<正> Objective: To investigate changes of Ca2+ activated potassium channels （ KCa） in autogenous vein grafts. Methods: Contraction of venous ring was measured by means of perfusion in vitro. The intimal rabbits proliferation of vascular and proliferation of cultured smooth muscle cells （ vascular smooth muscle cells

VSMCs） were observed by the means of computerised image analysis and MTT method respectively. Furthermore

whole cell mode of patch clamp was used to record KCa of VSMCs isolated from autogenous vein grafts. Results: One week after transplantation there were no significant differences of contraction and intimal relative thickness between autogenous vein grafts and control. Contraction and intimal relative thickness of autogenous vein graft were significantly increased 2 weeks after transplantation （P < 0. 05

n = 8 vs control）

and they was more enhanced 4 weeks after vein transplantation （ P < 0. 01

n =8 vs control ）. TEA（ blocker of Ca2+ activated potassium channels） increased MTT A490 nm