Matched adaptations of electrophysiological, physiological, and histological properties of skeletal muscles in response to chronic hypoxia
Matched adaptations of electrophysiological, physiological, and histological properties of skeletal muscles in response to chronic hypoxia
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DOI：
10.1007/s00424-004-1370-6
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发表时间：
2005-04-01
影响因子：
4.5
通讯作者：
Badier, M
中科院分区：
文献类型：
--
作者：
Faucher, M;Guillot, C;Badier, M
本研究试图区分慢性缺氧对大鼠慢肌和快肌的电生理和生理特性及组织学特征的影响。动物在一个月的时间里吸入浓度为10%的O-2。然后对慢肌[比目鱼肌（SOL）]和快肌[指长伸肌（EDL）]进行体外生理、电生理测量和组织学分析。结果与年龄匹配的正常缺氧组相应肌肉的结果进行了比较。缺氧后：(1)SOL有F-max升高的趋势，抽搐力和强直频率显著增加，m波持续时间缩短，I型纤维比例减少，而IIa型纤维比例增加一倍；(2) EDL时，F-max和强直频率降低，肌肉抗疲劳能力下降，IId/x型纤维比例减半。然后，缺氧1个月后，在SOL肌肉中，收缩和组织学性质与快速肌肉相似。相比之下，EDL变慢了，尽管其组织学受到轻微影响。缺氧时肌肉使用的减少可以解释EDL适应性恶化的趋势，而SOL更快的特性可能是由于缺氧诱导的生长相关的肌肉纤维类型的快到慢转变的抑制。
This study tried to differentiate the consequences of chronic hypoxia on the electrophysiological and physiological properties and the histological characteristics of slow and fast muscles in rats. Animals inhaled a 10% O-2 concentration for a 1-month period. Then, slow [soleus (SOL)] and fast [extensor digitorum longus (EDL)] muscles were analyzed in vitro by physiological and electrophysiological measurements and histological analyses. The results were compared to those obtained in corresponding muscles of an age-matched normoxic group. After exposure to hypoxia: (1) in SOL, there was a tendency to elevated F-max, a significant increase in twitch force and tetanic frequency and a shortening of M-wave duration, and a reduced percentage of type I fibres, whereas the proportion of type IIa fibres doubled; (2) in EDL, F-max and tetanic frequency were lowered, the muscle became less resistant to fatigue, and the proportion of type IId/x fibres was halved. Then, after 1 month of hypoxia, in the SOL muscle, both the contractile and histological properties resemble those of a fast muscle. By contrast, the EDL became slower, despite its histology was modestly affected. Reduced muscle use in hypoxia could explain the tendency for deteriorating adaptations in EDL, and the faster properties of SOL could result from hypoxia-induced inhibition of the growth-related fast-to-slow shift in muscle fibre types.