Cao X S, Wu X Y, Wu Y H, Zhang L N, Zhang L F
Department of Aerospace Biodynamics, Faculty of Aerospace Medicine, The Fourth Military Medical University, Xi'an, China.
Space Med Med Eng (Beijing). 2000 Oct;13(5):328-31.
Objective. To study the effects of different intermittent +45 degrees head-up-tilt (IHUT) on tail-suspended rats. Method. 28 male SD rats were randomly and equally divided into: control group (C), tail-suspended group (S), IHUT 2 h group (H2), and IHUT 4 h group (H4). On the basis of tail-suspension to simulate weightlessness, H rats were given 2 h or 4 h IHUT each day. The effects of 3 wk IHUT on tail-suspended rats were evaluated by measuring physical and mechanical parameters of the femur. Result. Femoral mass (fresh, dry and ash), diameter, and density (fresh, except H2 group) in S, H2 and H4 rats were declined significantly compared to C rats (P<0.01 or P<0.05). Diameter (P<0.05) and density of femur (P<0.01) in H2 rats were significantly improved compared to S rats. Compared to C rats, the strength and stiffness of femora were obviously weakened (P<0.01) in S rats. Elastic load in H2 rats improved markedly (P<0.05) than those in S group; in H4 group, elastic load, maximum load, and bending toughness coefficient improved significantly (P< 0.01 or P<0.05). Conclusion. Using IHUT, mechanical parameters of weight bearing bones of tail-suspended rats can be improved apparently, by extending the exposure time, mechanical parameters can be improved.
目的。研究不同时长的 +45 度头高位倾斜（IHUT）对尾部悬吊大鼠的影响。方法。将 28 只雄性 SD 大鼠随机均分为：对照组（C）、尾部悬吊组（S）、IHUT 2 小时组（H2）和 IHUT 4 小时组（H4）。在尾部悬吊模拟失重的基础上，对 H 组大鼠每天给予 2 小时或 4 小时的 IHUT。通过测量股骨的物理和力学参数来评估 3 周 IHUT 对尾部悬吊大鼠的影响。结果。与 C 组大鼠相比，S、H2 和 H4 组大鼠的股骨质量（新鲜、干燥和灰分）、直径和密度（新鲜，H2 组除外）均显著下降（P<0.01 或 P<0.05）。与 S 组大鼠相比，H2 组大鼠的股骨直径（P<0.05）和密度（P<0.01）显著改善。与 C 组大鼠相比，S 组大鼠股骨的强度和刚度明显减弱（P<0.01）。H2 组大鼠的弹性载荷比 S 组明显改善（P<0.05）；在 H4 组，弹性载荷、最大载荷和弯曲韧性系数显著改善（P<0.01 或 P<0.05）。结论。采用 IHUT 可明显改善尾部悬吊大鼠承重骨的力学参数，延长暴露时间可进一步改善力学参数。
