目的　观察模拟失重对兔股静脉应力 应变关系的影响及股静脉的组织形态学变化。　方法　建立头低位 (- 2 0°)倾斜的模拟失重家兔模型。 2 4只雄性健康新西兰兔 ,随机分为模拟失重 2 1d组、模拟失重 10d组和对照组 ,每组 8只。各组取股静脉各做成血管条及血管环并分别做轴向和环向拉伸实验 ;对照组和实验组的血管试样均行显微结构观察。　结果　随着载荷应力的增加 ,血管试样的轴向和环向形变均显著增加 (P <0 .0 1) ,卸载时 ,均显著减少 (P <0 .0 1) ,相同应力下 ,3组试样的轴、环向卸载形变均较加载时增大 (P <0 .0 5 ) ,存在明显滞后环。相同应力 (轴向 :0～ 2 g ;环向 0 .5～ 1g)下 ,HDT 2 1d及HDT 10d组的轴、环向加卸载形变均较对照组显著增加 ,且HDT 2 1d组较HDT 10d组仍有显著增加。组织形态学观察表明 ,模拟失重时股静脉的管壁材料组份及结构均发生变化 ,内皮细胞呈矮柱或立方状 ,并伴有部分内皮细胞脱落 ,平滑肌层变薄等萎缩性改变。　结论　模拟失重后股静脉顺应性明显增加 ,且 2 1d组较 10d组增加更显著 ,同时股静脉管壁的组织结构发生明显改变 ,这可能是其顺应性增加的重要原因之一。 Objective To observe the effect of simulated weightlessness on the stress-strain relationship of rabbit femoral vein and the histomorphological changes of femoral vein. Methods A model of simulated weightlessness was established in the head low (-2 °) tilt. Twenty-four male New Zealand white rabbits were randomly divided into 2 groups: simulated weightlessness 21d, simulated weightless 10d and control group 8 rats in each group. In each group, the vascular strips and vascular rings were taken from the femoral vein, and the axial and circumferential tensile tests were performed respectively. The vascular samples of the control group and the experimental group were observed microscopically. Results With the increase of load stress, the axial and circumferential deformations of vascular samples increased significantly (P <0.01) and decreased significantly at unloading (P <0.01). Under the same stress, 3 The axial deformation and the unloading deformation of the group specimens were larger than those under loading (P <0. 05), and obvious hysteresis loops existed. Under the same stress (0 ~ 2 g in the axial direction and 0.5 ~ 1 g in the circumferential direction), the axial unloading and deforming in the HDT 2 1d and HDT 10d groups were significantly increased compared with the control group, and HDT 2 1d group had higher HDT 10d group still increased significantly. Morphological observation showed that the composition and structure of the wall material of the femoral vein changed under the simulated weightlessness. The endothelial cells were in the form of short columns or cubes, accompanied by some atrophic changes such as shedding of endothelial cells and thinning of the smooth muscle layer. Conclusions The compliance of femoral vein after simulated weightlessness increased obviously, and more significantly increased in 21d group than in 10d group, meanwhile the organizational structure of femoral vein wall changed significantly, which may be one of the important reasons for its increased compliance.