间断头高位与站立位可对抗模拟失重大鼠股动脉收缩反应性的降低

目的 观察和比较头高位（HUT）与站立位（STD）对模拟失重所致股动脉收缩反应性降低的影响及其时间依赖性。方法 49只雄笥SD大鼠随机分为对照组、模拟失重组、头高位2h组、头高位4h组、站立位1h组、站立位2h组和站立位4h组，每组7只。利用离体股动脉血管环技术测定7组大鼠股动脉对血管收缩剂的反应。结果 悬吊大鼠股动脉血管环对KCl和苯肾上腺素的收缩反应性显降低，头高位与站立位组大鼠的股动脉血管环对KCl和苯肾上腺素收缩反应均较悬吊组显增强，与同步对照组相比已无显差异。结论 4wk模拟失重可以使大鼠股动脉的收缩反应性降低，而头高位与站立位均可对抗大鼠股动脉的收缩反应性的降低，这些结果提示间断性人工重力可对抗失重对血管所产生的影响。

Daily head-up tilt or standing can prevent vasoreactivity decline in femoral ar teries of simulated weightless rats

AIM To examine and compare influence and time dependence of head up tilt (HUT) or standing (STD) on decline of contraction responses of rat femoral artery caused by simulated weightlessness. METHODS Forty nine male Sprague Dawley rats were divided into 7 groups: controlgroup, simulated weightless group, 2 h HUT group, 4 h HUT group, 1 h STD group, 2 h STD group and 4 h STD group. Responses to KCl and phenylephrine (PE) were examined in vitro using isolated femoral arterial rings. RESULTS The contractile responsiveness to KCl and PE of femoral arterial rings isolated from simulated weightless rats significantly decreased, as compared with control group. And the contractile responsiveness to KCl or PE of femoral arterial rings isolated from HUT and STD group significantly enhanced, as compared with that of simulated weightless rats. Whereas there was no difference among HUT, STD and control group. CONCLUSION Simulated weightlessness may result in an decreased contractile responses to KCl and PE of rat femoral artery. Both HUT and STD prevent the decrease of contractile response to KCl and PE of femoral arteries. The results indicate that intermittent artificial gravity is effective in counteract decreased contractile response of arteries induced by simulated weightlessness.