STUDY OF FOETAL AND NEW-BORN RAT MUSCLE FIBRES
STUDY OF FOETAL AND NEW-BORN RAT MUSCLE FIBRES
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DOI：
10.1113/jphysiol.1962.sp006941
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发表时间：
1962-01-01
影响因子：
5.5
通讯作者：
MILEDI, R
中科院分区：
文献类型：
--
作者：
DIAMOND, J;MILEDI, R
用细胞内微电极检查了胎儿（17-22天）和几周龄以内的幼鼠隔膜中的肌肉纤维。用离子导入法测定其对乙酰胆碱的敏感性。自发阈下电位可以记录在胎儿肌纤维的任何地方，但它们的起源地点是在成人终板最终形成的纤维中间。这些电位是由于乙酰胆碱，在大多数方面类似于成人纤维的微型终板电位;但它们发生的频率要低得多，而且它们的时程也较慢。大多数胎儿肌肉表现出自发收缩（和动作电位），筒箭毒碱大大减少或消除。整个长度的胎儿肌纤维是敏感的乙酰胆碱。出生时，某些纤维的腱端对药物没有反应。随着进一步的发展，肌纤维膜的化学敏感特性继续从肌腱端向纤维中部消退。成人敏感长度在出生后几周达到。它的结论是，神经肌肉连接的建立限制了化学敏感性的肌肉纤维的交界区，及其周围环境。
Muscle fibers in the diaphragm of foetal (17-22 day) and young rats up to several weeks old were examined with intracellular micro-electrodes. Their sensitivity to acetylcholine was tested with the method of iontophoretic drug application. Spontaneous subthreshold potentials could be recorded anywhere in foetal muscle fibres, but their site of origin was in the middle of the fibres where the adult end-plates are ultimately formed. These potentials are due to acetylcholine and resemble in most respects the miniature end-plate potentials of adult fibres; but they occur at a much lower frequency and their time course is slower. Most foetal muscles showed spontaneous contractions (and action potentials) which were greatly reduced or abolished by tubocurarine. The entire length of foetal muscle fibres was sensitive to acetylcholine. At birth the tendon ends of some fibres do not react to the drug. With further development the chemo-sensitive properties of the muscle fibre membrane continue to recede from the tendon ends towards the middle of the fibre. The adult sensitive length is attained a few weeks after birth. It is concluded that the establishment of neuromuscular connexions restricts the chemo-sensitivity of muscle fibres to the junctional region, and its immediate surroundings.