressive-like behavior and increased hippocampal brain-derived neurotrophic factor (BDNF). The ovarian steroids could "buffer" the effect of this adverse experience in females on these parameters. Finally, the dexamethasone (DEX) suppression test indicated that the chronic stress associated with social isolation impairs feedback inhibition in both sexes in which an increase in the abundance of glucocorticoid receptors (GRs) in the hippocampus was found. Altogether, these results demonstrate that social isolation affects neuroendocrine

  7. Sex differences in the outcome of juvenile social isolation on HPA axis function in rats.

    PubMed

    Pisu, M G; Garau, A; Boero, G; Biggio, F; Pibiri, V; Dore, R; Locci, V; Paci, E; Porcu, P; Serra, M

    2016-04-21

    Women are more likely than men to suffer from anxiety disorders and major depression. These disorders share hyperresponsiveness to stress as an etiological factor. Thus, sex differences in brain arousal systems and their regulation by chronic stress may account for the increased vulnerability to these disorders in women. Social isolation is a model of early life stress that results in neurobiological alterations leading to increased anxiety-like and depressive-like behaviors. Here we investigated the sex difference in the effects of post-weaning social isolation on acute stress sensitivity and behavior in rats. In both sexes, social isolation at weaning reduced basal levels of the neuroactive steroid allopregnanolone in the brain and of corticosterone in plasma. Moreover, acute stress increased plasma corticosterone levels in both group-housed and socially isolated male and female rats; however this effect was greater in male than female rats subjected to social isolation. Intriguingly, group-housed female rats showed no change in plasma and brain levels of allopregnanolone after acute foot-shock stress. The absence of stress-induced effects on allopregnanolone synthesis might be due to the physiologically higher levels of this hormone in females vs. males. Accordingly, increasing allopregnanolone levels in male rats blunted the response to foot-shock stress in these animals. Socially isolated male, but not female, rats also display depressive-like behavior and increased hippocampal brain-derived neurotrophic factor (BDNF). The ovarian steroids could "buffer" the effect of this adverse experience in females on these parameters. Finally, the dexamethasone (DEX) suppression test indicated that the chronic stress associated with social isolation impairs feedback inhibition in both sexes in which an increase in the abundance of glucocorticoid receptors (GRs) in the hippocampus was found. Altogether, these results demonstrate that social isolation affects neuroendocrine

  8. [Cardioprotective effect of heme oxygenase-1 induction by hemin on the isolated rat heart during ischemia--reperfusion].

    PubMed

    Kukoba, T V; Moĭbenko, O O; Kotsioruba, A V

    2003-01-01

    The aim of the study was to determine the role of both an inducible isoform of heme oxygenase (HO-1) and products of heme catabolism (carbon monoxide (CO), cardiac bilirubin and Fe2+) in protecting myocardium against post-ischemic myocardial dysfunction. Rat hearts were isolated and perfused according to the Langendorff technique to evaluate the recovery of myocardial function after total ischemia (20 min) and reperfusion (40 min) and production of reactive oxygen forms at a reperfusion phase. Ischemia/reperfusion caused impairment in myocardial function: left ventricular developing pressure (LVDP) was shown to be decreased, while end-diastolic pressure (EDP) and both coronary perfusion pressure and coronary resistance increased. Free oxygen radicals were generated at the reperfusion phase which led to injuries to cardiomyocytes and creatine kinase efflux into perfusate. We have found that upregulation of HO-1 by preliminary (24 h before ischemia) injections of 25 mg/kg hemin (i.p.) resulted in improving the myocardial function due to increasing the enzyme activity and forming the cardial bilirubine, while generation of reactive oxygen forms was inhibited, as well as the contents of creatine kinase reduced. As a result, impairment in cardiomyocytes diminished, and coronary vessels dilated to improve the functional parametres of the heart work.

  9. Down-regulation of hippocampal BDNF and Arc associated with improvement in aversive spatial memory performance in socially isolated rats.

    PubMed

    Pisu, Maria Giuseppina; Dore, Riccardo; Mostallino, Maria Cristina; Loi, Manila; Pibiri, Francesca; Mameli, Roberta; Cadeddu, Roberto; Secci, Pietro Paolo; Serra, Mariangela

    2011-09-12

    Rats deprived of social contact with other rats at a young age experience a form of prolonged stress that leads to long-lasting changes in behavioral profile. Such isolation is thought to be anxiogenic for these normally gregarious animals, and the abnormal reactivity of isolated rats to environmental stimuli is thought to be a product of prolonged stress. We now show that isolation of rats at weaning reduced immobility time in the forced swim test, decreased sucrose intake and preference, and down-regulated both brain-derived neurotrophic factor (BDNF) and activity-regulated cytoskeletal associated protein (Arc) in the hippocampus. In the Morris water maze, isolated rats showed a reduced latency to reach the hidden platform during training, indicative of an improved learning performance, compared with group-housed rats. The cumulative search error during place training trials indicated a reliable difference between isolated and group-housed rats on days 4 and 5. The probe trial revealed a significant decrease of the average proximity to the target location in the isolated rats suggesting an improvement in spatial memory. Isolated rats also showed an increase in the plasma level of corticosterone on the 5th day of training and increased expression of BDNF and Arc in the hippocampus on both days 1 and 5. These results show that social isolation from weaning in rats results in development of depressive-like behavior but has a positive effect on spatial learning, supporting the existence of a facilitating effect of stress on cognitive function.

  10. Inhalation of the BKCa-Opener NS1619 Attenuates Right Ventricular Pressure and Improves Oxygenation in the Rat Monocrotaline Model of Pulmonary Hypertension

    PubMed Central

    Revermann, Marc; Neofitidou, Skevi; Kirschning, Thomas; Schloss, Manuel; Brandes, Ralf P.; Hofstetter, Christian

    2014-01-01

    Background Right heart failure is a fatal consequence of chronic pulmonary hypertension (PH). The development of PH is characterized by increased proliferation of vascular cells, in particular pulmonary artery smooth muscle cells (PASMCs) and pulmonary artery endothelial cells. In the course of PH, an escalated right ventricular (RV) afterload occurs, which leads to increased perioperative morbidity and mortality. BKCa channels are ubiquitously expressed in vascular smooth muscle cells and their opening induces cell membrane hyperpolarization followed by vasodilation. Moreover, BK activation induces anti-proliferative effects in a multitude of cell types. On this basis, we hypothesized that treatment with the nebulized BK channel opener NS1619 might be a therapy option for pulmonary hypertension and tested this in rats. Methods (1) Rats received monocrotaline injection for PH induction. Twenty-four days later, rats were anesthetized and NS1619 or the solvent was administered by inhalation. Systemic hemodynamic parameters, RV hemodynamic parameters, and blood gas analyses were measured before as well as 30 and 120 minutes after inhalation. (2) Rat PASMCs were stimulated with PDGF-BB in the presence and absence of NS1619. AKT, ERK1 and ERK2 activation were investigated by western blot analyses, and relative cell number was determined 48 hours after stimulation. Results Inhalation of a 12 µM and 100 µM NS1619 solution significantly reduced RV pressure without affecting systemic arterial pressure. Blood gas analyses demonstrated significantly reduced carbon dioxide and improved oxygenation in NS1619-treated animals pointing towards a considerable pulmonary shunt-reducing effect. In PASMC’s, NS1619 (100 µM) significantly attenuated PASMC proliferation by a pathway independent of AKT and ERK1/2 activation. Conclusion NS1619 inhalation reduces RV pressure and improves oxygen supply and its application inhibits PASMC proliferation in vitro. Hence, BK opening might be

  11. Enhanced expression of endothelial nitric oxide synthase in the myocardium ameliorates the progression of left ventricular hypertrophy in L-arginine treated Wistar-Kyoto rats.

    PubMed

    Ahmad, A; Sattar, M A; Rathore, H A; Abdulla, M H; Khan, S A; Abdullah, N A; Johns, E J

    2016-02-01

    The present study investigated the role of endothelial nitric oxide synthase (eNOS) enzyme in the development of left ventricular hypertrophy (LVH) in Wistar-Kyoto rats. The effect of L-arginine administration on cardiac structure, arterial stiffness, renal and systemic hemodynamic parameters was studied and the change in expression of eNOS and cystathione γ lyase (CSE) in the myocardium of LVH rats was evaluated. LVH was induced using isoprenaline (5 mg/kg, S.C.) and caffeine (62 mg/L in drinking water) for 14 days. Following to that, L-arginine (1.25 g/L in drinking water) was given for 5 weeks as a donor of NO. eNOS and CSE gene expressions were down regulated in the LVH group by about 35% and 67% respectively when compared to control. However, in the LVH group treated with L-arginine there was up regulation of eNOS by almost 27% and down regulation in CSE by 24% when compared to control (all P < 0.05). Heart index and H2S plasma levels were reduced by almost 53% in the L-arginine treated LVH group compared to the control (all P < 0.05). Mean arterial pressure, heart rate and pulse wave velocity were reduced while renal blood perfusion increased in L-arginine treated LVH rats compared to their untreated counterparts (all P < 0.05). The enhanced expression of eNOS in L-arginine treated LVH rats resulted in the amelioration of oxidative and haemodynamic parameters suggesting that NO system is an important therapeutic target in cardiac and LV hypertrophies. PMID:27010893

  12. Long-term pretreatment with desethylamiodarone (DEA) or amiodarone (AMIO) protects against coronary artery occlusion induced ventricular arrhythmias in conscious rats.

    PubMed

    Morvay, Nikolett; Baczkó, István; Sztojkov-Ivanov, Anita; Falkay, György; Papp, Julius Gy; Varró, András; Leprán, István

    2015-09-01

    The aim of this investigation was to compare the effectiveness of long-term pretreatment with amiodarone (AMIO) and its active metabolite desethylamiodarone (DEA) on arrhythmias induced by acute myocardial infarction in rats. Acute myocardial infarction was induced in conscious, male, Sprague-Dawley rats by pulling a previously inserted loose silk loop around the left main coronary artery. Long-term oral pretreatment with AMIO (30 or 100 mg·(kg body mass)(-1)·day(-1), loading dose 100 or 300 mg·kg(-1) for 3 days) or DEA (15 or 50 mg·kg(-1)·day(-1), loading dose 100 or 300 mg·kg(-1) for 3 days), was applied for 1 month before the coronary artery occlusion. Chronic oral treatment with DEA (50 mg·kg(-1)·day(-1)) resulted in a similar myocardial DEA concentration as chronic AMIO treatment (100 mg·kg(-1)·day(-1)) in rats (7.4 ± 0.7 μg·g(-1) and 8.9 ± 2.2 μg·g(-1)). Both pretreatments in the larger doses significantly improved the survival rate during the acute phase of experimental myocardial infarction (82% and 64% by AMIO and DEA, respectively, vs. 31% in controls). Our results demonstrate that chronic oral treatment with DEA resulted in similar cardiac tissue levels to that of chronic AMIO treatment, and offered an equivalent degree of antiarrhythmic effect against acute coronary artery ligation induced ventricular arrhythmias in conscious rats.

  13. Replication of parainfluenza (Sendai) virus in isolated rat pulmonary type II alveolar epithelial cells.

    PubMed Central

    Castleman, W. L.; Northrop, P. J.; McAllister, P. K.

    1989-01-01

    The major objectives of this study were to determine whether alveolar type II epithelial cells isolated from rat lung and maintained in tissue culture would support productive replication of parainfluenza type 1 (Sendai) virus and to determine whether isolated type II cells from neonatal (5-day-old) rats that are more susceptible to viral-induced alveolar dysplasia supported viral replication to a greater extent than those from weanling (25-day-old) rats. Isolated and cultured type II cells from neonatal and weanling rats that were inoculated with Sendai virus supported productive replication as indicated by ultrastructural identification of budding virions and viral nucleocapsids in type II cells and by demonstration of rising titers of infectious virus from inoculated type II cell cultures. Alveolar macrophages from neonatal and weanling rats also supported viral replication, although infectious viral titers in macrophage cultures were lower than those from type II cell cultures. Only minor differences were detected between viral titers from neonatal and weanling type II epithelial cell cultures. Higher densities of viral nucleocapsids were observed in neonatal type II cells than in those from weanling rats. The results indicate that isolated type II alveolar epithelial cells support productive replication of parainfluenza virus and that type II cells are probably more efficient in supporting productive viral replication than are alveolar macrophages. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:2541612

  14. Reduction of prohibitin expression contributes to left ventricular hypertrophy via enhancement of mitochondrial reactive oxygen species formation in spontaneous hypertensive rats.

    PubMed

    Zheng, H; Lu, G M

    2015-02-01

    Left ventricular hypertrophy (LVH) in hypertension is characterized by thickening of myocardium and decrease in heart chamber volume in response to mechanical or pathological stress, but the underlying molecular mechanisms remain to be defined. In this work, we investigate whether mitochondrial prohibitin (PHB) was involved in the progression of LVH in spontaneous hypertensive rats (SHR). First, it was found that mitochondrial dysfunction occurred in left ventricles of SHR. Through analysis using quantitative reverse transcription polymerase chain reaction and Western blotting, it was found that PHB mRNA and mitochondrial PHB levels in left ventricles of SHR were significantly lower than that in Wistar-Kyoto rats. Furthermore, PHB mRNA levels were negatively correlated to left ventricles weight-to-body weight ratio in SHR. Knockdown of PHB led to increased formation of mitochondrial reactive oxygen species (ROS) and reduced activities of complex I, mitochondrial adenosine triphosphate generation and mitochondrial membrane potential in cultured cardiomyocytes. Knockdown of PHB contributed to the cardiomyocyte hypertrophy, which could be attenuated by treatment with the Tempol. Angiotensin II (AngII) was increased in plasma and left ventricles of SHR. Incubation with AngII reduced mitochondrial PHB expression in cardiomyocytes, which was reversed when pretreated with losartan. In conclusion, reduction of PHB expression in left ventricles in SHR contributed to LVH, at least in part, through promoting mitochondrial ROS formation.

  15. Association between hypoalgesia and hypertension in rats after short-term isolation.

    PubMed

    Naranjo, J R; Fuentes, J A

    1985-02-01

    By isolating young rats (90-100 g) a state of hypertension and tachycardia was induced after 7 days or a longer period of social deprivation. Clonidine, a drug used to treat hypertension in man, readily reversed the high blood pressure and heart rate in this experimental model of hypertension. In two different tests, an elevated nociceptive threshold was shown to be present in isolated animals as compared to group-housed rats. Naloxone was found to reverse this hypoalgesic state. The opiate antagonist also diminished the high blood pressure in the socially-deprived animals. Moreover, after 7 days of isolation, 24 hr of housing the rats in groups of five made the level of blood pressure and the sensitivity to pain return to control values. In this experimental model, in which hypertension was linked to stressful housing conditions, the data suggest that high blood pressure and hypoalgesia are closely associated. PMID:3990918

  16. Glucose production and storage in hepatocytes isolated from normal versus diabetic rats

    SciTech Connect

    Olivieri, M.C.; Dragland-Meserve, C.J.; Parker Botelho, L.H.

    1987-05-01

    The rates of glucose production and storage were compared in hepatocytes isolated from normal versus insulin-resistant diabetic rats. A single low-dose (40 mg/kg) IV injection of streptozotocin to 250 g rats resulted in a Type II diabetic animal model which was hyperglycemic with normal insulin levels. Addition of 8 mM /sup 14/C-lactate and 2 mM pyruvate to hepatocytes resulted in a linear increase in total glucose production (/sup 14/C-glucose and unlabeled glucose) and incorporation into glycogen measured over 120 min. The rate of gluconeogenesis was estimated from the production of /sup 14/C-glucose and the rate of glycogenolysis was estimated from the production of unlabeled glucose in cells incubated in the presence or absence of /sup 14/C-labelled substrate. There was not significant difference in total glucose production in hepatocytes isolated from normal versus diabetic rats, however, the contribution from gluconeogenesis versus glycogenolysis was significantly different. Following a 1 h incubation of cells from normal rats, 42% of the total glucose production was due to gluconeogenesis and 58% was due to glycogenolysis. In cells from diabetic rats, 83% of total glucose production was from gluconeogenesis and 17% from glycogenolysis. Also, incubation with /sup 14/C-lactate/pyruvate resulted in a 3.3-fold increase in /sup 14/C-glucose incorporation into glycogen in hepatocytes isolated from normal rats compared to diabetic rats. These data suggest that alterations occur in the rate-limiting enzymes responsible for glucose production and storage in hepatocytes isolated from a rat model of insulin-resistant Type II diabetes.

  17. A rapid immunological procedure for the isolation of hormonally sensitive rat fat-cell plasma membrane.

    PubMed Central

    Luzio, J P; Newby, A C; Hales, C N

    1976-01-01

    1. A rapid method for the isolation of hormonally sensitive rat fat-cell plasma membranes was developed by using immunological techniques. 2. Rabbit anti-(rat erythrocyte) sera were raised and shown to cross-react with isolated rat fat-cells. 3. Isolated rat fat-cells were coated with rabbit anti-(rat erythrocyte) antibodies, homogenized and the homogenate made to react with an immunoadsorbent prepared by covalently coupling donkey anti-(rabbit globulin) antibodies to aminocellulose. Uptake of plasma membrane on to the immunoadsorbent was monitored by assaying the enzymes adenylate cyclase and 5'-nucleotidase and an immunological marker consisting of a 125I-labelled anti-(immunoglobulin G)-anti-cell antibody complex bound to the cells before fractionation. Contamination of the plasma-membrane preparation by other subcellular fractions was also investigated. 4. By using this technique, a method was developed allowing 25-40% recovery of plasma membrane from fat-cell homogenates within 30 min of homogenization. 5. Adenylate cyclase in the isolated plasma-membrane preparation was stimulated by 5 mum-adrenaline. Images PLATE 1 PMID:776177

  18. Sarcolemmal localisation of Na+/H+ exchange and Na+-HCO3- co-transport influences the spatial regulation of intracellular pH in rat ventricular myocytes.

    PubMed

    Garciarena, Carolina D; Ma, Yu-ling; Swietach, Pawel; Huc, Laurence; Vaughan-Jones, Richard D

    2013-05-01

    Membrane acid extrusion by Na(+)/H(+) exchange (NHE1) and Na(+)-HCO3(-) co-transport (NBC) is essential for maintaining a low cytoplasmic [H(+)] (∼60 nm, equivalent to an intracellular pH (pHi) of 7.2). This protects myocardial function from the high chemical reactivity of H(+) ions, universal end-products of metabolism. We show here that, in rat ventricular myocytes, fluorescent antibodies map the NBC isoforms NBCe1 and NBCn1 to lateral sarcolemma, intercalated discs and transverse tubules (t-tubules), while NHE1 is absent from t-tubules. This unexpected difference matches functional measurements of pHi regulation (using AM-loaded SNARF-1, a pH fluorophore). Thus, myocyte detubulation (by transient exposure to 1.5 m formamide) reduces global acid extrusion on NBC by 40%, without affecting NHE1. Similarly, confocal pHi imaging reveals that NBC stimulation induces spatially uniform pHi recovery from acidosis, whereas NHE1 stimulation induces pHi non-uniformity during recovery (of ∼0.1 units, for 2-3 min), particularly at the ends of the cell where intercalated discs are commonly located, and where NHE1 immunostaining is prominent. Mathematical modelling shows that this induction of local pHi microdomains is favoured by low cytoplasmic H(+) mobility and long H(+) diffusion distances, particularly to surface NHE1 transporters mediating high membrane flux. Our results provide the first evidence for a spatial localisation of [H(+)]i regulation in ventricular myocytes, suggesting that, by guarding pHi, NHE1 preferentially protects gap junctional communication at intercalated discs, while NBC locally protects t-tubular excitation-contraction coupling.

  19. Chronic Psychosocial Stress Impairs Bone Homeostasis: A Study in the Social Isolation Reared Rat.

    PubMed

    Schiavone, Stefania; Morgese, Maria G; Mhillaj, Emanuela; Bove, Maria; De Giorgi, Angelo; Cantatore, Francesco P; Camerino, Claudia; Tucci, Paolo; Maffulli, Nicola; Cuomo, Vincenzo; Trabace, Luigia

    2016-01-01

    Chronic psychosocial stress is a key player in the onset and aggravation of mental diseases, including psychosis. Although a strong association between this psychiatric condition and other medical co-morbidities has been recently demonstrated, few data on the link between psychosis and bone homeostasis are actually available. The aim of this study was to investigate whether chronic psychosocial stress induced by 4 or 7 weeks of social isolation in drug-naïve male Wistar rats could alter bone homeostasis in terms of bone thickness, mineral density and content, as well as markers of bone formation and resorption (sclerostin, cathepsin K, and CTX-I). We found that bone mineral density was increased in rats exposed to 7 weeks of social isolation, while no differences were detected in bone mineral content and area. Moreover, 7 weeks of social isolation lead to increase of femur thickness with respect to controls, suggesting the development of a hyperostosis condition. Isolated rats showed no changes in sclerostin levels, a marker of bone formation, compared to grouped animals. Conversely, bone resorption markers were significantly altered after 7 weeks of social isolation in terms of decrease in cathepsin K and increase of CTX-I. No alterations were found after 4 weeks of isolation rearing. Our observations suggest that chronic psychosocial stress might affect bone homeostasis, more likely independently from drug treatment. Thus, the social isolation model might help to identify possible new therapeutic targets to treat the burden of chronic psychosocial stress and to attempt alternative therapy choices.

  20. Functional contribution of α1D-adrenoceptors in the renal vasculature of left ventricular hypertrophy induced with isoprenaline and caffeine in Wistar-Kyoto rats.

    PubMed

    Ahmad, Ashfaq; Sattar, Munavvar A; Rathore, Hassaan A; Abdulla, Mohammad H; Khan, Safia A; Abdullah, Nor A; Kaur, Gurjeet; Johns, Edward J

    2014-12-01

    This study investigated the role of α1D-adrenoceptor in the modulation of renal haemodynamics in rats with left ventricular hypertrophy (LVH). LVH was established in Wistar-Kyoto (WKY) rats with isoprenaline (5.0 mg · (kg body mass)(-1), by subcutaneous injection every 72 h) and caffeine (62 mg · L(-1) in drinking water, daily for 14 days). Renal vasoconstrictor responses were measured for noradrenaline (NA), phenylephrine (PE), and methoxamine (ME) before and immediately after low or high dose intrarenal infusions of BMY 7378, a selective α1D-adrenoceptor blocker. The rats with LVH had higher mean arterial blood pressure and circulating NA levels, but lower renal cortical blood perfusion compared with the control group (all P < 0.05). In the LVH group, the magnitude of the renal vasoconstrictor response to ME was blunted, but not the response to NA or PE (P < 0.05), compared with the control group (LVH vs. C, 38% vs. 50%). The magnitude of the drop in the vasoconstrictor responses to NA, PE, and ME in the presence of a higher dose of BMY 7378 was significantly greater in the LVH group compared with the control group (LVH vs. C, 45% vs. 25% for NA, 52% vs. 33% for PE, 66% vs. 53% for ME, all P < 0.05). These findings indicate an impaired renal vasoconstrictor response to adrenergic agonists during LVH. In addition, the α1D-adrenoceptor subtype plays a key role in the modulation of vascular responses in this diseased state. PMID:25403946

  1. Functional contribution of α1D-adrenoceptors in the renal vasculature of left ventricular hypertrophy induced with isoprenaline and caffeine in Wistar-Kyoto rats.

    PubMed

    Ahmad, Ashfaq; Sattar, Munavvar A; Rathore, Hassaan A; Abdulla, Mohammad H; Khan, Safia A; Abdullah, Nor A; Kaur, Gurjeet; Johns, Edward J

    2014-12-01

    This study investigated the role of α1D-adrenoceptor in the modulation of renal haemodynamics in rats with left ventricular hypertrophy (LVH). LVH was established in Wistar-Kyoto (WKY) rats with isoprenaline (5.0 mg · (kg body mass)(-1), by subcutaneous injection every 72 h) and caffeine (62 mg · L(-1) in drinking water, daily for 14 days). Renal vasoconstrictor responses were measured for noradrenaline (NA), phenylephrine (PE), and methoxamine (ME) before and immediately after low or high dose intrarenal infusions of BMY 7378, a selective α1D-adrenoceptor blocker. The rats with LVH had higher mean arterial blood pressure and circulating NA levels, but lower renal cortical blood perfusion compared with the control group (all P < 0.05). In the LVH group, the magnitude of the renal vasoconstrictor response to ME was blunted, but not the response to NA or PE (P < 0.05), compared with the control group (LVH vs. C, 38% vs. 50%). The magnitude of the drop in the vasoconstrictor responses to NA, PE, and ME in the presence of a higher dose of BMY 7378 was significantly greater in the LVH group compared with the control group (LVH vs. C, 45% vs. 25% for NA, 52% vs. 33% for PE, 66% vs. 53% for ME, all P < 0.05). These findings indicate an impaired renal vasoconstrictor response to adrenergic agonists during LVH. In addition, the α1D-adrenoceptor subtype plays a key role in the modulation of vascular responses in this diseased state.

  2. 17β-Estradiol mediates superior adaptation of right ventricular function to acute strenuous exercise in female rats with severe pulmonary hypertension.

    PubMed

    Lahm, Tim; Frump, Andrea L; Albrecht, Marjorie E; Fisher, Amanda J; Cook, Todd G; Jones, Thomas J; Yakubov, Bakhtiyor; Whitson, Jordan; Fuchs, Robyn K; Liu, Aiping; Chesler, Naomi C; Brown, M Beth

    2016-08-01

    17β-Estradiol (E2) exerts protective effects on right ventricular (RV) function in pulmonary arterial hypertension (PAH). Since acute exercise-induced increases in afterload may lead to RV dysfunction in PAH, we sought to determine whether E2 allows for superior RV adaptation after an acute exercise challenge. We studied echocardiographic, hemodynamic, structural, and biochemical markers of RV function in male and female rats with sugen/hypoxia (SuHx)-induced pulmonary hypertension, as well as in ovariectomized (OVX) SuHx females, with or without concomitant E2 repletion (75 μg·kg(-1)·day(-1)) immediately after 45 min of treadmill running at 75% of individually determined maximal aerobic capacity (75% aerobic capacity reserve). Compared with males, intact female rats exhibited higher stroke volume and cardiac indexes, a strong trend for better RV compliance, and less pronounced increases in indexed total pulmonary resistance. OVX abrogated favorable RV adaptations, whereas E2 repletion after OVX markedly improved RV function. E2's effects on pulmonary vascular remodeling were complex and less robust than its RV effects. Postexercise hemodynamics in females with endogenous or exogenous E2 were similar to hemodynamics in nonexercised controls, whereas OVX rats exhibited more severely altered postexercise hemodynamics. E2 mediated inhibitory effects on RV fibrosis and attenuated increases in RV collagen I/III ratio. Proapoptotic signaling, endothelial nitric oxide synthase phosphorylation, and autophagic flux markers were affected by E2 depletion and/or repletion. Markers of impaired autophagic flux correlated with endpoints of RV structure and function. Endogenous and exogenous E2 exerts protective effects on RV function measured immediately after an acute exercise challenge. Harnessing E2's mechanisms may lead to novel RV-directed therapies. PMID:27288487

  3. Effects of extracts of ginkgo, onion, and celery on the contractility of isolated rat atria.

    PubMed

    Radenković, Mirjana; Kitić, Dušanka; Kostić, Milica; Mrkaić, Ana; Pavlović, Dragana; Miladinović, Bojana; Branković, Suzana

    2013-01-01

    The acute negative inotropic and chronotropic effects of the commercial extract of ginkgo leaf (Gingium(®)) and ethanolic extracts of onion bulbs and celery root on spontaneous and noradrenalin-stimulated contractions of the Wistar rat atria were investigated. All analyzed extracts exerted negative inotropic effects on the isolated rat atria. Among the tested extracts, the extract of ginkgo showed the strongest negative inotropic effects on rat atria, either in spontaneous or noradrenalin-induced contractions, being more potent than the onion and celery extracts, respectively.

  4. Social isolation increases aggressive behaviour and alters the effects of diazepam in the rat social interaction test.

    PubMed

    Wongwitdecha, N; Marsden, C A

    1996-02-01

    Isolation rearing in the early stages of life has been shown to modify a variety of behaviours in many animals and the responsitivity to psychotropic drugs. The aims of the present study were to investigate the effects of isolation rearing on anxiety using the social interaction paradigm and to compare the effects of diazepam on social interaction behaviours in isolation and socially reared rats. Male Lister hooded rats were reared from weaning either alone (isolation reared) or in groups of four (socially reared) for 6 weeks and then were tested for social interaction. Both isolation and socially reared rats were exposed to the social interaction test either without drug treatment or following saline or diazepam (1 and 2.5 mg/kg, i.p., 30 min before testing). The results demonstrate that under high light in an unfamiliar arena, the isolation compared to the socially reared rats showed a significantly (P < 0.01) higher level of social interaction, manifested as increases in aggressive and avoidance behaviours, and that this interaction occur for a greater length of time during the test period (10 min). However, when the light level was decreased or when the arena was familiar, active social interaction of isolation reared rats decreased but increased in the socially reared rats. In both conditions the isolation reared rats displayed more aggressive behaviours, in particular biting and boxing the partners which did not occur with the socially reared rats. Pretreatment of diazepam (1 and 2.5 mg/kg., i.p.) caused a dose-related reduction in aggressive behaviours in rats reared under both conditions but increased passive interactions in the socially reared rats. In contrast diazepam (2.5 mg/kg) reduced active interaction in the isolation reared rats but had no effect on passive interaction. These results indicate that isolation rearing increases aggressive behaviours and alters the effects of diazepam.

  5. Kinetic mRNA Profiling in a Rat Model of Left-Ventricular Hypertrophy Reveals Early Expression of Chemokines and Their Receptors

    PubMed Central

    Nemska, Simona; Monassier, Laurent; Gassmann, Max; Frossard, Nelly; Tavakoli, Reza

    2016-01-01

    Left-ventricular hypertrophy (LVH), a risk factor for heart failure and death, is characterized by cardiomyocyte hypertrophy, interstitial cell proliferation, and leukocyte infiltration. Chemokines interacting with G protein-coupled chemokine receptors may play a role in LVH development by promoting recruitment of activated leukocytes or modulating left-ventricular remodeling. Using a pressure overload-induced kinetic model of LVH in rats, we examined during 14 days the expression over time of chemokine and chemokine receptor mRNAs in left ventricles from aortic-banded vs sham-operated animals. Two phases were clearly distinguished: an inflammatory phase (D3-D5) with overexpression of inflammatory genes such as il-1ß, tnfa, nlrp3, and the rela subunit of nf-kb, and a hypertrophic phase (D7-D14) where anp overexpression was accompanied by a heart weight/body weight ratio that increased by more than 20% at D14. No cardiac dysfunction was detectable by echocardiography at the latter time point. Of the 36 chemokines and 20 chemokine receptors analyzed by a Taqman Low Density Array panel, we identified at D3 (the early inflammatory phase) overexpression of mRNAs for the monocyte chemotactic proteins CCL2 (12-fold increase), CCL7 (7-fold increase), and CCL12 (3-fold increase), for the macrophage inflammatory proteins CCL3 (4-fold increase), CCL4 (2-fold increase), and CCL9 (2-fold increase), for their receptors CCR2 (4-fold increase), CCR1 (3-fold increase), and CCR5 (3-fold increase), and for CXCL1 (8-fold increase) and CXCL16 (2-fold increase). During the hypertrophic phase mRNA expression of chemokines and receptors returned to the baseline levels observed at D0. Hence, this first exhaustive study of chemokine and chemokine receptor mRNA expression kinetics reports early expression of monocyte/macrophage-related chemokines and their receptors during the development of LVH in rats, followed by regulation of inflammation as LVH progresses. PMID:27525724

  6. Is rate–pressure product of any use in the isolated rat heart? Assessing cardiac ‘effort’ and oxygen consumption in the Langendorff‐perfused heart

    PubMed Central

    Aksentijević, Dunja; Lewis, Hannah R.

    2016-01-01

    . Experiments were repeated in the presence of isoprenaline and in unpaced hearts where heart rate was increased by cumulative isoprenaline challenge. In KH buffer‐perfused hearts, MV˙O2 increased with increasing heart rate, but given that left ventricular developed pressure decreased with increases in rate, RPP was not correlated with MV˙O2, lactate production or phosphocreatine/ATP ratio. Although the provision of substrates or β‐adrenoceptor stimulation changed the shape of the RPP–MV˙O2 relationship, neither intervention resulted in a positive correlation between RPP and oxygen consumption. Rate–pressure product is therefore an unreliable index of oxygen consumption or ‘cardiac effort’ in the isolated rat heart. PMID:26585840

  7. Forebrain gene expression predicts deficits in sensorimotor gating after isolation rearing in male rats.

    PubMed

    Swerdlow, Neal R; Light, Gregory A; Trim, Ryan S; Breier, Michelle R; Hines, Samantha R; Powell, Susan B

    2013-11-15

    Compared to socially housed (SH) rats, adult isolation-reared (IR) rats exhibit phenotypes relevant to schizophrenia (SZ), including reduced prepulse inhibition (PPI) of startle. PPI is normally regulated by the medial prefrontal cortex (mPFC) and nucleus accumbens (NAC). We assessed PPI, auditory-evoked local field potentials (LFPs) and expression of seven PPI- and SZ-related genes in the mPFC and NAC, in IR and SH rats. Buffalo (BUF) rats were raised in same-sex groups of 2-3 (SH) or in isolation (IR). PPI was measured early (d53) and later in adulthood (d74); LFPs were measured approximately on d66. Brains were processed for RT-PCR measures of mPFC and NAC expression of Comt, Erbb4, Grid2, Ncam1, Slc1a2, Nrg1 and Reln. Male IR rats exhibited PPI deficits, most pronounced at d53; male and female IR rats had significantly elevated startle magnitude on both test days. Gene expression levels were not significantly altered by IR. PPI levels (d53) were positively correlated with mPFC expression of several genes, and negatively correlated with NAC expression of several genes, in male IR but not SH rats. Late (P90) LFP amplitudes correlated significantly with expression levels of 6/7 mPFC genes in male rats, independent of rearing. After IR that disrupts early adult PPI in male BUF rats, expression levels of PPI- and SZ-associated genes in the mPFC correlate positively with PPI, and levels in the NAC correlate negatively with PPI. These results support the model that specific gene-behavior relationships moderate the impact of early-life experience on SZ-linked behavioral and neurophysiological markers.

  8. Biological characteristics of muscle-derived satellite cells isolated from rats at different postnatal days.

    PubMed

    Yu, Ren; Haiqing, Wu; Hefei, Wang; Dong, Liu; Xiao, Wang; Yuzhen, Ma; Dongjun, Liu

    2015-05-01

    This study investigated the in vitro growth characteristics and differential potential of muscle-derived satellite cells (MDSCs) derived from rats at different postnatal (P) stages, in order to expand the range of source material for tissue engineering. Rat MDSCs were isolated from P5, P10, P15, P21 and P42 rat skeletal muscles using double enzyme digestion and differential adherent culture. Neurogenic, osteogenic and myogenic induction media were used to induce directed differentiation. Differentiated nerve cells, osteoblasts and myotubes were identified by their morphology and immunohistochemical staining. Most cells transformed into spindle-shaped mononuclear cells after 48 h and proliferated rapidly. MDSCs were difficult to isolate from P42 rats. After neurogenesis, four groups MDSCs formed neuron-specific enolase positive polygonal-shaped dendritic cells. After osteogenesis, P5, P10, P15 and P21 MDSCs formed Alizarin red- and osteocalcin-positive bone nodules. After myogenesis, myotubes were formed and were fast muscle myosin-positive. MDSCs derived from P5, P10, P15 and P21 rat skeletal muscle are easy to isolate, culture and amplify in vitro, which increases the range of source material available for tissue engineering.

