Effects of Panax notoginseng saponin Rg1 on cardiac electrophysiological properties and ventricular fibrillation threshold in dogs.

To study the effects of Rg1 isolated from saponins of Panax notoginseng on cardiac electrophysiological properties and ventricular fibrillation threshold (VFT).Seventeen open-chest dogs were randomly allocated into a Rg1 group (20 mg kg-1, iv) and a control group. The electrophysiological variables and VFT were evaluated by standard electric stimuli and monophasic action potential (MAP) recording.Rg1 prolonged sinus node recovery time (SNRT) by 19.1%, AV conduction Wenckebach cycle length (AVWCL) by 7.1%, and ventricular effective refractory period (VERP) by 7.9%. It prolonged ventricular MAPD30, MAPD50, and MAPD90 by 25.5%, 24.2%, and 13.5%, respectively. VFT was increased by 19.2%.Rg1 prolonged ventricular refractoriness and repolarization, and increased VFT. It was indicated that cardiac electrophysiological effects of Rg1 were similar to those of amiodarone.