The Experts below are selected from a list of 234 Experts worldwide ranked by ideXlab platform
M H Boskabadi - One of the best experts on this subject based on the ideXlab platform.
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Effects of hydro-ethanolic extract of berberis vulgaris fruit on rabbit Isolated Heart
DARU, 2006Co-Authors: H Parsaee, M N Shafiei, M H BoskabadiAbstract:Several therapeutic effects including antimicrobial, antidiarrhea, hepatoprotection and cardiotonic for Berberis vulgaris have been described. In the present study, the effects of hydro-ethanolic extract of Berberis vulgaris on the rate and contractility of Isolated Heart were examined. The Heart mounted on a modified Langendorff apparatus and circulation was perfused through aorta. Heart rate and contractility were determined in the presence of four concentrations of hydro-ethanolic extract (0.5, 1.0, 2.0 and 5.0 mg/100ml) and diltiazem, a calcium channel blocker (0.1, 1,10 and 100 µM) in comparison with baseline values in two different groups of experiments as follows: 1) Perfused Heart with normal Krebs solution (group1 experiments, n=10). 2) Perfused Heart with calcium free Krebs solution (group 2 experiments, n=9). In group 1 only 3 highest concentrations of diltiazem showed significant reduction in Heart rate (p
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effects of hydro ethanolic extract of berberis vulgaris fruit on rabbit Isolated Heart
DARU, 2006Co-Authors: H Parsaee, M N Shafiei, M H BoskabadiAbstract:Several therapeutic effects including antimicrobial, antidiarrhea, hepatoprotection and cardiotonic for Berberis vulgaris have been described. In the present study, the effects of hydro-ethanolic extract of Berberis vulgaris on the rate and contractility of Isolated Heart were examined. The Heart mounted on a modified Langendorff apparatus and circulation was perfused through aorta. Heart rate and contractility were determined in the presence of four concentrations of hydro-ethanolic extract (0.5, 1.0, 2.0 and 5.0 mg/100ml) and diltiazem, a calcium channel blocker (0.1, 1,10 and 100 µM) in comparison with baseline values in two different groups of experiments as follows: 1) Perfused Heart with normal Krebs solution (group1 experiments, n=10). 2) Perfused Heart with calcium free Krebs solution (group 2 experiments, n=9). In group 1 only 3 highest concentrations of diltiazem showed significant reduction in Heart rate (p<0.05 to P<0.001). However, 3 highest concentrations of diltiazem showed significant decrease and the last 2 concentrations of hydro-ethanolic extract increased Heart contractility significantly (p<0.01 to P<0.001). In group 2 only the last concentration of diltiazem showed significant reduction in Heart rate and contractility (p<0.05). The relationship between concentrations of hydro-ethanolic extract and Heart rate in both group were negative (p<0.01 to p<0.001). However, there was positive correlation between concentrations of hydro-ethanolic extract and Heart contractility. These results showed that of hydro-ethanolic extract of Berberis vulgaris has strong effect on Heart contractility. The results of the present study may also indicate an activatoion of the calcium channel of Isolated Heart by the extract.
Benedict R. Lucchesi - One of the best experts on this subject based on the ideXlab platform.
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Free radicals upregulate complement expression in rabbit Isolated Heart.
American Journal of Physiology-Heart and Circulatory Physiology, 2000Co-Authors: Elaine J. Tanhehco, Koji Yasojima, Patrick L. Mcgeer, Ruth A. Washington, Benedict R. LucchesiAbstract:Both free radicals and complement activation can injure tissue. Our study determined whether free radicals alter complement production by the myocardium. Isolated Hearts from New Zealand White rabb...
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antiarrhythmic agent ms 551 protects against pinacidil hypoxia induced ventricular fibrillation in langendorff perfused rabbit Isolated Heart
Journal of Cardiovascular Pharmacology, 1994Co-Authors: Gregory S. Friedrichs, Liguo Chi, Shawn C. Black, P. J. Manley, Benedict R. LucchesiAbstract:We studied the electrophysiologic and antifibrillatory effects of the class III agent MS-551 in a rabbit Isolated Heart model in which ventricular fibrillation (VF) occurs reproducibly under conditions of hypoxia/reoxygenation in the presence of the ATP-dependent potassium channel opener, pinacidil. Ten minutes after MS-551 or vehicle administration, addition of pinacidil (1.25 microM) to the buffer was followed by a 12-min hypoxic period and 40-min reoxygenation. At a low concentration of MS-551 (1.0 microM), VF occurred in 5 of 6 Hearts, the same incidence as in the control group (5 of 6). In contrast 0 of 6 Hearts treated with 15 microM MS-551 developed VF (p < 0.05 vs. vehicle). Ventricular effective refractory period (VERP) was determined in a separate group of Isolated Hearts (n = 13). Pinacidil alone, during normoxic perfusion, decreased VERP 48 +/- 11% (p < 0.05) 15 min after exposure. Five minutes of hypoxia alone also decreased VERP (57 +/- 8%, p < 0.05). Under normoxic conditions, MS-551 increased ERP 31 +/- 10% (p < 0.05 vs. baseline). VERP prolongation by MS-551 was reduced in the presence of pinacidil but remained 22 +/- 6% (p < 0.05) above baseline. The results suggest that VERP shortening owing to pinacidil-mediated ATP-dependent K+ channel opening is associated with development of VF in Isolated Heart. MS-551 attenuates the pinacidil-mediated decrease in VERP and prevents pinacidil+hypoxia-reoxygenation-induced VF. Because pinacidil and hypoxia open myocardial KATP channels, putatively decreasing VERP, MS-551 may exert its antifibrillatory effect through partial blockade of KATP channels.
