Objective To study the calcium antagonist effect of Panaxadial Sapanins(PDS) of optimal concentration on myocardial ischemia and reperfusion injury.Methods Thirty isolated working rabbit hearts undergoing myocardial ischemia and reperfusion injury were divided into the control group and four experimental groups randomly,six in each group.St.Thomas' solution as the cardioplegic solution were used in the control group,and the PDS 40,80,160,320mg/L as it's additive agent were used in the four experimental groups respectively.The cardioplegic solutions were perfused at the moment,30 minutes and 60 minutes after the aortic cross-clamping respectively.The samples of the myocardial biopsy were taken just in heart working 10 minutes of pre-occlusion and the heart working 30 minutes of heart recovering beat.The calcic content in the myocardium were measured.Results After reperfusion,the calcic content in the myocardium of PDS 40,80,160mg/L groups were lower than that of control group(P<0.05 or P<0.01) and the calcic content of PDS 160mg/L group was the lowest(P<0.01).There was no significant difference(P>0.05) between the PDS 320mg/L group and the control group of calcic content in the myocardium.Conclusion As the additive agent of the cardioplegic solution,the dosage of PDS in the range of 40～160mg/L has the calcium antagonist effect on myocardial ischemia and reperfusion injury.And the effect increases when the concentration of PDS is increased.When the concentration of PDS is increased to 320mg/L,the calcium antagonist effect lost.