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This study was designed to evaluate the effects of total extract of Phytolacca Decandra on electrophysiological properties of atrioventricular node. Male rat heart after isolation was attached to a Langendorff perfusion system. The stimulation protocol was carried out during control condition (No intervention) and on the presence of selected concentration (1.10-7 %w/v, 2.10-7 %w/v, 5.10-7 %w/v) of Phytolacca Decandra. The basic (Wenchebach, AVCT and ERP) and functional (Recovery) properties of AV-node were studied in solated, perfused male rat cardiac preparations. Total extract of P.decandra significantly increased WBCL, AVCT and ERP in the concentration dependent manner, but had no significant effect on the time constant of recovery. The results of this study demonstrate that total extract of P.decandra had parasympathic-like effect on time-independent properties of AV-node and the above results also showed a potential anti-arrhythmic role of P.decandra in terminating supraventricular tachyarrhythmia.

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Background & Objective: Pharmacological studies and traditional medical literature point to the cardiovascular effects of the Citrus aurantium L. (Rutaceae) in many instances. In the present study, we used isolated perfused AV-node of rabbit as an experimental model to determine the effect of various concentrations of essence of Citrus aurantium (0.1-0.3 v/v) on electrophysiological properties of isolated heart. The second goal of the present study was to assess the protective role of essence of Citrus aurantium on arrhythmogenic effects of ouabain. Materials & Methods: This was a semi-experimental study. We used isolated perfused rabbit AV-nodal preparation, in three groups. In the first group, the effect of various concentration of the Citrus aurantium (0.1, 0.2, 0.3 ml/l) was assesed on the AV-node. In the second and third groups, the effect of Citrus aurantium was tested in the presence of ouabain (0.1?molar) and verapamil (0.1?molar). We used 6 rabbit in each group. Statistical analysis was preformed by SPSS Mean±SE was used in the all results. Results: Our results showed depressant effects of extract of Citrus aurantium on Wenchebach Cycle Length (WBCL), AV Conduction Time (AVCT), Effective and Functional Refractory Periods (ERP & FRP). Rate-dependent properties such as Facilitation and fatigue significantly increased by Citrus.a (0.3ml/l). We had significant increase in the AVCT (32.6±3.6 to 40±6.08 msec) and FRP (147±5.1 to 166.6±3.6 msec) by Citrus.a. We had a protective role of Citrus aurantium on ouabain induced AV-nodal depression. The magnitude of facilitation and fatigue in the concentration of 0.3 C.aurantium was 7.5±0.3 and 6.5±0.5, respectively. Conclusion: The above results indicated potential inhibitory and antiarrhythmic effect of Citrus aurantium in treating supraventricular tachyarrhythmia.

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Background&Objective: Herbal remedies are suitable alternatives for synthetic drugs due to their availability, minimal side effects and lower price. Biologically active substances of plant origin represent an essential branch of modern cardiovascular pharmacotherapy. The aim of the present study was to determine concentration-dependent effects of aqueous extract of Croucus sativus on the nodal basic and functional properties. Materials&Methods: This was an experimental study. Male Newsland rabbits (1-1.3 kg) were used in all of experiments various experimental stimulating protocols (WBCL, Recovery, Facilitation, Fatigue) were applied to assessing electrophysiological properties of Node in two groups (first group n=10 and second group n=7). We used isolated preparation including some post up AV-nodal tissue preparation. All protocols were repeated in the presence and absence (control) of different concentration (A=9×10-2, B=19×10-2, C=28×10-2 mg/l) of Croucus sativus and verapamil (0.1μM). Results were shown as Mean±SE and a probability of 5% was taken to indicate statistical significance. Results: Our results showed concentratration dependent depressant effects of extract of Croucus.s on Wenchebach Cycle Length (WBCL), AV Conduction Time (AVCT), Functional Refractory Periods (FRP).Rate-dependent properties such as Facilitation and fatigue significantly increased by 19×10-2 mg/l of Croucus.s. The effect of extract was prominent on fast pathway. Conclusion: The above results indicated potential antiarrhythmic effect of Croucus.s in treating supraventricular tachyarrhythmia.

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Background and Objective: A brief and short duration episode of ischemia is recorded in ischemic preconditioning (IPC). This latter condition provides a status in which large region of heart is protected when prolonged ischemia occurred. Levothyroxine play a protective role in IPC induction, and simultaneously with stress oxidative. This study was conducted to determine the protective effect of levothyroxine with oxidative stress reduction mechanism in ischemic preconditioning model in rat heart.
Methods: This experimental study was performed on 30 male Wistar rats in three groups of 10, as follows. In the reperfusion ischaemia group (IR), the heart of the animal was placed in a Langendorff apparatus. In the ischemic preconditioning group (IPC), prior to major ischemia, was exposed to 4 periods of 5-minute ischemia with reperfusion. In the intraperitoneally administered group, levothyroxine at a dose of 25 microgram per 100 g of body weight, the heart was exposed to reperfusion ischemia. The area of infarct and the level of malondialdehyde in the heart tissue were measured.
Results: The volume of Infarcted region in IR and IPC groups was 26.55 and 11.11 respectively. The same index for the Levothyroxine receiver was 12.56. Based on these findings it was demonstrated that Levothyroxine injection reduced the Infarcted region significantly similar with IPC (P<0.05). The MDA Levels in IR and IPC were 1328 and 777, respectively and in Levothyroxine group it was determined as 762. The size of Infarcted region in both IPC and treated with Levothyroxine groups significantly reduced in compared to IR group (P<0.05).
Conclusion: Injection of levothyroxine with ischemic preconditioning reduced the effect of reperfusion maladaptive ischemia in rat heart.