Rat hindlimb unloading: soleus histochemistry, ultrastructure, and electromyography.
Rat hindlimb unloading: soleus histochemistry, ultrastructure, and electromyography.
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大鼠后肢卸载：比目鱼肌组织化学、超微结构和肌电图。
DOI：
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发表时间：
1990
影响因子：
3.3
通讯作者：
J. W. Mellender
中科院分区：
文献类型：
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作者：
D. Riley;G. Slocum;J. Bain;F. R. Sedlak;T. Sowa;J. W. Mellender
雄性Sprague-Dawley大鼠（305 +/- 15 g）后肢卸药4、7、10-14 d，诱导比目鱼肌萎缩。对照组（291 +/- 14 g）置于动物笼中。观察悬挂尾前后比目鱼肌电图（EMG）活动。卸载导致肌肉与体重的比例逐渐降低。14 d后，I型和IIa型纤维的面积分别减少63%和47%。肌层下线粒体和肌原纤维的降解速度快于肌纤维间线粒体和细胞膜。10天后，3%的纤维出现节段性坏死；受影响的纤维均为高氧化IIa型纤维。提示缺血性损伤。到13天，30%的纤维出现中心核样病变，主要涉及I型纤维。视频监测显示后脚异常足底屈曲4天；这种姿势缩短了比目鱼肌的活动范围。核样病变显示了对缩短长度的适应。未见形态学上的去神经现象。肌电活动由强直型转为相位型，7天后肌电活动总量为正常值的13%。这些结果表明，萎缩和病理变化是由无负荷收缩、使用减少、血流受损和工作时间缩短引起的。
Soleus muscle atrophy was induced by hindlimb unloading of male Sprague-Dawley rats (305 +/- 15 g) for 4, 7, and 10-14 days. Controls (291 +/- 14 g) were housed in vivarium cages. Soleus electromyogram (EMG) activity was recorded before and during tail suspension. Unloading caused progressive reduction in the muscle-to-body weight ratio. After 14 days, type I and IIa fibers decreased in area 63 and 47%, respectively. Subsarcolemmal mitochondria and myofibrils were degraded more rapidly than intermyofibrillar mitochondria and the cell membrane. After 10 days, 3% of the fibers exhibited segmental necrosis; affected fibers were all high-oxidative type IIa fibers. This suggested ischemic injury. By 13 days, 30% of the fibers possessed central corelike lesions involving primarily type I fibers. Video monitoring revealed abnormal plantar flexion of the hindfeet by 4 days; this posture shortened the soleus working range. Corelike lesions indicated adaptation to the shortened length. No morphological signs of denervation were detected. EMG activity shifted from tonic to phasic, and aggregate activity was 13% of normal after 7 days. These findings indicate that the atrophy and pathological changes result from unloaded contractions, reduced use, compromised blood flow, and shortened working length.