尾部悬吊对大鼠比目鱼肌梭内外肌纤维SDH活性的影响

Changes of Activities of Succinic Dehydrogenase in Intrafusal and Extrafusal Fibres of the Soleus Muscle in Tail Suspended Rats

:【目的】研究尾部悬吊对大鼠比目鱼肌梭内、外肌纤维琥珀酸脱氢酶 (succinicdehydrogenase,SDH)活性的影响 ,旨在探讨失重或模拟失重状态下肌梭的代谢和功能变化。【方法】用尾部悬吊法模拟失重 ,雌性Sprague Dawley大鼠按体质量配对原则 ,随机分为尾部悬吊 3、7、14、30d组及同步饲养的对照组。以氯化硝基四氮唑蓝盐 (nitrobluetetrazolium ,Nitro BT)法检测比目鱼肌梭内、外肌纤维SDH的活性。【结果】尾部悬吊导致Ⅰ型肌纤维的构成比减少 ,Ⅱ型肌纤维各亚型的构成比增加 ,以Ⅱb型增加最显著。尾部悬吊 3、7、14、30d组的Ⅰ型肌纤维构成比分别为 87.92 % ,84.0 0 % (P <0 .0 5 ) ,6 9.90 %(P <0 .0 1) ,6 7.90 % (P <0 .0 1) ;Ⅱb型肌纤维的构成比分别是 3 .75 % ,5 .6 3% (P <0 .0 5 ) ,15 .35 % (P <0 .0 1) ,18.33%(P <0 .0 1)。梭内肌纤维SDH活性增强 ,核袋 1纤维SDH染色由阳性转变为强阳性 ,核袋 2纤维由阴性转变为中等以上阳性 ,核链纤维由仅有一条呈弱阳性转变为均呈强阳性。【结论】模拟失重导致梭内、外肌纤维代谢改变 ,骨骼肌发生肌纤维类型转换 ,肌梭的功能活动可能受影响。

Objective To explore changes of the histochemical activities of myofibrillar succinic dehydrogenase(SDH) in intrafusal and extrafusal fibres of the rat soleus muscle under condition of the simulated weightlessness. Methods The condition of weightlessness was simulated by suspension of rat's tail. The histochemical activities of myofibrillar SDH in intrafusal and extrafusal fibres of the soleus muscles were studied from 3-days(SUS-3), 7-days(SUS-7), 14-days(SUS-14), 30-days(SUS-30) tail suspended rats and control rats with nitroblue tetrazolium (Nitro-BT) method. Results The constituent ratios of type Ⅰ muscle fibre became less, while the type II's turned higher after tail suspension. The constituent ratios of type Ⅰ muscle fibre in the soleus muscle from SUS-3, SUS-7, SUS-14 and SUS-30 were 87 92%, 84 00% (P<0 05), 69 90% (P<0 01), 67 90% (P<0 01), and type Ⅱb were 3 75%, 5 63% (P<0 05), 15 35% (P<0 01), 18 33% (P<0 01) respectively. The bag1, chain intrafusal fibers exhibited higher histochemical activities of myofibrillar SDH, and bag2 intrafusal fibres appeared medium or higher activity instead of negative reaction compaired with their own control. Conclusion The simulated weightlessness changes histochemical activities of myofibrillar SDH and metabolism in intrafusal and extrafusal fibres, and possible due to transformation of type Ⅰ to type Ⅱ muscle fibres.