  9. Hemidesmus indicus and Hibiscus rosa-sinensis Affect Ischemia Reperfusion Injury in Isolated Rat Hearts

    PubMed Central

    Khandelwal, Vinoth Kumar Megraj; Balaraman, R.; Pancza, Dezider; Ravingerová, Táňa

    2011-01-01

    Hemidesmus indicus (L.) R. Br. (HI) and Hibiscus rosa-sinensis L. (HRS) are widely used traditional medicine. We investigated cardioprotective effects of these plants applied for 15 min at concentrations of 90, 180, and 360 μg/mL in Langendorff-perfused rat hearts prior to 25-min global ischemia/120-min reperfusion (I/R). Functional recovery (left ventricular developed pressure—LVDP, and rate of development of pressure), reperfusion arrhythmias, and infarct size (TTC staining) served as the endpoints. A transient increase in LVDP (32%–75%) occurred at all concentrations of HI, while coronary flow (CF) was significantly increased after HI 180 and 360. Only a moderate increase in LVDP (21% and 55%) and a tendency to increase CF was observed at HRS 180 and 360. HI and HRS at 180 and 360 significantly improved postischemic recovery of LVDP. Both the drugs dose-dependently reduced the numbers of ectopic beats and duration of ventricular tachycardia. The size of infarction was significantly decreased by HI 360, while HRS significantly reduced the infarct size at all concentrations in a dose-dependent manner. Thus, it can be concluded that HI might cause vasodilation, positive inotropic effect, and cardioprotection, while HRS might cause these effects at higher concentrations. However, further study is needed to elucidate the exact mechanism of their actions. PMID:20953394

  10. A study on fear memory retrieval and REM sleep in maternal separation and isolation stressed rats.

    PubMed

    Sampath, Dayalan; Sabitha, K R; Hegde, Preethi; Jayakrishnan, H R; Kutty, Bindu M; Chattarji, Sumantra; Rangarajan, Govindan; Laxmi, T R

    2014-10-15

    As rapid brain development occurs during the neonatal period, environmental manipulation during this period may have a significant impact on sleep and memory functions. Moreover, rapid eye movement (REM) sleep plays an important role in integrating new information with the previously stored emotional experience. Hence, the impact of early maternal separation and isolation stress (MS) during the stress hyporesponsive period (SHRP) on fear memory retention and sleep in rats were studied. The neonatal rats were subjected to maternal separation and isolation stress during postnatal days 5-7 (6h daily/3d). Polysomnographic recordings and differential fear conditioning was carried out in two different sets of rats aged 2 months. The neuronal replay during REM sleep was analyzed using different parameters. MS rats showed increased time in REM stage and total sleep period also increased. MS rats showed fear generalization with increased fear memory retention than normal control (NC). The detailed analysis of the local field potentials across different time periods of REM sleep showed increased theta oscillations in the hippocampus, amygdala and cortical circuits. Our findings suggest that stress during SHRP has sensitized the hippocampus-amygdala-cortical loops which could be due to increased release of corticosterone that generally occurs during REM sleep. These rats when subjected to fear conditioning exhibit increased fear memory and increased fear generalization. The development of helplessness, anxiety and sleep changes in human patients, thus, could be related to the reduced thermal, tactile and social stimulation during SHRP on brain plasticity and fear memory functions.

  11. Contribution of sarcolemmal sodium-calcium exchange and intracellular calcium release to force development in isolated canine ventricular muscle

    PubMed Central

    1992-01-01

    The aim of this work was to determine the relationship between peak twitch amplitude and sarcoplasmic reticulum (SR) Ca2+ content during changes of stimulation frequency in isolated canine ventricle, and to estimate the extent to which these changes were dependent upon sarcolemmal Na(+)-Ca2+ exchange. In physiological [Na+]o, increased stimulation frequency in the 0.2-2-Hz range resulted in a positive inotropic effect characterized by an increase in peak twitch amplitude and a decrease in the duration of contraction, measured as changes in isometric force development or unloaded cell shortening in intact muscle and isolated single cells, respectively. Action potentials recorded from single cells indicated that the inotropic effect was associated with a progressive decrease of action potential duration and a marked reduction in average time spent by the cell near the resting potential during the stimulus train. The frequency-dependent increase of peak twitch force was correlated with an increase of Ca2+ uptake into and release from the SR. This was estimated indirectly using the phasic contractile response to rapid (less than 1 s) lowering of perfusate temperature from 37 degrees C to 0-2 degrees C and changes of twitch amplitude resulting from perturbations in the pattern of electrical stimulation. Lowering [Na+]o from 140 to 70 mM resulted in an increase of contractile strength, which was accompanied by a similar increase of apparent SR Ca2+ content, both of which could be abolished by exposure to ryanodine (1 x 10(-8) M), caffeine (3 x 10(-3) M), or nifedipine (2 x 10(-6) M). Increased stimulation frequency in 70 mM [Na+]o resulted in a negative contractile staircase, characterized by a graded decrease of peak isometric force development or unloaded cell shortening. SR Ca2+ content estimated under identical conditions remained unaltered. Rate constants derived from mechanical restitution studies implied that the depressant effect of increased stimulation

  12. Static cardiomyoplasty with synthetic elastic net suppresses ventricular dilatation and dysfunction after myocardial infarction in the rat: a chronic study.

    PubMed

    Kato, Nobusuke; Kawaguchi, Akira T; Kishida, Akio; Yamaoka, Tetsuji

    2013-07-01

    Although static cardiomyoplasty prevents the left ventricle (LV) from dilatation, it may interfere with diastolic relaxation, or cause restriction. We developed a synthetic net with dual elasticity and tested its effect late after myocardial infarction in the rat. LV pressure-volume relationships (PVR) were successively analyzed before, after intravenous volume load, and 10 minutes after occlusion of the left anterior descending artery. Rats were then randomized into groups receiving synthetic net wrapping around the heart (NET+, n = 8) and only partially behind LV (NET-, n = 9), and they underwent the same PVR studies 6 weeks later. End-diastolic and end-systolic PVR were defined, and LV size and function were compared under standardized loading conditions. Although there was no difference in Day 0, increase in LV end-diastolic and end-systolic volumes were significantly attenuated in NET+ rats 6 weeks later when there was a significant correlation between LV volumes by PVR estimation and actual measurements, with significant differences in both measures between the groups: NET+ < NET-. The presence or absence of net did not show restrictive hemodynamics under acute volume load. Static cardiomyoplasty using a synthetic elastic net significantly attenuated LV dilatation and dysfunction without restriction late after myocardial infarction in the rat.

  13. Left Ventricular Gene Expression Profile of Healthy and Cardiovascular Compromised Rat Models Used in Air Pollution Studies

    EPA Science Inventory

    The link between pollutant exposure and cardiovascular disease (CVD) has prompted mechanistic research with animal models of CVD. We hypothesized that the cardiac gene expression patterns of healthy and genetically compromised, CVD-prone rat models, with or without metabolic impa...

  14. Early-Life Social Isolation Impairs the Gonadotropin-Inhibitory Hormone Neuronal Activity and Serotonergic System in Male Rats.

    PubMed

    Soga, Tomoko; Teo, Chuin Hau; Cham, Kai Lin; Idris, Marshita Mohd; Parhar, Ishwar S

    2015-01-01

    Social isolation in early life deregulates the serotonergic system of the brain, compromising reproductive function. Gonadotropin-inhibitory hormone (GnIH) neurons in the dorsomedial hypothalamic nucleus are critical to the inhibitory regulation of gonadotropin-releasing hormone neuronal activity in the brain and release of luteinizing hormone by the pituitary gland. Although GnIH responds to stress, the role of GnIH in social isolation-induced deregulation of the serotonin system and reproductive function remains unclear. We investigated the effect of social isolation in early life on the serotonergic-GnIH neuronal system using enhanced green fluorescent protein (EGFP)-tagged GnIH transgenic rats. Socially isolated rats were observed for anxious and depressive behaviors. Using immunohistochemistry, we examined c-Fos protein expression in EGFP-GnIH neurons in 9-week-old adult male rats after 6 weeks post-weaning isolation or group housing. We also inspected serotonergic fiber juxtapositions in EGFP-GnIH neurons in control and socially isolated male rats. Socially isolated rats exhibited anxious and depressive behaviors. The total number of EGFP-GnIH neurons was the same in control and socially isolated rats, but c-Fos expression in GnIH neurons was significantly reduced in socially isolated rats. Serotonin fiber juxtapositions on EGFP-GnIH neurons were also lower in socially isolated rats. In addition, levels of tryptophan hydroxylase mRNA expression in the dorsal raphe nucleus were significantly attenuated in these rats. These results suggest that social isolation in early-life results in lower serotonin levels, which reduce GnIH neuronal activity and may lead to reproductive failure. PMID:26617573

  15. Early-Life Social Isolation Impairs the Gonadotropin-Inhibitory Hormone Neuronal Activity and Serotonergic System in Male Rats

    PubMed Central

    Soga, Tomoko; Teo, Chuin Hau; Cham, Kai Lin; Idris, Marshita Mohd; Parhar, Ishwar S.

    2015-01-01

    Social isolation in early life deregulates the serotonergic system of the brain, compromising reproductive function. Gonadotropin-inhibitory hormone (GnIH) neurons in the dorsomedial hypothalamic nucleus are critical to the inhibitory regulation of gonadotropin-releasing hormone neuronal activity in the brain and release of luteinizing hormone by the pituitary gland. Although GnIH responds to stress, the role of GnIH in social isolation-induced deregulation of the serotonin system and reproductive function remains unclear. We investigated the effect of social isolation in early life on the serotonergic–GnIH neuronal system using enhanced green fluorescent protein (EGFP)-tagged GnIH transgenic rats. Socially isolated rats were observed for anxious and depressive behaviors. Using immunohistochemistry, we examined c-Fos protein expression in EGFP–GnIH neurons in 9-week-old adult male rats after 6 weeks post-weaning isolation or group housing. We also inspected serotonergic fiber juxtapositions in EGFP–GnIH neurons in control and socially isolated male rats. Socially isolated rats exhibited anxious and depressive behaviors. The total number of EGFP–GnIH neurons was the same in control and socially isolated rats, but c-Fos expression in GnIH neurons was significantly reduced in socially isolated rats. Serotonin fiber juxtapositions on EGFP–GnIH neurons were also lower in socially isolated rats. In addition, levels of tryptophan hydroxylase mRNA expression in the dorsal raphe nucleus were significantly attenuated in these rats. These results suggest that social isolation in early-life results in lower serotonin levels, which reduce GnIH neuronal activity and may lead to reproductive failure. PMID:26617573

  16. Effect of trimebutine maleate on the contractile response of the isolated ileum from diabetic rats.

    PubMed

    Uchida, M; Iwata, T; Takagi, S; Sugiyama, Y; Ishitani, K; Honda, H; Sakai, Y

    1994-05-01

    1. Tension of the isolated ileum from diabetic rats induced by streptozotocin was measured isometrically to study the mode of action of trimebutine maleate (TMB). 2. The hyperreactivity of contractile response to KCl was observed in the isolated ileum from diabetic rats. TMB inhibited the contraction induced by KCl and acetylcholine (ACh) in normal solution. 3. In Ca2+ free solution, the hyperreactivity of contractile response to KCl was attenuated, and TMB did not inhibit the contraction induced by KCl. In contrast, TMB inhibited the contraction induced by ACh even in Ca2+ free solution. 4. These results suggest that the hyperreactivity of contractile response to KCl in the ileum from diabetic rats is due to the enhancement of Ca2+ influx through voltage-dependent Ca2+ channel and that TMB inhibits the hyperreactivity of contractile response through the inhibition of Ca2+ movement by the cell. PMID:7926598

  17. L-Arginine ameliorates cardiac left ventricular oxidative stress by upregulating eNOS and Nrf2 target genes in alloxan-induced hyperglycemic rats

    SciTech Connect

    Ramprasath, Tharmarajan; Hamenth Kumar, Palani; Syed Mohamed Puhari, Shanavas; Senthil Murugan, Ponniah; Vasudevan, Varadaraj; Selvam, Govindan Sadasivam

    2012-11-23

    Highlights: Black-Right-Pointing-Pointer L-Arginine treatment reduced the metabolic disturbances in diabetic animals. Black-Right-Pointing-Pointer Antioxidant marker proteins were found high in myocardium by L-arginine treatment. Black-Right-Pointing-Pointer Elevated antioxidant status, mediates the reduced TBA-reactivity in left ventricle. Black-Right-Pointing-Pointer L-Arginine treatment enhanced the Nrf2 and eNOS signaling in left ventricle. Black-Right-Pointing-Pointer Improved cell survival signaling by arginine, offers a novel tactic for targeting. -- Abstract: Hyperglycemia is independently related with excessive morbidity and mortality in cardiovascular disorders. L-Arginine-nitric oxide (NO) pathway and the involvement of NO in modulating nuclear factor-E2-related factor-2 (Nrf2) signaling were well established. In the present study we investigated, whether L-arginine supplementation would improve the myocardial antioxidant defense under hyperglycemia through activation of Nrf2 signaling. Diabetes was induced by alloxan monohydrate (90 mg kg{sup -1} body weight) in rats. Both non-diabetic and diabetic group of rats were divided into three subgroups and they were administered either with L-arginine (2.25%) or L-NAME (0.01%) in drinking water for 12 days. Results showed that L-arginine treatment reduced the metabolic disturbances in diabetic rats. Antioxidant enzymes and glutathione levels were found to be increased in heart left ventricles, thereby reduction of lipid peroxidation by L-arginine treatment. Heart histopathological analysis further validates the reversal of typical diabetic characteristics consisting of alterations in myofibers and myofibrillary degeneration. qRT-PCR studies revealed that L-arginine treatment upregulated the transcription of Akt and downregulated NF-{kappa}B. Notably, transcription of eNOS and Nrf2 target genes was also upregulated, which were accompanied by enhanced expression of Nrf2 in left ventricular tissue from diabetic

  18. The cardiodepressant and vasodepressant effects of tumour necrosis factor in rat isolated atrial and aortic tissues.

    PubMed Central

    Foulkes, R.; Shaw, S.

    1992-01-01

    1. The ability of recombinant human tumour necrosis factor-alpha (rec huTNF) to elicit cardiodepressor and vasodepressor effects in rat isolated tissues was investigated. 2. rec huTNF (3 x 10(-11)-3 x 10(-8) M) administered directly to the organ bath, caused a concentration-dependent relaxation of the isoprenaline-induced inotropic response in electrically stimulated rat left atria. This occurred within 20 min of administration. In contrast, rec huTNF was without effect on the chronotropic response to isoprenaline in isolated spontaneously beating atria. 3. rec huTNF (1 microgram kg-1) was also given systemically to rats and the atria studied in vitro. Only 60 min of rec huTNF pretreatment was sufficient to cause a marked attenuation of the isoprenaline-induced inotropic response. This effect was not further augmented when rats were pretreated with rec huTNF for 24 h. 4. In isolated aortic rings taken from rats 60 min after rec huTNF (1 microgram kg-1, i.v.) administration, there was no effect seen on the constriction induced by phenylephrine in either endothelium-intact or denuded tissues. In addition, any responses to L-arginine or NG-nitro-L-arginine methyl ester (L-NAME) administration were unaffected by rec huTNF pretreatment. 5. In aortic rings taken from rats 24 h after rec huTNF administration, the phenylephrine-induced constriction was significantly attenuated in tissues with an intact endothelium. Furthermore, the relaxation to subsequent L-arginine administration was greater in these tissues than in those saline-treated rats.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1382789

  19. Carbon Nanohorns Promote Maturation of Neonatal Rat Ventricular Myocytes and Inhibit Proliferation of Cardiac Fibroblasts: a Promising Scaffold for Cardiac Tissue Engineering.

    PubMed

    Wu, Yujing; Shi, Xiaoli; Li, Yi; Tian, Lei; Bai, Rui; Wei, Yujie; Han, Dong; Liu, Huiliang; Xu, Jianxun

    2016-12-01

    Cardiac tissue engineering (CTE) has developed rapidly, but a great challenge remains in finding practical scaffold materials for the construction of engineered cardiac tissues. Carbon nanohorns (CNHs) may be a potential candidate due to their special structure and properties. The purpose of this study was to assess the effect of CNHs on the biological behavior of neonatal rat ventricular myocytes (NRVMs) for CTE applications. CNHs were incorporated into collagen to form growth substrates for NRVMs. Transmission electron microscopy (TEM) observations demonstrated that CNHs exhibited a good affinity to collagen. Moreover, it was found that CNH-embedded substrates enhanced adhesion and proliferation of NRVMs. Immunohistochemical staining, western blot analysis, and intracellular calcium transient measurements indicated that the addition of CNHs significantly increased the expression and maturation of electrical and mechanical proteins (connexin-43 and N-cadherin). Bromodeoxyuridine staining and a Cell Counting Kit-8 assay showed that CNHs have the ability to inhibit the proliferation of cardiac fibroblasts. These findings suggest that CNHs can have a valuable effect on the construction of engineered cardiac tissues and may be a promising scaffold for CTE. PMID:27263018

  20. Carbon Nanohorns Promote Maturation of Neonatal Rat Ventricular Myocytes and Inhibit Proliferation of Cardiac Fibroblasts: a Promising Scaffold for Cardiac Tissue Engineering

    NASA Astrophysics Data System (ADS)

    Wu, Yujing; Shi, Xiaoli; Li, Yi; Tian, Lei; Bai, Rui; Wei, Yujie; Han, Dong; Liu, Huiliang; Xu, Jianxun

    2016-06-01

    Cardiac tissue engineering (CTE) has developed rapidly, but a great challenge remains in finding practical scaffold materials for the construction of engineered cardiac tissues. Carbon nanohorns (CNHs) may be a potential candidate due to their special structure and properties. The purpose of this study was to assess the effect of CNHs on the biological behavior of neonatal rat ventricular myocytes (NRVMs) for CTE applications. CNHs were incorporated into collagen to form growth substrates for NRVMs. Transmission electron microscopy (TEM) observations demonstrated that CNHs exhibited a good affinity to collagen. Moreover, it was found that CNH-embedded substrates enhanced adhesion and proliferation of NRVMs. Immunohistochemical staining, western blot analysis, and intracellular calcium transient measurements indicated that the addition of CNHs significantly increased the expression and maturation of electrical and mechanical proteins (connexin-43 and N-cadherin). Bromodeoxyuridine staining and a Cell Counting Kit-8 assay showed that CNHs have the ability to inhibit the proliferation of cardiac fibroblasts. These findings suggest that CNHs can have a valuable effect on the construction of engineered cardiac tissues and may be a promising scaffold for CTE.

  1. Effect of Ca2+ efflux pathway distribution and exogenous Ca2+ buffers on intracellular Ca2+ dynamics in the rat ventricular myocyte: a simulation study.

    PubMed

    Pásek, Michal; Simurda, Jiří; Orchard, Clive H

    2014-01-01

    We have used a previously published computer model of the rat cardiac ventricular myocyte to investigate the effect of changing the distribution of Ca(2+) efflux pathways (SERCA, Na(+)/Ca(2+) exchange, and sarcolemmal Ca(2+) ATPase) between the dyad and bulk cytoplasm and the effect of adding exogenous Ca(2+) buffers (BAPTA or EGTA), which are used experimentally to differentially buffer Ca(2+) in the dyad and bulk cytoplasm, on cellular Ca(2+) cycling. Increasing the dyadic fraction of a particular Ca(2+) efflux pathway increases the amount of Ca(2+) removed by that pathway, with corresponding changes in Ca(2+) efflux from the bulk cytoplasm. The magnitude of these effects varies with the proportion of the total Ca(2+) removed from the cytoplasm by that pathway. Differences in the response to EGTA and BAPTA, including changes in Ca(2+)-dependent inactivation of the L-type Ca(2+) current, resulted from the buffers acting as slow and fast "shuttles," respectively, removing Ca(2+) from the dyadic space. The data suggest that complex changes in dyadic Ca(2+) and cellular Ca(2+) cycling occur as a result of changes in the location of Ca(2+) removal pathways or the presence of exogenous Ca(2+) buffers, although changing the distribution of Ca(2+) efflux pathways has relatively small effects on the systolic Ca(2+) transient.

  2. New Findings on the Effects of Tannic Acid: Inhibition of L-Type Calcium Channels, Calcium Transient and Contractility in Rat Ventricular Myocytes.

    PubMed

    Zhu, Fengli; Chu, Xi; Wang, Hua; Zhang, Xuan; Zhang, Yuanyuan; Liu, Zhenyi; Guo, Hui; Liu, Hongying; Liu, Yang; Chu, Li; Zhang, Jianping

    2016-03-01

    Tannic acid (TA) is a group of water-soluble polyphenolic compounds that occur mainly in plant-derived feeds, food grains and fruits. Many studies have explored its biomedical properties, such as anticancer, antibacterial, antimutagenic, antioxidant, antidiabetic, antiinflammatory and antihypertensive activities. However, the effects of TA on the L-type Ca(2+) current (ICa-L) of cardiomyocytes remain undefined. The present study examined the effects of TA on ICa-L using the whole-cell patch-clamp technique and on intracellular Ca(2+) handling and cell contractility in rat ventricular myocytes with the aid of a video-based edge detection system. Exposure to TA resulted in a concentration- and voltage-dependent blockade of ICa-L, with the half maximal inhibitory concentration of 1.69 μM and the maximal inhibitory effect of 46.15%. Moreover, TA significantly inhibited the amplitude of myocyte shortening and peak value of Ca(2+) transient and increased the time to 10% of the peak. These findings provide new experimental evidence for the cellular mechanism of action of TA and may help to expand clinical treatments for cardiovascular disease. PMID:26762248

  3. Lithospermic acid B isolated from Salvia miltiorrhiza ameliorates ischemia/reperfusion-induced renal injury in rats.

    PubMed

    Kang, Dae Gill; Oh, Hyuncheol; Sohn, Eun Jin; Hur, Tae Young; Lee, Kang Chang; Kim, Kwang Jin; Kim, Tai Yo; Lee, Ho Sub

    2004-08-27

    The present study was designed to examine whether lithospermic acid B (LSB) isolated from Salvia miltiorrhiza has an ameliorative effect on renal functional parameters in association with the expression of aquaporin 2 (AQP 2) and Na,K-ATPase in the ischemia-reperfusion induced acute renal failure (ARF) rats. LSB showed strong antioxidant activity against production of reactive oxygen species (ROS), ROS-induced hemolysis, and production of lipid peroxide in a dose-dependent manner. Polyuria caused by down-regulation of renal AQP 2 in the ischemia-reperfusion induced ARF rats was partially restored by administration of LSB (40 mg/kg, i.p.), restoring expression of AQP 2, in renal inner and outer medulla. The expression of Na,K-ATPase alpha1 subunit in outer medulla of the ARF rats was also restored in the ARF rats by administration of LSB, while beta1 subunit level was not altered. The renal functional parameters including creatinine clearance, urinary sodium excretion, urinary osmolality, and solute-free reabsorption were also partially restored in ischemia-ARF rats by administration of LSB. Histological study also showed that renal damages in the ARF rats were abrogated by administration of LSB. Taken together, these data indicate that LSB ameliorates renal defects in rats with ischemia-reperfusion induced ARF, most likely via scavenging of ROS.

  4. Ethanol inhibition of glucose absorption in isolated, perfused small bowel of rats

    SciTech Connect

    Cobb, C.F.; Van Thiel, D.H.; Wargo, J.

    1983-08-01

    There is evidence for both humans and rats that malnutrition frequently occurs when ethanol is chronically ingested. Small bowel /sup 14/C-labelled glucose absorption was measured with an ex vivo system in which the small bowel of the rat was surgically removed and then arterially perfused with an artificial medium. Glucose absorption for a control group of seven rats was 248 +/- 8 microM/min/gm dry weight of small bowel (mean +/- SEM). This was significantly greater than the value 112 +/- 12 microM/min/gm dry weight (P less than 0.005) for a group of five rats in which a competitive inhibitor of glucose absorption, phlorizin (0.2 mM), was added to the bowel lumen. In the presence of 3% ethanol within the gut lumen of five rats, glucose absorption was also reduced (to 131 +/- 12 microM/min/gm dry weight) compared to absorption in the control group (P less than 0.005). The calculated amount of glucose absorbed was corrected for metabolism to lactate and carbon dioxide. We conclude that both phlorizin and ethanol inhibit glucose absorption in the isolated and perfused small bowel of rats and that probably at least part of the malnutrition in ethanol-fed rats is due to glucose malabsorption.

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

    PubMed

    Zemancíková, Anna; Török, Jozef

    2013-08-31

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

  6. The calcium-independent transient outward potassium current in isolated ferret right ventricular myocytes. I. Basic characterization and kinetic analysis

    PubMed Central

    1993-01-01

    Enzymatically isolated myocytes from ferret right ventricles (12-16 wk, male) were studied using the whole cell patch clamp technique. The macroscopic properties of a transient outward K+ current I(to) were quantified. I(to) is selective for K+, with a PNa/PK of 0.082. Activation of I(to) is a voltage-dependent process, with both activation and inactivation being independent of Na+ or Ca2+ influx. Steady-state inactivation is well described by a single Boltzmann relationship (V1/2 = -13.5 mV; k = 5.6 mV). Substantial inactivation can occur during a subthreshold depolarization without any measurable macroscopic current. Both development of and recovery from inactivation are well described by single exponential processes. Ensemble averages of single I(to) channel currents recorded in cell-attached patches reproduce macroscopic I(to) and indicate that inactivation is complete at depolarized potentials. The overall inactivation/recovery time constant curve has a bell-shaped potential dependence that peaks between -10 and -20 mV, with time constants (22 degrees C) ranging from 23 ms (-90 mV) to 304 ms (-10 mV). Steady-state activation displays a sigmoidal dependence on membrane potential, with a net aggregate half- activation potential of +22.5 mV. Activation kinetics (0 to +70 mV, 22 degrees C) are rapid, with I(to) peaking in approximately 5-15 ms at +50 mV. Experiments conducted at reduced temperatures (12 degrees C) demonstrate that activation occurs with a time delay. A nonlinear least- squares analysis indicates that three closed kinetic states are necessary and sufficient to model activation. Derived time constants of activation (22 degrees C) ranged from 10 ms (+10 mV) to 2 ms (+70 mV). Within the framework of Hodgkin-Huxley formalism, Ito gating can be described using an a3i formulation. PMID:8505627

  7. Homologous beta-adrenergic desensitization in isolated rat hepatocytes.

    PubMed Central

    García-Sáinz, J A; Michel, B

    1987-01-01

    Hepatocytes from hypothyroid rats have a marked beta-adrenergic responsiveness. Preincubation of these hepatocytes with isoprenaline induced a time-dependent and concentration-dependent desensitization of the beta-adrenergic responsiveness without altering that to glucagon (homologous desensitization). The desensitization was evidenced both in the cyclic AMP accumulation and in the stimulation of ureagenesis induced by the beta-adrenergic agonists. Under the same conditions, preincubation with glucagon induced no desensitization. Propranolol was also unable to induce desensitization, but blocked that induced by isoprenaline. Pertussis-toxin treatment did not alter the homologous beta-adrenergic desensitization induced by isoprenaline. PMID:2825633

  8. Polyphenol (-)-Epigallocatechin Gallate during Ischemia Limits Infarct Size Via Mitochondrial KATP Channel Activation in Isolated Rat Hearts

    PubMed Central

    Song, Dae-Kyu; Kim, June Hong; Chun, Kook-Jin; Lee, Deokhee; Xu, Zhelong

    2010-01-01

    Polyphenol (-)-epigallocatechin gallate (EGCG), the most abundant catechin of green tea, appears to attenuate myocardial ischemia/reperfusion injury. We investigated the involvement of ATP-sensitive potassium (KATP) channels in EGCG-induced cardioprotection. Isolated rat hearts were subjected to 30 min of regional ischemia and 2 hr of reperfusion. EGCG was perfused for 40 min, from 10 min before to the end of index ischemia. A nonselective KATP channel blocker glibenclamide (GLI) and a selective mitochondrial KATP (mKATP) channel blocker 5-hydroxydecanoate (HD) were perfused in EGCG-treated hearts. There were no differences in coronary flow and cardiodynamics including heart rate, left ventricular developed pressure, rate-pressure product, +dP/dtmax, and -dP/dtmin throughout the experiments among groups. EGCG-treatment significantly reduced myocardial infarction (14.5±2.5% in EGCG 1 µM and 4.0±1.7% in EGCG 10 µM, P<0.001 vs. control 27.2±1.4%). This anti-infarct effect was totally abrogated by 10 µM GLI (24.6±1.5%, P<0.001 vs. EGCG). Similarly, 100 µM HD also aborted the anti-infarct effect of EGCG (24.1±1.2%, P<0.001 vs. EGCG ). These data support a role for the KATP channels in EGCG-induced cardioprotection. The mKATP channels play a crucial role in the cardioprotection by EGCG. PMID:20191036

  9. Four-parametric non-linear regression fit of isovolumic relaxation in isolated ejecting rat and guinea pig hearts.

    PubMed

    Langer, S F

    2000-02-01

    Left ventricular isovolumic pressure fall is characterized by the time constant tau obtained by fitting the exponential p(t) = p(infinity) + (p(0)-p(infinity))3exp(-t/tau) to pressure fall. It has been shown that tau, calculated from the first half of pressure fall, differs considerably from that found at late relaxation in normal and pathophysiological conditions. The present study aims at testing for such differences statistically and to quantify tau changes during relaxation. Two improvements of the common regression procedure are introduced for that purpose: the use of the four-parametric regression function, p(t) = p(infinity) + (p(0)-p(infinity))3exp[-t/(tau(0)+b(tau)t)], and an optimal data-dependent split of the isovolumic pressure fall interval. The residual regression errors of the methods are statistically compared in one-hundred isolated working rat and one-hundred guinea pig hearts, additionally including a logistic regression method. Regression error is significantly reduced by introducing that b(tau). b(tau) is negative in most cases, indicating accelerated relaxation during isovolumic pressure fall, but zero and positive b(tau) are occasionally seen. Optimal interval tripartition further improves the regression error in most cases. The statistically proved acceleration of the time constant during isovolumic relaxation justifies factor b(t) as a direct and continuous measure of differences between early and late relaxation. This difference between early and late isovolumic relaxation is probably caused by residually contracted myocardium at the beginning of pressure fall, and is therefore important to describe pathophysiological effects on relaxation phases.

  10. Arrhythmogenic Right Ventricular Dysplasia

    MedlinePlus

    MENU Return to Web version Arrhythmogenic Right Ventricular Dysplasia Overview What is arrhythmogenic right ventricular dysplasia? Arrhythmogenic right ventricular dysplasia (say: “uh-rith-mo-jen-ic right ven-trick- ...

  11. Myocardial pharmacokinetics of ebastine, a substrate for cytochrome P450 2J, in rat isolated heart

    PubMed Central

    Kang, W; Elitzer, S; Noh, K; Bednarek, T; Weiss, M

    2011-01-01

    BACKGROUND AND PURPOSE It is well established that cytochrome P450 2J (CYP2J) enzymes are expressed preferentially in the heart, and that ebastine is a substrate for CYP2J, but it is not known whether ebastine is metabolized in myocardium. Therefore, we investigated its pharmacokinetics in the rat isolated perfused heart. EXPERIMENTAL APPROACH Rat isolated hearts were perfused in the recirculating mode with ebastine for 130 min. The concentrations of ebastine and its metabolites, hydroxyebastine and carebastine, were measured using liquid chromatography with a tandem mass spectrometry. The data were analysed by a compartmental model. The time course of negative inotropic response was linked to ebastine concentration to determine the concentration–effect relationship. KEY RESULTS Ebastine was metabolized to an intermediate compound, hydroxyebastine, which was subsequently further metabolized to carebastine. No desalkylebastine was found. The kinetics of the sequential metabolism of ebastine was well described by the compartmental model. The EC50 of the negative inotropic effect of ebastine in rat isolated heart was much higher than free plasma concentrations in humans after clinical doses. CONCLUSIONS AND IMPLICATIONS The kinetics of ebastine conversion to carebastine via hydroxyebastine resembled that observed in human liver microsomes. The results may be of interest for functional characterization of CYP2J activity in rat heart. PMID:21410688

  12. NSAIDs acutely inhibit TRPC channels in freshly isolated rat glomeruli

    SciTech Connect

    Ilatovskaya, Daria V.; Levchenko, Vladislav; Ryan, Robert P.; Cowley, Allen W.; Staruschenko, Alexander

    2011-05-06

    Highlights: {yields} We have established a unique approach to search for physiologically relevant mechanisms of TRPC channels in podocytes. {yields} This study describes endogenous TRPC channels in the isolated decapsulated glomeruli preparation. {yields} We report for the first time that NSAIDs inhibit TRPC channels in podocytes. -- Abstract: Using a novel approach for analysis of TRPC channel activity, we report here that NSAIDs are involved into regulation of TRPC channels in the podocytes of the freshly isolated decapsulated glomeruli. Fluorescence and electron microscopy techniques confirmed the integrity of podocytes in the glomeruli. Western blotting showed that TRPC1, 3 and 6 are highly expressed in the glomeruli. Single-channel patch clamp analysis revealed cation currents with distinct TRPC properties. This is the first report describing single TRPC-like currents in glomerular podocytes. Furthermore, our data provide a novel mechanism of NSAIDs regulation of TRPC channels, which might be implicated in maintaining the glomerular filtration barrier.

  13. Chronic Psychosocial Stress Impairs Bone Homeostasis: A Study in the Social Isolation Reared Rat

    PubMed Central

    Schiavone, Stefania; Morgese, Maria G.; Mhillaj, Emanuela; Bove, Maria; De Giorgi, Angelo; Cantatore, Francesco P.; Camerino, Claudia; Tucci, Paolo; Maffulli, Nicola; Cuomo, Vincenzo; Trabace, Luigia

    2016-01-01

    Chronic psychosocial stress is a key player in the onset and aggravation of mental diseases, including psychosis. Although a strong association between this psychiatric condition and other medical co-morbidities has been recently demonstrated, few data on the link between psychosis and bone homeostasis are actually available. The aim of this study was to investigate whether chronic psychosocial stress induced by 4 or 7 weeks of social isolation in drug-naïve male Wistar rats could alter bone homeostasis in terms of bone thickness, mineral density and content, as well as markers of bone formation and resorption (sclerostin, cathepsin K, and CTX-I). We found that bone mineral density was increased in rats exposed to 7 weeks of social isolation, while no differences were detected in bone mineral content and area. Moreover, 7 weeks of social isolation lead to increase of femur thickness with respect to controls, suggesting the development of a hyperostosis condition. Isolated rats showed no changes in sclerostin levels, a marker of bone formation, compared to grouped animals. Conversely, bone resorption markers were significantly altered after 7 weeks of social isolation in terms of decrease in cathepsin K and increase of CTX-I. No alterations were found after 4 weeks of isolation rearing. Our observations suggest that chronic psychosocial stress might affect bone homeostasis, more likely independently from drug treatment. Thus, the social isolation model might help to identify possible new therapeutic targets to treat the burden of chronic psychosocial stress and to attempt alternative therapy choices. PMID:27375486

  14. MicroRNAs 29 are involved in the improvement of ventricular compliance promoted by aerobic exercise training in rats

    PubMed Central

    Soci, U. P. R.; Fernandes, T.; Hashimoto, N. Y.; Mota, G. F.; Amadeu, M. A.; Rosa, K. T.; Irigoyen, M. C.; Phillips, M. I.

