CO-OPERATIVE ACTION OF CALCIUM IONS IN TRANSMITTER RELEASE AT NEUROMUSCULAR JUNCTION
CO-OPERATIVE ACTION OF CALCIUM IONS IN TRANSMITTER RELEASE AT NEUROMUSCULAR JUNCTION
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DOI：
10.1113/jphysiol.1967.sp008367
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发表时间：
1967-01-01
影响因子：
5.5
通讯作者：
RAHAMIMO.R
中科院分区：
文献类型：
--
作者：
DODGE, FA;RAHAMIMO.R
本文用细胞内电位记录技术，以终板电位（epp）的幅值作为神经肌肉接头释放包数的指标，研究了神经肌肉接头递质释放对外界Ca ~（2+）浓度的定量依赖性。[Ca]和epp之间的关系是高度非线性的。在双对数坐标系中，该关系式的初始部分给出一条斜率接近4的直线（平均值为3.78 [±] 0.2 S.D.）。28个实验）。添加恒定量的Mg降低epp，而不改变log epp/log Ca关系的斜率。随着[Ca]向正常水平升高，该对数关系的斜率减小。结果定量解释的假设，即Ca离子联合收割机与特定的网站X上的神经末梢形成CaX，和包的乙酰胆碱释放的数量是成比例的4次方[CaX]。分析表明，神经冲动释放每个量子包的递质需要约4个Ca离子的协同作用。
The quantitative dependence of transmitter release on external Ca concentration was studied at the frog neuromuscular junction, using intracellular recording and taking the amplitude of the end-plate potential (epp) as an index of the number of packets released. The relation between [Ca] and the epp is highly non-linear. The initial part of this relation on double logarithmic coordinates gives a straight line with a slope of nearly 4 (mean 3.78 [plus or minus] 0.2 S.D. in 28 experiments). Addition of a constant amount of Mg reduces the epp without altering the slope of the log epp/log Ca relation. The slope of this logarithmic relation diminishes as [Ca] is raised towards the normal level. The results are explained quantitatively on the hypothesis that Ca ions combine with a specific site X on the nerve terminal forming CaX, and that the number of packets of acethyl-choline released is proportional to the 4th power of [CaX]. The analysis suggests that a co-operative action of about 4 Ca ions is necessary for the release of each quantal packet of transmitter by the nerve impulse.