尾悬吊大鼠后肢动脉平滑肌细胞钾离子通道活性的改变  

Changes of Potassium Channel Activity of Hindlimb Arterial Smooth Muscle Cells in Tail-suspended Rats

作　　者：付兆君[1] 程宏伟[1] 张立藩[1] 马进[1] 张乐宁[1] 马孝武[1] 

机构地区：[1]第四军医大学航空航天生理学教研室,陕西西安710032

出　　处：《航天医学与医学工程》2003年第4期253-256,共4页Space Medicine & Medical Engineering

基　　金：国家自然科学基金资助 (3 0 170 3 5 5 )

摘　　要：目的观察模拟失重是否可引起大鼠后肢动脉平滑肌细胞钾离子通道功能改变 ,以阐明模拟失重所致后肢动脉血管收缩反应降低的机理。方法用离体股动脉血管环制备测定 1周及 4周模拟失重大鼠股动脉对钾离子通道阻断剂盐酸四乙铵 (TEA)和 4 氨基吡啶 ( 4 AP)收缩反应的变化。并采用膜片钳全细胞记录方法直接观察隐动脉平滑肌细胞 (VSMCs)大电导钙激活钾离子通道 (BKCa)和电压依赖性钾离子通道 (KV)电流密度的改变。结果 1周及 4周模拟失重大鼠股动脉血管环对 60mMKCl的收缩反应下降 ;对TEA或 4 AP的收缩反应与其对 60mMKCl收缩反应的比值在模拟失重 1周及 4周后则均显著升高 ,但该比值在模拟失重 1周与 4周组间无显著差异。膜片钳实验结果表明 ,1周模拟失重大鼠隐动脉VSMCsBKCa电流密度和KV 电流密度均显著升高。结论模拟失重大鼠股动脉对KCl的收缩反应降低 ;而后肢动脉平滑肌细胞BKCa及KV 活性增高 。Objective To examine the change of potassium channel function in hindlimb arterial smooth muscle cells in tail suspended rats and to elucidate the underlying electro physiological mechanisms responsible for the depressed vascular responsiveness of hindlimb arteries induced by simulated weightlessness. Method The contractile responsiveness of femoral arterial rings of 1 wk and 4 wk tail suspended rats to potassium channel blockers, tetraethylammonium chloride (TEA) and 4 aminopyridine (4 AP), were recorded, and the currents of large conductance calcium dependet potassium channel (BK Ca ) and voltage activated potassium channel (K V) of vascular smooth muscle cells (VSMCs) in saphenous arteries from 1 wk tail suspended rats were recorded using the whole cell recording mode of patch clamp technique. Result The femoral arteries from of 1 wk and 4 wk tail suspended rats showed a decreased contractile response to 60 mM KCl, and the ratio of their contractile responses induced by TEA or 4 AP to their responses induced by 60 mM KCl increased significantly after 1 wk and 4 wk simulated weightlessness.However no difference was found between 1 wk and 4 wk tail suspended rats.The whole cell current recording showed that BK Ca current densities and K V current densities of VSMCs in saphenous artery increased significantly after 1 wk simulated weightlessness. Conclusion The contractile response of hindlimb arteries to KCl decreased after simulated weightlessness.The activities of BK Ca and K V of smooth muscle cells in hindlimb arteries from tail suspended rats increased,and these changes might be among the electro physiological mechanisms involved in the depressed vasoreactivity of hindlimb arteries due to simulated weightlessness.

关 键 词：失重模拟 尾吊 钾 离子通道 股动脉 隐动脉 血管平滑肌细胞 

分 类 号：R852.22[医药卫生—航空、航天与航海医学]