    2011-01-01

    MiRNAs regulate cardiac development, hypertrophy, and angiogenesis, but their role in cardiac hypertrophy (CH) induced by aerobic training has not previously been studied. Aerobic training promotes physiological CH preserving cardiac function. This study assessed involvement of miRNAs-29 in CH of trained rats. Female Wistar rats (n = 7/group) were randomized into three groups: sedentary (S), training 1 (T1), training 2 (T2). T1: swimming sessions of 60 min/5 days/wk/10 wk. T2: similar to T1 until 8th wk. On the 9th wk rats swam 2×/day, and on the 10th wk 3×/day. MiRNAs analysis was performed by miRNA microarray and confirmed by real-time PCR. We assessed: markers of training, CH by ratio of left ventricle (LV) weight/body wt and cardiomyocytes diameter, pathological markers of CH (ANF, skeletal α-actin, α/β-MHC), collagen I and III (COLIAI and COLIIIAI) by real-time PCR, protein collagen by hydroxyproline (OH-proline) concentration, CF and CH by echocardiography. Training improved aerobic capacity and induced CH. MiRNAs-1, 133a, and 133b were downregulated as observed in pathological CH, however, without pathological markers. MiRNA-29c expression increased in T1 (52%) and T2 (123%), correlated with a decrease in COLIAI and COLIIIAI expression in T1 (27%, 38%) and T2 (33%, 48%), respectively. MiRNA-29c was inversely correlated to OH-proline concentration (r = 0.61, P < 0.05). The E/A ratio increased in T2, indicating improved LV compliance. Thus, these results show that aerobic training increase miR-29 expression and decreased collagen gene expression and concentration in the heart, which is relevant to the improved LV compliance and beneficial cardiac effects, associated with aerobic high performance training. PMID:21447748

  15. Calcium-sensing receptor activation contributed to apoptosis stimulates TRPC6 channel in rat neonatal ventricular myocytes

    SciTech Connect

    Sun, Yi-hua; Li, Yong-quan; Feng, Shan-li; Li, Bao-xin; Pan, Zhen-wei; Xu, Chang-qing; Li, Ting-ting; Yang, Bao-feng

    2010-04-16

    Capacitative calcium entry (CCE) refers to the influx of calcium through plasma membrane channels activated on depletion of endoplasmic sarcoplasmic/reticulum (ER/SR) Ca{sup 2+} stores, which is performed mainly by the transient receptor potential (TRP) channels. TRP channels are expressed in cardiomyocytes. Calcium-sensing receptor (CaR) is also expressed in rat cardiac tissue and plays an important role in mediating cardiomyocyte apoptosis. However, there are no data regarding the link between CaR and TRP channels in rat heart. In this study, in rat neonatal myocytes, by Ca{sup 2+} imaging, we found that the depletion of ER/SR Ca{sup 2+} stores by thapsigargin (TG) elicited a transient rise in cytoplasmic Ca{sup 2+} ([Ca{sup 2+}]{sub i}), followed by sustained increase depending on extracellular Ca{sup 2+}. But, TRP channels inhibitor (SKF96365), not L-type channels or the Na{sup +}/Ca{sup 2+} exchanger inhibitors, inhibited [Ca{sup 2+}]{sub i} relatively high. Then, we found that the stimulation of CaR with its activator gadolinium chloride (GdCl{sub 3}) or by an increased extracellular Ca{sup 2+}([Ca{sup 2+}]{sub o}) increased the concentration of intracelluar Ca{sup 2+}, whereas, the sustained elevation of [Ca{sup 2+}]{sub i} was reduced in the presence of SKF96365. Similarly, the duration of [Ca{sup 2+}]{sub i} increase was also shortened in the absence of extracellular Ca{sup 2+}. Western blot analysis showed that GdCl{sub 3} increased the expression of TRPC6, which was reversed by SKF96365. Additionally, SKF96365 reduced cardiomyocyte apoptosis induced by GdCl{sub 3}. Our results suggested that CCE exhibited in rat neonatal myocytes and CaR activation induced Ca{sup 2+}-permeable cationic channels TRPCs to gate the CCE, for which TRPC6 was one of the most likely candidates. TRPC6 channel was functionally coupled with CaR to enhance the cardiomyocyte apoptosis.

  16. Endophytic fungal metabolite fumigaclavine C causes relaxation of isolated rat aortic rings.

    PubMed

    Ma, Hsiao-Yen; Song, Yong-Chun; Mao, Ying-Ying; Jiang, Ji-Hong; Tan, Ren-Xiang; Luo, Lan

    2006-04-01

    Two indole alkaloids were isolated from the culture of Aspergillus fumigatus (strain No. CY018), an endophytic fungus harboring inside the elder leaf of Cynodon dactylon. These two chemicals were identified as fumigaclavine C and fumitremorgin C. In screening the bioactivity of these two indole alkaloids, their vasorelaxant effects on isolated rat thoracic aortic rings were observed. The results showed that fumigaclavine C exhibited potent concentration-dependent vasorelaxant actions in isolated rat aortic rings pre-contracted by high K+ or phenylephrine (with EC50 values of 5.62 micromol/L and 1.58 micromol/L, respectively) whereas fumitremorgin C displayed a weaker vasorelaxation. A detailed investigation was therefore performed with fumigaclavine C. The vasorelaxing action of fumigaclavine C is independent of the presence of endothelium, suggesting its effect of vasorelaxation was not related to endothelial mediators. Blockage of L-type voltage-dependent calcium channels, activation of ATP-sensitive potassium channels and inhibition of Ca2+ release from intracellular Ca2+ stores may be involved in fumigaclavine C induced relaxation of rat isolated aortic rings. These results demonstrate that fumigaclavine C from the endophytic fungus has a potential capacity in vascular protection and thus may have therapeutic use in protection against cardiovascular disease. PMID:16557450

  17. Precedence-effect-induced enhancement of prepulse inhibition in socially reared but not isolation-reared rats.

    PubMed

    Du, Yi; Li, Jingyu; Wu, Xihong; Li, Liang

    2009-03-01

    Attention to a prepulse presented shortly before a startling stimulus enhances prepulse inhibition (PPI) of startle in normal people, but not in schizophrenics. Fear conditioning for the prepulse enhances PPI in socially reared, but not isolation-reared, rats. In humans, selective attention to acoustic signals against masking can be facilitated by precedence-effect-induced perceived spatial separation between the signal and the masker. This study investigated whether perceived spatial separation between a prepulse and a noise masker enhances PPI in socially reared rats and isolation-reared rats. The results show that both PPI and conditioning-induced PPI enhancement were larger in socially reared rats than in isolation-reared rats. More important, in socially reared, but not isolation-reared, rats, a further PPI enhancement was induced by precedence-effect-induced perceived separation between a prepulse and a masker only after the prepulse became fear conditioned. Thus, perceived separation facilitates normal rats' attention to a conditioned prepulse and enhances PPI. Isolation rearing impairs rats' ability to attend to ecologically significant acoustic events. PMID:19246326

  18. Kidney in potassium depletion. II. K/sup +/ handling by the isolated perfused rat kidney

    SciTech Connect

    Hayashi, M.; Katz, A.I.

    1987-03-01

    In a companion paper the authors reported a large increment in Na/sup +/-K/sup +/-ATPase activity and (/sup 3/H)ouabain binding the inner stripe of outer medullary collecting tubules from K-depleted rats. To test the hypothesis that the increased number of Na/sup +/-K/sup +/ pumps in these animals may be involved in potassium reabsorption they examined the effect of ouabain on K excretion by isolated, perfused kidneys from rats fed a K-free diet for 3 wk. Kidneys from K-depleted rats retain potassium avidly, both the fractional (FE/sub K/) and absolute K excretion being approximately fivefold lower than in control kidneys. Ouabain (5 mM) increased FE/sub K/ in kidneys from each K-depleted rat; similar results were obtained when kidneys were perfused with low and high potassium concentrations. In contrast, ouabain produced a variable effect in control kidneys, that depended on the perfusate potassium concentration. In K-depleted rats amiloride did not significantly alter K excretion and did not block the ouabain-induced kaliuresis, suggesting that the latter is not due to enhanced secretion secondary to increased distal fluid delivery. These results provide evidence for ouabain-sensitive potassium reabsorption in kidneys of chronically K-depleted rats, and suggest an explanation for the increased Na/sup +/-K/sup +/-ATPase observed in such animals.

  19. [Early social isolation increases aggression and impairs a short-term habituation in acoustic startle reflex in rats].

    PubMed

    Krupina, N A; Khlebnikova, N N; Orlova, I N

    2015-01-01

    Prolonged social isolation in early ontogeny leads to various changes in behavior and cognitive dysfunction in adult rats; however, data on the disorders are contradictory. In the present work, we studied the effects of early social isolation in Wistar rats by indices of psychomotor activity, aggression, anxiety, depression-like behavior, sensorimotor reactivity and short-term habituation of acoustic startle reflex. On the 24th postnatal day, rats were weaned from the dams and housed in individual cages for nine consecutive weeks. Animal behavior was evaluated at the age of one, two and three months. Immediately after weaning from the dam rats in the experimental group did not differ from the control on any of the indices. After four weeks of social isolation, rats showed an increased aggression in the social contact test. In rats isolated for an 8-weeks period, the increase in active non-aggressive contacts with a slight increase in motor activity in the elevated plus maze (E PM) accompanied increased aggression. At any terms of examination, isolated rats did not differ from the control in the anxiety in EPM, in the anxiety-phobic score, which is evaluated in a battery of tests, and in the duration of immobility which characterizes depression in the forced swimming test. Rats isolated for an 8-weeks period increased daily liquid intake by increasing the consumption of sucrose. After nine weeks of isolation, basal startle amplitude and prepulse inhibition that is, the characteristics of sensorimotor gating did not differ from the control, but there was a lack of short-term habituation of the acoustic startle reflex. Based on the data obtained, Wistar rats subjected to prolonged social isolation can be seen as a model of increased aggression with signs of cognitive deficits by indices of non-associative learning in the acoustic startle reflex.

  20. [Early social isolation increases aggression and impairs a short-term habituation in acoustic startle reflex in rats].

    PubMed

    Krupina, N A; Khlebnikova, N N; Orlova, I N

    2015-01-01

    Prolonged social isolation in early ontogeny leads to various changes in behavior and cognitive dysfunction in adult rats; however, data on the disorders are contradictory. In the present work, we studied the effects of early social isolation in Wistar rats by indices of psychomotor activity, aggression, anxiety, depression-like behavior, sensorimotor reactivity and short-term habituation of acoustic startle reflex. On the 24th postnatal day, rats were weaned from the dams and housed in individual cages for nine consecutive weeks. Animal behavior was evaluated at the age of one, two and three months. Immediately after weaning from the dam rats in the experimental group did not differ from the control on any of the indices. After four weeks of social isolation, rats showed an increased aggression in the social contact test. In rats isolated for an 8-weeks period, the increase in active non-aggressive contacts with a slight increase in motor activity in the elevated plus maze (E PM) accompanied increased aggression. At any terms of examination, isolated rats did not differ from the control in the anxiety in EPM, in the anxiety-phobic score, which is evaluated in a battery of tests, and in the duration of immobility which characterizes depression in the forced swimming test. Rats isolated for an 8-weeks period increased daily liquid intake by increasing the consumption of sucrose. After nine weeks of isolation, basal startle amplitude and prepulse inhibition that is, the characteristics of sensorimotor gating did not differ from the control, but there was a lack of short-term habituation of the acoustic startle reflex. Based on the data obtained, Wistar rats subjected to prolonged social isolation can be seen as a model of increased aggression with signs of cognitive deficits by indices of non-associative learning in the acoustic startle reflex. PMID:27116871

  1. Immediate and Enduring Effects of Neonatal Isolation on Maternal Behavior in Rats

    PubMed Central

    Kosten, Therese A.; Kehoe, Priscilla

    2009-01-01

    Previously, we showed that neonatal isolation (1-hr isolation/day from dam, litter, and nest on PND 2-9) facilitates cocaine self-administration and increases extracellular dopamine responses in ventral striatum after stimulant administration in adulthood. Recent studies suggest that enduring alterations in neurobehavioral responses associated with early life manipulations reflect changes in maternal behavior. Thus, we sought to determine if neonatal isolation alters maternal care and if dams with neonatal isolation experience as pups showed differential maternal care towards their pups. In Experiment 1, litters were assigned to one of three conditions: neonatal isolation, handled (5-min separation of dam from litter), or non-handled (no separation). Maternal behaviors were rated on PND 2-9 for 60-min immediately following reunion of mother and litter. In Experiment 2, female rats with or without neonatal isolation experience were assigned to either the neonatal isolation or non-handled litter condition and maternal behaviors rated. Dams of isolated and handled litters spent more time licking pups and less time picking up pups to put outside the nest than dams of non-handled litters. Further, dams of isolated and handled vs non-handled litters showed less non-maternal behaviors of burrowing and grooming. Neonatal isolation-experienced dams with isolated litters failed to increase pup-licking and decrease non-maternal behaviors. Rather, these dams picked up pups to place outside the nest more than non-handled-experienced dams. Neonatal isolation alters maternal behavior that, in turn, may shape neurobehavioral responses of offspring including effects on maternal care. Such changes may reflect epigenetic effects resulting from changes in maternal behavior. PMID:19782745

  2. Contraceptive studies of isolated fractions of Cuminum cyminum in male albino rats.

    PubMed

    Saxena, Poonam; Gupta, Rajnish; Gupta, R S

    2015-01-01

    The contraceptive efficacy of Cuminum cyminum isolated fractions (CcFr) in male albino rats was investigated. Oral dose of CcFr at 50 mg/rat/day for 60 days revealed no significant changes in body weight, while marked abnormalities in spermatogenesis were observed with decreased counts (P ≤ 0.001) in round spermatids, preleptotene spermatocytes and secondary spermatocytes. Cross sectional surface area of Sertoli cells as well as number of mature Leydig cell were decreased significantly (P ≤ 0.001). Testicular as well as accessory sex organ biochemical parameters were significantly changed (P ≤ 0.001). Sperm motility, density and morphology were resulted in 100% negative fertility. Testosterone levels were declined significantly. In conclusion, Cuminum cyminum inhibited spermatogenesis in rats, indicating the possibility of developing an herbal male contraceptive.

  3. Assessment of benzene induced oxidative impairment in rat isolated pancreatic islets and effect on insulin secretion.

    PubMed

    Bahadar, Haji; Maqbool, Faheem; Mostafalou, Sara; Baeeri, Maryam; Rahimifard, Mahban; Navaei-Nigjeh, Mona; Abdollahi, Mohammad

    2015-05-01

    Benzene (C6H6) is an organic compound used in petrochemicals and numerous other industries. It is abundantly released to our environment as a chemical pollutant causing widespread human exposure. This study mainly focused on benzene induced toxicity on rat pancreatic islets with respect to oxidative damage, insulin secretion and glucokinase (GK) activity. Benzene was dissolved in corn oil and administered orally at doses 200, 400 and 800mg/kg/day, for 4 weeks. In rats, benzene significantly raised the concentration of plasma insulin. Also the effect of benzene on the release of glucose-induced insulin was pronounced in isolated islets. Benzene caused oxidative DNA damage and lipid peroxidation, and also reduced the cell viability and total thiols groups, in the islets of exposed rats. In conclusion, the current study revealed that pancreatic glucose metabolism is susceptible to benzene toxicity and the resultant oxidative stress could lead to functional abnormalities in the pancreas.

  4. Myocardial kinetics of carbon-11-epinephrine in the isolated working rat heart

    SciTech Connect

    Nguyen, N.T.B.; DeGrado, T.R.; Chakraborty, P.

    1997-05-01

    The kinetics of EPI were studied in the isolated rat heart model to evaluate {sup 11}C-epinephrine (EPI) as a radiotracer for the assessment of sympathetic neuronal function in the heart. Isolated rat hearts were perfused in a working mode. Carbon-11-EPI was added to the perfusate during wash-in period of 20 min, followed by a washout period of 40 min. Radioactivity in the heart was externally monitored and time-activity curves were recorded as a function of time. Effluent samples were collected throughout each study to determine the fraction of {sup 11}C radioactivity as intact tracer. Time-activity curves of control hearts showed that {sup 11}C-EPI is taken up and retained by the myocardium. Desipramine inhibition (DMI) of uptake-1 resulted in a significant decrease in myocardial uptake and retention of {sup 11}C-EPI by 91% compared to controls. Addition of DMI to the perfusion medium during washout did not affect kinetics of {sup 11}C-EPI compared to control hearts. Reserpine pretreated rat hearts also showed significant decrease in tracer retention of 95% compared to controls. The metabolic data showed that, in control conditions, about 61% of {sup 11}C-EPI taken up by the rat heart is rapidly metabolized and released. Carbon-11-EPI traces sympathetic nerve terminals in the isolated rat heart. Uptake blockade by DMI and reserpine suggest that uptake and storage of {sup 11}C-EPI appear to be similar to that of norepinephrine. However, the prominent metabolic pathway warrants further consideration. These results suggest that {sup 11}C-EPI may be a suitable radiolabeled tracer for the evaluation of sympathetic vesicular function of the heart by PET. 23 refs., 3 figs., 3 tabs.

  5. Signaling responses after exposure to 5 alpha-dihydrotestosterone or 17 beta-estradiol in norepinephrine-induced hypertrophy of neonatal rat ventricular myocytes.

    PubMed

    Koshman, Yevgeniya E; Piano, Mariann R; Russell, Brenda; Schwertz, Dorie W

    2010-03-01

    Androgens appear to enhance, whereas estrogens mitigate, cardiac hypertrophy. However, signaling pathways in cells for short (3 min) and longer term (48 h) treatment with 17beta-estradiol (E2) or 5 alpha-dihydrotestosterone (DHT) are understudied. We compared the effect of adrenergic stimulation by norepinephrine (NE; 1 microM) alone or in combination with DHT (10 nM) or E2 (10 nM) treatment in neonatal rat ventricular myocytes (NRVMs) by cell area, protein synthesis, sarcomeric structure, gene expression, phosphorylation of extracellular signal-regulated (ERK), and focal adhesion kinases (FAK), and phospho-FAK nuclear localization. NE alone elicited the expected hypertrophy and strong sarcomeric organization, and DHT alone gave a similar but more modest response, whereas E2 did not alter cell size. Effects of NE dominated when used with either E2 or DHT with all combinations. Both sex hormones alone rapidly activated FAK but not ERK. Long-term or brief exposure to E2 attenuated NE-induced FAK phosphorylation, whereas DHT had no effect. Neither hormone altered NE-elicited ERK activation. Longer term exposure to E2 alone reduced FAK phosphorylation and reduced nuclear phospho-FAK, whereas its elevation was seen in the presence of NE with both sex hormones. The mitigating effects of E2 on the NE-elicited increase in cell size and the hypertrophic effect of DHT in NRVMs are in accordance with results observed in whole animal models. This is the first report of rapid, nongenomic sex hormone signaling via FAK activation and altered FAK trafficking to the nucleus in heart cells. PMID:20044473

  6. Isolation-induced locomotor hyperactivity and hypoalgesia in rats are prevented by handling and reversed by resocialization.

    PubMed

    Gentsch, C; Lichtsteiner, M; Frischknecht, H R; Feer, H; Siegfried, B

    1988-01-01

    Differences in locomotor activity in the open field were found between individually and group-housed rats (isol greater than soc). Daily handling, initiated at postnatal day 1, was without effect in group-housed rats but prevented the isolation-induced hyperactivity. For tail-flick latency, strikingly similar differences (isol greater than soc; prevention by handling) have been observed. The isolation-induced aberrations in both locomotor reactivity in a novel environment and in pain sensitivity could be reversed by subsequent resocialization. This indicates that the altered sensitivities to external stimuli are caused by the environmental manipulation. PMID:3413245

  7. [Effects of creatinol O-phosphate on the isolated rabbit's atrium and on the rat's phrenic nerve diaphragm preparation].

    PubMed

    Ferrini, R; Miragoli, G

    1975-11-01

    Creatinol O-phosphate (COP) enhanced the semiisometric contraction of isolated rabbit's atria and those of rat's phrenic - diaphragm preparations immersed in hypocalcic Ringer or Krebs solution. Creatine-phosphate elicited a similar effect.

  8. Effect of vasoactive agents on prostanoid synthesis in isolated rat glomeruli.

    PubMed

    Podjarny, E; Magen, H; Shapira, J; Rathaus, M; Bernheim, J

    1986-11-01

    We studied the influence of vasoactive substances (angiotensin II, epinephrine, norepinephrine and acetylcholine) on the synthesis of prostanoids in isolated rat glomeruli. A significant increase of prostaglandin E2, and of thromboxane B2, but not of prostaglandin F2 alpha synthesis was observed after the administration of angiotensin II at physiological doses. Neither catecholamines nor acetylcholine influenced prostaglandin synthesis. The stimulation of vasoactive prostaglandins by angiotensin II, may modify the hemodynamic status of the glomerulus.

  9. The influence of oxygen tension on theophylline clearance in the rat isolated perfused liver.

    PubMed

    Miller, R; Oliver, I F

    1986-03-01

    The effect of changes in the rate of perfusion and oxygen tension (PO2) on theophylline clearance was determined in the rat isolated perfused liver. Changes in rate of perfusion had no effect on the extraction ratio of theophylline while a decrease in the PO2 significantly increased the half life of theophylline. These results suggest that changes in PO2 whether due to disease states or oxygen administration may necessitate theophylline dosage adjustment.

  10. Kinetics of reversible-sequestration of leukocytes by the isolated perfused rat lung

    SciTech Connect

    Goliaei, B.

    1980-08-01

    The kinetics and morphology of sequestration and margination of rat leukocytes were studied using an isolated perfused and ventilated rat lung preparation. Whole rat blood, bone marrow suspension, or leukocyte suspensions, were used to perfuse the isolated rat lung. The lung was also perfused with latex particle suspensions and the passage of particles through the lung capillaries was studied. When a leukocyte suspension was perfused through the lung in the single-pass mode, the rate of sequestration decreased as more cells were perfused. In contrast, latex particles of a size comparable to that of leukocytes were totally stopped by the lung. When the leukocyte suspension was recirculated through the lung, cells were rapidly removed from circulation until a steady state was reached, after which no net removal of cells by the lung occurred. These results indicate that leukocytes are reversibly sequestered from circulation. The sequestered cells marginated and attached to the luminal surface of the endothelium of post-capillary venules and veins. A mathematical model was developed based on the assumption that the attachment and detachment of leukocytes to blood vessel walls follows first-order kinetics. The model correctly predicts the following characteristics of the system: (a) the kinetics of the sequestration of leukocytes by the lung; (b) the existence of a steady state when a suspension of leukocytes is recirculated through the lung; and (c) the independence of the fraction of cells remaining in circulation from the starting concentration for all values of starting concentration. (ERB)

  11. Triacylglycerol metabolism in isolated rat kidney cortex tubules

    PubMed Central

    Wirthensohn, Gabriele; Guder, Walter G.

    1980-01-01

    Triacylglycerol metabolism has been studied in kidney cortex tubules from starved rats, prepared by collagenase treatment. Triacylglycerol was determined by a newly developed fully enzymic method. Incubation of tubules in the absence of fatty acids led to a decrease of endogenous triacylglycerol by about 50% in 1h. Addition of albuminbound oleate or palmitate resulted in a steady increase of tissue triacylglycerol over 2h. The rate of triacylglycerol synthesis was linearly dependent on oleate concentration up to 0.8mm, reaching a saturation at higher concentrations. Triacylglycerol formation from palmitate was less than that from oleate. This difference was qualitatively the same when net synthesis was compared with incorporation of labelled fatty acids. Quantitatively, however, the difference was less with the incorporation technique. Gluconeogenic substrates, which by themselves had no effect on triacylglycerol concentrations, stimulated neutral lipid formation from fatty acids. Glucose and lysine did not have such a stimulatory effect. Inhibition of gluconeogenesis from lactate by mercaptopicolinic acid likewise inhibited triacylglycerol formation. This inhibitory effect was seen with oleate as well as with oleate plus lactate. When [2-14C]lactate was used the incorporation of label into triacylglycerol was found in the glycerol moiety exclusively. Addition of dl-β-hydroxybutyrate (5mm) to the incubation medium in the presence of oleate or oleate plus lactate led to a significant increase in triacylglycerol formation. In contrast with the gluconeogenic substrates, dl-β-hydroxybutyrate had no stimulatory effect on fatty acid uptake. The results suggest that renal triacylglycerol formation is a quantitatively important metabolic process. The finding that gluconeogenic substrates, but not glucose, increase lipid formation, indicates that the glycerol moiety is formed by glyceroneogenesis in the proximal tubules. The effect of ketone bodies seems to be caused by

  12. [Electrophysiological features (EEG) of ethanol withdrawal syndromes on isolated perfused rat brain].

    PubMed

    Tezikov, E B; Litvicki, P F

    2015-01-01

    On isolated rat brains we studied native EEC and its derivates (mean EEC amplitude and power spectrums - Fourier transformation) during perfusion with ethanol (65 Mm/ L) and after its withdrawal. Previously rats were undergone ethanol burden for 6 days according to Majchrowicz procedures to get alcohol withdrawal syndrome. Duration perfusion without ethanol was 5, 10 and 20 min depending on the experimental schedule. Ethanol infusion between periods of withdrawal comprised 20 min. 55% of isolated brains shown epileptiform activity after 1-2 min of ethanol withdrawal but others manifested only increased mean amplitude and the power spectrums of EEC as well as an appearance of single or batch spikes. Differences between in vivo and in vitro conditions can be explained by the accelerated rate of ethanol elimination. The high positive correlation was obtained between EEC findings at the 5-th min of the first ethanol withdrawal and the same findings at the 5-th min of ethanol withdrawal in the second and the third episodes of ethanol withdrawal. Prolongation of withdrawal period more than 5th min caused brain death showing epileptiform activity. Isolated rat brain is the convenient subject to study pathogenesis of excitability of neurons and examination of drugs to treat alcohol withdrawal syndrome.

  13. Action of a new cholinergic agonist, aclatonium napadisilate, on isolated rat pancreatic acini

    SciTech Connect

    Fujii, M.; Okabayashi, Y.; Nakamura, T.; Tani, S.; Fujisawa, T.; Otsuki, M. )

    1990-07-01

    The effect of aclatonium napadisilate, a newly synthesized choline ester, on pancreatic exocrine function was compared with that of the muscarinic agonist carbamylcholine in isolated rat pancreatic acini. Both compounds increased amylase release and {sup 45}Ca{sup 2+} efflux in a dose-dependent fashion, and similarly decreased the binding of (N-methyl-{sup 3}H)scopolamine to isolated rat pancreatic acini. While aclatonium napadisilate was 20-30 times less potent than carbamylcholine in stimulations of amylase release and {sup 45}Ca{sup 2+} efflux, the potency of aclatonium napadisilate in inhibiting (N-methyl-{sup 3}H)scopolamine binding was nearly the same as that of carbamylcholine. These results indicate that aclatonium napadisilate stimulates pancreatic exocrine secretion via muscarinic receptors and Ca{sup 2+} mobilization, and its intrinsic activity is less than carbamylcholine in the isolated rat pancreatic acini. Since aclatonium napadisilate is known to increase motility and peristalsis of the gastrointestinal tract, stimulatory effects of aclatonium napadisilate, shown in the present study, on digestive enzyme secretion from the pancreas may provide additional benefit of aclatonium napadisilate in the treatment of various gastrointestinal disorders.

  14. Protective effect of apigenin on ischemia/reperfusion injury of the isolated rat heart.

    PubMed

    Hu, Jing; Li, Zilin; Xu, Li-ting; Sun, Ai-jun; Fu, Xiao-yan; Zhang, Li; Jing, Lin-lin; Lu, An-dong; Dong, Yi-fei; Jia, Zheng-ping

    2015-07-01

    Apigenin (Api), a mainly bioactive component of Apium graveolens L. var. dulce DC. (a traditional Chinese medicinal herb), possesses a wide range of biological activities, including antioxidant effects. It also has been shown to associate with lower prevalence of cardiovascular diseases, but its mechanisms of action remain unclear. The aim of the present study is to investigate the role of Api in isolated rat heart model of ischemia/reperfusion (I/R). Langendorff-perfused isolated rat hearts were used in our study. Api was added to the perfusate before ischemia and during reperfusion in the isolated pulsed rat heart exposed to 30-min ischemia followed by 50-min reperfusion. The treatment with Api conferred a cardioprotective effect, and the treated hearts demonstrated an improved ischemic cardiac functional recovery, a decreased myocardial infarct size, a reduced activities of creatine kinase isoenzyme and lactate dehydrogenase in the coronary flow, a reduced number of apoptotic cardiomyocytes, a reduced activity of caspase-3, up-regulation of the anti-apoptotic protein Bcl-2 and down-regulation of the pro-apoptotic protein Bax. In addition, Api inhibited the phosphorylation of p38 MAPKS during I/R. In conclusion, these observations provide preliminary evidence that Api can protect cardiomyocytes from I-/R-induced injury, at least partially, through the inhibition of p38 MAPKS signaling pathway. PMID:25377428

  15. Social isolation after a single defeat reduces striatal dopamine transporter binding in rats.

    PubMed

    Isovich, E; Engelmann, M; Landgraf, R; Fuchs, E

    2001-03-01

    A single social defeat in male rats has long lasting physiological and behavioural consequences, which are similar to those seen in depressive patients. In addition, the housing conditions after social defeat appear to be crucial for the development of depression-like symptoms. Because the dopaminergic system is thought to be altered in depressive illness, we investigated the impact of individual and group housing on the temporal development of changes of dopamine transporter (DAT) binding in male rats after a single social defeat. The number of striatal DAT binding sites was reduced in animals that remained isolated after being defeated. The isolation length after social defeat amplified this effect, indicating a temporal development of the changes on the striatal DAT. In animals which returned to the familiar group after social defeat the density of striatal DAT binding sites was not affected. We conclude that social isolation after a single defeat reduces the number of DAT binding sites. In contrast, a familiar environment after a single social defeat appears to prevent the stress-induced alterations on the dopaminergic system. This finding suggests that housing conditions are critical when investigating the central nervous effects of social defeat in male rats.

  16. Silibinin protects OTA-mediated TNF-alpha release from perfused rat livers and isolated rat Kupffer cells.

    PubMed

    Al-Anati, Lauy; Essid, Ebtisam; Reinehr, Roland; Petzinger, Ernst

    2009-04-01

    We studied the inhibitory effect of silibinin on ochratoxin A (OTA) and LPS-mediated tumor necrosis factor alpha (TNF-alpha) release and the leakage of cytotoxic markers glutamate dehydrogenase (GLDH) and lactate dehydrogenase (LDH), from isolated blood-free perfused rat livers, and from isolated pure rat Kupffer cells. In the recirculation perfusion model at the end point 90 min, 2.5 micromol/L OTA released 2600 pg/mL TNF-alpha without effects on liver vitality. LPS at 0.1 microg/mL induced 3000 pg TNF-alpha/mL with slight leakage of GLDH and LDH. Under similar experimental conditions, the addition of silibinin 10 min prior to OTA and LPS showed dose-dependent protection against OTA or LPS-induced hepatic TNF-alpha release. High-dose of silibinin (12.5 microg/mL) also completely restored GLDH and LDH levels in the perfusate. Pretreatment of isolated Kupffer cells with 0.02, 0.1, 0.5, 2.5, and 12.5 microg silibinin/mL 30 min prior to OTA reduced OTA-induced TNF-alpha levels to 90, 70, 25, 25, and 25% at 4 h, respectively, and abrogated any TNF-alpha release at 24 h. Similarly, in the presence of silibinin LPS-induced TNF-alpha levels decreased at 4 h to 71, 57, 18, 22, and 18%, respectively. However, after 24 h of LPS exposition the protection by silibinin vanished and TNF-alpha partially recurred into the incubation medium under LPS. In summary, silibinin had hepatoprotective effects against OTA- or LPS-mediated TNF-alpha release and also reduced the cytotoxicity of both toxins. Isolated Kupffer cells were even more sensitive to the protective effect than perfused livers and responded to very low concentrations of silibinin with a strong inhibition of toxins-mediated TNF-alpha release. PMID:19156713

  17. Inotropic response to endothelin-1, isoprenaline and calcium in cardiomyocytes isolated from endotoxin treated rats: effects of ethyl-isothiourea and dexamethasone.

    PubMed

    Spiers, J P; Kelso, E J; Allen, J D; Silke, B; McDermott, B J

    2000-07-01

    1. The contractile effects of endothelin-1, isoprenaline and extracellular calcium were assessed on ventricular cardiomyocytes isolated from lipopolysaccharide-treated rats. The involvement of nitric oxide was investigated using dexamethasone (in vivo) and ethyl isothiourea (in vitro). 2. Male Wistar rats (n=70) were injected with either saline (1 ml kg(-1)) or lipopolysaccharide (LPS; 5 mg kg(-1)) alone, or following pre-treatment with dexamethasone (DEX+LPS; 5 mg kg(-1)). Ventricular cell shortening was recorded using a video edge detection system, and concentration-response relationships were established for endothelin-1, isoprenaline and calcium, in the absence or presence of ethyl isothiourea (ETU; 10 microM). iNOS expression was assessed using reverse transcription-polymerase chain reaction. 3. iNOS mRNA expression was greater (P<0.001) in the LPS (iNOS/GAPDH ratio: 0.90+/-0.09) treated group compared to saline (iNOS/GAPDH ratio: 0.36+/-0.02). Baseline contractile amplitude was reduced (P<0.05) in the LPS (7.3+/-0.2 microm) and DEX+LPS groups (6.7+/-0.3 microm) compared to saline (8. 0+/-0.2 microm). 4. The concentration-dependent contractile response to endothelin-1 was attenuated (P<0.05) in the LPS group compared to saline (maximum change: 0.45+/-0.2 vs 1.8+/-0.2 microm). Neither ETU nor dexamethasone improved contractile function in the LPS-treated animals. 5. The concentration-dependent increase in the contractile response to isoprenaline was attenuated in the LPS-treated group compared to saline (P<0.05; maximum change: 1.7+/-0.4 vs 3.1+/-0.4 microm). This effect was reversed by ETU (maximum change: 3.7+/-0.6 microm). Pre-treatment with dexamethasone prevented a significant fall in contraction amplitude (maximum change: 2.4+/-0.4 microm). 6. The contractile response to calcium was reduced (P<0.05) in the LPS group compared to saline (maximum change: 8.7+/-0.6 vs 10.7+/-0.8 microm). Neither ETU nor dexamethasone restored contractile function in the LPS

  18. Effects of Postconditioning, Preconditioning and Perfusion of L-carnitine During Whole Period of Ischemia/ Reperfusion on Cardiac Hemodynamic Functions and Myocardial Infarction Size in Isolated Rat Heart

    PubMed Central

    Najafi, Moslem

    2013-01-01

    Objective(s): In the present work, the effects of L-carnitine (LC) on postischemic cardiac hemodynamic functions and infarction size were studied in isolated rat heart. Materials and Methods: The hearts were subjected to 30 min regional ischemia followed by 120 min reperfusion. Then they were perfused by a drug-free or LC-enriched Krebs–Henseleit (K/H) solution during ischemia/ reperfusion (I/R) (Protocol 1), 10 min before ischemia induction (Protocol 2; preconditioning group) or the first 10 min of reperfusion (Protocol 3; postconditioning group). Results: The perfusion of LC in protocol 1 significantly reduced left ventricular end diastolic pressure (LVEDP) (P<0.05), and increased left ventricular developed pressure (LVDP) (P<0.05), rate pressure product (RPP) (P<0.01) and coronary flow rate (CFR) (P<0.05). The short-term preischemic administration of LC in protocol 2 improved RPP, CFR and decreased the extent of LVEDP elevation. However, protective effects of LC in this protocol were low compared to the whole period perfusion. In protocol 3, LC preserved postischemic cardiac functions not as much as the other protocols. In addition, infarct size significantly decreased by LC in all protocols as opposed to the control group (P<0.001). Conclusion: The results of the present work showed that LC produced protective effects against I/R injury. These protective actions were reversed by concomitant use of etomoxir (a CPT-I inhibitor), suggesting that the efficacy of LC could be due to its mitochondrial action, probably related to the raise in glucose oxidation of the reperfused hearts. PMID:24250943

  19. Effects of Postconditioning, Preconditioning and Perfusion of L-carnitine During Whole Period of Ischemia/ Reperfusion on Cardiac Hemodynamic Functions and Myocardial Infarction Size in Isolated Rat Heart

    PubMed Central

    Najafi, Moslem

    2013-01-01

    Objective(s): In the present work, the effects of L-carnitine (LC) on postischemic cardiac hemodynamic functions and infarction size were studied in isolated rat heart. Materials and Methods: The hearts were subjected to 30 min regional ischemia followed by 120 min reperfusion. Then they were perfused by a drug-free or LC-enriched Krebs–Henseleit (K/H) solution during ischemia/ reperfusion (I/R) (Protocol 1), 10 min before ischemia induction (Protocol 2; preconditioning group) or the first 10 min of reperfusion (Protocol 3; postconditioning group). Results: The perfusion of LC in protocol 1 significantly reduced left ventricular end diastolic pressure (LVEDP) (P<0.05), and increased left ventricular developed pressure (LVDP) (P<0.05), rate pressure product (RPP) (P<0.01) and coronary flow rate (CFR) (P<0.05). The short-term preischemic administration of LC in protocol 2 improved RPP, CFR and decreased the extent of LVEDP elevation. However, protective effects of LC in this protocol were low compared to the whole period perfusion. In protocol 3, LC preserved postischemic cardiac functions not as much as the other protocols. In addition, infarct size significantly decreased by LC in all protocols as opposed to the control group (P<0.001). Conclusion: The results of the present work showed that LC produced protective effects against I/R injury. These protective actions were reversed by concomitant use of etomoxir (a CPT-I inhibitor), suggesting that the efficacy of LC could be due to its mitochondrial action, probably related to the raise in glucose oxidation of the reperfused hearts. PMID:24250945

  20. Characterization of ascorbic acid uptake by isolated rat kidney cells

    SciTech Connect

    Bowers-Komro, D.M.; McCormick, D.B. )

    1991-01-01

    Isolated kidney cells accumulated L(1-14C)ascorbic acid in a time-dependent manner and reached a steady state after 15 min at 37 degrees C. Initial velocity for uptake was over 300 pmol/mg protein per min when cells were separated from the bathing solution using a density gradient established during centrifugation. The uptake process was saturable with an apparent concentration at half maximal uptake of 36 mumols/L. Ascorbate uptake was reduced by metabolic inhibitors and was temperature dependent. Although ascorbic acid is an acid anion at pH 7.4, uptake did not appear to be inhibited by other acid anions such as p-aminohippurate and probenecid; however, involvement of the ion gradient established by Na+, H(+)-adenosine triphosphatase could not be confirmed. Replacing the sodium ion with other monovalent ions reduced the accumulation of ascorbate significantly. Isoascorbic and dehydroascorbic acids inhibited ascorbate uptake (34 and 13 mmol/L, respectively), whereas high concentrations of glucose showed some stimulation. These findings indicated that ascorbic acid is reabsorbed by the kidney in a sodium-dependent active transport process that is not common to other acid anions and has some specificity for the ascorbic acid structure.

