Department of Physiology C240, University of Colorado School of Medicine, Denver, Colorado 80262, U.S.A.
Proc Biol Sci. 1994 Dec 22;258(1353):321-6. doi: 10.1098/rspb.1994.0180.
Previously, suggestions have been made that postjunctional folds at the vertebrate motor end plate might, in some way, serve to enhance neuromuscular transmission. This suggestion was examined quantitatively using a model junction with geometry similar to that seen in mammalian 'fast twitch' muscles. It was found that the depolarization produced at the top of an interfold by a quantum of acetylcholine is significantly greater than that produced in the absence of folds because of the series resistance of the interfold myoplasm. As a result, voltage-sensitive sodium channels in the postsynaptic membrane are activated more readily. In the model, activation of as few as four interfolds by eight quanta is sufficient for excitation to spread to the remainder of the muscle. With no folds, 19 quanta are required.
先前有研究表明，脊椎动物运动终板的突触后褶皱可能以某种方式增强神经肌肉传递。本研究使用类似于哺乳动物“快肌”的模型接头定量检验了这一假说。结果发现，由于褶皱间肌浆的串联电阻，量子乙酰胆碱在褶皱顶部产生的去极化明显大于无褶皱时的去极化。因此，突触后膜上的电压门控钠通道更容易被激活。在该模型中，8 个量子足以激活 4 个褶皱，从而使兴奋扩散到肌肉的其余部分。而没有褶皱时，则需要 19 个量子。
