慢性缺氧大鼠膈肌纤维类型适应性变化

CHANGES IN PROPORTION OF MUSCLE FIBER TYPES IN RAT DIAPHRAGM IN RESPONSE TO CHRONIC HYPOXIA

采用肌球蛋白ＡＴＰ酶（ｍＡＴＰ酶）组化将肌纤维分为Ⅰ、ⅡＡ和ⅡＢ三种类型，通过慢性常压和减压间断缺氧大鼠模型，观察慢性缺氧（分别缺氧１个月和３个月）大鼠膈肌纤维类型的适应性变化，并与肢体肌肉进行比较。结果表明，慢性缺氧大鼠膈肌纤维由酵解型向氧化型转化，主要表现为ⅡＡ纤维比例上升（Ｐ＜０．０５）和ⅡＢ（Ｐ＜０．０５－０．０１）下降，肋膈肌变化大于脚膈肌和肢体肌肉。肌肉间适应性变化的差异可能与其功能要求不同有关。

? The adaptive changes in proportion of muscle fiber types,which were indentified by histochemistry,in rat costal and crural diaphragm (DⅠcos and DⅠcru)compared with hindlimb muscles after exposure to nomobaric hypoxia (10% O2)or simulated hypobaric hypoxia (5000 m above sea level) for one or three months were observed.The results showed that there was a tendency of transformation in muscle fiber types from glycolytic (ⅡB) to oxidative (ⅡA) fibers in both DⅠcos and DⅠcru.The changes in DⅠcos were earlier and more significant than that in DⅠcru and hindlimb muscles observed.The results indicated that the effect of chronic hypoxia on muscles may be different according to their functional demand.