  1. Anoxic disturbance of the isolated respiratory network of neonatal rats.

    PubMed

    Völker, A; Ballanyi, K; Richter, D W

    1995-01-01

    Tissue oxygen (PO2), K+ (aKe), pH (pHe) and Ca2+ ([Ca2+]e) were measured in the region of the ventral respiratory group (VRG) in the in vitro brainstem-spinal cord preparation of neonatal rats. During tissue anoxia, elicited by superfusion of N2-gassed solutions, an initial increase in the frequency of respiratory activity, lasting between 2 and 12 min, turned into a frequency depression. During anoxia periods of up to 60 min, respiratory activity persisted in solutions containing CO2/bicarbonate, whereas a complete blockade was observed after 15-25 min in N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid- (Hepes)-buffered salines. After such anoxic apnea, respiratory rhythmicity could be reactivated by superfusion of hypoxic, CO2/bicarbonate-buffered solutions. In both types of hypoxic solutions, aKe increased by maximally 1.5 mM, whereas an initial increase of pHe by up to 0.05 pH units turned, after 2-4 min, into an acidification which could exceed 0.5 pH units. In contrast, [Ca2+]e remained unaffected by anoxia. Addition of 2-5 mM cyanide (CN-) to oxygenated Hepes-buffered saline evoked an increase in PO2 in the VRG from 100 to more than 300 mmHg. The effects of CN- on respiratory activity, aKe and pHe were almost identical to those during anoxia. In oxygenated, CO2/bicarbonate-free solutions of different pH, however, an increase in pHe in the VRG led to a decrease in respiratory frequency, whereas a fall of pHe produced a frequency acceleration. A rise of aKe in the VRG by more than 2 mM as induced by superfusion of a 7 mM K+ solution led to a sustained increase of respiratory frequency. The results indicate that blockade of aerobic metabolism does not severely perturb K+ and Ca2+ homeostasis and that the biphasic response to anoxia is not directly related to the observed changes in PO2, aKe, pHe, or [Ca2+]e. In the respiratory network of neonatal mammals, CO2 might provide a stimulus for long-term maintenance of respiratory activity under oxygen depletion.

  2. Negative visuospatial priming in isolation-reared rats: Evidence of resistance to the disruptive effects of amphetamine.

    PubMed

    Amitai, Nurith; Powell, Susan; Weber, Martin; Swerdlow, Neal R; Young, Jared W

    2015-12-01

    Negative visuospatial priming (NP) represents a quantifiable measure of inhibitory information processing that is disrupted in several neurodevelopmental and psychiatric disorders, including schizophrenia. We developed a novel rodent NP task to investigate mechanisms underlying NP and its role in various disorders, and to test potential therapeutics. In the present studies, we further characterized this novel paradigm by investigating whether NP is disrupted in rats reared in isolation, a developmental manipulation that produces a range of abnormalities in behavior, neurochemistry, and brain structure that mirror aspects of schizophrenia pathology. We also further explored the role of monoaminergic signaling in NP and the effects of isolation rearing by challenging both socially reared and isolation-reared rats with D-amphetamine during the NP task. Although fewer isolation-reared animals learned the complex NP task, those that learned exhibited unaffected NP compared with socially reared rats. Consistent with previous reports, D-amphetamine impaired NP and increased motor impulsivity in socially reared rats. In contrast, D-amphetamine did not affect NP or motor impulsivity in isolation-reared rats. These data confirm a monoaminergic influence on NP behavior and indicate that rats reared in isolation have altered dopaminergic sensitivity. PMID:26220402

  3. Altered synthesis of some secretory proteins in pancreatic lobules isolated from streptozotocin-induced diabetic rats

    SciTech Connect

    Duan, R.D.; Erlanson-Albertsson, C. )

    1990-03-01

    The in vitro incorporation of (35S)cysteine into lipase, colipase, amylase, procarboxypeptidase A and B, and the serine proteases and total proteins was studied in pancreatic lobules isolated from normal and diabetic rats with or without insulin treatment. The incorporation of (35S)cysteine into total proteins was 65% greater in pancreatic lobules from diabetic animals than from normal rats. The increased incorporation was partly reversed by insulin treatment (2 U/100 g/day for 5 days) of diabetic rats. The relative rates of biosynthesis for amylase and the procarboxypeptidases in diabetic pancreatic lobules were decreased by 75 and 25%, respectively, after 1 h of incubation, while those for lipase, colipase, and the serine proteases were increased by 90, 85, and 35%, respectively. The absolute rates of synthesis for these enzymes changed in the same direction as the relative rates in diabetic lobules, except that for the procarboxypeptidases, which did not change. The changed rates of biosynthesis for the pancreatic enzymes were reversed by insulin treatment of the diabetic rats. Kinetic studies showed that the incorporation of (35S)cysteine into amylase, lipase, and colipase was linear until up to 2 h of incubation in normal pancreatic lobules, while in the diabetic lobules the incorporation into lipase and colipase was accelerated, reaching a plateau level already after 1 h of incubation. It is concluded that the biosynthesis of pancreatic secretory proteins in diabetic rats is greatly changed both in terms of quantity and kinetics.

  4. Bi-layered polyurethane - Extracellular matrix cardiac patch improves ischemic ventricular wall remodeling in a rat model.

    PubMed

    D'Amore, Antonio; Yoshizumi, Tomo; Luketich, Samuel K; Wolf, Matthew T; Gu, Xinzhu; Cammarata, Marcello; Hoff, Richard; Badylak, Stephen F; Wagner, William R

    2016-11-01

    As an intervention to abrogate ischemic cardiomyopathy, the concept of applying a temporary, local patch to the surface of the recently infarcted ventricle has been explored from a number of design perspectives. Two important features considered for such a cardiac patch include the provision of appropriate mechanical support and the capacity to influence the remodeling pathway by providing cellular or biomolecule delivery. The objective of this report was to focus on these two features by first evaluating the incorporation of a cardiac extracellular matrix (ECM) component, and second by evaluating the impact of patch anisotropy on the pathological remodeling process initiated by myocardial infarction. The functional outcomes of microfibrous, elastomeric, biodegradable cardiac patches have been evaluated in a rat chronic infarction model. Ten weeks after infarction and 8 wk after patch epicardial placement, echocardiographic function, tissue-level structural remodeling (e.g., biaxial mechanical response and microstructural analysis), and cellular level remodeling were assessed. The results showed that the incorporation of a cardiac ECM altered the progression of several keys aspects of maladaptive remodeling following myocardial infarction. This included decreasing LV global mechanical compliance, inhibiting echocardiographically-measured functional deterioration, mitigating scar formation and LV wall thinning, and promoting angiogenesis. In evaluating the impact of patch anisotropy, no effects from the altered patch mechanics were detected after 8 wk, possibly due to patch fibrous encapsulation. Overall, this study demonstrates the benefit of a cardiac patch design that combines both ventricle mechanical support, through a biodegradable, fibrillary elastomeric component, and the incorporation of ECM-based hydrogel components. PMID:27579776

  5. Diet and carcinogen alter luminal butyrate concentration and intracellular pH in isolated rat colonocytes.

    PubMed

    Zoran, D L; Barhoumi, R; Burghardt, R C; Chapkin, R S; Lupton, J R

    1997-01-01

    A 2 x 2 factorial experiment was conducted to examine the effects of two different dietary fibers and carcinogen treatment on colonic luminal short-chain fatty acid (SCFA) concentrations and intracellular pH (pHi) in rats. Twenty-four male Sprague-Dawley rats were divided into four groups, injected with a carcinogen [azoxymethane (AOM)] or normal saline (Sal), and fed one of two diets differing only in the type of dietary fiber [cellulose (Cell) or pectin (Pect)]. After 38 weeks of consuming these diets, the rats were euthanized, luminal contents were collected for analysis of SCFA concentrations, and colonocytes were isolated from the proximal and distal colon for subsequent determination of pHi. Changes in pHi after the addition of exogenous sodium butyrate to the culture medium were also tested. The highest concentrations of SCFAs were produced by the control rats (saline injected) consuming the pectin diet. Luminal butyrate concentrations were reduced in three of four colonic segments of carcinogen-injected groups [proximal and distal cellulose (Prox Cell and Dist Cell) and distal pectin (Dist Pect)] compared with saline controls. The pHi was consistently higher in colonocytes isolated from carcinogen-injected rats (Prox Cell/AOM = 6.95 vs. Prox Cell/Sal = 6.65, Prox Pect/AOM = 6.75 vs. Prox Pect/Sal = 6.65, Dist Cell/AOM = 6.94 vs. Dist Cell/AOM = 6.85, Dist Pect/AOM = 6.92 vs. Dist Pect/Sal = 6.79) than in cells from saline-injected rats. Furthermore, in the majority of rats, pHi was lower in the proximal than in the distal colon. Addition of butyrate to cultured colonocytes consistently lowered pHi, but the effect was more pronounced in the carcinogen-injected animals. These data identify changes that occur intraluminally and intracellularly in colons of rats injected with AOM and suggest that, during tumorigenesis, alterations in butyrate production and basic colonocyte physiology may play an important role in the process.

  6. Antispasmodic effects of curcuminoids on isolated guinea-pig ileum and rat uterus.

    PubMed

    Itthipanichpong, Chandhanee; Ruangrungsi, Nijsiri; Kemsri, Wandee; Sawasdipanich, Anugool

    2003-06-01

    Curcuminoids, a yellow constituent isolated from Curcuma longa Linn. rhizomes was studied for its antispasmodic activity in isolated guinea-pig ileum and rat uterus. Curcuminoids at the concentration of 12 microg/ml significantly inhibited the ileum pre-contracted with acetylcholine (ACh) 5 x 10(-7) M and histamine 5 x 10(-7) M. (Force of contraction was 62.84 +/- 4.66% and 75.60 +/- 4.66% respectively) and the effects were prominently observed when the concentration of curcuminoids was increased to 36 microg/ml. (Force of contraction was 44.93 +/- 4.33% and 42.79 +/- 1.98%). In potassium depolarizing Tyrode solution, curcuminoids 4 microg/ml and 20 microg/ml reduced the contraction induced by calcium chloride (CaCl2) 1.8 mM. (The contraction was 63.31 +/- 1.80% and 36.87 +/- 3.25%). In rat uterus smooth muscle preparation, curcuminoids 8 microg/ml and 16 microg/ml significantly reduced force and frequency of contraction induced by oxytocin 1 x 10(-2) IU/ml. Curcuminoids 8 microg/ml produced 54.68 +/- 3.34 per cent force of contraction and 79.09 +/- 2.29 per cent frequency of contraction. Curcuminoids 16 microg/ml caused more relaxation of rat uterus smooth muscle. (Force of contraction was 43.38 +/- 3.56%, frequency of contraction was 49.96 +/- 5.20%). Curcuminoids 8 and 16 microg/ml significantly reduced force of contraction induced by KCl 50 mM. (Force of contraction was 54.10 +/- 4.92% and 36.60 +/- 2.99%). The results obtained from this study concluded that curcuminoids produced a smooth muscle, relaxation effect on isolated guinea-pig ileum and rat uterus by receptor-dependent and independent mechanism. PMID:12930003

  7. Handling and isolation in three strains of rats affect open field, exploration, hoarding and predation.

    PubMed

    Rebouças, R C; Schmidek, W R

    1997-11-01

    Male albino (Al), brown hooded (Br) and black hooded (Bl) rats were raised in social isolation or in pairs, with or without systematic handling. At 90 and 180 days of age, the animals were individually tested for activity in an open field (Of), exploratory behavior in a complex environment, food hoarding (Hd) and insect predation (Pd). Multivariate analysis of the results showed significant influences of all three factors (strain, handling and social isolation) and interactions among them. Strain affected Of, Hd and Pd, with contrastingly high performances of Br in Of, Al in Hd and Bl in Pd. Handling increased Of and exploration scores in both test series. Isolation induced higher performances in all the four behaviors in the second test series. Accentuated and stable individual differences occurred in the performances off all the behaviors. The results emphasize the subtleness and complexity of the interplay of genetic and environmental influences and stress the independence of the regulatory processes of different behaviors.

  8. A unique method for the isolation of nasal olfactory stem cells in living rats.

    PubMed

    Stamegna, Jean-Claude; Girard, Stéphane D; Veron, Antoine; Sicard, Gilles; Khrestchatisky, Michel; Feron, François; Roman, François S

    2014-05-01

    Stem cells are attractive tools to develop new therapeutic strategies for a variety of disorders. While ethical and technical issues, associated with embryonic, fetal and neural stem cells, limit the translation to clinical applications, the nasal stem cells identified in the human olfactory mucosa stand as a promising candidate for stem cell-based therapies. Located in the back of the nose, this multipotent stem cell type is readily accessible in humans, a feature that makes these cells highly suitable for the development of autologous cell-based therapies. However, preclinical studies based on autologous transplantation of rodent olfactory stem cells are impeded because of the narrow opening of the nasal cavity. In this study, we report the development of a unique method permitting to quickly and safely biopsy olfactory mucosa in rats. Using this newly developed technique, rat stem cells expressing the stem cell marker Nestin were successfully isolated without requiring the sacrifice of the donor animal. As an evidence of the self-renewal capacity of the isolated cells, several millions of rat cells were amplified from a single biopsy within four weeks. Using an olfactory discrimination test, we additionally showed that this novel biopsy method does not affect the sense of smell and the learning and memory abilities of the operated animals. This study describes for the first time a methodology allowing the derivation of rat nasal cells in a way that is suitable for studying the effects of autologous transplantation of any cell type present in the olfactory mucosa in a wide variety of rat models.

  9. Transmural differences in rat ventricular protein kinase C epsilon correlate with its functional regulation of a transient cardiac K+ current.

    PubMed

    Thorneloe, K S; Liu, X F; Walsh, M P; Shimoni, Y

    2001-05-15

    The effects of PKC activation on a transient (It) and a sustained (Iss) cardiac K+ current and the subcellular distribution of the epsilon isoform of PKC (PKC(epsilon)) were compared in epicardial and endocardial regions of the rat ventricle. Activation of PKC(epsilon) with a diacylglycerol analogue (di-octanoyl-glycerol (DiC8), 20 (mu)M) leads to differential effects in epicardial and endocardial cells. In epicardial cells (n = 20) It and Iss are attenuated by 17.7 +/- 2.1 % and 11.9 +/- 3.1 %, respectively (means +/- S.E.M.). In endocardial cells It attenuation was significantly smaller (4.6 +/- 1.6 %, n = 14, P < 0.0005). Iss attenuation was similar to that in epicardial cells (10.5 +/- 3.8 %). PKC[epsilon] expression was measured by Western blotting. Calculated endocardial/epicardial ratios showed no regional differences in total protein extracts (1.04 +/- 0.11, mean +/- S.E.M, n = 4), but PKC[epsilon] distribution in the cytosolic fraction showed a marked difference, with significantly (P < 0.05) higher levels in endocardial extracts. The cytosolic endocardial/epicardial PKC[epsilon] ratio was 2.64 +/- 0.24 (n = 4), indicating a reduced amount of PKC[epsilon] in the membrane fraction of the endocardium. This could account for the reduced effect of DiC8 on It in endocardial myocytes. Under both hypothyroid and streptozotocin-induced diabetic conditions the difference in endocardial and epicardial cytosolic PKC[epsilon] levels was absent (ratios of 0.86 +/- 0.21 (n = 4) and 1.09 +/- 0.16 (n = 3), respectively; means +/- S.E.M.). Ratios in the total protein extracts were not significantly different from those in control conditions. The results show transmural differences in the functional effects of PKC(epsilon) activation on a cardiac K+ current, and in the subcellular distribution of PKC(epsilon). These differences are absent in diabetic and hypothyroid conditions.

  10. Crocin, a carotenoid component of Crocus cativus, exerts inhibitory effects on L-type Ca(2+) current, Ca(2+) transient, and contractility in rat ventricular myocytes.

    PubMed

    Liu, Tao; Chu, Xi; Wang, Hua; Zhang, Xuan; Zhang, Yuanyuan; Guo, Hui; Liu, Zhenyi; Dong, Yongsheng; Liu, Hongying; Liu, Yang; Chu, Li; Zhang, Jianping

    2016-03-01

    Crocin, a carotenoid component of Crocus sativus L. belonging to the Iridaceae family, has demonstrated cardioprotective effects. To investigate the cellular mechanisms of these cardioprotective effects, here we studied the influence of crocin on L-type Ca(2+)current (I(Ca-L)), intracellular Ca(2+) ([Ca(2+)]i), and contraction of isolated rat cardiomyocytes by using the whole-cell patch-clamp technique and video-based edge detection and dual excitation fluorescence photomultiplier systems. Crocin inhibited I(Ca-L) in a concentration-dependent manner with the half-maximal inhibitory concentration (IC50) of 45 μmol/L and the maximal inhibitory effect of 72.195% ± 1.54%. Neither current-voltage relationship of I(Ca-L), reversal potential of I(Ca-L), nor the activation/inactivation of I(Ca-L) was significantly changed. Crocin at 1 μmol/L reduced cell shortening by 44.64% ± 2.12% and the peak value of the Ca(2+) transient by 23.66% ± 4.52%. Crocin significantly reduced amplitudes of myocyte shortening and [Ca(2+)]i with an increase in the time to reach 10% of the peak (Tp) and a decrease in the time to 10% of the baseline (Tr). Thus, the cardioprotective effects of crocin may be attributed to the attenuation of [Ca(2+)]i through the inhibition of I(Ca-L) in rat cardiomyocytes and negative inotropic effects on myocardial contractility.

  11. Crocin, a carotenoid component of Crocus cativus, exerts inhibitory effects on L-type Ca(2+) current, Ca(2+) transient, and contractility in rat ventricular myocytes.

    PubMed

    Liu, Tao; Chu, Xi; Wang, Hua; Zhang, Xuan; Zhang, Yuanyuan; Guo, Hui; Liu, Zhenyi; Dong, Yongsheng; Liu, Hongying; Liu, Yang; Chu, Li; Zhang, Jianping

    2016-03-01

    Crocin, a carotenoid component of Crocus sativus L. belonging to the Iridaceae family, has demonstrated cardioprotective effects. To investigate the cellular mechanisms of these cardioprotective effects, here we studied the influence of crocin on L-type Ca(2+)current (I(Ca-L)), intracellular Ca(2+) ([Ca(2+)]i), and contraction of isolated rat cardiomyocytes by using the whole-cell patch-clamp technique and video-based edge detection and dual excitation fluorescence photomultiplier systems. Crocin inhibited I(Ca-L) in a concentration-dependent manner with the half-maximal inhibitory concentration (IC50) of 45 μmol/L and the maximal inhibitory effect of 72.195% ± 1.54%. Neither current-voltage relationship of I(Ca-L), reversal potential of I(Ca-L), nor the activation/inactivation of I(Ca-L) was significantly changed. Crocin at 1 μmol/L reduced cell shortening by 44.64% ± 2.12% and the peak value of the Ca(2+) transient by 23.66% ± 4.52%. Crocin significantly reduced amplitudes of myocyte shortening and [Ca(2+)]i with an increase in the time to reach 10% of the peak (Tp) and a decrease in the time to 10% of the baseline (Tr). Thus, the cardioprotective effects of crocin may be attributed to the attenuation of [Ca(2+)]i through the inhibition of I(Ca-L) in rat cardiomyocytes and negative inotropic effects on myocardial contractility. PMID:26674933

  12. Ameliorative Effects of Taurine Against Methimazole-Induced Cytotoxicity in Isolated Rat Hepatocytes

    PubMed Central

    Heidari, Reza; Babaei, Hossein; Eghbal, Mohammad Ali

    2012-01-01

    Methimazole is used as an antithyroid drug to control the symptoms of hyperthyroidism and maintain patients in a euthyroid state. Administration of this drug is associated with agranulocytosis and hepatotoxicity, which are the two most significant adverse effects. The present investigation was conducted to study the protective role of taurine against cytotoxicity induced by methimazole and its proposed reactive intermediary metabolite, N-methylthiourea, in an in vitro model of isolated rat hepatocytes. At different points in time, markers such as cell viability, reactive oxygen species (ROS) formation, lipid peroxidation, mitochondrial membrane potential, and hepatocyte glutathione content were evaluated. Treating hepatocytes with methimazole resulted in cytotoxicity characterized by the reduction in cell viability, an increase in ROS formation and lipid peroxidation, mitochondrial membrane potential collapse, and a reduction in cellular glutathione content. Furthermore, a significant amount of oxidized glutathione (GSSG) was formed when rat hepatocytes were treated with methimazole. N-methylthiourea toxicity was accompanied by a reduction in cellular GSH content, but no significant changes in lipid peroxidation, ROS formation, GSSG production, or changes in mitochondrial membrane potential were detected. Administration of taurine (200 μM) effectively reduced the toxic effects of methimazole or its metabolite in isolated rat hepatocytes. PMID:23264945

  13. Cyproheptadine metabolites inhibit proinsulin and insulin biosynthesis and insulin release in isolated rat pancreatic islets

    SciTech Connect

    Chow, S.A.; Falany, J.L.; Fischer, L.J. )

    1989-06-01

    The contribution of drug metabolites to cyproheptadine (CPH)-induced alterations in endocrine pancreatic beta-cells was investigated by examining the inhibitory activity of CPH and its biotransformation products, desmethylcyproheptadine (DMCPH), CPH-epoxide and DMCPH-epoxide, on hormone biosynthesis and secretion in pancreatic islets isolated from 50-day-old rats. Measurement of (pro)insulin (proinsulin and insulin) synthesis using incorporation of 3H-leucine showed that DMCPH-epoxide, DMCPH and CPH-epoxide were 22, 10 and 4 times, respectively, more potent than CPH in inhibiting hormone synthesis. The biosynthesis of (pro)insulin was also inhibited by CPH and DMCPH-epoxide in islets isolated from 21-day-old rat fetuses. The inhibitory action of CPH and its metabolites was apparently specific for (pro)insulin, and the synthesis of other islet proteins was not affected. Other experiments showed the metabolites of CPH were active in inhibiting glucose-stimulated insulin secretion but were less potent than the parent drug in producing this effect. CPH and its structurally related metabolites, therefore, have differential inhibitory activities on insulin synthesis and release. The observation that CPH metabolites have higher potency than CPH to inhibit (pro)insulin synthesis, when considered with published reports on the disposition of the drug in rats, indicate that CPH metabolites, particularly DMCPH-epoxide, are primarily responsible for the insulin depletion observed when the parent compound is given to fetal and adult animals.

  14. Influence of microwaves on the beating rate of isolated rat hearts.

    PubMed

    Yee, K C; Chou, C K; Guy, A W

    1988-01-01

    Previous reports have shown that microwave exposure can decrease the beating rate of isolated rat hearts. These experiments were conducted at room temperature and with the hearts exposed to air. We observed arrhythmia frequently at room temperature, and the variation of heart beat was so large that it makes the results difficult to reproduce. Therefore, we employed a double-circulating system to provide perfusion through the coronary artery and around the outside of the heart to maintain the rat hearts at 37.7 degrees C. No arrhythmias were observed in our experiments, and the hearts were beating for at least 1 h. The effects of 16-Hz modulated 2,450-MHz pulsed microwaves (10 microseconds, 100 pps) on the beating rate of 50 isolated rat hearts were studied. Results showed no statistically significant changes of heart rate in exposed groups at SARs of 2 and 10 W/kg compared with the control group. The effect seen at 200 W/kg was shown to be similar to that resulting from heating the heart.

  15. Influence of microwaves on the beating rate of isolated rat hearts

    SciTech Connect

    Yee, K.C.; Chou, C.K.; Guy, A.W.

    1988-01-01

    Previous reports have shown that microwave exposure can decrease the beating rate of isolated rat hearts. These experiments were conducted at room temperature and with the hearts exposed to air. We observed arrhythmia frequently at room temperature, and the variation of heart beat was so large that it makes the results difficult to reproduce. Therefore, we employed a double-circulating system to provide perfusion through the coronary artery and around the outside of the heart to maintain the rat hearts at 37.7 degrees C. No arrhythmias were observed in our experiments, and the hearts were beating for at least 1 h. The effects of 16-Hz modulated 2,450-MHz pulsed microwaves (10 microseconds, 100 pps) on the beating rate of 50 isolated rat hearts were studied. Results showed no statistically significant changes of heart rate in exposed groups at SARs of 2 and 10 W/kg compared with the control group. The effect seen at 200 W/kg was shown to be similar to that resulting from heating the heart.

  16. Swertianlarin, isolated from Swertia mussotii Franch, increases detoxification enzymes and efflux transporters expression in rats

    PubMed Central

    Feng, Xin-Chan; Du, Xiaohuang; Chen, Sheng; Yue, Dongmei; Cheng, Ying; Zhang, Liangjun; Gao, Yu; Li, Shaoxue; Chen, Lei; Peng, Zhihong; Yang, Yong; Luo, Weizao; Wang, Rongquan; Chen, Wensheng; Chai, Jin

    2015-01-01

    Swertianlarin, isolated from Swertia mussotii Franch and Enicostemma axillare, has hepatoprotective effects against cholestasis in rat models of hepatotoxicity. However, the underlying molecular mechanism is not clear. We then treated rats with swertianlarin for 7 d and then measured serum liver injury markers, lipids, and bile salts, as well as the expression of bile acid synthesis and detoxification enzymes (e.g. Cyp7a1 and Cyp3a), membrane influx and efflux transporters (e.g. Ntcp and Mrp3), nuclear receptors (e.g. Pxr and Fxr/Shp) and transcriptional factors (e.g. Nrf2 and Hnf3β) in the liver. We found a significant induction of the expression of the basolateral efflux transporters Mrp3 and Mrp4 and canalicular transporter Mdr1 in rats treated with swertianlarin, compared with the controls (1.9-fold and 2.2-fold, P < 0.005, and 3.4-fold, P < 0.05, respectively). The expression of detoxification enzymes Cyp3a, Ugt2b, Sult2a1 and Gsta1 in rats treated with swertianlarin was significantly higher than that in controls (3.7-fold, 2.8-fold, 2.1-fold, and 1.7-fold, respectively, all P < 0.05). Expression of the synthetic enzyme, Cyp8b1, was higher in rats treated with swertianlarin than that in controls (1.8-fold at mRNA level and 3.4-flod at protein level, P < 0.05). Elevated serum levels of the conjugated bile acids, taurocholic acid and taurodeoxycholic acid, and a reduction in levels of serum ALP, unconjugated bile acid αMCA, and TG were observed (all P < 0.05). In conclusion, swertianlarin significantly up-regulates hepatic bile acid detoxification enzymes and efflux transporters in rats, which can increase the water solubility of hydrophobic bile acids and elimination of conjugated bile acids. PMID:25755705

  17. 4-Nitrophenol isolated from diesel exhaust particles disrupts regulation of reproductive hormones in immature male rats.

    PubMed

    Li, Xuezheng; Li, Chunmei; Suzuki, Akira K; Taneda, Shinji; Watanabe, Gen; Taya, Kazuyoshi

    2009-08-01

    In previous studies, we found that 4-nitrophenol (PNP) isolated from diesel exhaust particles exhibited both estrogenic and anti-androgenic activities. This compound is also a degradation product of the insecticide parathion. Here, we investigated the in vivo effect of PNP on reproductive function in immature male rats. Twenty-eight-day-old rats were injected subcutaneously with PNP (0.01, 0.1, 1, or 10 mg/kg) daily for 14 days. Plasma concentrations of luteinizing hormone (LH) were significantly lower in all PNP dosage groups than in the control group, and follicle-stimulating hormone (FSH) was significantly decreased in rats treated with 0.1, 1, or 10 mg/kg PNP. However, plasma concentrations of testosterone were significantly increased by 10 mg/kg PNP, and plasma concentrations of immunoreactive (ir)-inhibin were also significantly increased in the 0.1, 1, and 10 mg/kg PNP groups. Plasma concentrations of prolactin were significantly increased by 10 mg/kg PNP, and plasma concentrations of corticosterone were significantly increased in all treatment groups. These findings clearly show that PNP influences the hypothalamic-pituitary-gonadal axis in immature male rats, with decreased secretion of LH and FSH and increased secretion of testosterone and inhibin. PNP, therefore, appears to disrupt endocrine activity in the immature male reproductive system.

  18. Influence of age on inducibility and cholinergic modulation of arrhythmia in isolated rat right atria.

    PubMed

    Faria, D M; Viviane, A G; Galvão, K M; Caricati-Neto, A; Godoy, C M G

    2009-03-01

    The effects of carbachol and atropine on the number of trains (NT) and on the train stimulus strength (SS) necessary to induce arrhythmia were studied in isolated right atria of infant, young, adult and mature rats submitted to electric field stimulation (66.7 Hz, 5 ms pulse-duration, 250 pulses). Carbachol (1 microM) decreased NT from four (control) to two in all ages tested. Atropine (1 microM) prevented tachyarrhythmia induction in tissue of all ages, even with NT equal to 12, except for mature rats (typically four trains). The SS decreases from infant to adult age [5- to 2-fold atrial threshold (AT)] and increases in mature animals (5-fold AT). Carbachol changes this result only for mature rats (5- to 2-fold AT). The SS was decreased by carbachol (1 microM) from 5- to 3-fold AT in mature rats, but atropine did not modify SS in this age. These results indicate that inducibility and cholinergic modulation of atrial tachyarrhythmia is influenced by age. PMID:19234768

  19. The effects of 4-pentenoic and pentanoic acids on the isolated rat atria.

    PubMed

    Varela, A; Felip, M N; Montesi, A; Savino, E A

    1988-12-01

    The peak developed tension and the pacemaker frequency of the isolated atria from fed and fasted rats, declined progressively during the incubation in a glucose-free medium containing 2-deoxyglucose. The atria from fed rats exhibited a faster decline than those from fasted rats, which was associated to a slower triacylglycerol lipolysis. 4-Pentenoic acid inhibited the lipolysis of both groups of atria but did not alter the atrial contractile performance. However, it enhanced the decline of the pacemaker frequency in the atria from fasted rats whereas, in contrast, it alleviated the decline in the fed atria. n-Pentanoic acid ameliorated the impairment of the contractile and pacemaker activities in both groups of atria, without affecting the lipolysis. It was concluded that, since the inhibition of the intramyocardial lipolysis did not correlate with changes of the atrial functions, 4-pentenoic acid was not appropriate to assess about the contribution of endogenous triacylglycerol to the maintenance of the atrial contractile and pacemaker activities.

  20. Adenosine triphosphate-dependent copper transport in isolated rat liver plasma membranes.

    PubMed Central

    Dijkstra, M; In 't Veld, G; van den Berg, G J; Müller, M; Kuipers, F; Vonk, R J

    1995-01-01

    The process of hepatobiliary copper (Cu) secretion is still poorly understood: Cu secretion as a complex with glutathione and transport via a lysosomal pathway have been proposed. The recent cloning and sequencing of the gene for Wilson disease indicates that Cu transport in liver cells may be mediated by a Cu transporting P-type ATPase. Biochemical evidence for ATP-dependent Cu transport in mammalian systems, however, has not been reported so far. We have investigated Cu transport in rat liver plasma membrane vesicles enriched in canalicular or basolateral membranes in the presence and absence of ATP (4 mM) and an ATP-regenerating system. The presence of ATP clearly stimulated uptake of radiolabeled Cu (64Cu, 10 microM) into canalicular plasma membrane vesicles and, to a lesser extent, also into basolateral plasma membrane vesicles. ATP-dependent Cu transport was dose-dependently inhibited by the P-type ATPase inhibitor vanadate, and showed saturation kinetics with an estimated Km of 8.6 microM and a Vmax of 6.9 nmol/min/mg protein. ATP-stimulated Cu uptake was similar in canalicular membrane vesicles of normal Wistar rats and those of mutant GY rats, expressing a congenital defect in the activity of the ATP-dependent canalicular glutathione-conjugate transporter (cMOAT). These studies demonstrate the presence of an ATP-dependent Cu transporting system in isolated plasma membrane fractions of rat liver distinct from cMOAT. PMID:7814642

  1. Thyroid hormone regulation of transmembrane signalling in neonatal rat ventricular myocytes by selective alteration of the expression and coupling of G-protein alpha-subunits.

