间断性水平位站立对模拟失重大鼠股骨力学特性的影响

目的　研究不同时段间断性水平站立对尾吊大鼠股骨的影响。　方法　 SD雄性大鼠35只 ,按体重配对后随机分为 5组 :对照组 ( C)、悬吊组 ( S)及站立对抗组 (包括 L1、L2和 L4组 ) ,每组各 7只。在尾吊大鼠模拟失重的基础上 ,对抗组大鼠每日分别给予 1h、2 h和 4h水平站立作用。利用物理测量和三点弯曲等实验 ,观察了 3周间断性站立措施对尾吊大鼠股骨生长、生物力学特性的影响。　结果　和 S组相比 ,各对抗组在直径和密度改善方面有显著性意义 ( P<0 .0 1) ;在股骨重量(鲜、干 )和灰分方面增加趋势明显 ,部分指标改善有显著性意义。各对抗组弹性载荷和最大载荷提高有显著性意义 ( P<0 .0 5或 P<0 .0 1) ;韧性系数降低有显著性意义 ( P<0 .0 1) ;刚性系数增加趋势明显。各对抗组之间所有指标差异无显著性意义。　结论　间断性水平位站立显著改善了尾吊大鼠承重骨的生物力学特性及生长代谢 ;延长作用时间 ,对抗效果无显著提高。

Effects of intermittent standing on femur mechanical parameters of tail-suspension rats

Objective To explore the effects of intermittent standing on femur of tail suspension rats. Methods Thirty five male SD rats were randomly divided into 5 groups (n=7): control group (C), tail suspension group (S) and 3 standing groups (including: L1, L2 and L4 groups). Tail suspension was used to simulate weightlessness in group S and 3 L groups. The rats of later 3 groups underwent standing instead of tail suspension for 1 h, 2 h or 4 h each day. Physical and mechanical parameters of femur of rats were measured after 3 weeks of experiment. Results As compared with group C, the physical and mechanical properties of femur in 4 experimental groups were significantly lowered (P<0.01). As compared with group S, in group L1, L2, L4 diameter and density of femur were significantly increased (P<0.01), elastic load (EL) and maximum load (ML) improved markedly (P<0.05, P<0.01), and bending rigidity coefficient (BRC) declined significantly. Conclusion The negative effect of simulated weightlessness on physical and mechanical properties of femur in rats can be alleviated significantly by intermittent standing. No apparently better result was found by elongation of time of intermittent standing.