Huang S K, Zhu P H, Qu F J, Chen K Y
Shanghai Institute of Physiology, Academia Sinica, China.
Cell Tissue Res. 1989 Jan;255(1):209-13. doi: 10.1007/BF00229083.
In normal (untreated) rats the mean length ratio of postsynaptic to presynaptic membrane was 2.7 +/- 0.8 for neuromuscular junctions of slow-twitch soleus muscle fibres and 4.2 +/- 1.0 for neuromuscular junctions of fast-twitch extensor digitorum longus muscle fibres; this difference was significant (P less than 0.001). After experimental double innervation by fast and slow muscle nerves for four months, the ratio was (1) 2.9 +/- 0.8 for the original slow-twitch fibre end-plate and 2.8 +/- 0.8 for the newly established one, both not significantly different from that of the normal slow-twitch fibres; and (2) 2.2 +/- 0.5 for the original fast-twitch fibre end-plate and 2.2 +/- 0.7 for the newly established one, both significantly smaller than that of the normal fast-twitch fibres (P less than 0.001). This means that the double innervated slow-twitch muscle fibres retained their original neuromuscular junction type, whereas the doubly-innervated fast-twitch muscle fibres underwent a dramatic transformation of their neuromuscular junction from the fast-muscle to the slow-muscle type. In both doubly innervated fibres, the ultrastructural characteristics of neuromuscular junctions, whether altered or not, were identical at both end-plate regions.
在正常（未处理）大鼠中，慢肌比目鱼肌纤维神经肌肉接头处突触后膜与突触前膜的平均长度比为2.7±0.8，快肌趾长伸肌纤维神经肌肉接头处为4.2±1.0；这种差异具有显著性（P＜0.001）。在由快、慢肌神经进行实验性双重支配四个月后，该比值为：（1）原来的慢肌纤维终板为2.9±0.8，新形成的终板为2.8±0.8，两者与正常慢肌纤维的比值均无显著差异；（2）原来的快肌纤维终板为2.2±0.5，新形成的终板为2.2±0.7，两者均显著小于正常快肌纤维的比值（P＜0.001）。这意味着双重支配的慢肌纤维保留了其原来的神经肌肉接头类型，而双重支配的快肌纤维其神经肌肉接头则经历了从快肌型到慢肌型的显著转变。在两种双重支配的纤维中，无论神经肌肉接头的超微结构特征是否改变，在两个终板区域都是相同的。