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Antifibrillatory effects of ibutilide in the rabbit Isolated Heart: mediation via ATP-dependent potassium channels.
The Journal of pharmacology and experimental therapeutics, 1993Co-Authors: Gregory S. Friedrichs, Liguo Chi, Shawn C. Black, P. J. Manley, Benedict R. LucchesiAbstract:This study determined if ibutilide, a drug with class III activity, exhibited antifibrillatory effects in an Isolated Heart model of ventricular fibrillation (VF). Langendorff-perfused Hearts were randomized among six groups. Group I (n = 9) served as the vehicle-treated control group. Groups II (n = 6), III (n = 10) and IV (n = 9) were pretreated with ibutilide 0.1; 1.0 or 3.0 microM, respectively. Ten minutes after perfusion in the presence of vehicle or ibutilide, Hearts were perfused with the ATP-dependent potassium channel opener, pinacidil (1.25 microM) and subjected to a 12-min hypoxic period followed by 40 min of reoxygenation, or until the onset of VF. Groups V and VI were used to investigate electrophysiological effects of ibutilide (n = 12), as well as its chemical defibrillatory activity (n = 9), respectively. Additional experiments involved isometric tension recordings from canine atrial pectinate muscle exposed to increasing concentrations of pinacidil (3-300 microM) in the presence of ibutilide (3-30 microM). Ibutilide decreased the incidence of VF in a concentration-dependent manner; eight of nine control Hearts developed VF vs. two of nine Hearts (P = .018 chi 2) treated with 3.0 microM ibutilide. In atrial pectinate tissue, ibutilide attenuated the negative inotropic effect of pinacidil. An unexpected finding was the ability of ibutilide to achieve chemical defibrillation when added to the perfusion medium after the electrical induction of ventricular fibrillation in the Isolated Heart. The antifibrillatory effect of ibutilide may result from inhibition of the ATP-dependent potassium channel made susceptible to opening by pinacidil during hypoxia.
H Parsaee - One of the best experts on this subject based on the ideXlab platform.
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Effects of hydro-ethanolic extract of berberis vulgaris fruit on rabbit Isolated Heart
DARU, 2006Co-Authors: H Parsaee, M N Shafiei, M H BoskabadiAbstract:Several therapeutic effects including antimicrobial, antidiarrhea, hepatoprotection and cardiotonic for Berberis vulgaris have been described. In the present study, the effects of hydro-ethanolic extract of Berberis vulgaris on the rate and contractility of Isolated Heart were examined. The Heart mounted on a modified Langendorff apparatus and circulation was perfused through aorta. Heart rate and contractility were determined in the presence of four concentrations of hydro-ethanolic extract (0.5, 1.0, 2.0 and 5.0 mg/100ml) and diltiazem, a calcium channel blocker (0.1, 1,10 and 100 µM) in comparison with baseline values in two different groups of experiments as follows: 1) Perfused Heart with normal Krebs solution (group1 experiments, n=10). 2) Perfused Heart with calcium free Krebs solution (group 2 experiments, n=9). In group 1 only 3 highest concentrations of diltiazem showed significant reduction in Heart rate (p
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effects of hydro ethanolic extract of berberis vulgaris fruit on rabbit Isolated Heart
DARU, 2006Co-Authors: H Parsaee, M N Shafiei, M H BoskabadiAbstract:Several therapeutic effects including antimicrobial, antidiarrhea, hepatoprotection and cardiotonic for Berberis vulgaris have been described. In the present study, the effects of hydro-ethanolic extract of Berberis vulgaris on the rate and contractility of Isolated Heart were examined. The Heart mounted on a modified Langendorff apparatus and circulation was perfused through aorta. Heart rate and contractility were determined in the presence of four concentrations of hydro-ethanolic extract (0.5, 1.0, 2.0 and 5.0 mg/100ml) and diltiazem, a calcium channel blocker (0.1, 1,10 and 100 µM) in comparison with baseline values in two different groups of experiments as follows: 1) Perfused Heart with normal Krebs solution (group1 experiments, n=10). 2) Perfused Heart with calcium free Krebs solution (group 2 experiments, n=9). In group 1 only 3 highest concentrations of diltiazem showed significant reduction in Heart rate (p<0.05 to P<0.001). However, 3 highest concentrations of diltiazem showed significant decrease and the last 2 concentrations of hydro-ethanolic extract increased Heart contractility significantly (p<0.01 to P<0.001). In group 2 only the last concentration of diltiazem showed significant reduction in Heart rate and contractility (p<0.05). The relationship between concentrations of hydro-ethanolic extract and Heart rate in both group were negative (p<0.01 to p<0.001). However, there was positive correlation between concentrations of hydro-ethanolic extract and Heart contractility. These results showed that of hydro-ethanolic extract of Berberis vulgaris has strong effect on Heart contractility. The results of the present study may also indicate an activatoion of the calcium channel of Isolated Heart by the extract.
