目的　研究尾部悬吊对大鼠比目鱼肌梭内、外肌纤维的mATP酶活性的影响 ,旨在探讨失重条件下梭内、外肌代谢的改变。方法　采用尾部悬吊法建立模拟失重模型 ,以钙增强的mATPase法检测模拟失重不同时期大鼠比目鱼肌梭内、外肌的mATP酶活性。结果　尾部悬吊可使梭外肌Ⅰ型肌纤维的构成比减少 ,Ⅱ型肌纤维的构成比增加 ,梭内肌纤维mATP酶活性增强 ,核袋 1纤维mATP酶染色不变或由阴性转变为弱阳性 ,核袋 2纤维和核链纤维由阳性转变为强阳性。结论　模拟失重导致梭内、外肌代谢发生改变 ,梭外肌纤维类型发生转化。 Objective To investigate the effect of tail suspension on mATPase activity in the muscle fibers of the soleus muscle and outer muscle of rat soleus muscle, aiming to explore the changes of the metabolism of shuttle and outer muscle under the condition of weightlessness. Methods The tail suspension model was used to establish the simulated weightlessness model. The mATPase activity of the soleus muscle and outer muscle of the soleus muscle in different periods of simulated weightlessness was detected by calcium-enhanced mATPase. RESULTS: Tail suspension could decrease the ratio of type Ⅰ muscle fibers in the shuttle muscle, increase the ratio of type Ⅱ muscle fibers, enhance the activity of mATP in intrasternal muscle fibers, change the m-bag 1 fiber mATP enzyme from negative or from negative to weakly positive, Nuclear bag 2 fibers and nuclear chain fibers from positive to strong positive. Conclusion Simulated weightlessness leads to the change of the metabolism of shuttle and outer muscle and the transformation of extrafusal muscle fibers.