Objectives: To evaluate concentration-dependent effects of total extract of Rusta graveolens and its purified alkaloid fraction on the nodal basic and functional properties. Methods: In the present experimental study, we used the Langendorff model for perfusion of isolated rat hearts to determine the effects of various concentrations of methanolic extract of Rue (1.25 × 10-6 weight per volume percent W/V; 2.5 × 10-6% W/V; 3.7 × 10-6 % W/ V) and total alkaloid of Rue (0.25 × 10-6% W/V; 0.5 × 10-6% W/V) on electrophysiological properties of cardiac tissue. Selective stimulation protocols were used to independently quantify atrioventricular (AV) nodal recovery, facilitation, and fatigue. We used 3 groups (N=24) of isolated perfused rat AV nodal preparations to assess the effect of Rue extracts. The study was carried out in October 2006 in the electrophysiology laboratory of the Cardiovascular Research Center of Golestan University of Medical Sciences, Golestan, Gorgan, Iran. Results: Our results showed that both the total plant extract and the alkaloid fraction of Ruta graveolens had a similar trend of action on nodal conduction time and refractorines. Furthermore, we observed increased atrioventricular conduction time (83±4 to 108±5 msec) and functional refractory period (157.6±3 to 163.7±4 msec) at a maximum concentration of 3.75 × 10-6% W/V. Conclusion: The above results indicated a potential antiarrhythmic effect of Ruta graveolens in treating supra ventricular tachyarrhythmia
