Abstract:It was found that Ginsenoside B(GSB)could reduce the myocardial systolic power and frequency of the isolatedatrium of guinea pigs in a concentration-dependent way,and obviously prolong the functional refractory peried of theleft atrium. GSB could competitively antagonize the positive inotropic action of Iso,and non-competitively antagonizethe positive inotropic action of CaCl2 on the isolated right atrium of guinea pigs.