OBJECTIVE:To study the pharmacological effects of saponin H,a new saponin isolated from Polygala tenuifolia Willd,on isolated smooth muscle and herat.METHODS:Isolated rabbit ileum,aorta strip,Langendorff heart,guinea pig trachea,and rat uterus were prepared.Their changes in tension 3 min after administration of H were recorded.RESULTS:19 and 76 μmol.L-1of H showed contracting on above-mentioned smooth muscles,with increasing their tensions by 64% and 167%,30% and 118%,20% and 50%,100% and 118%,respectively.19,38 and 76μmol.L-1 of H showed dose-dependent inhibition on heart,decreased contractile force by 20%,23% and 34%,and reduced the heart rate by 17%,20% and 35%,respectively,but failed to affect the coronary flow.The contracting action of H on uterus was not influnced by diphenhydramine,but partly attenuated by indomethacin.CONCLUSION:H excited the isolated smooth muscles but inhibited the heart.Its action on uterus was partly related to the activation of prostaglandin synthetase.