[Inotropic action of Astragalus membranaceus Bge. saponins and its possible mechanism].

Astragalus membranaceus saponins (AMS) 50-200 micrograms/ml had a positive inotropic action on the isolated working heart of rats, but in the case of 30 micrograms/ml the inotropic action turned negative. The contractility recovered after washing out the AMS. Strophanthin K performed in a similar manner as AMS. AMS 500 micrograms/ml decreased the resting potential of cultured rat heart cells by 10 mV. The results suggest that AMS plays its inotropic role through influencing the Na-K-ATPase.