温度降低对小鼠神经肌肉接头处递质量子释放的影响。

The effect of a reduction in temperature on the quantal release of transmitter at the mouse neuromuscular junction.

Nishimura M, Shimizu Y, Satoh E, Yokoyama T, Yagasaki O

Department of Pharmacology, University of Obihiro, School of Veterinary Medicine, Japan.

Gen Pharmacol. 1993 Sep;24(5):1235-9. doi: 10.1016/0306-3623(93)90374-7.

Abstract

The effects of a reduction in temperature were examined on evoked and spontaneous release of transmitter quanta and on presynaptic negative signals, blocked by Cd2+, measured externally at neuromuscular junctions in mouse diaphragm muscles in low-Ca2+, high-Mg2+ Krebs-Ringer solutions. 2. The evoked release was enhanced with lowering of the temperature, whereas the extent of spontaneous release was reduced. Cooperativity of Ca2+ in the evoked release was slightly reduced by lowering the temperature. 3. The presynaptic negative signals increased in duration with lowering of the temperature. 4. These results support the hypothesis that the effect of a reduction in temperature reflects the improved efficacy of the calcium-mediated mechanism of transmitter release, manifested as a prolongation of the inflow of Ca2+. The process involved in the evoked release is probably attributable to an almost passive mechanism.

摘要

在低钙、高镁的 Krebs-Ringer 溶液中，研究了温度降低对小鼠膈肌神经肌肉接头处递质量子的诱发释放和自发释放以及对细胞外测量的、被 Cd2+阻断的突触前负信号的影响。2. 随着温度降低，诱发释放增强，而自发释放的程度降低。温度降低会使诱发释放中 Ca2+的协同作用略有降低。3. 突触前负信号的持续时间随温度降低而增加。4. 这些结果支持了以下假设：温度降低的影响反映了钙介导的递质释放机制的效率提高，表现为 Ca2+内流的延长。诱发释放所涉及的过程可能归因于一种几乎被动的机制。