Chi-keung Chan - One of the best experts on this subject based on the ideXlab platform.
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Predicting self-terminating ventricular fibrillations in an Isolated Heart
EPL (Europhysics Letters), 2013Co-Authors: Alexey V. Dvornikov, Pik-yin Lai, Chi-keung ChanAbstract:Ventricular fibrillations (VFs) in Isolated Hearts induced by fast pacing are studied in a Langendorff preparation by measuring the electrical signals from the right atrium and the ventricle . We find that when there is a strong component of Vv detected in Va during VF, the induced VFs are usually not self-terminating. Criteria for the prediction of self-terminating VFs are developed based on the analysis of Vv and Va by the cross-wavelet power spectrum and cross-Fourier power spectrum methods. The success rate of our prediction criteria is about 80?90 %. Our findings suggest that a Heart under VF can recover its sinus rhythm only when the sino-atrial node of the Heart is not under strong influence of the VF from its ventricle.
Michael J Curtis - One of the best experts on this subject based on the ideXlab platform.
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endogenous protection against reperfusion induced ventricular fibrillation role of neuronal versus non neuronal sources of nitric oxide and species dependence in the rat versus rabbit Isolated Heart
Journal of Molecular and Cellular Cardiology, 1996Co-Authors: Ravinder Pabla, Michael J CurtisAbstract:Nitric oxide (NO) is an endogenous protectant against reperfusion-induced ventricular fibrillation (VF) in the rat Isolated Heart. Here, the following were investigated: (1) the tissue source of cardioprotective NO using a novel inhibitor (7-nitro indazole; 7-NI) of the neuronal form of NO synthase (NOS) and direct detection of coronary effluent NO by chemiluminescence; and (2) the species dependence by comparing rat and rabbit Hearts. Perfusion with modified Krebs solution was followed by 60 min left regional ischemia and 10 min reperfusion. 7-NI (1μM) increased the incidence of VF from 0% to 60% in rat Hearts (n=10;P<0.05). Co-perfusion withL-arginine (1 mM) reduced VF incidence to 20% (P:N.S.vcontrols). The inactive analog of 7-NI (6-amino indazole; 6-AI) had no pro-fibrillatory activity. Neither 7-NI nor 6-AI affected coronary flow or recovery of flow during reperfusion. 7-NI reduced basal coronary effluent NO levels to below the limit of detection (<1 pmol), but a massive increase in NO levels occurred whenL-arginine was co-perfused with 7-NI. Although 7-NI had no effect on basal coronary flow and, by implication, resting NO release, it was found, in separate studies, to antagonise substance P-induced vasodilatation and NO release, suggesting that its neuronal selectivity is lost in the presence of an exogenously administered activator of endothelial NOS in rat Hearts. In rabbit Hearts, in contrast, 7-NI had no effect on VF or NO levels. However, in rabbit Hearts the isozyme non-selective NO synthase blocker, NG-nitro-l-arginine methyl ester (L-NAME; 100μM), increased VF incidence from 0 to 50% (P<0.05) and, during the first minute of reperfusion, reduced NO levels from 4929±893 to 2505±483 pmol/min/g (P<0.05) and recovery of coronary flow by 22% (P<0.05). Each of these effects were prevented byL-arginine co-perfusion. These data indicate a role for basally released NO as an endogenous antifibrillatory cardioprotectant in rat and rabbit Isolated Heart and indicate that the tissue source (neuronal in rat but not in rabbit Heart) is species-dependent.