    PubMed Central

    Bahouth, S W

    1995-01-01

    Thyroid hormone exerts profound effects on the activity of the hormone-sensitive adenylate cyclase system in the heart. Distinct guanine nucleotide-binding regulatory proteins (G-proteins) mediate stimulatory and inhibitory influences on adenylate cyclase activity. To examine whether the effects of thyroid hormone on adenylate cyclase involve specific changes in G-protein subunit expression, the influence of tri-iodothyronine (T3) on the biosynthesis and activity of G-proteins in neonatal rat ventricular myocytes was determined. In myocytes challenged with T3 for 5 days, Gs alpha levels increased by 4 +/- 0.5-fold, whereas Gi2 alpha levels declined by more than 80%. T3 down-regulated Gi2 alpha mRNA by 60% within 3 days, but had no effect on Gs alpha mRNA. The basis for the decline in Gi2 alpha mRNA was the T3-mediated suppression of Gi2 alpha gene transcription by 80 +/- 9% within 4 h. The decline in Gi2 alpha mRNA in response to T3 produced a 2-fold decrease in relative rate of synthesis of Gi2 alpha but not in its half-life (46 +/- 7 h). Gs alpha synthesis was not altered by T3, but the half-life of Gs alpha increased from 50 +/- 6 h in control cells to 72 +/- 8 h in T3-treated cells. In addition, T3 provoked the translocation of Gs alpha from the cytoplasmic to the membranous compartment. Membranous Gs alpha increased from 30 +/- 6% to 61 +/- 7% of total cellular Gs alpha, whereas cytoplasmic Gs alpha declined from 68 +/- 6% to 33 +/- 8% within 1 day of exposure to T3. T3-mediated up-regulation of Gs alpha enhanced the activation of myocardial adenylate cyclase by the stimulatory pathway whereas the down-regulation of Gi2 alpha attenuated the deactivation of myocardial adenylate cyclase by the inhibitory pathway. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:7741715

  2. Assessment of magnesium influence on fatty acid content in isolated rat hepatocytes subjected to incubation.

    PubMed

    Całyniuk, B; Grochowska-Niedworok, E; Kardas, M; Muc-Wierzgoń, M; Nowakowska-Zajdel, E

    2016-01-01

    Magnesium salts are components of many dietary supplements used in treatment or prevention of magnesium deficiency. Hypomagnesemia usually results from an improper lifestyle, including unbalanced diet. Isolated hepatocytes of animals or humans are the preferred model used to study the in vitro effects of exogenous factors on cellular metabolic changes. The aim of this study was to evaluate the content of saturated, monounsaturated and polyunsaturated fatty acids and their esters in isolated rat hepatocytes influenced by different magnesium concentrations. The isolated rat hepatocytes were used as the test material. Hepatocytes were prepared in culture medium (Hepatocyte Medium) + MgCl(2) solution to concentrations of 2 mM/dm(3) MgCl(2), 4 mM/dm(3) MgCl(2). After incubation with different concentrations of magnesium ions, changes in the content of fatty acids and their esters were found for the whole hepatocytes and hepatocyte membranes. Despite changes in the fatty acid content in the whole hepatocytes and their membranes, there were no changes in the coefficient of degree of saturation of fatty acids when different concentrations of MgCl2 were used.

  3. Early postweaning social isolation but not environmental enrichment modifies vermal Purkinje cell dendritic outgrowth in rats.

    PubMed

    Pascual, Rodrigo; Bustamante, Carlos

    2013-01-01

    In the present study, we analyzed the effects of enriched, social and isolated experiences on vermal Purkinje cell of the rat, together with anxiety-like behavior in the elevated-plus maze. Sprague-Dawley male rats were randomly submitted to either enriched, social, or isolated environments during the early postweaning period (postnatal days 22-32) and were then behaviorally evaluated in the elevated-plus maze and euthanized for histological analysis. Vermal Purkinje cells (sub-lobules VIa and VIb) were sampled, drawn under camera lucida and morphometrically assessed using the Sholl's concentric ring method. Data obtained indicate that environmental enrichment did not significantly modify the Purkinje cell dendritic branching. On the contrary, Purkinje cell of animals reared in social isolation exhibited a significant reduction in dendritic arborization, which was closely associated with anxiety-like behaviors. The data obtained indicate that, although environmental stimulation in normal animals does not produce significant changes in vermal Purkinje cell dendritic arborization, these cells are vulnerable to early stressful experiences, which is in close association with anxiety-like behaviors.

  4. Quantifying single microvessel permeability in isolated blood-perfused rat lung preparation.

    PubMed

    Kandasamy, Kathirvel; Parthasarathi, Kaushik

    2014-01-01

    The isolated blood-perfused lung preparation is widely used to visualize and define signaling in single microvessels. By coupling this preparation with real time imaging, it becomes feasible to determine permeability changes in individual pulmonary microvessels. Herein we describe steps to isolate rat lungs and perfuse them with autologous blood. Then, we outline steps to infuse fluorophores or agents via a microcatheter into a small lung region. Using these procedures described, we determined permeability increases in rat lung microvessels in response to infusions of bacterial lipopolysaccharide. The data revealed that lipopolysaccharide increased fluid leak across both venular and capillary microvessel segments. Thus, this method makes it possible to compare permeability responses among vascular segments and thus, define any heterogeneity in the response. While commonly used methods to define lung permeability require postprocessing of lung tissue samples, the use of real time imaging obviates this requirement as evident from the present method. Thus, the isolated lung preparation combined with real time imaging offers several advantages over traditional methods to determine lung microvascular permeability, yet is a straightforward method to develop and implement.

  5. Protection of isolated perfused working rat heart from oxidative stress by exogenous L-propionyl carnitine.

    PubMed

    Ronca, G; Ronca, F; Yu, G; Zucchi, R; Bertelli, A

    1992-01-01

    The effect of exogenous L-propionyl carnitine on peroxidative injury was investigated on isolated working rat hearts. The addition of 190 microM hydrogen peroxide to the perfusion buffer caused a marked decrease in aortic flow, minute work and peak aortic pressure, and a release of intracellular enzymes. In the presence of L-propionyl carnitine the haemodynamic damage was significantly lower and enzyme leakage remarkably decreased. The protection was concentration-dependent and the whole structure of the molecule was required, since carnitine alone was found less effective and propionate had no effect. In the absence of hydrogen peroxide L-propionyl carnitine increased heart performance. The effect of L-propionyl carnitine on oxidative stress could account for the beneficial effect of this substance in different models of ischaemic injury. L-propionyl carnitine increases the cardiac performance and protects the rat heart from peroxidation through metabolic and antiperoxidative mechanisms. PMID:1308473

  6. Regulation of vascular tone by UTP and UDP in isolated rat intrapulmonary arteries.

    PubMed

    Rubino, A; Ziabary, L; Burnstock, G

    1999-04-01

    Vasoconstrictor and vasodilator responses of isolated rat intrapulmonary arteries to the pyrimidine nucleotides UTP and UDP were evaluated and compared with vascular responses to ATP and its analogues. UTP and UDP (1-500 microM) were equipotent in inducing concentration-dependent vasoconstriction, unaffected by the P2 receptor antagonists suramin (100 microM) and Reactive blue 2 (50 microM); ATP (10-500 microM) produced weaker vasoconstriction. UTP and UDP lacked vasodilator activity, while ATP and its analogue 2-methylthio ATP evoked endothelium-dependent vasodilatation. These results indicate that UTP and UDP evoke vasoconstriction of rat intrapulmonary arteries whereas ATP is predominantly a vasodilator at the same arteries. Furthermore, the pharmacological profile of the native UTP/UDP receptor differs from that of the known P2Y2, P2Y4 and P2Y6 recombinant receptors for pyrimidine nucleotides.

  7. Arbutus unedo induces endothelium-dependent relaxation of the isolated rat aorta.

    PubMed

    Ziyyat, Abderrahim; Mekhfi, Hassane; Bnouham, Mohamed; Tahri, Abdelhafid; Legssyer, Abdelkhaleq; Hoerter, Jacqueline; Fischmeister, Rodolphe

    2002-09-01

    Arbutus unedo L. (Ericaceae) is used in oriental Morocco to treat arterial hypertension. We studied its vasodilator effect and mechanisms of action in vitro. The root aqueous extract of Arbutus (0.25 mg/mL) produced a relaxation of noradrenaline-precontracted ring preparations of rat aorta with intact endothelium. Relaxation by Arbutus did not occur in specimens without endothelium and was inhibited by pretreatment with 100 microM N(G)-methyl-L-arginine (L-NMA), 10 microM methylene blue or 50 microM 1H-[1,2,4] oxadiazolo [4,3-a] quinoxaline-1-one (ODQ) but not by 10 microM atropine. These results suggest that Arbutus produces an endothelium-dependent relaxation of the isolated rat aorta which may be mediated mainly by a stimulation of the endothelial nitric oxide synthase by mechanisms other than activation of muscarinic receptors. PMID:12237817

  8. Lysophosphatidic acids induce contraction of rat isolated colon by two different mechanisms.

    PubMed

    Tokumura, A; Yube, N; Fujimoto, H; Tsukatani, H

    1991-11-01

    Lysophosphatidic acids (1-linoleoyl-, 1-linolenoyl, 1-arachidonoyl- and 1-O-hexadecyl-sn-glycero-3-phosphate) induced rapid contraction of rat isolated colon which was dependent on external Ca2+, 1-linolenoyl-lysophosphatidic acid having the greatest effect. The contraction induced by 1-linolenoyl-lysophosphatidic acid was reduced considerably by nifedipine and verapamil, but not by atropine or indomethacin. Phosphatidic acids with two short-chain acyl groups induced a small, atropine-sensitive contraction at 100 microM, but phosphatidic acids with two long-chain acyl groups were inactive. These results suggest that unlike phosphatidic acids, lysophosphatidic acids act directly on extracellular sites of the plasma membrane of smooth muscle cells in rat colon, mainly through activation of voltage-sensitive Ca2+ channels.

  9. Characterization of epidermal growth factor receptors on plasma membranes isolated from rat gastric mucosa

    SciTech Connect

    Hori, R.; Nomura, H.; Iwakawa, S.; Okumura, K. )

    1990-06-01

    The binding of human epidermal growth factor (hEGF), beta-urogastrone, to plasma membranes isolated from rat gastric mucosa was studied to characterize gastric EGF receptors. The binding of ({sup 125}I)hEGF was temperature dependent, reversible, and saturable. A single class of binding sites for EGF with a dissociation constant of 0.42 nM and maximal binding capacity of 42 fmol/mg protein was suggested. There was little change in the binding of ({sup 125}I)hEGF upon addition of peptide hormones (secretin, insulin), antiulcer drugs (cimetidine), or an ulcer-inducing reagent (aspirin). Cross-linking of ({sup 125}I)hEGF to gastric plasma membranes with the use of disuccinimidyl suberate resulted in the labeling of a protein of 150 kDa. These results indicate the presence of EGF receptors on plasma membranes of rat gastric mucosa.

  10. Mechanism of the negative inotropic action of leukotrienes C4 and D4 on isolated rat heart.

    PubMed

    Bittl, J A; Pfeffer, M A; Lewis, R A; Mehrotra, M M; Corey, E J; Austen, K F

    1985-07-01

    Leukotrienes C4 and D4 (LTC4 and LTD4), possible mediators of cardiac dysfunction during inflammatory injury, may depress cardiac function by reducing coronary flow or by exerting a negative effect directly on the myocardium. We used an isovolumic rat heart preparation perfused at constant pressure and measured left ventricular developed pressure (mmHg), coronary flow (ml.min-1), oxygen extraction, and myocardial oxygen consumption and delivery (mumol O2.[gramme dry weight]-1.min-1) during infusion of five doses of angiotensin II, LTC4, LTD4 (approximately 10 to approximately 300 pmol.min-1), and noradrenaline (400 to 2000 pmol.min-1), or perfusion with medium which contained calcium at half-concentration. LTC4 and LTD4 were equipotent with angiotensin. At low effective doses, increased oxygen extraction offset the decrease in oxygen delivery, maintaining a stable level of oxygen consumption and left ventricular developed pressure. At the highest doses, angiotensin, LTC4 and LTD4 reduced coronary flow from 21 to 15, 21 to 13, and 21 to 13 ml.min-1, respectively. And, despite greater oxygen extraction of 59%, 58% and 65% for angiotensin, LTC4 and LTD4, left ventricular developed pressure fell from a baseline of 120 mmHg to 113, 106 and 92, respectively. In contrast, low calcium perfusion reduced left ventricular developed pressure (126 to 92) and oxygen extraction (46 to 30%) without changing coronary flow or oxygen delivery. These results suggest that LTC4 and LTD4 are potent coronary vasoconstricting agents which depress cardiac function by limiting oxygen delivery.

  11. Effects of pancreatic polypeptide on insulin action in exocrine secretion of isolated rat pancreas.

    PubMed Central

    Park, H J; Lee, Y L; Kwon, H Y

    1993-01-01

    1. Effects of pancreatic polypeptide (PP) on insulin action in pancreatic exocrine secretion was investigated by using an isolated rat pancreas that was perfused with Krebs-Henseleit solution containing 2.5 mM glucose, 0.1% bovine serum albumin and 3% Dextran T-70 at a vascular flow rate of 1.2 ml min-1. 2. Cholecystokinin-8 (CCK-8) at a concentration of 14 pM stimulated basal flow rate and amylase output of the isolated pancreas. Twenty-five millimolar glucose not only increased the basal flow rate and amylase output but also potentiated the CCK-stimulated flow rate and amylase output. 3. Porcine insulin, administered intra-arterially at a concentration of 100 nM, also increased the basal flow rate and amylase output, and also potentiated the CCK-stimulated flow rate and amylase output. 4. Rat PP, given intra-arterially at a concentration of 10 pM, completely abolished the potentiation effects of both the 25 mM glucose and the exogenous insulin on the CCK-stimulated flow rate and amylase output. Rat PP also inhibited the flow rate and amylase output increased by either 25 mM glucose alone or exogenous insulin alone. However, rat PP did not change the flow rate and amylase output stimulated by CCK-8 alone. 5. These results indicate that insulin is an important stimulatory hormone of pancreatic exocrine secretion, and that PP exerts the inhibitory role in pancreatic exocrine secretion by modulating the insulin action. PMID:7504106

  12. The role of Na(+), K(+)-ATPase in the hypoxic vasoconstriction in isolated rat basilar artery.

    PubMed

    Shen, Haitao; Liang, Peng; Qiu, Suhua; Zhang, Bo; Wang, Yongli; Lv, Ping

    2016-06-01

    Hypoxia-induced cerebrovascular dysfunction is a key factor in the occurrence and the development of cerebral ischemia. Na(+), K(+)-ATPase affects the regulation of intracellular Ca(2+) concentration and plays an important role in vascular smooth muscle function. However, the potential role of Na(+), K(+)-ATPase in hypoxia-induced cerebrovascular dysfunction is unknown. In this study, we found that the KCl-induced contraction under hypoxia in rat endothelium-intact basilar arteries is similar to that of denuded arteries, suggesting that hypoxia may cause smooth muscle cell (SMC)-dependent vasoconstriction in the basilar artery. The Na(+), K(+)-ATPase activity of the isolated basilar artery with or without endothelium significantly reduced with prolonged hypoxia. Blocking the Na(+)-Ca(2+) exchanger with Ni(2+) (10(-3)M) or the L-type Ca(2+) channel with nimodipine (10(-8)M) dramatically attenuated KCl-induced contraction under hypoxia. Furthermore, prolonged hypoxia significantly reduced Na(+), K(+)-ATPase activity and increased [Ca(2+)]i in cultured rat basilar artery SMCs. Hypoxia reduced the protein and mRNA expression of the α2 isoform of Na(+), K(+)-ATPase in SMCs in vitro. We used a low concentration of the Na(+), K(+)-ATPase inhibitor ouabain, which possesses a high affinity for the α2 isoform. The contractile response in the rat basilar artery under hypoxia was partly inhibited by ouabain pretreatment. The decreased Na(+), K(+)-ATPase activity in isolated basilar artery and the increased [Ca(2+)]i in SMCs induced by hypoxia were partly inhibited by pretreatment with a low concentration of ouabain. These results suggest that hypoxia may educe Na(+), K(+)-ATPase activity in SMCs through the α2 isoform contributing to vasoconstriction in the rat basilar artery.

  13. Isolation and characterization of a membrane protein from rat erythrocytes which inhibits lysis by the membrane attack complex of rat complement.

    PubMed Central

    Hughes, T R; Piddlesden, S J; Williams, J D; Harrison, R A; Morgan, B P

    1992-01-01

    The membrane attack complex (MAC) of complement in humans is regulated by several membrane-bound proteins; however, no such proteins have so far been described in other species. Here we report the isolation and characterization of a rat erythrocyte membrane glycoprotein of molecular mass 21 kDa which inserts into cell membranes and is a potent inhibitor of the rat MAC. This protein, here called rat inhibitory protein (RIP), was first partially purified by column chromatography from a butanol extract of rat erythrocyte membranes. Monoclonal antibodies (Mabs) were raised against RIP and used for its affinity purification. Affinity-purified RIP was shown to inhibit in a dose-dependent manner the cobra venom factor (CVF)-mediated 'reactive' lysis of guinea pig erythrocytes by rat complement. Conversely, the anti-RIP MAbs 6D1 and TH9 were shown to markedly enhance the CVF-mediated lysis of rat erythrocytes by rat complement. RIP acted late in the assembly of the MAC (at or after the C5b-8 stage) and was releasable from the membranes of rat erythrocytes by phosphatidylinositol-specific phospholipase C. These features, together with its size, deglycosylation pattern and N-terminal amino acid sequence, lead us to conclude that RIP is the rat homologue of the human MAC-inhibitory protein CD59 antigen. Images Fig. 1. Fig. 3. PMID:1376109

  14. Decreased ribonucleic acid synthesis in isolated rat liver nuclei during starvation

    PubMed Central

    Rickwood, D.; Klemperer, H. G.

    1970-01-01

    1. Isolated nuclei from starved rats showed a lowered incorporation of [14C]UMP into RNA. 2. The Mg2+-dependent incorporation was decreased by 30% after 1 day of starvation, but incorporation in the presence of Mn2+ and ammonium sulphate decreased only after longer periods of starvation. 3. RNA synthesis by nuclei in the presence of excess of added RNA polymerase was unchanged after 1 day of starvation and was inhibited by 20% after 4 days. 4. The capacity of nuclei to bind actinomycin D was unchanged after 1 day and was decreased by 20% after 4 days of starvation. PMID:5493859

  15. Renal accumulation of /sup 99m/Tc-DMSA in the artificially perfused isolated rat kidney

    SciTech Connect

    Goldraich, N.P.; Alvarenga, A.R.; Goldraich, I.H.; Ramos, O.L.; Sigulem, D.

    1985-12-01

    In order to investigate aspects of the renal handling of /sup 99m/Tc-DMSA, 68 isolated rat kidneys were artificially perfused. The experimental groups were: Group 1 (no. = 32)-oxygenated filtering kidneys; Group 2 (no. = 29)-oxygenated non-filtering kidneys; Group 3 (no. = 7)-anaerobic non-filtering kidneys. The authors conclude that the /sup 99m/Tc-DMSA complex is strongly bound to albumin, is not filtered and is removed from perfusion fluid through the renal peritubular capillary route and that this occurs by an active process which depends upon aerobic metabolism. This process has a high capacity and is not inhibited by probenecid.

  16. A diurnal rhythm in the absorption of glucose and water by isolated rat small intestine.

    PubMed

    Fisher, R B; Gardner, M L

    1976-01-01

    1. Glucose and water absorption by isolated small intestine from rats which have had unrestricted access to food is 50-60% higher at night than during the daytime. 2. When the feeding time is restricted to 06.00-09.00 hr G.M.T. glucose and water absorption rates in the period from 3 to 7 hr after withdrawal of food are almost as high as the rates observed at night-time in the animals with unrestricted feeding. 3. These changes in absorption rates appear to be associated with feeding time and not with the pattern of illumination.

  17. Non-nucleolar transcription complexes of rat liver as revealed by spreading isolated nuclei.

    PubMed

    Harper, F; Puvion-Dutilleul, F

    1979-12-01

    Miller's technique was applied to isolated nuclei of rat liver. Both the usual nucleolar and non-nucleolar transcription complexes were visualized. In addition, an unusual type of putative non-ribosomal transcription unit was revealed. It was charcaterized by a high density of the lateral ribonucleoprotein (RNP) fibrils. Although these particular units exhibited a regular increase of fibril lengths, the length of the transcript-covered deoxyribonucleoprotein (DNP) fibres and the morphological aspect of the RNP fibrils distinguished them from the nucleolar 'Christmas-tree'-like figures. The linear and granular configuration of the transcripts and the absence of terminal knobs made them similar to non-nucleolar nascent RNP fibrils.

  18. Ventricular septal defect (image)

    MedlinePlus

    Ventricular septal defect is a congenital defect of the heart, that occurs as an abnormal opening in ... wall that separates the right and left ventricles. Ventricular septal defect may also be associated with other ...

  19. Isolation and partial characterisation of neuronal growth cones from neonatal rat forebrain.

    PubMed

    Gordon-Weeks, P R; Lockerbie, R O

    1984-09-01

    We have devised a method for the isolation of viable neuronal growth cones from neonatal rat forebrain. The method involves differential and density gradient centrifugation and exploits the relatively low buoyant density (approximately 1.018 g/cm3) of growth cones. There are no known biochemical markers for growth cones and it was necessary therefore to monitor for their presence during the isolation using transmission electron microscopy. Several criteria were used to identify isolated growth cones including the presence of filopodia, an extensive system of branching, tubular smooth endoplasmic reticulum and a region rich in microfilaments subjacent to the plasma membrane. These morphological features are similar to those of growth cones identified unequivocally in intact developing brain and in tissue culture. Electron microscopical analysis showed that greater than 90% of membrane-bound, identifiable objects in one fraction were growth cones by these criteria. The major contaminant consisted of membrane sacs and vesicles of unidentified origin. There were only small amounts of isolated rough endoplasmic reticulum and mitochondria. Isolated growth cones were roughly spherical in shape with a diameter of 1.9 +/- 0.5 micron (mean +/- 1 SD). They usually contained mitochondria, large granular vesicles and small vesicles, and occasionally contained coated vesicles, lysosomes, lamellar bodies and multivesicular bodies, and only very rarely, intermediate filaments. Occasionally, growth cones had rudimentary synapses on them. The viability of isolated growth cones was investigated by observing their behaviour in short-term culture. After a few hours in culture on poly-D-lysine-coated coverslips, growth cones flattened down and extended filopodia-like processes. This behaviour was inhibited by cytochalasin B and reversibly by cold (4 degrees C). We conclude that physiologically active growth cones can be isolated rapidly and in large numbers by the method described here.

  20. Social, thermal, and temporal influences on isolation-induced and maternally potentiated ultrasonic vocalizations of rat pups.

    PubMed

    Shair, Harry N; Brunelli, Susan A; Masmela, Jenny R; Boone, Emilie; Hofer, Myron A

    2003-03-01

    Sensory and temporal factors have been demonstrated to be involved in the regulation of isolation-induced ultrasonic vocalizations (USV) of young rats. Sensory cues include thermal, olfactory, and tactile modalities. Temporal factors include the time spent in isolation. The goal of the present research was to examine the interaction of these factors in both isolation-induced and maternally potentiated USV. Maternal potentiation of USV occurs when a brief interaction with the dam, even a passive (anesthetized) dam, elicits an augmented vocal response to a subsequent isolation, with rates of USV in rat pups well above those emitted in standard isolation tests. We found that passive maternal potentiation of USV did occur under all conditions tested. Neither a 30-min prior isolation nor high ambient temperature prevented an increase in USV rate over the rate of the original isolation. After 30-min isolation at warm temperatures when the rate of USV had fallen to zero, the pups increased vocalization in the presence of the dam as well as in the subsequent isolation. Temporal and thermal factors also interacted significantly in regulating the level of the USV emitted by the pups during the first isolation, in the presence of the anesthetized dam, and during the second isolation. PMID:12555284

  1. Uterotonic effect of Harpagophytum procumbens DC (Pedaliaceae) secondary root aqueous extract on rat isolated uterine horns.

    PubMed

    Mahomed, Ismail M; Ojewole, John A O

    2009-10-01

    Some traditional health practitioners of South Africa have claimed that Harpagophytum procumbens DC (family: Pedaliaceae) secondary root is a useful obstetric remedy for induction or acceleration of labour, as well as for expelling retained placentas in pregnant women. In the present study, therefore, we investigated the effect of H. procumbens secondary root aqueous extract (HPE) on longitudinal, tubular uterine horn muscle strips taken from non-pregnant and pregnant, young adult, female rats. HPE (10-800 microg/ml) induced concentration-related and significant (P<0.05) increases in the baseline tone, and caused powerful rhythmic, myogenic contractions of, oestrogen-dominated rat longitudinal uterine horn muscle strips taken from stilboesterol-pretreated, non-pregnant female rats. Relatively low to high concentrations of HPE (10-800 microg/ml) also provoked concentration-dependent and significant (P<0.05-0.001) increases in the baseline tone of, and contracted, longitudinal, tubular uterine horn muscle strips taken from female rats in the early, middle and late stages of pregnancy. Moderate to high concentrations of HPE (200-1,000 microg/ml) always provoked powerful contractions of isolated longitudinal, tubular uterine horn muscle preparations of non-pregnant and pregnant rats. The results of this in vitro study indicate that H. procumbens secondary root aqueous extract possesses spasmogenic, uterotonic action on mammalian uterine muscles. These findings lend pharmacological credence to the suggested folkloric obstetric uses of the plant's secondary root for induction and/or acceleration of labour, as well as for expelling retained placentas in pregnant women. PMID:19907121

  2. Uterotonic effect of Harpagophytum procumbens DC (Pedaliaceae) secondary root aqueous extract on rat isolated uterine horns.

    PubMed

    Mahomed, Ismail M; Ojewole, John A O

    2009-10-01

    Some traditional health practitioners of South Africa have claimed that Harpagophytum procumbens DC (family: Pedaliaceae) secondary root is a useful obstetric remedy for induction or acceleration of labour, as well as for expelling retained placentas in pregnant women. In the present study, therefore, we investigated the effect of H. procumbens secondary root aqueous extract (HPE) on longitudinal, tubular uterine horn muscle strips taken from non-pregnant and pregnant, young adult, female rats. HPE (10-800 microg/ml) induced concentration-related and significant (P<0.05) increases in the baseline tone, and caused powerful rhythmic, myogenic contractions of, oestrogen-dominated rat longitudinal uterine horn muscle strips taken from stilboesterol-pretreated, non-pregnant female rats. Relatively low to high concentrations of HPE (10-800 microg/ml) also provoked concentration-dependent and significant (P<0.05-0.001) increases in the baseline tone of, and contracted, longitudinal, tubular uterine horn muscle strips taken from female rats in the early, middle and late stages of pregnancy. Moderate to high concentrations of HPE (200-1,000 microg/ml) always provoked powerful contractions of isolated longitudinal, tubular uterine horn muscle preparations of non-pregnant and pregnant rats. The results of this in vitro study indicate that H. procumbens secondary root aqueous extract possesses spasmogenic, uterotonic action on mammalian uterine muscles. These findings lend pharmacological credence to the suggested folkloric obstetric uses of the plant's secondary root for induction and/or acceleration of labour, as well as for expelling retained placentas in pregnant women.

  3. Exercise at anaerobic threshold intensity and insulin secretion by isolated pancreatic islets of rats

    PubMed Central

    de Oliveira, Camila Aparecida Machado; Paiva, Mauricio Ferreira; Mota, Clécia Alencar Soares; Ribeiro, Carla; de Almeida Leme, José Alexandre Curiacos; Luciano, Eliete

    2010-01-01

    To evaluate the effect of acute exercise and exercise training at the anaerobic threshold (AT) intensity on aerobic conditioning and insulin secretion by pancreatic islets, adult male Wistar rats were submitted to the lactate minimum test (LMT) for AT determination. Half of the animals were submitted to swimming exercise training (trained), 1 h/day, 5 days/week during 8 weeks, with an overload equivalent to the AT. The other half was kept sedentary. At the end of the experimental period, the rats were submitted to an oral glucose tolerance test and to another LMT. Then, the animals were sacrificed at rest or immediately after 20 minutes of swimming exercise at the AT intensity for pancreatic islets isolation. At the end of the experiment mean workload (% bw) at AT was higher and blood lactate concentration (mmol/L) was lower in the trained than in the control group. Rats trained at the AT intensity showed no alteration in the areas under blood glucose and insulin during OGTT test. Islet insulin content of trained rats was higher than in the sedentary rats while islet glucose uptake did not differ among the groups. The static insulin secretion in response to the high glucose concentration (16.7 mM) of the sedentary group at rest was lower than the sedentary group submitted to the acute exercise and the inverse was observed in relation to the trained groups. Physical training at the AT intensity improved the aerobic condition and altered insulin secretory pattern by pancreatic islets. PMID:21099318

  4. Isolation and characterization of all-trans-retinoic acid-responsive genes in the rat testis.

    PubMed

    Gaemers, I C; Van Pelt, A M; Themmen, A P; De Rooij, D G

    1998-05-01

    By way of differential screening of testis cDNA libraries from vitamin A-deficient (VAD) rats before and after administration of all-trans retinoic acid (ATRA), genes, the transcription of which was influenced by ATRA, were isolated. Most clones with an increased transcription encoded different subunits of the same mitochondrial protein complex, cytochrome c oxidase (COX). The mRNA expression of COX increased by a factor 3.9 +/- 1.5 (mean +/- SD, n = 4). This increased expression seems to reflect an increased energy demand in the ATRA-supplemented VAD testis. Also, one gene was isolated, the transcription of which was reduced to about 70% by ATRA. This gene, sulfated glycoprotein 2 (Sgp-2), is a major secretion product of Sertoli cells, the function of which is still unknown. The effect of ATRA on Sgp-2 expression may be direct, since the promoter of Sgp-2 contains a putative ATRA-responsive element (RARE). PMID:9547504

  5. Direct nephrotoxicity of Russell's viper venom demonstrated in the isolated perfused rat kidney.

    PubMed

    Ratcliffe, P J; Pukrittayakamee, S; Ledingham, J G; Warrell, D A

    1989-03-01

    Envenoming by Russell's Viper (Vipera russelli) is an important cause of acute renal failure. The mechanism of renal damage is unresolved. It is difficult to obtain evidence of a direct nephrotoxic action because of the coincidental disturbance to the systemic circulation. We studied the action of Russell's Viper venom on the function of the isolated perfused rat kidney. Direct nephrotoxic action was indicated by a dose dependent decrease in inulin clearance and an increase in fractional excretion of sodium seen at venom concentrations down to 50 ng/ml, a concentration likely to be achieved in the human circulation after envenoming. The isolated perfused kidney was also used to assess the efficiency of antivenom and for a comparison with snake venoms from the Thai cobra (Naja kauothia) and the Nigerian Saw-Scaled Viper (Echis ocellatus). PMID:2929855

  6. Isolation of insulin-sensitive phosphatidylinositol-glycan from rat adipocytes. Its impaired breakdown in the streptozotocin-diabetic rat.

    PubMed Central

    Macaulay, S L; Larkins, R G

    1990-01-01

    In this study an insulin-sensitive glycophospholipid from rat adipocytes was isolated and partially characterized. A material that activated pyruvate dehydrogenase was extracted from rat adipocyte membrane supernatants. Its release was stimulated by insulin and phosphatidylinositol-specific-phospholipase C and its activity was destroyed by nitrous acid deamination. These findings suggested that insulin might stimulate breakdown of a glycophospholipid containing inositol and glucosamine, as previously reported for some other cell types [Low & Saltiel (1988) Science 239, 268-275]. A lipid that incorporated [3H]glucosamine, [3H]galactose, [3H]inositol, and [3H]myristate and whose turnover was stimulated by insulin was subsequently isolated from intact adipocytes by sequential t.l.c. using an acidic solvent system followed by a basic solvent system. The effects of insulin on turnover of the lipid in these cells were transient, with maximal effects at 1 min, and there was a typical concentration-response curve to insulin (0.07 nM-7 nM), with effects being detected over the physiological range of insulin concentrations. In contrast with studies in other cells, there was appreciable turnover of the sugar labels. The majority of the [3H]glucosamine and [3H]galactose labels were cycled through to triacylglycerol in the adipocyte. However, of that recovered in the glycophospholipid band, a major proportion (less than 40%) was recovered as the native label. Digestion of the purified molecule with phosphatidylinositol-specific phospholipase C generated a material that activated both pyruvate dehydrogenase and low-Km cyclic AMP phosphodiesterase. Impairment in insulin-stimulated breakdown of the molecule in adipocytes of streptozotocin-diabetic rats was found, consistent with the impaired insulin activation of pyruvate dehydrogenase and glucose utilization seen in this model. These findings suggest that insulin stimulates breakdown of this glycophospholipid by stimulating an

  7. Spatiotemporal evolution of ventricular fibrillation

    NASA Astrophysics Data System (ADS)

    Witkowski, Francis X.; Leon, L. Joshua; Penkoske, Patricia A.; Giles, Wayne R.; Spano, Mark L.; Ditto, William L.; Winfree, Arthur T.

    1998-03-01

    Sudden cardiac death is the leading cause of death in the industrialized world, with the majority of such tragedies being due to ventricular fibrillation. Ventricular fibrillation is a frenzied and irregular disturbance of the heart rhythm that quickly renders the heart incapable of sustaining life. Rotors, electrophysiological structures that emit rotating spiral waves, occur in several systems that all share with the heart the functional properties of excitability and refractoriness. These re-entrant waves, seen in numerical solutions of simplified models of cardiac tissue, may occur during ventricular tachycardias,. It has been difficult to detect such forms of re-entry in fibrillating mammalian ventricles. Here we show that, in isolated perfused dog hearts, high spatial and temporal resolution mapping of optical transmembrane potentials can easily detect transiently erupting rotors during the early phase of ventricular fibrillation. This activity is characterized by a relatively high spatiotemporal cross-correlation. During this early fibrillatory interval, frequent wavefront collisions and wavebreak generation are also dominant features. Interestingly, this spatiotemporal pattern undergoes an evolution to a less highly spatially correlated mechanism that lacks the epicardial manifestations of rotors despite continued myocardial perfusion.

