间断性头高位45°对模拟失重兔股静脉顺应性的影响

Effects of intermittent 45° HUT on compliance of femoral vein in rabbits during simulated weightlessness

目的观察间断性头高位45°锻炼对模拟失重兔股静脉应力-应变关系的影响。方法采用兔头低位-20°倾斜的方法模拟失重。24只雄性健康兔,随机分为对照组、模拟失重21d组(HDT)和每天2h头高位45°对抗组(HUT),每组8只。实验21d后测试离体股静脉轴向和环向应力-应变关系的变化。结果在相同应力下,模拟失重组兔股静脉环向加、卸载形变较对照组均显著增加(P<0·05或P<0·01),而轴向加、卸载形变较对照组均无明显变化。对抗组与模拟失重组相比,在同等应力情况下,环向形变明显减小(P<0·05或P<0·01),轴向形变无明显变化。对抗组与对照组相比,轴向及环向形变均无显著差异。结论21d模拟失重可引起兔股静脉顺应性显著增加,每天2h头高位45°锻炼可部分对抗模拟失重所引起的股静脉顺应性的增加。

Objective To observe the effects of simulated weightlessness and intermittent headup tilt （HUT） 45°on stress strain relationship of femoral vein in rabbits. Methods The weightlessness simulation model was set up by -20° head-down tilt （HDT）. Twenty four healthy male rabbits were randomly divided into three groups： 21-day weightlessness（HDT） group, 45° head up tilt 2 h per day（HUT） group, control group, 8 rabbits in each group. The stress strain relationship of femoral vein strips and rings was observed after simulated weightlessness. Results Under the same stress,both the up-load and down-load circumferential strains in HDT group were significantly higher than those of control group （P〈0. 05 or P〈0. 01）. While the differences between the up-load and download longitudinal strains of the HDT group and those of control group were non significant. In comparison with HDT group, the circumferential strains in HUT group decreased more significantly under the same stress, but no significant difference was found in longitudinal strains. Conclustons Weightlessness simulation for 21 d may lead to the increase of compliance of femoral vein in rabbits, and 45° HUT 2 h per day may partly counteract the effects of simulated weightless on compliance of the femoral vein。