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目的探讨模拟失重对大鼠整体比目鱼肌和腓肠肌力学特征的影响。方法ＳＤ大鼠经７天和１５天悬吊结束，在股骨下端切断右侧后肢，腓肠肌向上固定于实验台上。利用电刺激和疲劳刺激的方法，测定大鼠整体比目鱼肌和腓肠肌力学参数的变化。结果７天尾吊使大鼠体重增长速度减慢（Ｐ＜０．０１），１５天悬吊更显著（Ｐ＜０．００１）；７天和１５天悬吊使比目鱼肌明显萎缩，湿重降低（Ｐ＜０．０１），腓肠肌湿重降低较少（Ｐ＜０．０５）；７天悬吊后整体比目鱼肌半舒张时间、峰张力和单位重量峰张力降低（Ｐ＜０．０５），１５天悬吊降低更明显（Ｐ＜０．０１），但对腓肠肌影响不大；７天悬吊后低频刺激容易引起比目鱼肌疲劳。结论失重或模拟失重引起骨骼肌力学特征的变化程度与骨骼肌纤维成分有关，慢肌纤维含量越高（如比目鱼肌），影响越明显，反之则少（如腓肠肌）。
Objective To investigate the effects of simulated weightlessness on the mechanical properties of soleus muscle and gastrocnemius in rats. Methods SD rats were suspended after 7 days and 15 days. The right hindlimb was cut off at the lower femur, and the gastrocnemius muscle was fixed upward on the experimental bench. The changes of mechanical parameters of whole soleus and gastrocnemius were measured by electrical stimulation and fatigue stimulation. Results After 7 days of tail suspension, the weight gain of rats was slowed down (P <0.01), and the suspension was more significant at 15 days (P <0.001). The suspensions at 7 and 15 days significantly reduced the soleus muscle weight and wet weight (P <0.05); after 6 days of suspension, the soleus muscle half-relaxation time, peak tension and the peak tension of the unit weight decreased (P <0.05) (P <0.01), but had little effect on gastrocnemius muscle. After 7 days of suspension, low frequency stimulation easily caused soleus muscle fatigue. Conclusion The changes of skeletal muscle mechanical properties caused by weightlessness or simulated weightlessness are related to the composition of skeletal muscle fibers. The higher the content of slow muscle fibers (such as soleus muscle), the more obvious the effect is, and vice versa (eg gastrocnemius).