  8. The isolation and culture of endothelial colony-forming cells from human and rat lungs.

    PubMed

    Alphonse, Rajesh S; Vadivel, Arul; Zhong, Shumei; Zong, Shumei; McConaghy, Suzanne; Ohls, Robin; Yoder, Mervin C; Thébaud, Bernard

    2015-11-01

    Blood vessels are crucial for the normal development, lifelong repair and homeostasis of tissues. Recently, vascular progenitor cell-driven 'postnatal vasculogenesis' has been suggested as an important mechanism that contributes to new blood vessel formation and organ repair. Among several described progenitor cell types that contribute to blood vessel formation, endothelial colony-forming cells (ECFCs) have received widespread attention as lineage-specific 'true' vascular progenitors. Here we describe a protocol for the isolation of pulmonary microvascular ECFCs from human and rat lung tissue. Our technique takes advantage of an earlier protocol for the isolation of circulating ECFCs from the mononuclear cellular fraction of peripheral blood. We adapted the earlier protocol to isolate resident ECFCs from the distal lung tissue. After enzymatic dispersion of rat or human lung samples into a cellular suspension, CD31-expressing cells are positively selected using magnetic-activated cell sorting and plated in endothelial-specific growth conditions. The colonies arising after 1-2 weeks in culture are carefully separated and expanded to yield pure ECFC cultures after a further 2-3 weeks. The resulting cells demonstrate the defining characteristics of ECFCs such as (i) 'cobblestone' morphology of cultured cell monolayers; (ii) acetylated low-density lipoprotein uptake and Ulex europaeus lectin binding; (iii) tube-like network formation in Matrigel; (iv) expression of endothelial cell-specific surface markers and the absence of hematopoietic or myeloid surface antigens; (v) self-renewal potential displayed by the most proliferative cells; and (vi) contribution to de novo vessel formation in an in vivo mouse implant model. Assuming typical initial cell adhesion and proliferation rates, the entire procedure can be completed within 4 weeks. Isolation and culture of lung vascular ECFCs will allow assessment of the functional state of these cells in experimental and human

  9. The isolation and culture of endothelial colony-forming cells from human and rat lungs.

    PubMed

    Alphonse, Rajesh S; Vadivel, Arul; Zhong, Shumei; Zong, Shumei; McConaghy, Suzanne; Ohls, Robin; Yoder, Mervin C; Thébaud, Bernard

    2015-11-01

    Blood vessels are crucial for the normal development, lifelong repair and homeostasis of tissues. Recently, vascular progenitor cell-driven 'postnatal vasculogenesis' has been suggested as an important mechanism that contributes to new blood vessel formation and organ repair. Among several described progenitor cell types that contribute to blood vessel formation, endothelial colony-forming cells (ECFCs) have received widespread attention as lineage-specific 'true' vascular progenitors. Here we describe a protocol for the isolation of pulmonary microvascular ECFCs from human and rat lung tissue. Our technique takes advantage of an earlier protocol for the isolation of circulating ECFCs from the mononuclear cellular fraction of peripheral blood. We adapted the earlier protocol to isolate resident ECFCs from the distal lung tissue. After enzymatic dispersion of rat or human lung samples into a cellular suspension, CD31-expressing cells are positively selected using magnetic-activated cell sorting and plated in endothelial-specific growth conditions. The colonies arising after 1-2 weeks in culture are carefully separated and expanded to yield pure ECFC cultures after a further 2-3 weeks. The resulting cells demonstrate the defining characteristics of ECFCs such as (i) 'cobblestone' morphology of cultured cell monolayers; (ii) acetylated low-density lipoprotein uptake and Ulex europaeus lectin binding; (iii) tube-like network formation in Matrigel; (iv) expression of endothelial cell-specific surface markers and the absence of hematopoietic or myeloid surface antigens; (v) self-renewal potential displayed by the most proliferative cells; and (vi) contribution to de novo vessel formation in an in vivo mouse implant model. Assuming typical initial cell adhesion and proliferation rates, the entire procedure can be completed within 4 weeks. Isolation and culture of lung vascular ECFCs will allow assessment of the functional state of these cells in experimental and human

  10. Ultracentrifugal isolation of vesicular carriers of biliary cholesterol in native human and rat bile.

    PubMed

    Ulloa, N; Garrido, J; Nervi, F

    1987-01-01

    We have utilized ultracentrifugation of native bile-Metrizamide density gradients to isolate a vesicular transport system of biliary lipids in both man and rat. We identified vesicular structures by electron microscopy. Fresh bile specimens were obtained from bile fistula rats (unsaturated bile) and from patients 1 week after bile duct surgery (supersaturated bile). Metrizamide was dissolved in bile (33% w/v), and continuous density gradients were performed with undiluted bile (density limits = 1.020 to 1.300 gm per ml). The relative distribution of biliary cholesterol, phospholipid and bile salt was studied as a function of the density of the fractions. Approximately 50% of total rat biliary cholesterol and between 61 and 90% of human biliary cholesterol was concentrated in the lightest fractions of the gradients (density less than 1.060 gm per ml). In contrast, less than 20% of bile salts was present in fractions with densities lower than 1.060 gm per ml. The highest amounts of bile salts and phospholipids of the bile-Metrizamide density gradients were found in the density range of 1.075 to 1.100 gm per ml in both human and rat bile. More than 80% of biliary proteins was found in fractions with densities greater than 1.075 gm per ml, and only 2% was found in the cholesterol-rich fraction with density less than 1.060 gm per ml in both species. When bile salt concentration was raised in rat bile from 38 to 97 mM by adding taurocholate, the low density cholesterol-rich fraction almost disappeared. Electron microscopy of negatively stained preparations of the fractions with density less than 1.060 gm per ml showed 40 to 120 nm vesicles, which were not apparent in the other fractions. Similar vesicles were demonstrated also in fresh rat bile and within the canaliculi after acute depletion of the bile salt pool (biliary bile salt concentration of 3.45 mM; total biliary lipid concentration of 0.25 gm%). The structure of these vesicles was shown in thin sections of liver

  11. Isolation of Leptospira interrogans from suburban rats in Tandil, Buenos Aires, Argentina.

    PubMed

    Scialfa, E; Bolpe, J; Bardón, J C; Ridao, G; Gentile, J; Gallicchio, O

    2010-01-01

    The main objective of this study was to investigate the role of wild rodents as Leptospira spp. reservoirs in a suburban area of Tandil city, Buenos Aires province (Argentina), where a person had died due to pulmonary leptospirosis. The specific objectives were: to estimate the rodent density near the patient's home, to determine the serological prevalence and isolation of leptospirosis from wild rodents, and to identify the isolated strains. The area examined was a suburban neighbourhood in Tandil near the Langueyú stream, where the patient's house is located. Rattus norvegicus were trapped on the stream banks during two nights and a high capture rate (70%), was obtained. All rats (42) were examined serologically by the microscopic agglutination test (MAT), and 22 of them (52.3%) reacted with Leptospira serovars castellonis, canicola, grippotyphosa, icterohaemorrhagiae and hebdomadis at a titer of 1:50. The kidneys from 25 animals were cultured, and 24 isolates of L. interrogans (96%) were obtained. The isolated strains were identified as Icterohaemorrhagiae serogroup by MAT performed with rabbit hyperimmune reference sera. These findings showed a high density of suburban rodents highly infected with pathogenic leptospira, sharing environment in close contact with humans with evidence of leptospiral disease.

  12. Distribution of capillary transit times in isolated lungs of oxygen-tolerant rats.

    PubMed

    Ramakrishna, Madhavi; Gan, Zhuohui; Clough, Anne V; Molthen, Robert C; Roerig, David L; Audi, Said H

    2010-11-01

    Rats pre-exposed to 85% O₂ for 5-7 days tolerate the otherwise lethal effects of 100% O₂. The objective was to evaluate the effect of rat exposure to 85% O₂ for 7 days on lung capillary mean transit time t(c) and distribution of capillary transit times (h(c)(t)). This information is important for subsequent evaluation of the effect of this hyperoxia model on the redox metabolic functions of the pulmonary capillary endothelium. The venous concentration vs. time outflow curves of fluorescein isothiocyanate labeled dextran (FITC-dex), an intravascular indicator, and coenzyme Q₁ hydroquinone (CoQ₁H₂), a compound which rapidly equilibrates between blood and tissue on passage through the pulmonary circulation, were measured following their bolus injection into the pulmonary artery of isolated perfused lungs from rats exposed to room air (normoxic) or 85% O₂ for 7 days (hyperoxic). The moments (mean transit time and variance) of the measured FITC-dex and CoQ₁H₂ outflow curves were determined for each lung, and were then used in a mathematical model [Audi et al. J. Appl. Physiol. 77: 332-351, 1994] to estimate t(c) and the relative dispersion (RD(c)) of h (c)(t). Data analysis reveals that exposure to hyperoxia decreases lung t(c) by 42% and increases RD(c), a measure h(c)(t) heterogeneity, by 40%.

  13. Isolation of a bile salt sulfatase-producing Clostridium strain from rat intestinal microflora.

    PubMed Central

    Huijghebaert, S M; Mertens, J A; Eyssen, H J

    1982-01-01

    Bile acid sulfates, formed in human and rat livers, are desulfated by the intestinal microflora. In our study we first isolated from conventional rat feces an unnamed bacterium, termed strain S1, which desulfated the 5 beta-bile salt 3 alpha-sulfates in vitro and in vivo after association with gnotobiotic rats. Strain S1 also possessed 12 alpha-hydroxysteroid dehydrogenase and bile salt-deconjugating activities. The strain was a strict anaerobic, CO2-requiring, gram-negative, sporeforming rod and was designated as belonging to the genus Clostridium. Growth was scarce in culture media, unless in the presence of 0.1% taurine, a sulfur-containing amino acid. Addition of this substance raised the number of bacteria in thioglycolate and peptone yeast media from 10(4) per ml to 10(6) to 10(7) per ml and increased the colony diameter on agar medium from 0.2 mm to 0.5 to 0.9 mm. Sulfatase activity was specific for the 5 beta-bile salt sulfates, leaving the 5 alpha-bile salt sulfates unchanged. In addition, the sulfatase activity was cell bound, and its production was dependent on the composition of the culture medium, although no minimal sulfur medium was required for sulfatase activity. Images PMID:7055372

  14. Exogenous Angiotensin I Metabolism in Aorta Isolated from Streptozotocin Treated Diabetic Rats

    PubMed Central

    Bujak-Giżycka, B.; Jawień, J.; Olszanecki, R.; Madej, J.; Rutowski, J.; Korbut, R.

    2016-01-01

    Purpose. Products of angiotensin (ANG) I metabolism may predispose to vascular complications of diabetes mellitus. Methods. Diabetes was induced with streptozotocin (75 mg/kg i.p.). Rat aorta fragments, isolated 4 weeks later, were pretreated with perindoprilat (3 μM), thiorphan (3 μM), or vehicle and incubated for 15 minutes with ANG I (1 μM). Products of ANG I metabolism through classical (ANG II, ANG III, and ANG IV) and alternative (ANG (1–9), ANG (1–7), and ANG (1–5)) pathways were measured in the buffer, using liquid chromatography-mass spectrometry. Results. Incubation with ANG I resulted in higher concentration of ANG II (P = 0.02, vehicle pretreatment) and lower of ANG (1–9) (P = 0.048, perindoprilat pretreatment) in diabetes. Preference for the classical pathway is suggested by higher ANG III/ANG (1–7) ratios in vehicle (P = 0.03), perindoprilat (P = 0.02), and thiorphan pretreated (P = 0.02) diabetic rat. Within the classical pathway, ratios of ANG IV/ANG II (P = 0.01) and of ANG IV/ANG III (P = 0.049), but not of ANG III/ANG II are lower in diabetes. Conclusions. Diabetes in rats led to preference toward deleterious (ANG II, ANG III) over protective (ANG IV, ANG (1–9), and ANG (1–7)) ANG I metabolites. PMID:27803936

  15. Direct cardiac effects of dobutamine, dopamine, epinephrine, and levosimendan in isolated septic rat hearts.

    PubMed

    Zausig, York A; Geilfus, Diana; Missler, Goetz; Sinner, Barbara; Graf, Bernhard M; Zink, Wolfgang

    2010-09-01

    In septic patients, myocardial depression-the so-called septic cardiomyopathy-needing inotropic support is common. The aim of this study was to compare the dose-responsive electrophysiological and mechanical properties concerning metabolic effects of clinically available inotropic agents in an isolated septic rat heart model. After 20 h of incubation, both sham-operated and septic (cecal ligation and single puncture) hearts from male Wistar rats (n = 64) were isolated and received dobutamine, dopamine, epinephrine, or levosimendan at concentrations of 10 to 10 M. Electrophysiological, mechanical, and metabolic properties were measured, and the myocardial oxygen supply-demand ratio and cardiac efficiency were calculated. With the exception of levosimendan, all of the drugs tested showed dose-dependent, significantly positive changes in chronotropy, inotropy, and lusitropy in all hearts. Maximum increases in septic hearts were dose-dependent and were ordered as follows: epinephrine > dopamine > dobutamine > levosimendan. These increases in cardiac performance were accompanied by a decrease in the myocardial oxygen supply-demand ratio. However, cardiac efficiency was significantly improved in the epinephrine-treated septic hearts. With the drug-induced increase in cardiac performance, the myocardial oxygen supply-demand ratio decreased proportionally in the epinephrine-, dobutamine-, and dopamine-treated septic hearts. However, epinephrine showed the most favorable results with regard to cardiac efficiency, and levosimendan showed no beneficial effect in septic hearts with regard to efficiency in this study.

  16. Comparative cytotoxicity between butylated hydroxytoluene and its methylcarbamate derivative, terbucarb, on isolated rat hepatocytes

    SciTech Connect

    Nakagawa, Y.; Yaguchi, K.; Suzuki, T. )

    1994-08-01

    Butylated hydroxytoluene (3,5-di-tert-butyl-4-hydroxytoluene; BHT) is widely used as phenolic antioxidant in processed foods, cosmetics and petroleum products. It is well known that high doses of BHT cause acute hepatic damage accompanied by centrilobular necrosis in rats. The hepatic damage is associated with prolonged depletion of glutathione (GSH). Terbucarb (2,6-di-tert-butyl-para-tolyl-methylcarbamate), which has a methylcarbamate group substituted for the phenol group on BHT, was developed as an insecticide and is also presently used as a herbicide on turfgrass. Despite the metabolic and toxicological details known about BHT in vivo and in vitro, no extensive studies have been reported on the metabolism and toxicity of Terbucarb. The isolated hepatocyte system provides a very useful system for the study of the temporal sequences leading to cell damage caused by chemicals and drugs. Here, using freshly isolated rat hepatocytes, we report on the comparative toxic effects of BHT and its methylcarbamate derivative, Terbucarb. 17 refs., 2 figs., 2 tabs.

  17. Intestinal microflora in rats: isolation and characterization of strictly anaerobic bacteria requiring long-chain fatty acids.

    PubMed Central

    Morotomi, M; Kawai, Y; Mutai, M

    1976-01-01

    Three strains of strictly anaerobic bacteria, isolated from the cecal contents of rats, have strict requirements for long-chain fatty acids. The effect of exogenous fatty acids on the growth and fatty acid composition of the bacteria was examined. Biohydrogenation of linoleic acid into octadecenoic acid was observed. These observations suggest that long-chain fatty acids in the intestine are factors in controlling the localization and the population levels of indigenous bacteria in vivo in rats. PMID:1267446

  18. Leptin decreases heart rate associated with increased ventricular repolarization via its receptor.

    PubMed

    Lin, Yen-Chang; Huang, Jianying; Hileman, Stan; Martin, Karen H; Hull, Robert; Davis, Mary; Yu, Han-Gang

    2015-11-15

    Leptin has been proposed to modulate cardiac electrical properties via β-adrenergic receptor activation. The presence of leptin receptors and adipocytes in myocardium raised a question as to whether leptin can directly modulate cardiac electrical properties such as heart rate and QT interval via its receptor. In this work, the role of local direct actions of leptin on heart rate and ventricular repolarization was investigated. We identified the protein expression of leptin receptors at cell surface of sinus node, atrial, and ventricular myocytes isolated from rat heart. Leptin at low doses (0.1-30 μg/kg) decreased resting heart rate; at high doses (150-300 μg/kg), leptin induced a biphasic effect (decrease and then increase) on heart rate. In the presence of high-dose propranolol (30 mg/kg), high-dose leptin only reduced heart rate and sometimes caused sinus pauses and ventricular tachycardia. The leptin-induced inhibition of resting heart rate was fully reversed by leptin antagonist. Leptin also increased heart rate-corrected QT interval (QTc), and leptin antagonist did not. In isolated ventricular myocytes, leptin (0.03-0.3 μg/ml) reversibly increased the action potential duration. These results supported our hypothesis that in addition to indirect pathway via sympathetic tone, leptin can directly decrease heart rate and increase QT interval via its receptor independent of β-adrenergic receptor stimulation. During inhibition of β-adrenergic receptor activity, high concentration of leptin in myocardium can cause deep bradycardia, prolonged QT interval, and ventricular arrhythmias.

  19. Troxerutin protects the isolated perfused rat liver from a possible lipid peroxidation by coumarin.

    PubMed

    Adam, B S; Pentz, R; Siegers, C P; Strubelt, O; Tegtmeier, M

    2005-01-01

    For more than 40 years coumarin has been successfully used in the therapy of chronic venous insufficiency (CVI). The occurrence of liver injuries is rather rare and happens predominantly when doses are administered which are significantly higher than necessary for therapeutical use. Such effects caused by high coumarin concentrations are reproducible in in vivo experiments in mice or rats and HepG2-cells. In order to characterize the mechanism of liver injuries, the isolated perfused rat liver has been chosen as model. Since liver injuries are quite rare, if coumarin is used in co-medication with troxerutin, a possible protective influence of this flavonoid has been investigated. In concentrations higher than 4 mmol/l, coumarin alone is effective in the isolated perfused rat liver. Then the release of the enzymes alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) increases and there is a measurable reduction of perfusion flow, oxygen consumption and rate of bile secretion. Additionally, the concentrations of hepatic adenosine triphosphate (ATP) and oxidized and total glutathione (GSSG/GSH) decrease. In the livers of fasting animals, coumarin doubles the concentration of hepatic malondialdehyde (MDA). This effect cannot be detected if troxerutin is added. In general, troxerutin reduces the concentration of all coumarin-metabolites in the perfusate and bile and changes the ratio of the main metabolites, coumarin: 3-hydroxycoumarin: 7-hydroxycoumarin. An analysis of the metabolic steps also shows that the amount of coumarin eliminated via faeces does not stem from absorbed coumarin, because the amount of orally applied coumarin detectable in the bile is less than 1%. The study demonstrates that troxerutin has hepatoprotective properties and thus protects the liver from a possible lipid peroxidation caused by coumarin. However, it is necessary to point out that these adverse effects caused by coumarin can be detected only in very high concentrations

  20. Alterations to prepulse inhibition magnitude and latency in adult rats following neonatal treatment with domoic acid and social isolation rearing.

    PubMed

    Marriott, Amber L; Tasker, R Andrew; Ryan, Catherine L; Doucette, Tracy A

    2016-02-01

    Deficits in perceptual, informational, and attentional processing are consistently identified as a core feature in schizophrenia and related neuropsychiatric disorders. Neonatal injections of low doses of the AMPA/kainate agonist domoic acid (DOM) have previously been shown to alter various aspects of perceptual and attentional processing in adult rats. The current study investigated the effects of combined neonatal DOM treatment with isolation rearing on prepulse inhibition behaviour and relevant neurochemical measures, to assess the usefulness of these paradigms in modeling neurodevelopmental disorders. Daily subcutaneous injections of DOM (20 μg/kg) or saline were administered to male and female rat pups from postnatal days (PND) 8-14. After weaning, rats were either housed alone or in groups of 4. Both the magnitude and latency of prepulse inhibition were determined in adulthood (approximately 4.5 months of age) and post-mortem brain tissue was assayed using Western blot. Social isolation alone significantly lowered PPI magnitude in male (but not female) rats while DOM treatment appeared to make animals refractory to this effect. Combining social isolation and DOM treatment caused an additive decrease in PPI startle latency. No statistically significant differences were found in the expression of D1, D2, TH, GAD65 or GAD67 protein in either the prefrontal cortex or hippocampus, although some tendencies toward differences were noted. We conclude that both neonatal low-dose DOM and social isolation affect prepulse inhibition in rats but that each paradigm exerts these effects through different neuronal signalling systems.

  1. Mechanism of UV light-induced photorelaxation in isolated rat aorta.

    PubMed

    Kim, J H; Hong, Y; Shim, C S

    2000-12-01

    Isolated rat thoracic aorta which is pharmacologically precontracted by phenylephrine induces photorelaxation when exposed to long wave length UV-light. The aim of the present study was to characterize the mechanism of UV-light induced by photorelaxation in the rat aorta. 1. UV light relaxed both endothelium-intact and -denuded rat aortic rings contracted by phenylephrine. The magnitude of relaxation on UV light was dependent on the exposure time and slightly greatly in endothelium-denuded rings than in endothelium-intact preparations. 2. L-NAME (10 nM-100 uM) but not D-NAME completely inhibited the photorelaxation in a concentration dependent manner. 3. The UV-induced relaxation was inhibited by methylene blue (1 -100 uM), and verapamil (100 nM), and removal of extracellular Ca2+. In contrast, UV-light induced photorelaxation was potentiated by N(w)-nitro-Larginine (L-NOARG) treatment. 4. In immunocytochemical analysis of UV-light induced iNOS and eNOS expression in rat aortas, at which expression levels were increased in a time-dependent manner on UV-irradiation in aortic endothelium and smooth muscle, respectively. These results suggest that UV light-induced photorelaxation may be due to nitric oxide from exogenously administered L-arginine as well as endogenous nitric oxide donors such as amino acid and arginine derivatives. Additional suggestion is that UV light stimulates the expression of nitric oxide synthases, and its activity for nitric oxide generation is dependent on cytosolic Ca2+ originated from extracellular space.

  2. Optical mapping analysis of the spatiotemporal pattern of experimental tachyarrhythmia in improved isolated rat atrium preparation.

    PubMed

    Sakai, Tetsuro

    2008-04-01

    We have studied the experimental tachyarrhythmia in an improved isolated rat atrial preparation for the optical mapping of excitation spread. The atrial preparation, including the right or left auricle, was dissected from the adult rat heart, and an artificial hole was made in the center of the preparation. The preparation was then stained with a fast merocyanine-rhodanine voltage-sensitive dye (NK2761). Using a multi-element (16 x 16) photodiode array, the spread of excitation was assessed optically by timing the initiation of the action potential-related extrinsic absorption changes. In comparison with the intact isolated right atrial preparation, which we used previously, the mapping of the excitation spread was much easier and more precise because of the simple structure of the preparation. The electrical stimulation applied by a bipolar electrode evoked the sustained excitation with a fast rhythm, which we termed "experimental tachyarrhythmia" (ET). We optically mapped the spatiotemporal patterns of the spread of excitation during the initiation and the maintenance phases of ET. In most cases, a rotation of the excitatory wave around the artificial hole, i.e., a circus movement of the excitatory wave, was observed. These maps suggest that this circus movement resembles the basic mechanism of the tachycardia-like excitation observed in the intact isolated right atrial preparation. On the other hand, the appearance of an ectopic pacemaker with a fast rhythm was also observed. In some examples, two ectopic pacemakers appeared simultaneously. We consider that the experiment using the improved preparation is a superb in vitro model of atrial arrhythmia.

  3. High virulence in hamsters of four dominant Leptospira serovars isolated from rats in the Philippines.

    PubMed

    Villanueva, Sharon Y A M; Saito, Mitsumasa; Tsutsumi, Yutaka; Segawa, Takaya; Baterna, Rubelia A; Chakraborty, Antara; Asoh, Tatsuma; Miyahara, Satoshi; Yanagihara, Yasutake; Cavinta, Lolita L; Gloriani, Nina G; Yoshida, Shin-ichi

    2014-02-01

    Leptospirosis is caused by pathogenic species of Leptospira. The aim of this study was to determine and characterize the pathogenicity of four dominant Leptospira isolates prevailing among rats in the Philippines. The isolates were Leptospira interrogans serovar Manilae strain K64, L. interrogans serovar Losbanos strain K37, L. interrogans serovar Ratnapura strain K5 and Leptospira borgpetersenii serovar Javanica strain K6. Pathogenicities were studied using hamsters, which reproduce severe human leptospirosis. The minimum lethal doses were 10(0) ( = 1) leptospires for K64, K37 and K5, and 10(1) leptospires for K6. Weight loss amongst the Leptospira-infected hamsters was observed from 1 day before death (K64-, K37- and K5-infected hamsters) to as much as 1 week before death for K6-infected hamsters. Similar and varied gross and microscopic lesions were observed amongst infected hamsters, even for strains belonging to the same species (i.e. L. interrogans). The most significant and common histopathological findings were congestion of the glomerulus, disarrangement of hepatic cords and erythrophagocytosis. Other findings were foamy splenic macrophages for K6, severe petechial pulmonary haemorrhage for K64, and hematuria and severe pulmonary congestion for K37. Immunostaining and culture revealed the presence of leptospires in different organs of the infected hamsters. Based on these results, Leptospira isolates from rats in the Philippines were shown to be highly virulent, causing pulmonary haemorrhage, severe hepato-renal damage and death in hamsters even at lower doses. The present findings on experimental leptospirosis support clinical data showing that patients with severe manifestations of leptospirosis, such as pulmonary haemorrhage, are increasing in the Philippines. These findings may serve as a basis to strengthen the early diagnosis and treatment of human leptospirosis.

  4. RNA-sequencing data analysis of uterus in ovariectomized rats fed with soy protein isolate,17B-estradiol and casein

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This data file describes the bioinformatics analysis of uterine RNA-seq data comparing genome wide effects of feeding soy protein isolate compared to casein to ovariectomized female rats age 64 days relative to treatment of casein fed rats with 5 ug/kg/d estradiol and relative to rats treated with e...

  5. The isolation and properties of epithelial-cell "ghosts" from rat small intestine.

    PubMed

    Clark, B; Porteous, J W

    1965-08-01

    1. The preparation of gram quantities of isolated epithelial-cell ;ghosts' from mucosal scrapings of rat small intestine is described. The method involves dispersing the tissue by gentle homogenization in 6% dextran in Krebs-Ringer phosphate, pH7.4, followed by filtration through nylon cloth and sedimentation by low-speed centrifuging. 2. The isolated epithelial-cell ;ghosts' contained all of the DNA, but only 52% of the protein and 53-57% of the RNA of the original homogenate. They contained most of the activity of the following enzymes found in the homogenate: aminopeptidase (71%); alkaline beta-glycerophosphatase (82%); invertase (92%); adenosine triphosphatase (93-116%); acid beta-glycerophosphatase (83%); nonspecific esterase (76%); succinate dehydrogenase (96%). Only small proportions of the total lactate-dehydrogenase (10%) and phosphoglucose-isomerase (2%) activities found in the homogenate were recovered in the isolated cell ;ghosts'. 3. The epithelial-cell ;ghost' preparation did not respire unless cofactors and substrates were added, and did not consume glucose or produce lactic acid from glucose. 4. The effect of varying the composition of the homogenization medium was studied. Concentrations of dextran (mol.wt. 15x10(4)) from 1 to 12%, solutions of dextrans (all at 6%) with mol.wt. varying between 3.6x10(4) and 2x10(6), and a solution of 8% polyethylene glycol (mol.wt. 4000) served equally well for the production of epithelial-cell ;ghosts'. Two of these solutions, however, 12% dextran (mol.wt.15x10(4)) and 6% dextran (mol.wt. 2x10(6)), were too viscous to allow the complete sedimentation of the cell ;ghosts' at low relative centrifugal forces. Omission of either Krebs-Ringer phosphate or dextran from the medium resulted in almost complete cell breakage during the homogenization. 5. The isolated cell ;ghosts' were used as a starting material for subcellular fractionation of rat intestinal mucosa by differential centrifugation. The distributions of

  6. A study on premature ventricular contractions caused by ultrasound exposure with microbubbles using cultured ventricular muscle cells

    NASA Astrophysics Data System (ADS)

    Kudo, N.; Yokoyama, G.; Ikebuchi, M.; Okada, K.; Kawahara, K.; Yamamoto, K.

    2004-01-01

    It has been shown that diagnostic ultrasound examination using a contrast agent can cause premature ventricular contractions (PVCs). In this study, we investigated a usefulness of a new technique using cultured cardiac myocytes to study mechanisms of PVC production. Cardiac myocytes were isolated from neonatal rats and cultured on a cover glass. The cover glass was attached to an observation chamber in which it was possible to observe changes in myocytes during ultrasound exposure. In the experiments, cardiac myocytes were exposed to pulsed ultrasound in the presence and absence of microbubbles. The pressure amplitudes (peak-negative pressures) were set at 5 steps, -0.28, -0.55, -0.73, -0.92 and -1.1 MPa, and threshold pressure to produce a PVC was recorded. The results showed that the presence of microbubbles attached to a cell reduces threshold pressure for producing PVCs, and it was concluded that our method is useful for studying the mechanisms of PVC production.

  7. Antiapoptotic effects of cerium oxide and yttrium oxide nanoparticles in isolated rat pancreatic islets.

    PubMed

    Hosseini, A; Baeeri, M; Rahimifard, M; Navaei-Nigjeh, M; Mohammadirad, A; Pourkhalili, N; Hassani, S; Kamali, M; Abdollahi, M

    2013-05-01

    Type I diabetes mellitus is a metabolic disease caused by the impairment of pancreatic β-cells mainly mediated through oxidative stress and related apoptosis. Islets transplantation seems a promising treatment for these patients, but during islets transplant, various types of stresses related to the isolation and transplantation procedure compromise the function and viability of islets. We recently hypothesized that the combination of cerium oxide (CeO2) and yttrium oxide (Y2O3) nanoparticles with a potential free radical scavenger behavior should be useful to make isolated islets survive until transplanted. In the present study, oxidative stress-induced apoptosis in isolated rat pancreatic islets exposed to hydrogen peroxide (H2O2) and the protective effects of CeO2 and Y2O3 nanoparticles were investigated. Exposure of islets to H2O2 (50 µm, 2 h) increased intracellular oxidant formation such as reactive oxygen species and subsequently apoptosis and decreased viability, glucose-induced adenosine triphosphate (ATP) production and glucose-stimulated insulin secretion. Pretreatment with CeO2 and/or Y2O3 nanoparticles reduced the oxidant formation and apoptosis and increased viability, glucose-induced ATP production and glucose-stimulated insulin secretion. These results suggest that this combination may protect β-cell apoptosis by improving the oxidative stress-mediated apoptotic pathway.

  8. Mitochondrial oxidative stress and dysfunction induced by isoniazid: study on isolated rat liver and brain mitochondria.

    PubMed

    Ahadpour, Morteza; Eskandari, Mohammad Reza; Mashayekhi, Vida; Haj Mohammad Ebrahim Tehrani, Kamaleddin; Jafarian, Iman; Naserzadeh, Parvaneh; Hosseini, Mir-Jamal

    2016-01-01

    Isoniazid (INH or isonicotinic hydrazide) is used for the treatment and prophylaxis of tuberculosis. Liver and brain are two important target organs in INH toxicity. However, the exact mechanisms behind the INH hepatotoxicity or neurotoxicity have not yet been completely understood. Considering the mitochondria as one of the possible molecular targets for INH toxicity, the aim of this study was to evaluate the mechanisms of INH mitochondrial toxicity on isolated mitochondria. Mitochondria were isolated by differential ultracentrifugation from male Sprague-Dawley rats and incubated with different concentrations of INH (25-2000 μM) for the investigation of mitochondrial parameters. The results indicated that INH could interact with mitochondrial respiratory chain and inhibit its activity. Our results showed an elevation in mitochondrial reactive oxygen species (ROS) formation, lipid peroxidation and mitochondrial membrane potential collapse after exposure of isolated liver mitochondria in INH. However, different results were obtained in brain mitochondria. Noteworthy, significant glutathione oxidation, adenosine triphosphate (ATP) depletion and lipid peroxidation were observed in higher concentration of INH, as compared to liver mitochondria. In conclusion, our results suggest that INH may initiate its toxicity in liver mitochondria through interaction with electron transfer chain, lipid peroxidation, mitochondrial membrane potential decline and cytochrome c expulsion which ultimately lead to cell death signaling.

  9. Protective effects of Sesamum indicum extract against oxidative stress induced by vanadium on isolated rat hepatocytes.

    PubMed

    Hosseini, Mir-Jamal; Shahraki, Jafar; Tafreshian, Saman; Salimi, Ahmad; Kamalinejad, Mohammad; Pourahmad, Jalal

    2016-08-01

    Vanadium toxicity is a challenging problem to human and animal health with no entirely understanding cytotoxic mechanisms. Previous studies in vanadium toxicity showed involvement of oxidative stress in isolated liver hepatocytes and mitochondria via increasing of ROS formation, release of cytochrome c and ATP depletion after incubation with different concentrations (25-200 µM). Therefore, we aimed to investigate the protective effects of Sesamum indicum seed extract (100-300 μg/mL) against oxidative stress induced by vanadium on isolated rat hepatocytes. Our results showed that quite similar to Alpha-tocopherol (100 µM), different concentrations of extract (100-300 μg/mL) protected the isolated hepatocyte against all oxidative stress/cytotoxicity markers induced by vanadium in including cell lysis, ROS generation, mitochondrial membrane potential decrease and lysosomal membrane damage. Besides, vanadium induced mitochondrial/lysosomal toxic interaction and vanadium reductive activation mediated by glutathione in vanadium toxicity was significantly (P < 0.05) ameliorated by Sesamum indicum extracts. These findings suggested a hepato-protective role for extracts against liver injury resulted from vanadium toxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 979-985, 2016.

  10. Ethanol-induced impairment of hepatic glycoprotein secretion in the isolated rat liver perfusion model

    SciTech Connect

    Volentine, G.D.; Ogden, K.A.; Tuma, D.J.; Sorrell, M.F.

    1987-05-01

    The authors have previously shown that acute administration of ethanol inhibits hepatic glycoprotein secretion in vivo. This ethanol-induced effect appears to be mediated by its reactive metabolite, acetaldehyde. Since hormonal influences and vascular changes can not be controlled in vivo during ethanol administration, they investigated the effect of ethanol in the isolated perfused liver model. Rat liver from fed animals was perfused with oxygenated KRB at 3 ml/min/g liver for 4 hrs. Since ethanol inhibits proteins synthesis in vitro, protein acceptor pool size was equalized in both ethanol and control perfused livers with 1 mM cycloheximide. /sup 3/H-glucosamine was used to label hepatic secretory glycoproteins in the perfusate. Colchicine, a known inhibitor of protein secretion, impaired the secretion of labeled glycoproteins with a concomitant retention of these export proteins in the liver; therefore, confirming the authors secretory model. Ethanol (50 mM) inhibited the appearance of glucosamine-labeled glycoproteins by 60% into the perfusate as compared to control livers. Pretreatment of animals with cyanamide (an aldehyde dehydrogenase inhibitor) further potentiated this effect of ethanol in the isolated perfused liver. These data suggest that ethanol inhibits hepatic glycoprotein secretion in the isolated liver perfusion model, and this ethanol-induced impairment appears to be mediated by acetaldehyde.

  11. Contribution of Social Isolation, Restraint, and Hindlimb Unloading to Changes in Hemodynamic Parameters and Motion Activity in Rats

    PubMed Central

    Tsvirkun, Darya; Bourreau, Jennifer; Mieuset, Aurélie; Garo, Florian; Vinogradova, Olga; Larina, Irina; Navasiolava, Nastassia; Gauquelin-Koch, Guillemette; Gharib, Claude; Custaud, Marc-Antoine

    2012-01-01

    The most accepted animal model for simulation of the physiological and morphological consequences of microgravity on the cardiovascular system is one of head-down hindlimb unloading. Experimental conditions surrounding this model include not only head-down tilting of rats, but also social and restraint stresses that have their own influences on cardiovascular system function. Here, we studied levels of spontaneous locomotor activity, blood pressure, and heart rate during 14 days under the following experimental conditions: cage control, social isolation in standard rat housing, social isolation in special cages for hindlimb unloading, horizontal attachment (restraint), and head-down hindlimb unloading. General activity and hemodynamic parameters were continuously monitored in conscious rats by telemetry. Heart rate and blood pressure were both evaluated during treadmill running to reveal cardiovascular deconditioning development as a result of unloading. The main findings of our work are that: social isolation and restraint induced persistent physical inactivity, while unloading in rats resulted in initial inactivity followed by normalization and increased locomotion after one week. Moreover, 14 days of hindlimb unloading showed significant elevation of blood pressure and slight elevation of heart rate. Hemodynamic changes in isolated and restrained rats largely reproduced the trends observed during unloading. Finally, we detected no augmentation of tachycardia during moderate exercise in rats after 14 days of unloading. Thus, we concluded that both social isolation and restraint, as an integral part of the model conditions, contribute essentially to cardiovascular reactions during head-down hindlimb unloading, compared to the little changes in the hydrostatic gradient. PMID:22768322

  12. Cyclic AMP-dependent protein phosphorylation in isolated neuronal growth cones from developing rat forebrain.

    PubMed

    Lockerbie, R O; Eddé, B; Prochiantz, A

    1989-03-01

    We have shown recently that neuronal growth cones isolated from developing rat forebrain possess an appreciable activity of adenylate cyclase, which produces cyclic AMP and can be stimulated by various neurotransmitter receptor agonists and by forskolin. To investigate cyclic AMP-mediated biochemical mechanisms in isolated growth cones, we have centered the present study on cyclic AMP-dependent protein phosphorylation. One-dimensional gel electrophoretic analysis showed that cyclic AMP analogs increased incorporation of 32P into several phosphoproteins in molecular mass ranges of 50-58 and 76-82 kilodaltons, including those of 82, 76, and 51 kilodaltons. Two-dimensional electrophoresis, using isoelectric focusing in the first dimension, resolved phosphorylated alpha- and beta-tubulin species, actin, a very acidic protein (isoelectric point 4.0) with a molecular mass of 93 kilodaltons, and two proteins (x and x') closely neighboring beta-tubulin. Two other phosphoproteins seen in the gels had molecular masses of 56 and 51 kilodaltons (respective isoelectric points, 4.5 and 4.4) and, along with the 93-kilodalton phosphoprotein, were highly enriched in the isolated growth cones. Only the tubulin and actin species were major proteins in the isolated growth cones. Cyclic AMP analogs enhanced incorporation of 32P into phosphoproteins x and x', and, as assessed by immunoprecipitation, into beta-tubulin. Peptide digest experiments suggested that phosphoproteins x and x' are unrelated to beta-tubulin. Nonequilibrium two-dimensional electrophoresis resolved many phosphoproteins, of which a 79- and 75-kilodalton doublet, a 74-kilodalton species, and a 58-kilodalton doublet showed enhanced incorporation of 32P in the presence of cyclic AMP.

