BACKGROUND: At present, most researches on simulated weightlessness are confined to its effect on the artery. Therefore, the effect on the vein needs to be further studied.OBJECTIVE: To probe into the effect of simulated weightlessness on the ultrastructure of rabbit femoral vein and the remodeling of femoral vein.DESIGN: A completely randomized and controlled trial based on experimental animals.SETTING: Department of Aerospace and Aviation Medical Science, Fourth Military Medical University of Chinese PLA.MATERIALS: The experiment was completed in the Department of Aerospace and Aviation Medical Science, Fourth Military Medical University of Chinese PLA from December 2000 to December 2001. Altogether 24healthy male New Zealand rabbits, weighing 2.0-2.5 kg were obtained.INTERVENTIONS: The model of Head-Down Tilt( -20°) (HDT) simulated weightlessness was established in rabbits. A total of 24 healthy male New Zealand rabbits were randomly divided into control group, 10-day simulated weightlessness group and 21-day simulated weightlessness group, with 8rabbits in each group. The ultrastructure of the rabbit femoral vein was observed under transmission electron microscope.MAIN OUTCOME MEASURES: Changes and degeneration of endothelial cell, mitochondrion, internal elastic membrane, and smooth muscle.RESULTS: Cell organelles in endothelial cell of the femoral vein of HDT rabbits decreased, mitochondrion dissolved and disappeared, vacuolar degeneration in endothelial cell increased and phagolysosome in endothelial cell could be found. Internal elastic membrane became thinner and was broken. The smooth muscle layer became thinner and some smooth muscle cells became degenerated. Cell interstitial substance increased. There was significant difference in changes between 21-day and 10-day simulated weightlessness groups.CONCLUSION: The vascular remodeling of femoral vein occurs with atrophic changes during simulated weightlessness. The longer duration of simulated weightlessness is, the more obviously the structure of femoral vein changes.%背景:目前对模拟失重的研究大多数只局限于对动脉系统的影响,对静脉系统的影响有待研究.目的:观察模拟失重对家兔股静脉壁超微结构及血管重塑的影响.设计:以实验动物为研究对像完全随机对照研究.单位:解放军第四军医大学航空航天医学系.材料:实验于2000-12/2001-12在解放军第四军医大学航空航天医学系完成.24只雄性健康新西兰兔,体质量2.0～2.5kg.干预:建立头低位(-20°)倾斜的模拟失重家兔模型.24只雄性健康新西兰兔,随机分为:对照组、模拟失重10 d组、模拟失重21 d组,每组8只.用透射电镜观察兔股静脉壁的超微结构.主要观察指标:电镜下观察静脉血管壁内皮细胞、线粒体、内弹力板、平滑肌层的变化及变性情况.结果:实验组家兔股静脉内皮细胞细胞器减少,线粒体溶解、消失;空泡变性增多并可见吞噬体;内弹力板变薄且有断裂;平滑肌层变薄,部分平滑肌细胞有变性,间质增多.模拟失重21 d组较模拟失重10 d组变化更明显.结论:在模拟失重影响下,家兔股静脉壁结构发生血管重塑性变化,呈萎缩性改变,模拟失重时间越长,改变越明显.
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