Abstract:Objective To investigate the contraction of isolated varicose veins induced by Chaihu Shugan Powder and possible mechanisms of action. Methods Human varicose great saphenous vein and umbilical vein ring were selected, and microvascular tension was measured. The levels of 5-hydroxytryptamine (5-HT) and acetylcholine (Ach) were measured to evaluate the endothelial function of vein rings. Different concentrations of Chaihu Shugan Powder were added and the changes in the tension of the varicose great saphenous vein and the umbilical vein were measured. After the treatment with nifedipine, an L-calcium channel blocker, the changes in the tension of the varicose great saphenous vein were measured. Results Diosmin did not cause marked contraction of the isolated veins. Chaihu Shugan Powder directly caused contraction of the varicose great saphenous vein and the umbilical vein in a dose-dependent manner, and the umbilical vein had greater contraction than the varicose great saphenous vein. Nifedipine inhibited the contraction of the isolated varicose great saphenous vein caused by Chaihu Shugan Powder. Conclusion Chaihu Shugan Powder can cause the contraction of isolated veins, possibly by promoting the influx of extracellular calcium.