MOTOR UNITS IN CAT SOLEUS MUSCLE - PHYSIOLOGICAL, HISTOCHEMICAL AND MORPHOLOGICAL CHARACTERISTICS
MOTOR UNITS IN CAT SOLEUS MUSCLE - PHYSIOLOGICAL, HISTOCHEMICAL AND MORPHOLOGICAL CHARACTERISTICS
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DOI：
10.1113/jphysiol.1974.sp010540
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发表时间：
1974-01-01
影响因子：
5.5
通讯作者：
TSAIRIS, P
中科院分区：
文献类型：
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作者：
BURKE, RE;LEVINE, DN;TSAIRIS, P
1.在麻醉猫比目鱼肌运动单位的生理特性上，采用细胞内刺激运动神经元的方法，以确保单个单位的功能隔离。肌纤维属于6个单位，通过长时间刺激后糖原耗竭来鉴定，允许分析它们的组织化学特征和解剖组织。所研究的比目鱼肌单位均为S类型，在长时间的刺激下具有极强的抗疲劳能力。痉挛收缩时间~131ms，平均97.1ms；强直性张力3.5~36g，平均10.5g。大多数单位在短时间的高频破伤风后表现出抽动张力的抑制，很少有单位表现出任何明显程度的强直后抽动增强。属于单个比目鱼肌运动单位的肌纤维散布于各区域，占肌肉总体积的很大一部分。现有数据表明，不同的比目鱼肌运动神经元可能支配不到50到400多个肌纤维，平均神经支配比率在140到190个肌纤维/单位之间。将结果与在类似条件下对增效剂腓肠肌的S运动单位的观察结果进行了比较。这些证据表明，比目鱼肌单位并不等同于混合腓肠肌的S单位，而是构成一个独特的种群。
1. Physiological properties of motor units in the soleus muscle were studied in anaesthetized cats using intracellular stimulation of motoneurones to ensure functional isolation of single units. The muscle fibres belonging to 6 units were identified by glycogen depletion following prolonged stimulation, permitting analysis of their histochemical profiles and anatomical organization.2. The studied units in soleus were all classed as type S and were extremely resistant to fatigue during prolonged stimulation. Twitch contraction times ranged from 64 to 131 msec (mean 97·1 msec) and tetanic tensions ranged from 3·5 to 36 g (mean 10·5 g). Most units exhibited depression of twitch tension in the wake of a short high‐frequency tetanus and few of the units showed any significant degree of post‐tetanic twitch potentiation.3. Muscle fibres belonging to single soleus motor units were found to be scattered through territorial volumes occupying a large fraction of the total muscle volume. The available data suggest that different soleus motoneurones may innervate from less than 50 to more than 400 muscle fibres, with an average innervation ratio between 140 and 190 muscle fibres per unit.4. The results were compared with observations on type S motor units in the synergist gastrocnemius, obtained under similar conditions. The evidence suggests that soleus units are not equivalent to the type S units of the mixed gastrocnemius but rather constitute a unique population.