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目的:观察模拟失重对兔股静脉压力-容积关系的影响及静脉壁显微结构的变化,探讨微重力环境下造成立位耐力不良的发生机制。方法:采用头低位(-20°)倾斜的方法作为模拟失重家兔模型。24只雄性健康新西兰兔,随机分为对照组、模拟失重21d组和模拟失重10d组,每组8只。进行股静脉的压力-容积关系测试,并观察血管壁的显微结构。结果:模拟失重后股静脉P-V曲线向容积变化比增大的方向移动(同对照组比较P<0.01),模拟失重21d组较10d组移动更明显(P<0.01)。加载、卸载时,模拟失重21d组的P-V二次抛物线方程式系数B1,B2的值犤加载时为(3.6±1.6)10-2,(3.3±2.8)×10-4;卸载时(4.2±1.8)10-2,(4.6±3.4)×10-4〗显著高于对照组犤加载时为(1.3±0.6)10-2,(0.4±0.3)×10-4;卸载时(1.8±1.0)10-2,(0.8±0.8)×10-4犦及模拟失重10d组犤加载时为(1.7±0.6)10-2,(0.8±0.6)×10-4;卸载时(2.1±0.6)10-2,(1.3±0.7)×10-4〗(P<0.01),模拟失重10d组的B1,B2的值和对照组相比有增加的趋势。组织学研究表明,模拟失重组股静脉内皮细胞呈立方或矮柱状并有细胞脱落,平滑肌层变薄等变化。结论:模拟失重后股静脉顺应性增加,同时股静脉管壁结构也发生明显改变。
OBJECTIVE: To observe the effect of simulated weightlessness on the pressure-volume relationship of rabbit femoral vein and the changes of the microscopic structure of venous wall, and to explore the mechanism of poor endurance caused by microgravity. Methods: The method of tilting head low (-20 °) was used as model of simulated weightlessness in rabbits. Twenty-four male New Zealand white rabbits were randomly divided into control group, simulated weightlessness 21d group and simulated weightlessness 10d group, with 8 in each group. The pressure-volume relationship of the femoral vein was tested, and the microstructure of the vessel wall was observed. Results: The changes of P-V curve in the femoral vein shifted to the larger volume (P <0.01 compared with the control group), and more significant in the 21d group than that in the 10d group (P <0.01). At loading and unloading, values of PV second-order parabolic equation coefficients B1 and B2 in the simulated weightlessness 21d group were (3.6 ± 1.6) 10-2 and (3.3 ± 2.8) × 10-4 and 4.2 ± 1.8 ) Were significantly higher than those in the control group (P <0.05), while those in the control group were (1.3 ± 0.6) 10-2, (0.4 ± 0.3) × 10-4 and (1.8 ± 1.0) (1.7 ± 0.6) 10-2, (0.8 ± 0.6) × 10-4 at loading (0.8 ± 0.8) × 10-4 犦 and 10d after simulated weightlessness (2.1 ± 0.6) 10 -2, (1.3 ± 0.7) × 10-4 (P <0.01). The values of B1 and B2 in the 10-day simulated weight-overload group showed an increasing trend compared with the control group. Histological studies have shown that the simulated weightless group of femoral vein endothelial cells were cubic or short columnar cells with shedding, smooth muscle thinning and other changes. Conclusion: The compliance of femoral vein increased after simulated weightlessness, meanwhile the structure of femoral vein wall also changed obviously.