Khammari A, Noireaud J
Laboratory of Experimental Cardiology, Unité de Recherche Associée 1340, Hospital G. R. Laënnec, Nantes, France.
J Appl Physiol (1985). 1994 Nov;77(5):2420-5. doi: 10.1152/jappl.1994.77.5.2420.
Some contractile properties of soleus muscle (SOL) fibers isolated from tail-suspended (21 days) rats were compared with those determined in the slow-twitch SOL and the fast-twitch extensor digitorum longus muscle (EDL) of control rats. In SOL from suspended rats, the resting membrane potential and the intracellular Na+ activity were typical of fast-twitch muscles. The relationship between the amplitude of K+ contractures and the membrane potential was steeper for control SOL than for control EDL and suspended SOL. The inactivation curve was also shifted to more positive potentials after suspension. In the presence of perchlorate anions, the tension activation curves of control EDL and suspended SOL were similarly shifted to more negative potentials. Thus, in the present study, modifications induced by suspension in SOL, mainly related to changes in the voltage-sensing process involved in the excitation-contraction coupling mechanism, were that the SOL assumed some of the characteristics of fast-twitch muscles.
将从尾部悬吊（21天）大鼠分离出的比目鱼肌（SOL）纤维的一些收缩特性，与对照大鼠的慢肌比目鱼肌和快肌趾长伸肌（EDL）中测定的特性进行了比较。在悬吊大鼠的比目鱼肌中，静息膜电位和细胞内Na+活性是快肌的典型特征。K+挛缩幅度与膜电位之间的关系，对照比目鱼肌比对照趾长伸肌和悬吊比目鱼肌更陡峭。悬吊后失活曲线也向更正的电位移动。在高氯酸根阴离子存在的情况下，对照趾长伸肌和悬吊比目鱼肌的张力激活曲线同样向更负的电位移动。因此，在本研究中，悬吊引起的比目鱼肌的变化，主要与兴奋-收缩偶联机制中涉及的电压传感过程的变化有关，即比目鱼肌呈现出一些快肌的特征。
