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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.