CROSS-REINNERVATED MOTOR UNITS IN CAT MUSCLE .1. FLEXOR DIGITORUM LONGUS MUSCLE UNITS REINNERVATED BY SOLEUS MOTONEURONS
CROSS-REINNERVATED MOTOR UNITS IN CAT MUSCLE .1. FLEXOR DIGITORUM LONGUS MUSCLE UNITS REINNERVATED BY SOLEUS MOTONEURONS
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DOI：
10.1152/jn.1985.54.4.818
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发表时间：
1985-01-01
影响因子：
2.5
通讯作者：
BURKE, RE
中科院分区：
文献类型：
--
作者：
DUM, RP;ODONOVAN, MJ;BURKE, RE
在猫趾长屈肌运动神经元(FDL-FDL)和比目鱼肌(SOL-FDL)交叉神经支配(SOL-FDL)后30~50wk观察屈指长肌(FDL)和单个运动单位的特性。通过细胞内记录和刺激已识别的SOLα运动神经元，从功能上分离单个运动单位。糖原耗竭方法允许对属于生理特征肌肉单位的肌肉纤维进行组织化学研究。这些观察结果与正常猫FDL肌肉和运动单位的数据进行了比较(27)。故意自行支配的FDL肌(FDL-FDL；n=5)大小和湿重正常。肌萎缩侧索硬化症-肌萎缩侧索硬化症运动单位可分为与正常肌萎缩性脊柱炎相同的生理类型[类型：快收缩、疲劳性(FF)、快收缩、耐疲劳(FR)和慢速(S)；n=24]，其比例与正常大致相同。与这些类别相关的组织化学肌肉纤维类型也是定性正常的，尽管有证据表明正常的组织化学马赛克明显扭曲。这些数据证实了其他关于自我神经再支配的研究，并表明自我神经再支配可以产生肌肉纤维类型的完全相互转换。用SOL运动神经元(SOL-FDL；n=12)交叉神经支配FDL肌产生的肌肉比正常小(大约是正常湿重的一半)和更多的红色。SOL-FDL肌收缩较正常或FDL-FDL肌慢，且组织化学I型肌纤维比例较高。在那些SOL-FDL肌中，很少或根本没有不需要的自我神经支配，超过95%的肌肉纤维为I型。41个单独的运动单位在SOL-FDL肌中通过细胞内穿透功能识别的SOLα运动神经元而分离出来。生理指标(未融合性破伤风无“下垂”，抗疲劳能力强)，肌肉单位均为S型。SOL-FDL肌单位的收缩时间和疲劳特性与正常FDL中的S单位基本相同。通过糖原耗竭成功研究的7个单位均显示I型组织化学纤维。支配FDL肌单位的SOL运动神经元后超极化持续时间比正常SOL细胞略短，但轴突传导速度正常。
The properties of flexor digitorum longus (FDL) muscles and of individual motor units were studied in cats 30-50 wk after self-reinnervation by FDL motoneurons (FDL----FDL) or cross-reinnervation by soleus (SOL) motoneurons (SOL----FDL). Individual motor units were functionally isolated by intracellular recording and stimulation of identified SOL alpha-motoneurons. Glycogen-depletion methods permitted histochemical study of muscle fibers belonging to physiologically characterized muscle units. The observations were compared with data from normal cat FDL muscles and motor units (27). Intentionally self-reinnervated FDL muscles (FDL----FDL; n = 5) were normal in size and wet weight. FDL----FDL motor units could be classified into the same physiological categories found in normal FDL [types: fast contracting, fatigable (FF), fast contracting, fatigue resistant (FR), and slow (S); n = 24], with approximately the same proportions as normal. The histochemical muscle fiber types associated with these categories were also qualitatively normal although there was evidence of marked distortion of the normal histochemical mosaic. These data confirm other studies of self-reinnervation and suggest that self-reinnervation can produce complete interconversion of muscle fiber types. Cross-reinnervation of FDL muscle by SOL motoneurons (SOL----FDL; n = 12) produced muscles that were smaller (about half the normal wet weight) and more red than normal. SOL----FDL muscle contracted more slowly than normal or FDL----FDL muscles and had much higher proportions of histochemical type I muscle fibers. In those SOL----FDL muscles, in which little or no unwanted self-reinnervation could be demonstrated, greater than 95% of the muscle fibers were type I. Forty-one individual motor units in SOL----FDL muscles were isolated by intracellular penetration in functionally identified SOL alpha-motoneurons. Their muscle units were all type S by physiological criteria (absence of "sag" in unfused tetani and marked resistance to fatigue). SOL----FDL muscle units had contraction times and fatigue properties that were essentially identical to those of type S units in the normal FDL. All of the seven units, successfully studied by glycogen depletion, exhibited histochemical type I fibers. SOL motoneurons that innervated FDL muscle units had slightly shorter afterhyperpolarization durations than normal SOL cells, but axonal conduction velocities were normal.(ABSTRACT TRUNCATED AT 400 WORDS)