Nikolsky E E, Oranska T I, Vyskocil F
Kazan Medical University, Tatarstan, Russia.
Exp Physiol. 1996 May;81(3):341-8. doi: 10.1113/expphysiol.1996.sp003938.
The progressive decline and recovery of spontaneous quantal acetylcholine (ACh) release (miniature endplate potentials, MEPPs) and the H-effect were measured in the mouse diaphragm after nerve crush and during regeneration. The H-effect is the hyperpolarization of the muscle fibre membrane produced by the addition of (+)tubocurarine, which indicates non-quantal ACh release. One hour after nerve crush the H-effect had declined to 50% of control values and 4 h later the H-effect disappeared completely. There were no substantial changes in the MEPP frequency and amplitude during the first 4 h after denervation. MEPP frequency then increased, but after 6 h of denervation it decreased and after 16 h no MEPPs were found in any of the muscle fibres. The times of onset of these denervation changes in the proximal, central and distal parts of diaphragm were similar. During reinnervation, the H-effect was detectable in all muscle parts 3 days before the reappearance of MEPPs. The H-effect developed first on day 8 in the proximal endplates and then, with a delay of 3 and 6 days, in the central and distal areas, respectively. During axonal regrowth the non-quantal release was restored before detectable quantal release. Non-quantal release is the first indication of the ability of the nerve terminal to release ACh in the process of reinnervation.
在小鼠膈神经挤压后及再生过程中，测量了自发性量子化乙酰胆碱（ACh）释放（微小终板电位，MEPPs）的逐渐下降和恢复情况以及H效应。H效应是由添加（+）筒箭毒碱引起的肌纤维膜超极化，它表明非量子化ACh释放。神经挤压1小时后，H效应降至对照值的50%，4小时后H效应完全消失。去神经支配后的前4小时内，MEPP频率和幅度没有实质性变化。随后MEPP频率增加，但去神经支配6小时后又下降，16小时后在任何肌纤维中均未发现MEPPs。膈神经近端、中部和远端这些去神经支配变化的起始时间相似。在神经再支配过程中，在MEPPs重新出现前3天，所有肌肉部位均可检测到H效应。H效应首先在第8天出现在近端终板，然后分别在延迟3天和6天后出现在中部和远端区域。在轴突再生过程中，可检测到的量子化释放恢复之前，非量子化释放已恢复。非量子化释放是神经末梢在再支配过程中释放ACh能力的首个迹象。