  13. In vivo isolated liver perfusion technique in a rat hepatic metastasis model: 5-fluorouracil concentrations in tumor tissue.

    PubMed

    de Brauw, L M; van de Velde, C J; Tjaden, U R; de Bruijn, E A; Bell, A V; Hermans, J; Zwaveling, A

    1988-02-01

    An in vivo method of isolated rat liver perfusion was developed with true vascular isolation and recirculating perfusate. This new surgical technique to temporarily isolate the liver vascularly, and the perfusion procedure are described in depth. Twelve inbred WAG/RIJ rats were subjected to 25 min of normothermic liver perfusion without chemotherapy, and all rats survived the procedure. Hepatic functional and histological integrity were not significantly altered during perfusion. To determine the role of isolated liver perfusion (ILP) as a means of improved targeting of antitumor agents, 5-fluorouracil (5-FU) concentrations were monitored in hepatic tumor and liver tissues and in systemic plasma using high-performance liquid chromatography. Fifty-one rats with hepatic tumors of colonic origin were randomly assigned to one of three dosage groups (20, 40, or 80 mg/kg) receiving 5-FU by ILP, hepatic artery infusion (HAI), or jugular vein infusion (JVI). ILP resulted in significantly increased 5-FU concentrations in liver tissue. However, no significant differences were found in tumor tissue concentrations of 5-FU between the three treatment modalities. 5-FU concentrations in tumor tissue increased as a function of the dose with ILP, HAI, and JVI. ILP was associated with the lowest systemic drug concentrations. The low systemic 5-FU concentrations with ILP suggest a higher maximum tolerable dose. This mode of treatment deserves to be studied further in our model before conclusions can be drawn regarding its therapeutic potential. PMID:3339874

  14. Soy protein isolate and estradiol differ in their effects on the mammary gland of weanling male and female rats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Isoflavones are phytochemical components of soy diets that bind weakly to estrogen receptors (ERs). To study potential estrogen-like actions of soy in the mammary gland, we fed weanling male and female Sprague-Dawley rats a casein diet from PND21 to PND33, the same diet substituting soy protein isol...

  15. Dietary soy protein isolate attenuates metabolic syndrome in rats via effects on PPAR, LXR and SREBP signaling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Male and female rats (age 21 days) were fed AIN-93G diets made with casein, soy protein isolate (SPI+), isoflavone reduced SPI+ (SPI-), or casein plus purified genistein or daidzein. After 2 weeks, peroxisome proliferator activated receptor (PPAR) alpha-regulated genes involved in fatty acid degrada...

  16. ISOLATION AND GENOTYPING OF Toxoplasma gondii IN SERONEGATIVE URBAN RATS AND PRESENCE OF ANTIBODIES IN COMMUNICATING DOGS IN BRAZIL

    PubMed Central

    RUFFOLO, Bruno Bergamo; TOLEDO, Roberta dos Santos; MARTINS, Felippe Danyel Cardoso; BUGNI, Felipe Monteiro; da COSTA, Letícia; MARANA, Elizabete Regina Marangoni; NAVARRO, Italmar Teodorico; GARCIA, João Luis; SU, Chunlei; FREIRE, Roberta Lemos

    2016-01-01

    The role of rodents in the epidemiology of toxoplasmosis was investigated in Londrina, Paraná State, Brazil. One hundred and eighty-one Rattus rattus and one Mus musculus were caught in 37 places. Blood and tissues were collected and submitted to the indirect fluorescence antibody test (IFAT) and the bioassay. Serum samples from 61 contacting dogs were also collected. Sixteen rats (8.8%) were positive for Toxoplasma gondii, but just two of them were positive by serology and bioassay test. Antibodies were found in nine (4.9%) rats. Tissues of nine rats bioassayed were positive and four isolates were obtained. Restriction fragment length polymorphism (RFLP) analysis was performed using 12 markers (SAG1, SAG2, SAG2-alt, C22-8, C29-2, L358, PK1, BTUB, GRA6, SAG3, Apico, CS3). Genotyping revealed that the four strains isolated from this study have been isolated before in cats and chickens from Brazil. None of the isolates was identified like clonal archetypal T-types I, II, and III. The rats presented lower serologic Toxoplasma gondii prevalence (8.8%) compared to contacting dogs (70.5%). PMID:27074322

  17. Running Opposes the Effects of Social Isolation on Synaptic Plasticity and Transmission in a Rat Model of Depression

    PubMed Central

    Gómez-Galán, Marta; Femenía, Teresa; Åberg, Elin; Graae, Lisette; Van Eeckhaut, Ann; Smolders, Ilse; Brené, Stefan; Lindskog, Maria

    2016-01-01

    Stress, such as social isolation, is a well-known risk factor for depression, most probably in combination with predisposing genetic factors. Physical exercise on the other hand, is depicted as a wonder-treatment that makes you healthier, happier and live longer. However, the published results on the effects of exercise are ambiguous, especially when it comes to neuropsychiatric disorders. Here we combine a paradigm of social isolation with a genetic rat model of depression, the Flinders Sensitive Line (FSL), already known to have glutamatergic synaptic alterations. Compared to group-housed FSL rats, we found that social isolation further affects synaptic plasticity and increases basal synaptic transmission in hippocampal CA1 pyramidal neurons. These functional synaptic alterations co-exist with changes in hippocampal protein expression levels: social isolation in FSL rats reduce expression of the glial glutamate transporter GLT-1, and increase expression of the GluA2 AMPA-receptor subunit. We further show that physical exercise in form of voluntary running prevents the stress-induced synaptic effects but do not restore the endogenous mechanisms of depression already present in the FSL rat. PMID:27764188

  18. ISOLATION AND GENOTYPING OF Toxoplasma gondii IN SERONEGATIVE URBAN RATS AND PRESENCE OF ANTIBODIES IN COMMUNICATING DOGS IN BRAZIL.

    PubMed

    Ruffolo, Bruno Bergamo; Toledo, Roberta dos Santos; Martins, Felippe Danyel Cardoso; Bugni, Felipe Monteiro; Costa, Letícia da; Marana, Elizabete Regina Marangoni; Navarro, Italmar Teodorico; Garcia, João Luis; Su, Chunlei; Freire, Roberta Lemos

    2016-01-01

    The role of rodents in the epidemiology of toxoplasmosis was investigated in Londrina, Paraná State, Brazil. One hundred and eighty-one Rattus rattus and one Mus musculus were caught in 37 places. Blood and tissues were collected and submitted to the indirect fluorescence antibody test (IFAT) and the bioassay. Serum samples from 61 contacting dogs were also collected. Sixteen rats (8.8%) were positive for Toxoplasma gondii, but just two of them were positive by serology and bioassay test. Antibodies were found in nine (4.9%) rats. Tissues of nine rats bioassayed were positive and four isolates were obtained. Restriction fragment length polymorphism (RFLP) analysis was performed using 12 markers (SAG1, SAG2, SAG2-alt, C22-8, C29-2, L358, PK1, BTUB, GRA6, SAG3, Apico, CS3). Genotyping revealed that the four strains isolated from this study have been isolated before in cats and chickens from Brazil. None of the isolates was identified like clonal archetypal T-types I, II, and III. The rats presented lower serologic Toxoplasma gondii prevalence (8.8%) compared to contacting dogs (70.5%).

  19. IN VITRO EFFECTS OF PARTICULATE MATTER ON AIRWAY EPITHELIAL CELLS ISOLATED FROM CONCENTRATED AIR PARTICLES-EXPOSED SPONTANEOUS HYPERTENSIVE RATS

    EPA Science Inventory

    In vitro effects of particulate matter on airway epithelial cells isolated from concentrated air particles-exposed spontaneous hypertensive rats

    Ines Pagan, Urmila Kodavanti, Paul Evansky, Daniel L Costa and Janice A Dye. U.S. Environmental Protection Agency, ORD, National...

  20. Uterine responses to feeding soy protein isolate and treatment with 17B-estradiol differ in ovariectomized female rats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There are concerns regarding reproductive toxicity from consumption of soy foods, including an increased risk of endometriosis and endometrial cancer, as a result of phytoestrogen consumption. In this study, female rats were fed AIN-93G diets made with casein (CAS) or soy protein isolate (SPI) from ...

  1. [Electron microscopic analysis of the effect of modulated microwave radiation on isolated rat olfactory mucosa].

    PubMed

    Popov, V I; Novoselov, V I; Filippova, T M; Khutsian, S S; Fesenko, E E

    1996-01-01

    Isolated olfactory neuroepithelium and neighbouring respiratory epithelium of 6 Wistar rats after exposure to high frequency irradiation (the microwave carrier frequency was 0.9 GHz; the rectangular pulse modulation was 16 pulses per second; the pulse duration was 50%; the microwave power density in exposure glass chamber was 15 W/kg; the exposure time was 15 min) were studied using high resolution transmission electron microscopy. Ultrathin sections of both epithelia showed the drastic changes in ultrastructure of mucosa. Knobs of primary olfactory neurons and apical parts of supporting (sustacle) cells of the neuroepithelium showed strong vacuolization due to stimulating effect of the microwave irradiation on mucus secretion. The fusion of neighbouring cilia of respiratory cells was revealed. Such "giant cilia" contained more than 5-10 axonemes with basal bodies. In one case the mucus contained paracrystalline structures which were formed by microvilli and nonidentified filamentous protein (10 nm in dia). Degeneration of primary olfactory neuron axons was revealed.

  2. Uptake and release of [3H]GABA by growth cones isolated from neonatal rat brain.

    PubMed

    Gordon-Weeks, P R; Lockerbie, R O; Pearce, B R

    1984-11-23

    A subcellular fraction highly enriched in neuronal growth cones was isolated from 5-day-old rat forebrain by a recently described method. The growth cone fraction was shown to have a sodium- and temperature-dependent, high-affinity (Km = 4.4 microM) uptake system for [3H]GABA. Electron microscopic autoradiography confirmed that this uptake was into growth cones since only these structures were heavily labelled with silver grains. High potassium induced the release of newly accumulated [3H]GABA from the growth cone fraction, about half of which was Ca2+-dependent. The presence of uptake and release systems for GABA in growth cones may simply reflect the development of growth cones into nerve terminals. Alternatively, these observations may indicate a role for neurotransmitter release in synaptogenesis.

  3. Motion compensation of optical mapping signals from isolated beating rat hearts

    NASA Astrophysics Data System (ADS)

    Stender, B.; Ernst, F.; Wang, B.; Zhang, Z. X.; Schlaefer, A.

    2013-09-01

    Optical mapping is a well established technique for recording monophasic action potential traces on the epicardial surface of isolated hearts. This measuring technique offers a high spatial resolution but it is sensitive towards myocardial motion. Motion artifacts occur because the mapping between a certain tissue portion sending out fluorescent light and a pixel of the photo detector changes over time. So far this problem has been addressed by suppressing the motion or ratiometric imaging. We developed a different approach to compensate the motion artifacts based on image registration. We could demonstrate how an image deformation field temporally changing with the heart motion could be determined. Using these deformation field time series for image transformation motion signals could be generated for each image pixel which were then successfully applied to remove baseline shift and compensate motion artifacts potentially leading to errors within maps of the first arrival time. The investigation was based on five different rat hearts stained with Di-4-ANEPPS.

  4. Effect of cannabinoids on CGRP release in the isolated rat lumbar spinal cord.

    PubMed

    Milne, Michael; Ashton, John C

    2016-02-12

    Cannabinoids produce analgesia through a variety of mechanisms. It has been proposed that one mechanism is by modulating the release of CGRP in the spinal cord pain pathways. Previous studies have reported that cannabinoids, particularly CB2 receptor agonists, can modulate CGRP release in the isolated rat spinal cord. In our experiments, the TRPV1 agonist capsaicin evoked CGRP release and this was supressed by the TRPV1 antagonist capsazepine and by the opioid receptor agonist DAMGO. However, none of the cannabinoid receptor agonists that we tested were able to modulate evoked CGRP release; including WIN 55,212-2, methanandamide, and GW405833. These results question the role of spinal cord cannabinoid receptors in the regulation of CGRP signaling.

  5. A porcine model for acute ischaemic right ventricular dysfunction

    PubMed Central

    Haraldsen, Pernille; Lindstedt, Sandra; Metzsch, Carsten; Algotsson, Lars; Ingemansson, Richard

    2014-01-01

    OBJECTIVES To establish an experimental model for acute ischaemic isolated right ventricular dysfunction and the subsequent haemodynamic changes. METHODS An open-chest porcine model with ischaemic dysfunction of the right ventricle induced by ligation of the three main branches supporting the right ventricular free wall. Invasive monitoring of mean arterial blood pressure (MAP), central venous pressure (CVP), left atrial pressure (LAP) and right ventricular pressure (RVP); ultrasonic measurement of cardiac output (CO) and calculation of haemodynamic parameters such as stroke volume (SV), systemic vascular resistance (SVR), pulmonary vascular resistance (PVR) and right ventricular stroke work (RVSW) using standard formulae. RESULTS The ischaemic challenge to the right ventricle resulted in a significant (≥30%) reduction in RVSW associated with an increase (6–25%) in CVP and reduction (8–18%) in pulmonary artery pressure (PAP) despite unchanged PVR, all reflecting the failing right ventricle. There was also a significant drop in CO (14–22%) despite unchanged LAP indicating lessened transpulmonary delivery of left ventricular preload due to the failing right ventricle causing the haemodynamic compromise rather than left ventricular failure. Supraventricular and ventricular arrhythmias occurred in three and two out of seven pigs, respectively—all of which except one were successfully resuscitated with cardioversion and/or defibrillation. CONCLUSIONS This novel open-chest porcine model of induced ischaemia of the right ventricular free wall resulted in significant haemodynamic compromise confirmed using standard haemodynamic measurements making it useful for further research on acute, ischaemic isolated right ventricular failure. PMID:24092465

  6. Intracellular pH in isolated rat renal papillary thin limbs of Henle's loop.

    PubMed

    Dantzler, W H; Kim, Y K; Abbott, D E; Serrano, O K; Brokl, O H

    2000-05-01

    Intracellular pH (pHi) was measured in isolated, nonperfused and perfused rat papillary thin limbs of Henle's loops in N-2-hydroxyethylpiperazine-N'-2-ethansulfonic acid (HEPES)- or HEPES/bicarbonate-buffered medium at pH 7.4 using the pH-sensitive fluorescent dye 2',7'-bis(2-carboxyethyl)-5,6-carboxyfluorescein (BCECF). Resting pHi was about 6.7 in descending thin limbs (DTL) and about 6.9 in ascending thin limbs (ATL), even with a medium pH of 7.4. These values appeared to reflect the acid pH of the blood in the neighboring vasa recta found in vivo. The resting pHi did not differ whether or not the medium contained bicarbonate although the total buffering capacity of the tubule cells was increased in the presence of bicarbonate. In nonperfused DTL and ATL, pHi was further acidified following an NH4Cl pulse. The rate of recovery of pHi from this level to the resting pHi was reduced by Na+ removal from the bath in both DTL and ATL and by the addition of ethylisopropylamiloride (EIPA) to the bath in the presence of Na+ in DTL. The rate of recovery was not affected by Cl- removal from the bath or K+ (75 mM) or 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS) addition to the bath in either DTL or ATL. These results suggest that the common, amiloride-sensitive, basolateral Na+/H+ exchanger plays a role in the regulation of pHi in rat papillary DTL but that a different basolateral Na+/H+ exchanger or a luminal Na+/H+ exchanger is important in rat papillary ATL.

  7. High mitomycin C concentration in tumour tissue can be achieved by isolated liver perfusion in rats.

    PubMed

    Marinelli, A; Pons, D H; Vreeken, J A; Nagesser, S K; Kuppen, P J; Tjaden, U R; van de Velde, C J

    1991-01-01

    To enable the treatment of hepatic metastasis with higher, theoretically more effective, doses of systemically toxic anticancer drugs, an isolated liver perfusion (ILP) technique was developed in WAG/Ola rats. First, in a toxicity study the maximally tolerated dose (MTD) of mitomycin C (MMC) was determined for a 25-min ILP and for hepatic artery infusion (HAI) after the administration of a bolus dose. The MTD in the ILP setting (4.8 mg/kg) was 4 times that using HAI (1.2 mg/kg). Subsequently, in a rat colorectal hepatic-metastasis model, concentrations of MMC in tumour, liver, plasma and perfusate were measured during a 25-min ILP to investigate the expected pharmacokinetic advantage of ILP. The mean plasma level determined after ILP (1.2 as well as 4.8 mg/kg MMC) was significantly lower (P less than 0.001) than that obtained following HAI. This may explain both the absence of severe systemic toxicity and the higher MTD in ILP-treated groups. No significant difference in mean tumour and liver tissue concentrations of MMC were found when the groups treated with 1.2 mg/kg drug via HAI vs ILP were compared. The mean MMC concentration in tumour tissue was significantly higher (almost 5 times; P less than 0.05) in rats treated by ILP with the MTD (4.8 mg/kg) than in those treated via HAI with the MTD (1.2 mg/kg). ILP of MMC can be safely performed using a dose 4 times higher than the MTD in the HAI setting, leading to an almost 5-fold concentration of MMC in hepatic metastasis. ILP of MMC may therefore represent a promising therapy for metastasis confined to the liver. PMID:1905590

  8. Biotransformation and cytotoxic effects of hydroxychavicol, an intermediate of safrole metabolism, in isolated rat hepatocytes.

    PubMed

    Nakagawa, Yoshio; Suzuki, Toshinari; Nakajima, Kazuo; Ishii, Hidemi; Ogata, Akio

    2009-06-15

    The biotransformation and cytotoxic effects of hydroxychavicol (HC; 1-allyl-3,4-dihydroxybenzene), which is a catecholic component in piper betel leaf and a major intermediary metabolite of safrole in rats and humans, was studied in freshly isolated rat hepatocytes. The exposure of hepatocytes to HC caused not only concentration (0.25-1.0mM)- and time (0-3h)-dependent cell death accompanied by the loss of cellular ATP, adenine nucleotide pools, reduced glutathione, and protein thiols, but also the accumulation of glutathione disulfide and malondialdehyde, indicating lipid peroxidation. At a concentration of 1mM, the cytotoxic effects of safrole were less than those of HC. The loss of mitochondrial membrane potential and generation of oxygen radical species assayed using 2',7'-dichlorodihydrofluoresein diacetate (DCFH-DA) in hepatocytes treated with HC were greater than those with safrole. HC at a weakly toxic level (0.25 and/or 0.50mM) was metabolized to monoglucuronide, monosulfate, and monoglutathione conjugates, which were identified by mass spectra and/or (1)H nuclear magnetic resonance spectra. The amounts of sulfate rather than glucuronide or glutathione conjugate predominantly increased, accompanied by a loss of the parent compound, with time. In hepatocytes pretreated with either diethyl maleate or salicylamide, HC-induced cytotoxicity was enhanced, accompanied by a decrease in the formation of these conjugates and by the inhibition of HC loss. Taken collectively, our results indicate that (a) mitochondria are target organelles for HC, which elicits cytotoxicity through mitochondrial failure related to mitochondrial membrane potential at an early stage and subsequently lipid peroxidation through oxidative stress at a later stage; (b) the onset of cytotoxicity depends on the initial and residual concentrations of HC rather than those of its metabolites; (c) the toxicity of HC is greater than that of safrole, suggesting the participation of a catecholic

  9. The actions of isoprenaline and mirabegron in the isolated whole rat and guinea pig bladder.

    PubMed

    Persyn, Sara; De Wachter, Stefan; Wyndaele, Jean-Jacques; Eastham, Jane; Gillespie, James

    2016-07-01

    β3-adrenoceptor agonists influence overactive bladder in humans and animal models. However, data is emerging that the mode of action of these drugs is complex. The present study explored the actions of the β3-adrenergic agonist mirabegron and the non-selective agonist isoprenaline on the contractile systems in the rat and guinea pig bladder. Intravesical pressure was measured in isolated whole bladders from female adult animals. In both species spontaneous contractile activity was observed. The muscarinic agonist arecaidine produced complex responses consisting of an initial transient pressure rise followed by complex phasic activity. Three contractile elements were identified: intrinsic micro-contractile activity, initial transient response and steady state phasic activity. The intrinsic and steady state activity could be further divided into a baseline pressure with superimposed phasic activity. The effects of isoprenaline and mirabegron were investigated on these elements. In the rat, the micro-contractile activity could be completely inhibited by isoprenaline (full agonist). The arecaidine-induced initial and steady state baseline pressures were partially reduced, while the phasic activity was little affected. In the guinea pig, both the arecaidine-induced baseline pressure and the phasic activity were affected by isoprenaline. Mirabegron didn't produce significant inhibitory effects in any of the contractile elements in either species. These results show that complex contractile systems operate in the rat and guinea pig bladder that can be modulated by β1/β2-adrenoceptor mechanisms. No evidence was obtained for any β3-dependent regulation of contraction. These data support similar data in humans. Therefore the primary site of therapeutic action of β3-adrenergic agonists remains unknown.

  10. Effects of ascorbic acid on UV light-mediated photoreceptor damage in isolated rat retina.

    PubMed

    Tokuda, Kazuhiro; Zorumski, Charles F; Izumi, Yukitoshi

    2007-03-01

    Concerns have been raised about whether operating microscopes and endoillumination used during ophthalmic surgeries contribute to retinal damage. Despite the recognition that ascorbic acid (vitamin C) helps to protect the eye from light and the abundance of vitamin C in the retina, artificial aqueous humors used during surgery only contain the antioxidant glutathione. To test whether inclusion of antioxidants other than glutathione in surgical solutions might help to preserve retinal integrity, we studied the effects of vitamin C on acute toxicity in isolated rat retinas. Male Sprague-Dawley rats (PND 30+/-2) were sacrificed for retinal isolation. In the presence or absence of vitamin C (1 or 3 mM), retinas were exposed to 302 nm ultraviolet B (UVB) light for 1 h and were incubated for a total of 5 h at 30 degrees C. Retinal damage was assessed by morphological examination and biochemical assay measuring the amount of lactate dehydrogenase (LDH) released from injured cells. In control retinas, LDH release was significantly increased after UVB exposure. The presence of 1 mM vitamin C in the incubation media significantly reduced LDH release during the post-incubation period following UV exposure. No difference was found between 1 and 3 mM vitamin C. Microscopic examination revealed that disorganization in the outer nuclear layer after UVB exposure was markedly attenuated by administration of 1 mM vitamin C. Vitamin C (1 mM), a concentration found in the anterior chamber in humans, but not glutathione, prevented phototoxic injury following UV exposure. Although vitamin C itself cannot be used in intraocular irrigating solutions because of adverse interactions with iron released during bleeding, inclusion of antioxidants equivalent to vitamin C should be considered to help protect the retina from intraoperative light toxicity.

  11. The vasorelaxant effect of simvastatin in isolated aorta from diabetic rats

    PubMed Central

    Roghani-Dehkordi, Farshad; Roghani, Mehrdad

    2016-01-01

    BACKGROUND The increasing incidence of diabetes mellitus (DM) is of great clinical significance. In this study, we aimed to investigate whether exposure of endothelium-intact aortic rings to simvastatin could have a vasorelaxant effect in diabetic rats. METHODS For induction of diabetes, streptozotocin (STZ) (60 mg/kg, i.p., single dose) was used. After 1 month, the cumulative reaction of isolated endothelium-intact aortic rings was determined to KCl and phenylephrine (PE) in the absence and presence of nitric oxide (NO) synthase inhibitor, i.e., nitro-L-arginine-methyl ester (L-NAME), and prostaglandin synthesis inhibitor, i.e., indomethacin. Meanwhile, the role of extracellular calcium was assessed in this respect. RESULTS At the end of the study, the addition of simvastatin (at a concentration ≥ 10−5 M) caused a significant concentration-dependent relaxation response of PE-precontracted aortic rings for both control and diabetic groups (at a significant difference of P < 0.050), and this difference did not exist for KCl-precontracted aortic rings. Furthermore, both L-NAME (100 µM) and indomethacin (10 µM) significantly diminished the vasorelaxant response following simvastatin addition. Meanwhile, there was no statistically significant difference between control and diabetic groups in the absence of extracellular calcium. CONCLUSION The results of this study suggest that simvastatin is able to relax PE-precontracted aortic rings isolated from STZ-diabetic rats via modulation of NO- and prostaglandin-dependent signaling and its effect is not via modulation of calcium mobilization from intracellular stores. PMID:27429631

  12. On the histamine-induced depolarization of the isolated superior cervical ganglion of the rat.

    PubMed Central

    Field, J. L.; Newberry, N. R.

    1991-01-01

    1. Using a grease-gap technique, we studied the action of histamine on the d.c. potential recorded between the internal carotid nerve and the main body of the isolated superior cervical ganglion of the rat. 2. A small, slow depolarization was evoked by 10-300 microM histamine. This response was not reduced by lowering the calcium concentration in the superfusing medium (from 2.5 to 0.1 mM), or by superfusing tetrodotoxin, N-methylatropine, or propranolol (all at 1 microM). 3. Mepyramine (10 nM) antagonized this depolarization, but cimetidine (10 microM), metiamide (30 microM), burimamide (10 microM) and impromidine (1 microM) did not. Two other agonists also evoked a mepyramine-sensitive slow depolarization. The rank order of potencies was histamine greater than N alpha-methyl-histamine greater than 2-methyl-histamine. 4. At concentrations greater than 1 mM, histamine also evoked a larger, faster depolarization. This response was undiminished by reducing the calcium concentration of the medium to 0.1 mM or by adding 1 microM tetrodotoxin. The rank order of potency for the agonists was N alpha-methyl-histamine greater than histamine approximately 2-methyl-histamine. The histamine-induced fast response was not antagonized by any of the above-mentioned antagonists. It was slightly reduced by (+)-tubocurarine (100 microM) and N-methylbicuculline (100 microM) but such effects were not consistent with the blockade of nicotinic or GABAA receptor-mediated responses. 5. It was concluded that histamine depolarized the isolated superior cervical ganglion of the rat by activating H1 receptors. Relatively high concentrations of histamine also evoked a fast depolarization of this preparation, but this did not appear to be mediated by H1, H2 or H3 receptors. PMID:1933137

  13. Papaverine inhibits transcytotic vesicle transport and lipid excretion into bile in isolated perfused rat liver.

    PubMed

    Hayakawa, T; Katagiri, K; Hoshino, M; Nakai, T; Ohiwa, T; Kumai, T; Miyaji, M; Takeuchi, T; Corasanti, J; Boyer, J L

    1992-10-01

    Papaverine is a nonspecific smooth muscle relaxant and a phosphodiesterase inhibitor. Its effects on biliary excretion of lipids and horseradish peroxidase were investigated in a single-pass isolated perfused rat liver model. A constant infusion of papaverine (1.6 mumol/min; 40 mumol/L) significantly increased bile flow (microliters per minute per gram of liver) before (2.03 +/- 0.09 vs. 1.0 +/- 0.06) and after sodium taurocholate infusion (2.77 +/- 0.10 vs. 1.88 +/- 0.11). However, papaverine significantly and reversibly reduced biliary excretion of phospholipids and cholesterol (nanomoles per minute per gram of liver) after a 1.0 mumol/min sodium taurocholate infusion, from 7.45 +/- 0.83 and 1.42 +/- 0.15 to 1.75 +/- 0.18 and 0.39 +/- 0.06, respectively (p less than 0.01), whereas secretion of bile acids was unaffected. When a 1-min pulse of horseradish peroxidase (25 mg) was infused in isolated perfused rat liver after a continuous infusion of N6,O-2'-dibutyryladenosine 3',5'-cyclic monophosphate (0.25 mumol/min; 6.25 mumol/L), horseradish peroxidase appeared in bile in an early (4 to 6 min) and late (20 to 25 min) peak. Papaverine significantly reduced the late peak, from 1.211 +/- 0.264 to 0.498 +/- 0.107 (p less than 0.01). Papaverine had no significant effects on either cyclic AMP or cyclic GMP in the liver and bile, although it has been reported that papaverine is a phosphodiesterase inhibitor. These findings indicate that papaverine inhibits biliary excretion of lipids but not bile acids, and they suggest that papaverine has an inhibitory effect on transcytotic vesicle transport independent of an increase of cyclic nucleotides in hepatocytes.

  14. Zeneca ZD7114 acts as an antagonist at beta 3-adrenoceptors in rat isolated ileum.

    PubMed Central

    Growcott, J. W.; Holloway, B.; Green, M.; Wilson, C.

    1993-01-01

    1. The relaxant effects of Zeneca ZD7114, BRL37344 (putative beta 3-adrenoceptor agonists) and various phenylethylamine-based agonists were studied in isolated ileum of the rat where tone was increased with carbachol (0.5 microM). Agonist-induced relaxation.was measured under equilibrium conditions with alpha-, beta 1- and beta 2-adrenoceptors inhibited. 2. Relaxant responses were obtained to isoprenaline, noradrenaline, and BRL37344, although, the efficacy of this latter agent was significantly.lower than that of isoprenaline. Salbutamol caused weak relaxation (< 20%) at high concentrations (10 microM) and ZD7114 was without significant relaxant effect even at high concentrations (10 microM). 3. Relaxant responses to isoprenaline and BRL37344 were weakly antagonized by high concentrations of (+/-)-propranolol (10 and 100 microM) yielding pKB values of 5.7 with isoprenaline as the agonist and 5.5 with BRL37344 as the agonist. 4. The non-selective beta-adrenoceptor antagonist, (+/-)-alprenolol (1-100 microM) caused competitive antagonism of the relaxant responses to isoprenaline (pA2 value = 6.5). A similar pKB value was obtained when BRL37344 was used as the agonist (6.4). 5. Relaxant effects of isoprenaline and BRL37344 were also antagonized by ZD7114 (1-100 microM) yielding pA2 and pKB values of 6.3 and 6.7 respectively. 6. The low potencies of (+/-)-propranolol and (+/-)-alprenolol as antagonists of the relaxant responses to isoprenaline and BRL37344 indicate that both the agonists and antagonists employed in the current study may interact with beta 3-adrenoceptors in the rat isolated ileum.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7905770

  15. Some aspects of fatty acid oxidation in isolated fat-cell mitochondria from rat.

    PubMed Central

    Harper, R D; Saggerson, E D

    1975-01-01

    Mitochondrial were prepared from fat-cells isolated from rat epididymal adipose tissues of fed and 48 h-starved rats to study some aspects of fatty acid oxidation in this tissue. The data were compared with values obtained in parallel experiments with liver mitochondria that were prepared and incubated under identical conditions. 2. In the presence of malonate, fluorocitrate and arsenite, malate, but not pyruvate-bicarbonate, facilitated palmitoyl-group oxidation in both types of mitochondria. In the presence of malate, fat-cell mitochondria exhibited slightly higher rates of palmitoylcarnitine oxidation than liver. Rates of octanoylcarnitine oxidation were similar in liver and fat-cell mitochondria. Uncoupling stimulated acylcarnitine oxidation in liver, but not in fat-cell mitochondria. Oxidation of palmitoyl- and octanoyl-carnitine was partially additive in fat-cell but not in liver mitochondria. Starvation for 48 h significantly decreased both palmitoylcarnitine oxidation and latent carnitine palmitoyltransferase activity in fat-cell mitochondria. Starvation increased latent carnitine palmitoyltransferase activity in liver mitochondria but did not alter palmitoylcarnitine oxidation. These results suggested that palmitoylcarnitine oxidation in fat-cell but not in liver mitochondria may be limited by carnitine palmitoyltransferase 2 activity. 3. Fat-cell mitochondria also differed from liver mitochondria in exhibiting considerably lower rates of carnitine-dependent oxidation of palmitoyl-CoA or palmitate, suggesting that carnitine palmitoyltransferase 1 activity may severely rate-limit palmitoyl-CoA oxidation in adipose tissue. PMID:1227502

  16. Dexmedetomidine-Induced Contraction Involves CPI-17 Phosphorylation in Isolated Rat Aortas

    PubMed Central

    Ok, Seong-Ho; Kwon, Seong-Chun; Baik, Jiseok; Hong, Jeong-Min; Oh, Jiah; Han, Jeong Yeol; Sohn, Ju-Tae

    2016-01-01

    Dexmedetomidine, a highly selective α-2 adrenoceptor agonist, produces vasoconstriction, which leads to transiently increased blood pressure. The goal of this study was to investigate specific protein kinases and the associated cellular signal pathways responsible for the increased calcium sensitization induced by dexmedetomidine in isolated rat aortas, with a particular focus on phosphorylation-dependent inhibitory protein of myosin phosphatase (CPI-17). The effect of Y-27632 and chelerythrine on the dexmedetomidine-induced intracellular calcium concentration ([Ca2+]i) and tension were assessed using fura-2-loaded aortic strips. The effects of rauwolscine, Y-27632, chelerythrine, and ML-7 hydrochloride on the dexmedetomidine-induced phosphorylation of CPI-17 or of the 20-kDa regulatory light chain of myosin (MLC20) were investigated in rat aortic vascular smooth muscle cells. The effects of rauwolscine, Y-27632, and chelerythrine on the membrane translocation of Rho-kinase and protein kinase C (PKC) phosphorylation induced by dexmedetomidine were assessed. Y-27632 and chelerythrine each reduced the slopes of the [Ca2+]i-tension curves of dexmedetomidine-induced contraction, and Y-27632 more strongly reduced these slopes than did chelerythrine. Rauwolscine, Y-27632, chelerythrine, and ML-7 hydrochloride attenuated the dexmedetomidine-induced phosphorylation of CPI-17 and MLC20. Taken together, these results suggest that dexmedetomidine-induced contraction involves calcium sensitization, which appears to be mediated by CPI-17 phosphorylation via Rho-kinase or PKC. PMID:27706026

  17. Parasympathetic denervation increases responses to VIP in isolated rat parotid acini

    SciTech Connect

    McMillian, M.K.; Talamo, B.R. )

    1989-07-01

    Vasoactive intestinal peptide (VIP) is a putative neurotransmitter found in the salivary glands of many species, including the rat parotid gland. Parasympathetic denervation has been reported to deplete VIP in the rat parotid gland and to lead to supersensitivity to this peptide in vivo. We have compared the effects of VIP on acini isolated from parasympathetically denervated and unoperated parotid glands to examine possible supersensitivity to the peptide in vitro. VIP normally produced responses similar to those obtained with a low concentration of the beta adrenergic agonist isoproterenol (ISO), but strikingly different from the effects obtained with the muscarinic agonist carbachol (CARB). In parotid membrane preparations, VIP stimulated adenylate cyclase activity. Dissociated acini treated with VIP showed increases in cAMP accumulation and amylase release which were potentiated by forskolin and also by inhibition of phosphodiesterase. After parasympathetic denervation, maximal effects of VIP on adenylate cyclase, cAMP accumulation and amylase release in intact cells were increased two- to five-fold over contralateral control (or unoperated) parotid responses. The increase in adenylate cyclase-mediated responses after denervation was specific to VIP; there was no increased response nor increased sensitivity of any of these responses to ISO. Specific (125I)VIP binding to parotid acini increased two-fold per gland and three-fold per mg of protein after denervation; this probably explains the observed increases in the response to VIP.

  18. Cardioprotective Effects of Astragalin against Myocardial Ischemia/Reperfusion Injury in Isolated Rat Heart.

    PubMed

    Qu, Daoxu; Han, Jichun; Ren, Huanhuan; Yang, Wenxiao; Zhang, Xinjie; Zheng, Qiusheng; Wang, Dong

    2016-01-01

    This study aims to evaluate the cardioprotective effects of astragalin against myocardial ischemia/reperfusion (I/R) injury in isolated rat heart. The cardioprotective effects of astragalin on myocardial I/R injury were investigated on Langendorff apparatus. Adult male Sprague-Dawley rats were randomly divided into five groups. The results showed that astragalin pretreatment improved myocardial function. Compared with I/R group, lactate dehydrogenase (LDH) and creatine kinase (CK) activities in coronary flow decreased in astragalin pretreatment groups, whereas superoxide dismutase (SOD) activity and glutathione/glutathione disulfide (GSH/GSSG) ratio significantly increased. The levels of malondialdehyde (MDA), intracellular reactive oxygen species (ROS), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) decreased in astragalin-treated groups. The infarct size (IS) and apoptosis rate in hearts from astragalin-treated groups were lower than those in hearts from the I/R group. Western blot analysis also revealed that astragalin preconditioning significantly reduced Bax level, whereas Bcl-2 was increased in the myocardium. Therefore, astragalin exhibited cardioprotective effects via its antioxidative, antiapoptotic, and anti-inflammatory activities.

  19. Cardioprotective Effects of Astragalin against Myocardial Ischemia/Reperfusion Injury in Isolated Rat Heart

    PubMed Central

    Qu, Daoxu; Ren, Huanhuan; Yang, Wenxiao; Zhang, Xinjie; Zheng, Qiusheng; Wang, Dong

    2016-01-01

    This study aims to evaluate the cardioprotective effects of astragalin against myocardial ischemia/reperfusion (I/R) injury in isolated rat heart. The cardioprotective effects of astragalin on myocardial I/R injury were investigated on Langendorff apparatus. Adult male Sprague-Dawley rats were randomly divided into five groups. The results showed that astragalin pretreatment improved myocardial function. Compared with I/R group, lactate dehydrogenase (LDH) and creatine kinase (CK) activities in coronary flow decreased in astragalin pretreatment groups, whereas superoxide dismutase (SOD) activity and glutathione/glutathione disulfide (GSH/GSSG) ratio significantly increased. The levels of malondialdehyde (MDA), intracellular reactive oxygen species (ROS), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) decreased in astragalin-treated groups. The infarct size (IS) and apoptosis rate in hearts from astragalin-treated groups were lower than those in hearts from the I/R group. Western blot analysis also revealed that astragalin preconditioning significantly reduced Bax level, whereas Bcl-2 was increased in the myocardium. Therefore, astragalin exhibited cardioprotective effects via its antioxidative, antiapoptotic, and anti-inflammatory activities. PMID:26788251

  20. Histamine H1-receptors mediate endothelium-dependent relaxation of rat isolated pulmonary arteries.

    PubMed

    Szarek, J L; Bailly, D A; Stewart, N L; Gruetter, C A

    1992-01-01

    Histamine has been reported to cause endothelium-dependent relaxation of vascular smooth muscle and vasodilation. This study was undertaken to examine the inhibitory effects of histamine on cylindrical segments of extrapulmonary arteries isolated from male Sprague Dawley rats. In arterial segments precontracted with phenylephrine (10 microM), histamine (0.1-100 microM) elicited concentration-dependent relaxation responses. Removal of the endothelium or pretreatment with methylene blue (10 microM) abolished relaxation responses to low concentrations of histamine and markedly inhibited those caused by histamine at concentrations greater than 1 microM. Incubation of endothelium-intact arterial segments with pyrilamine (1 microM) caused a significant rightward shift of the histamine concentration-response curves. Treatment of the segments with cimetidine (100 microM) or indomethacin (10 microM) only minimally antagonized histamine-induced relaxation in arteries with endothelium. Residual relaxation responses observed in arteries stripped of endothelium were unaffected by pretreatment with cimetidine, indomethacin, or pyrilamine. The results suggest that the inhibitory effect of histamine in rat pulmonary arteries is mediated predominantly by activation of H1-receptors on the endothelium and the subsequent release of endothelium-derived relaxing factor(s).

  1. Differential effects of diadenosine phosphates on purinoceptors in the rat isolated perfused kidney.

    PubMed

    van der Giet, M; Khattab, M; Börgel, J; Schlüter, H; Zidek, W

    1997-04-01

    1. The activation of various purinoceptors in rat renal vasculature by P1,P2-diadenosine pyrophosphate (Ap2A), P1,P3-diadenosine triphosphate (Ap3A), P1,P4-diadenosine tetraphosphate (Ap4A), P1,P5-diadenosine pentaphosphate (Ap5A), P1,P6-diadenosine hexaphosphate (Ap6A) was studied by measuring their effects of perfusion pressure of a rat isolated perfused kidney. 2. The vasoconstrictive response to Ap5A was completely due to P2x purinoceptor activation, that to Ap4A and Ap6 was P2x purinoceptor mediated to a large extent, as evidenced by the inhibitory effects of suramin and pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid tetrasodium (PPADS). 3. The vasoconstrictive effects of Ap2A and Ap3A were mostly due to stimulation of A1-receptors, as shown by the inhibitory effect of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). 4. The vasoconstrictive response to Ap6A was partially insensitive to A1 and P2x purinoceptor blockers. 5. In raised tone preparations Ap2A and Ap3A evoked vasodilatation, which was blocked by the A2 receptor blocker, 3,7-dimethyl-1-propargylxanthine (DMPX). 6. In raised tone preparations Ap4A evoked vasodilatation when the P2-purinoceptors were blocked by suramin. 7. The activation of different purinoceptor subtypes by diadenosine phosphates critically depends on the number of phosphate groups.

  2. Association between microtubules and Golgi vesicles isolated from rat parotid glands.

    PubMed

    Coffe, G; Raymond, M N

    1990-01-01

    We report an isolation procedure of trans-Golgi vesicles (GVs) from rat parotid glands. Various organelle markers were used, particularly galactosyl transferase as a trans-Golgi marker, to test the purity of the GV fraction. A quantitative in vitro binding assay between microtubules and GVs is described. The vesicles were incubated with taxol-induced microtubules, layered between 50% and 43% sucrose cushions and subjected to centrifugation. Unlike free microtubules which were sedimented, the GV-bound microtubules co-migrated upward with GVs. Quantification of these bound microtubules was carried out by densitometric scanning of Coomassie blue-stained gels. The association between microtubules and GVs followed a saturation curve, with a plateau value of 20 micrograms of microtubule protein bound to 500 micrograms of GV fraction. The half-saturation of the GV sites was obtained with a microtubule concentration of 20 micrograms/ml. Electron microscopy of negatively stained re-floated material showed numerous microtubule-vesicle complexes. Coating of microtubules with an excess of brain microtubule-associated proteins (MAPs) abolished binding. In the absence of exogenous microtubules, we showed that the GV fraction was already interacting with a class of endogenous rat parotid microtubules. This class of colcemid and cold-stable microtubules represents 10-20% of the total tubulin content of the parotid cell. PMID:1983303

  3. Antidiarrheal activity of 19-deoxyicetexone isolated from Salvia ballotiflora Benth in mice and rats.

    PubMed

    Pérez-Gutiérrez, Salud; Zavala-Mendoza, Daniel; Hernández-Munive, Abigail; Mendoza-Martínez, Angel; Pérez-González, Cuauhtemoc; Sánchez-Mendoza, Ernesto

    2013-01-01

    The antidiarrheal properties of 19-deoxyicetexone, a diterpenoid isolated from Salvia ballotiflora were evaluated on castor oil-, arachidonic acid (AA)- and prostaglandin (PGE₂)-induced diarrhea in rodent models. The structure of 19-deoxyicetexone was determined by X-ray crystallography, mass spectrometry (EI-MS), as well as ultraviolet (UV-Vis), infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopies. This compound significantly and dose-dependently reduced frequency of stooling in castor oil-induced diarrhea, and at dose of 25 mg/kg it also inhibited diarrhea induced with AA, while it had no effect on PGE₂-induced diarrhea. This compound at doses of 25 mg/kg also diminished castor oil-induced enteropooling and intestinal motility, and inhibited the contraction of the rats' ileum induced by carbachol chloride at a concentration of 100 µg/mL. 19-Deoxyicetexone did not present acute toxicity at doses of 625 mg/kg. Its antidiarrheal activity may be due to increased reabsorption of NaCl and water and inhibition of the release of prostaglandins, gastrointestinal motility and fluid accumulation in the intestinal tracts of rats. These findings suggest that 19-deoxyicetexone may be used in the treatment of diarrhea, although more studies must be carried out to confirm this. PMID:23896615

  4. [Permeability of isolated rat hepatocyte plasma membranes for molecules of dimethyl sulfoxide].

    PubMed

    Kuleshova, L G; Gordienko, E A; Kovalenko, I F

    2014-01-01

    We have studied permeability of isolated rat hepatocyte membranes for molecules of dimethyl sulfoxide (DMSO) at different hypertonicity of a cryoprotective medium. The permeability coefficient of hepatocyte membranes κ1 for DMSO molecules was shown to be the differential function of osmotic pressure between a cell and an extracellular medium. Ten-fold augmentation of DMSO concentration in the cryoprotective medium causes the decrease of permeability coefficients κ1 probably associated with the increased viscosity in membrane-adjacent liquid layers as well as partial limitations appeared as a result of change in cell membrane shape after hepatocyte dehydration. We have found out that in aqueous solutions of NaCl (2246 mOsm/l) and DMSO (2250 mOsm/l) the filtration coefficient L(p) in the presence of a penetrating cryoprotectant (L(pDMSO) = (4.45 ± 0.04) x 10(-14) m3/Ns) is 3 orders lower compared to the case with electrolyte (L(pNaCl) = (2.25 ± 0.25) x 10(-11) m3/Ns). This phenomenon is stipulated by the cross impact of flows of a cryoprotectant and water at the stage of cell dehydration. Pronounced lipophilicity of DMSO, geometric parameters of its molecule as well as the presence of large aqueous pores in rat hepatocyte membranes allow of suggesting the availability of two ways of penetrating this cryoprotectant into the cells by non-specific diffusion through membrane lipid areas and hydrophilic channels.

  5. Isolation and Characterization of δ-Subspecies of Protein Kinase C from Rat Brain

    NASA Astrophysics Data System (ADS)

    Ogita, Kouji; Miyamoto, Shin-Ichi; Yamaguchi, Keizo; Koide, Hiroshi; Fujisawa, Naoko; Kikkawa, Ushio; Sahara, Setsuko; Fukami, Yasuo; Nishizuka, Yasutomi

    1992-03-01

    The δ-subspecies of protein kinase C (δ PKC) was purified to near homogeneity from the Triton X-100 extract of the rat brain particulate fraction by successive chromatographies on S-Sepharose fast flow, phenyl 5PW, heparin 5PW, hydroxyapatite, and Mono Q columns. The purified enzyme was a doublet with molecular masses of 78 and 76 kDa on SDS/PAGE. The doublet proteins were separated partially by Mono Q column chromatography; both were recognized by the antibodies raised against synthetic oligopeptides, parts of the deduced amino acid sequence of the rat δ PKC. Protein phosphatase 2A treatment suggested that the 78-kDa protein was a phosphorylated form of the 76-kDa protein. To confirm the structural and genetic identity of the doublet proteins, δ PKC was expressed in COS 7 cells by transfecting its cDNA-constructed plasmid and was purified for comparison. This recombinant enzyme was also a doublet. The enzymes isolated from the brain and COS 7 cells showed identical reactivities with δ PKC-specific antibodies, chromatographic behaviors, and V8 protease peptide mappings. In addition, these two enzyme preparations were indistinguishable from each other in their responses to phosphatidylserine, diacylglycerol, phorbol esters, free fatty acids, Ca2+, and enzyme inhibitors. Comparison was also made between the enzymologic properties of δ PKC and α PKC, which were distinctly different from each other.

  6. Percutaneous left ventricular restoration.

    PubMed

    Ige, Mobolaji; Al-Kindi, Sadeer G; Attizzani, Guilherme; Costa, Marco; Oliveira, Guilherme H

    2015-04-01

    The ventricular partitioning device known as Parachute is the first and only percutaneously implantable device aimed at restoration of normal left ventricular geometry in humans. Since its conception, this technology has undergone extensive animal and human testing, with proved feasibility and safety, and is currently being studied in a pivotal randomized clinical trial. This article discusses ventricular remodeling and therapies attempted in the past, details the components of the ventricular partitioning device, describes the implanting technique, and reviews the most current experience of this device in humans.

  7. Percutaneous left ventricular restoration.

    PubMed

    Ige, Mobolaji; Al-Kindi, Sadeer G; Attizzani, Guilherme; Costa, Marco; Oliveira, Guilherme H

    2015-04-01

    The ventricular partitioning device known as Parachute is the first and only percutaneously implantable device aimed at restoration of normal left ventricular geometry in humans. Since its conception, this technology has undergone extensive animal and human testing, with proved feasibility and safety, and is currently being studied in a pivotal randomized clinical trial. This article discusses ventricular remodeling and therapies attempted in the past, details the components of the ventricular partitioning device, describes the implanting technique, and reviews the most current experience of this device in humans. PMID:25834974

  8. Right ventricular mass estimation by angioechocardiography.

    PubMed

    Arcilla, R A; Mathew, R; Sodt, P; Lester, L; Cahill, N; Thilenius, O G

    1976-01-01

    A combined angiocardiographic-echocardiographic method for estimating right ventricular wall mass is described. Biplane cineangiocardiograms are analyzed for ventricular volume in end-diastole, and wall thickness is determined from echocardiograms obtained with a high frequency transducer and strip chart recorder, The intracavitary and the external surface volumes of the ventricle are derived, and the difference multiplied by 1.050, the specific gravity of myocardium. Excellent correlation was observed between right ventricular wall mass and body surface area in normal children (r = 0.93). The mean right ventricular mass was 44.5 g/M2 as compared to 78.1 g/M2 for the left ventricle, corresponding mass/EDV values were 0.48 g/cm3 and 1.26 g/cm3, respectively. In isolated right ventricular pressure overload, the increase in right ventricular mass is chiefly due to the increase in wall thickness; in volume overload, it is due mostly to the increase in chamber volume,

  9. Activation of GPER-1 Estradiol Receptor Downregulates Production of Testosterone in Isolated Rat Leydig Cells and Adult Human Testis

    PubMed Central

    Vaucher, Laurent; Funaro, Michael G.; Mehta, Akanksha; Mielnik, Anna; Bolyakov, Alexander; Prossnitz, Eric R.; Schlegel, Peter N.; Paduch, Darius A.

    2014-01-01

    Purpose Estradiol (E2) modulates testicular functions including steroidogenesis, but the mechanisms of E2 signaling in human testis are poorly understood. GPER-1 (GPR30), a G protein-coupled membrane receptor, mediates rapid genomic and non-genomic response to estrogens. The aim of this study was to evaluate GPER-1 expression in the testis, and its role in estradiol dependent regulation of steroidogenesis in isolated rat Leydig cells and human testis. Materials and Methods Isolated Leydig cells (LC) from adult rats and human testicular tissue were used in this study. Expression and localization studies of GPER-1 were performed with qRT-PCR, immunofluorescence, immunohistochemistry and Western Blot. Luteinizing Hormone (LH) -stimulated, isolated LC were incubated with estradiol, G-1 (GPER-1-selective agonist), and estrogen receptor antagonist ICI 182,780. Testosterone production was measured with radioimmunoassay. LC viability after incubation with G-1 was measured using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assay. Results GPER-1 mRNA is abundantly expressed in rat LC and human testis. Co-localization experiments showed high expression levels of GPER-1 protein in LC. E2-dependent activation of GPER-1 lowers testosterone production in isolated rats LCs and in human testis, with statistically and clinically significant drops in testosterone production by 20–30% as compared to estradiol-naïve LC. The exposure to G-1 does not affect viability of isolated LCs. Conclusions Our results indicate that activation of GPER-1 lowers testosterone levels in the rat and human testis. The expression of GPER-1 in human testis, which lack ERα, makes it an exciting target for developing new agents affecting testosterone production in men. PMID:24736568

  10. Effects of post-weaning social isolation and environment al enrichment on exploratory behavior and ankiety in Wistar rats.

    PubMed

    Tanaś, Łukasz; Ostaszewski, Paweł; Iwan, Anna

    2015-01-01

    Adverse early experience is generally regarded as a risk factor for both externalizing and internalizing behavioral disorders in humans. It can be modeled in rats by a post-weaning social isolation procedure. Effects of social isolation might possibly be ameliorated by environmental enrichment. In the current study, 24 male Wistar rats were divided post-weaning into four rearing conditions: control, environmental enrichment (EE), social isolation (SI) and a combination of the two experimental conditions; (EE+SI). Two observations of the effects of rearing conditions on the rate of social and object interactions were conducted during the juvenile and post-pubertal stages of development. The SI condition led to a marked increase of social interactions during the juvenile phase, but did not affect object interactions. The EE condition increased the level of social interactions during both the juvenile and post-pubertal measurements. The effects of early rearing conditions on adult exploratory behavior were less clear, with a significant difference between the groups obtained in one of three behavioral tests. Results suggest a general robustness in the development of adult exploratory behavior and anxiety when rats were exposed to early social isolation and provided brief opportunities for social play during the juvenile period. Further studies, aimed at distinguishing play-related protective factors serving against long-term adverse effects of juvenile social isolation, are suggested.

  11. Role of 4-bromophenol and 4-bromocatechol in bromobenzene covalent binding and toxicity in isolated rat hepatocytes

    SciTech Connect

    Dankovic, D.A.; Billings, R.E.

    1985-06-30

    4-Bromophenol and 4-bromocatechol are formed as metabolites of bromobenzene in vivo and in isolated rat hepatocytes. Both of these metabolites may potentially contribute to the hepatotoxicity of bromobenzene. Bromobenzene metabolism in hepatocytes isolated from phenobarbital-treated rats forms 0.12 to 0.17 mM 4-bromophenol and 4-bromocatechol in 2 hr, with 1 to 3 mM bromobenzene. The role of activated metabolites derived from 4-bromophenol and 4-bromocatechol in bromobenzene covalent binding and toxicity was investigated with isolated hepatocytes in suspension. The covalent binding of the phenol and the catechol was increased four- to eightfold by the addition of unlabeled bromobenzene. Two-hour incubations of 0.25 mM /sup 14/C-labeled 4-bromophenol or 4-bromocatechol with hepatocytes isolated from phenobarbital-treated rats resulted, under these conditions, in no significant toxicity, and approximately 4 and 25%, respectively, of the covalent binding associated with bromobenzene itself. Two- and six-hour incubations with higher 4-bromophenol and 4-bromocatechol concentrations demonstrated that 1 to 3 mM substrate concentrations were required for cytotoxicity. These results show that metabolically produced 4-bromophenol and 4-bromocatechol do not play significant roles in the production of bromobenzene cytotoxicity in isolated hepatocytes, and that they contribute only modestly to bromobenzene covalent binding.

  12. Zeneca ZD7114 acts as an antagonist at beta 3-adrenoceptors in rat isolated ileum.

    PubMed

    Growcott, J W; Holloway, B; Green, M; Wilson, C

    1993-12-01

    1. The relaxant effects of Zeneca ZD7114, BRL37344 (putative beta 3-adrenoceptor agonists) and various phenylethylamine-based agonists were studied in isolated ileum of the rat where tone was increased with carbachol (0.5 microM). Agonist-induced relaxation.was measured under equilibrium conditions with alpha-, beta 1- and beta 2-adrenoceptors inhibited. 2. Relaxant responses were obtained to isoprenaline, noradrenaline, and BRL37344, although, the efficacy of this latter agent was significantly.lower than that of isoprenaline. Salbutamol caused weak relaxation (< 20%) at high concentrations (10 microM) and ZD7114 was without significant relaxant effect even at high concentrations (10 microM). 3. Relaxant responses to isoprenaline and BRL37344 were weakly antagonized by high concentrations of (+/-)-propranolol (10 and 100 microM) yielding pKB values of 5.7 with isoprenaline as the agonist and 5.5 with BRL37344 as the agonist. 4. The non-selective beta-adrenoceptor antagonist, (+/-)-alprenolol (1-100 microM) caused competitive antagonism of the relaxant responses to isoprenaline (pA2 value = 6.5). A similar pKB value was obtained when BRL37344 was used as the agonist (6.4). 5. Relaxant effects of isoprenaline and BRL37344 were also antagonized by ZD7114 (1-100 microM) yielding pA2 and pKB values of 6.3 and 6.7 respectively. 6. The low potencies of (+/-)-propranolol and (+/-)-alprenolol as antagonists of the relaxant responses to isoprenaline and BRL37344 indicate that both the agonists and antagonists employed in the current study may interact with beta 3-adrenoceptors in the rat isolated ileum. Contrary to the previous findings in guinea-pig ileum, where BRL37344 and ZD7114 were full agonists, in the current study, BRL37344 was a partial agonist and ZD7114 an antagonist at the beta 3-adrenoceptor in rat ileum. PMID:7905770

  13. Effect of phorbol ester on the release of atrial natriuretic peptide from the hypertrophied rat myocardium.

    PubMed Central

    Kinnunen, P.; Taskinen, T.; Järvinen, M.; Ruskoaho, H.

    1991-01-01

    1. To determine the cellular mechanisms of atrial natriuretic peptide (ANP) release from ventricular cardiomyocytes, the secretory and the cardiac effects of a phorbol ester, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), known to stimulate protein kinase C activity in heart cells, were studied in isolated, perfused heart preparations from 2- and 21-month-old Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats. TPA was added to the perfusion fluid for 30 min at a concentration of 46 nM after removal of atrial tissue. Additionally, atrial and ventricular levels of immunoreactive ANP (IR-ANP) and ANP mRNA, the distribution of ANP within ventricles as well as the relative contribution of atria and ventricles in the release of ANP were studied. 2. Ventricular hypertrophy that gradually developed in hypertensive rats resulted in remarkable augmentation of ANP gene expression, as reflected by elevated levels of immunoreactive ANP and ANP mRNA. The total amount of IR-ANP in the ventricles of the SHR rats increased 41 fold and ANP mRNA levels 12.9 fold from the age of 2 to 21 months. At the age of 21 months, levels of IR-ANP and ANP mRNA in the ventricles of SHR rats were 5.4 fold and 3.7 fold higher, respectively, than in the normotensive WKY rats. Immunohistochemical studies demonstrated ANP granules within the hypertrophic ventricles of the old SHR rats, but not within normal ventricular tissue. 3. In isolated perfused heart preparations, the severely hypertrophied ventricular tissue of SHR rats after atrialectomy secreted more ANP into the perfusate than did the control hearts.(ABSTRACT TRUNCATED AT 250 WORDS) Images Figure 2 PMID:1826618

  14. Growth cones isolated from developing rat forebrain: uptake and release of GABA and noradrenaline.

    PubMed

    Lockerbie, R O; Gordon-Weeks, P R; Pearce, B R

    1985-08-01

    A growth cone-enriched fraction isolated from neonatal rat forebrain was shown to accumulate gamma-amino [3H]butyric acid ([3H]-GABA) and [3H]noradrenaline ([3H]NA). Uptake of both neurotransmitters was sodium- and temperature-dependent and exhibited saturation kinetics with Km values of 17.7 microM and 4.5 microM respectively and Vmax values of 114 pmol/min/mg protein and 59 pmol/min/mg protein respectively. Electron microscopic autoradiography showed that about 50% of isolated growth cones can accumulate [3H]GABA. Inhibitor studies showed that beta-alanine was a relatively weak inhibitor of [3H]GABA uptake compared to nipecotic acid and diamino-butyric acid. Growth cone fractions preloaded with [3H]GABA and [3H]NA demonstrated a K+ (25 mM) -induced release of both neurotransmitters. Of the K+-stimulated release of [3H]GABA 50% was Ca2+-dependent, whereas the release of [3H]NA was entirely Ca2+-independent.

  15. Isolation and characterization of neural stem cells from the neonatal rat cochlear nucleus.

    PubMed

    Rak, Kristen; Wasielewski, Natalia V; Radeloff, Andreas; Völkers, Johannes; Scherzed, Agmal; Jablonka, Sibylle; Hagen, Rudolf; Mlynski, Robert

    2011-03-01

    Neural stem cells have been identified in multiple parts of the postnatal mammalian brain, as well as in the inner ear. No investigation of potential neural stem cells in the cochlear nucleus has yet been performed. The aim of this study was to investigate potential neural stem cells from the cochlear nucleus by neurosphere assay and in histological sections to prove their capacity for self-renewal and for differentiation into progenitor cells and cells of the neuronal lineage. For this purpose, cells of the cochlear nucleus of postnatal day 6 rats were isolated and cultured for generation of primary neurospheres. Spheres were dissociated and cells analyzed for capacity for mitosis and differentiation. Cell division was detected by cell-counting assay and BrdU incorporation. Differentiated neural progenitor cells showed distinct labeling for Nestin and for Atoh1. Positive staining of ß-III Tubulin, glial fibrillary acid protein (GFAP) and myelin basic protein (MBP) showed differentiation into neurons, astrocytes and oligodendrocytes. Furthermore, Nestin- and BrdU-labeled cells could also be detected in histological sections. In conclusion, the isolated cells from the cochlear nucleus presented all the features of neural stem cells: cell division, presence of progenitor cells and differentiation into different cells of the neuronal lineage. The existence of neural stem cells may add to the understanding of developmental features in the cochlear nucleus. PMID:21258945

  16. Surface fluorescence studies of tissue mitochondrial redox state in isolated perfused rat lungs.

    PubMed

    Staniszewski, Kevin; Audi, Said H; Sepehr, Reyhaneh; Jacobs, Elizabeth R; Ranji, Mahsa

    2013-04-01

    We designed a fiber-optic-based optoelectronic fluorometer to measure emitted fluorescence from the auto-fluorescent electron carriers NADH and FAD of the mitochondrial electron transport chain (ETC). The ratio of NADH to FAD is called the redox ratio (RR = NADH/FAD) and is an indicator of the oxidoreductive state of tissue. We evaluated the fluorometer by measuring the fluorescence intensities of NADH and FAD at the surface of isolated, perfused rat lungs. Alterations of lung mitochondrial metabolic state were achieved by the addition of rotenone (complex I inhibitor), potassium cyanide (KCN, complex IV inhibitor) and/or pentachlorophenol (PCP, uncoupler) into the perfusate recirculating through the lung. Rotenone- or KCN-containing perfusate increased RR by 21 and 30%, respectively. In contrast, PCP-containing perfusate decreased RR by 27%. These changes are consistent with the established effects of rotenone, KCN, and PCP on the redox status of the ETC. Addition of blood to perfusate quenched NADH and FAD signal, but had no effect on RR. This study demonstrates the capacity of fluorometry to detect a change in mitochondrial redox state in isolated perfused lungs, and suggests the potential of fluorometry for use in in vivo experiments to extract a sensitive measure of lung tissue health in real-time.

  17. Some effects of vitamin A deficiency on the isolated rat lung alveolar type II cell.

    PubMed

    Zachman, R D; Chen, X; Verma, A K; Grummer, M A

    1992-01-01

    Alveolar Type II cells were isolated from control and vitamin A deficient rats and allowed to form a monolayer in plastic dishes for 16-18 hours. The vitamin A content (retinol plus retinyl palmitate) of deficient cells was 50-75% less than in control cells on a per mg protein basis. Isolated Type II cells took up [3H]-retinol, synthesized [3H]-retinyl palmitate, and after 4 hours, 24% of the radioactivity in the Type II cells was [3H]-retinoic acid. Deficiency did not appear to alter retinoic acid synthesis. Phosphatidylcholine (PC) and disaturated phosphatidylcholine (DSPC) synthesis, were slightly less in deficient cells compared to control (95 and 85% respectively). In addition, 10(-6) M and 10(-5) M retinoic acid in the reaction media stimulated both PC and DSPC synthesis by 120-140% in control cells. The stimulating effect of retinoic acid was present in deficient cells as well, but less pronounced (120% with 10(-5) M). Vitamin A deficient Type II cells also had less basal levels of both tissue transglutaminase and epidermal transglutaminase activity than control cells. PMID:1355470

  18. Regional Morphology and Transport of PAMAM Dendrimers Across Isolated Rat Intestinal Tissue.

    PubMed

    Hubbard, Dallin; Bond, Tanner; Ghandehari, Hamidreza

    2015-12-01

    Intestinal permeability of PAMAM dendrimers has been observed, giving rationale for their use in oral drug delivery as potential carriers of associated molecules. This study assessed the apparent permeability coefficients (Papp) of dendrimers across isolated rat intestinal regional mucosae, along with estimation of the maximum non-toxic concentration. Caco-2 monolayers were also used to assess the comparative Papp values between isolated mucosae and cell culture models. Concentrations from 0.1 to 10 mM of anionic and cationic dendrimers were tested in mucosae to assess their Papp, membrane TEER, [(14)C]-mannitol Papp, and histology. 0.1 mM concentrations of dendrimers were assessed over 120 min in Caco-2 cell monolayers as concentrations above that were cytotoxic. Jejunal transport of dendrimers was higher than transport in colonic epithelium. Monolayer Papp values of dendrimers were comparable to those of jejunal mucosae. Mucosae exposed to dendrimer concentrations of 10 mM for 120 min caused significant reduction in TEER and changes in tissue morphology; however, G3.5 was the only analogue that caused significant TEER reduction and morphological changes at 1 mM concentrations. Transport in jejunal mucosae appears to be the greatest indicating that the small intestinal will be the most likely region to target for oral drug delivery using PAMAM dendrimers.

  19. Interactions between ADH and prostaglandins in isolated erythrocyte-perfused rat kidney

    SciTech Connect

    Lieberthal, W.; Vasilevsky, M.L.; Valeri, C.R.; Levinsky, N.G.

    1987-02-01

    Interactions between antidiuretic hormone (ADH) and renal prostaglandins in the regulation of sodium reabsorption and urinary concentrating ability were studied in isolated erythrocyte-perfused rat kidneys (IEPK). In this model, hemodynamic characteristics are comparable to those found in vivo, and tubular morphology is preserved throughout the period of perfusion. (Deamino)-D-arginine vasopressin (dDAVP) markedly reduced fractional sodium excretion (FE/sub Na/) in the IEPK. After indomethacin, FE/sub Na/ fell still further. In the absence of dDAVP indomethacin had no effect on sodium excretion. dDAVP increased urine osmolality in the IEPK. When prostaglandin synthesis was blocked with indomethacin, urinary osmolality increased further. In isolated kidneys perfused without erythrocytes (IPK), dDAVP decreased FE/sub Na/ from 14.5 +/- 1.8% to 9.6 +/- 1.2%. dDAVP increased urine osmolality only modestly in the IPK and indomethacin did not increase concentrating ability further. Thus the IEPK (unlike the IPK) can excrete markedly hypertonic urine in response to ADH. ADH also enhances tubular reabsorption of sodium in the IEPK. Prostaglandins inhibit both these actions of ADH but do not directly affect sodium excretion in the absence of the hormone. Prostaglandius were measured by radioimmunoassay.

  20. In vitro study of lovastatin interactions with amiodarone and with carbon tetrachloride in isolated rat hepatocytes

    PubMed Central

    Krasteva, AZ; Mitcheva, MK; Kondeva-Burdina, MS; Descatoire, VA

    2007-01-01

    AIM: To investigate the interactions at a metabolic level between lovastatin, amiodarone and carbon tetrachloride in isolated rat hepatocytes. METHODS: For cell isolation two-step collagenase liver perfusion was performed. Lovastatin was administered alone in increasing concentrations (1 μmol/L, 3 μmol/L, 5 μmol/L and 10 μmol/L) and in combination with CCl4 (86 μmol/L). The cells were also pretreated with 14 μmol/L amiodarone and then the other two compounds were added. RESULTS: Lovastatin promoted concentration-dependent significant toxicity estimated by decrease in cell viability and GSH level by 45% and 84%, respectively. LDH-activity increased by 114% and TBARS content by 90%. CCl4 induced the expected severe damage on the examined parameters. CCl4 induced toxicity was attenuated after lovastatin pretreatment, which was expressed in less increased values of LDH activity and TBARS levels, as well as in less decreased cell viability and GSH concentrations. However, the pretreatment of hepatocytes with amiodarone abolished the protective effect of lovastatin. CONCLUSION: We suggest that the observed cytopro-tective effect was due to interactions between lovastatin, CCl4 and amiodarone at a metabolic level. PMID:17465501

  1. Charge Variants of an Avastin Biosimilar Isolation, Characterization, In Vitro Properties and Pharmacokinetics in Rat

    PubMed Central

    Liu, Wan-Hui; Tao, Wen-Jie; Liu, Li-Li; Shen, Zhen-Duo

    2016-01-01

    The similarity between a proposed biosimilar product and the reference product can be affected by many factors. This study is designed to examine whether any subtle difference in the distribution of the charge variants of an Avastin biosimilar can affect its in vitro potency and in vivo PK. Here, the acidic, basic and main peak fractions of a biosimilar product were isolated using high-performance cation-exchange chromatography and were subjected to various studies to compare their in vitro properties and in vivo PK profile. A serial of analytical methods, including size exclusion chromatography (SEC), imaged capillary isoelectric focusing (icIEF) capillary zone electrophoresis (CZE) and cation-exchange chromatography (CEX-HPLC) were also used to characterize the isolated charge variants. The kinetics constant was measured using a Biacore X100 system. The study indicates the biosimilar product has a high similarity with avastin in physicochemical properties. The potency in vitro and PK profile in rat of charge variants and biosimilar product are consistent with avastin. PMID:26987122

  2. Active Oxygen Metabolites and Thromboxane in Phorbol Myristate Acetate Toxicity to the Isolated, Perfused Rat Lung.

    NASA Astrophysics Data System (ADS)

    Carpenter, Laurie Jean

    When administered intravenously or intratracheally to rats, rabbits and sheep, phorbol myristate acetate (PMA) produces changes in lung morphology and function are similar to those seen in humans with the adult respiratory distress syndrome (ARDS). Therefore, it is thought that information about the mechanism of ARDS development can be gained from experiments using PMA-treated animals. Currently, the mechanisms by which PMA causes pneumotoxicity are unknown. Results from other studies in rabbits and in isolated, perfused rabbit lungs suggest that PMA-induced lung injury is mediated by active oxygen species from neutrophils (PMN), whereas studies in sheep and rats suggest that PMN are not required for the toxic response. The role of PMN, active oxygen metabolites and thromboxane (TxA_2) in PMA-induced injury to isolated, perfused rat lungs (IPLs) was examined in this thesis. To determine whether PMN were required for PMA to produce toxicity to the IPL, lungs were perfused for 30 min with buffer containing various concentrations of PMA (in the presence or absence of PMN). When concentrations >=q57 ng/ml were added to medium devoid of added PMN, perfusion pressure and lung weight increased. When a concentration of PMA (14-28 ng/ml) that did not by itself cause lungs to accumulate fluid was added to the perfusion medium containing PMN (1 x 10 ^8), perfusion pressure increased, and lungs accumulated fluid. These results indicate that high concentrations of PMA produce lung injury which is independent of PMN, whereas injury induced by lower concentrations is PMN-dependent. To examine whether active oxygen species were involved in mediating lung injury induced by PMA and PMN, lungs were coperfused with the oxygen radical scavengers SOD and/or catalase. Coperfusion with either or both of these enzymes totally protected lungs against injury caused by PMN and PMA. These results suggest that active oxygen species (the hydroxyl radical in particular), mediate lung injury in

  3. Endothelium-dependent relaxation in the isolated rat kidney: impairment by cyclosporine A.

    PubMed

    Stephan, D; Billing, A; Krieger, J P; Grima, M; Fabre, M; Hofner, M; Imbs, J L; Barthelmebs, M

    1995-12-01

    The therapeutical use of cyclosporine A (CsA) is hampered by the development of nephrotoxicity characterized by a marked increase in renal vascular resistance (RVR). We investigated vascular functions in kidneys of rats treated with CsA. The ex vivo vascular reactivity of kidneys from control rats and animals treated subacutely with CsA [50 mg/kg/day subcutaneously (s.c.) for 16-21 days] or an olive oil vehicle (1 ml/kg) was analyzed in male Wistar