Effects of calcium channel blockers on stimulation-induced changes in transmitter release at the frog neuromuscular junction.
Effects of calcium channel blockers on stimulation-induced changes in transmitter release at the frog neuromuscular junction.
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钙通道阻滞剂对刺激引起的青蛙神经肌肉接头递质释放变化的影响。
DOI：
10.1002/syn.890150402
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Mosier,DR
中科院分区：
文献类型：
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作者：
Zengel,JE;Lee,DT;Sosa,MA;Mosier,DR
我们研究了各种钙通道阻滞剂对刺激诱导的青蛙神经肌肉接头终板电位（EPP）振幅变化的影响。我们发现，在低钙浴林格氏液中加入小浓度（1-10 μM）的Cd ~（2+），既降低了对照EPP振幅，也降低了低量子条件下重复刺激时通常发生的EPP振幅增加。Cd 2+的这些作用在加入到洗浴溶液中后迅速发展，并且同样迅速逆转，这是由神经末梢释放的递质量的变化引起的。Cd 2+的主要影响似乎是对促进和增强组件的增加释放。Cd ~（2+）对释放的增强作用很小或没有影响。测试的其他二价阳离子Zn 2+、Co2+和Ni 2+也降低了对照EPP振幅和刺激诱导的EPP振幅增加，但需要更高浓度（>100 μM）的这些阳离子。降低刺激诱导的EPP振幅增加的有效性顺序为：Cd 2 +> Co2+、Zn 2 +> Ni 2+。有机钙通道阻滞剂维拉帕米（20-100 μM）和尼莫地平（20-50 μM）对刺激诱导的EPP振幅增加几乎没有影响。这项研究的结果是一致的，以前的建议，增加释放的不同组成部分代表不同的机制。此外，如果Cd 2+是通过减少Ca 2+进入神经末梢起作用，那么这些结果表明，促进和增强在某种程度上依赖于Ca 2+进入。© 1993 Wiley利斯公司
We have examined the effects of various calcium channel blockers on stimulation‐induced changes in end‐plate potential (EPP) amplitude at the frog neuro‐muscular junction. We found that the addition of small concentrations (1–10 μM) of Cd2+to the low calcium bathing Ringer reduced both the control EPP amplitude and the increase in EPP amplitude that normally occurs during repetitive stimulation under low quantal conditions. These effects of Cd2+, which developed rapidly following its addition to the bathing solution and were equally rapidly reversed, resulted from changes in the amount of transmitter released from the nerve terminal. The major effect of Cd2+appeared to be on the facilitation and augmentation components of increased release. Cd2+had little or no effect on potentiation of release. The other divalent cations tested, Zn2+, Co2+, and Ni2+, also decreased both control EPP amplitude and the stimulation‐induced increase in EPP amplitude, but higher concentrations (>100 μM) of these cations were required. The order of effectiveness in reducing stimulation‐induced increases in EPP amplitude was: Cd2+>>> Co2+, Zn2+> Ni2+. The organic calcium channel blockers ver‐apamil (20–100 μM) and nimodipine (20–50 μM) had little effect on stimulation‐induced increases in EPP amplitude. The results of this study are consistent with previous suggestions that the different components of increased release represent different mechanisms. Furthermore, if Cd2+is acting by reducing Ca2+entry into the nerve terminal, then these results suggest that facilitation and augmentation are dependent in some way on Ca2+entry. © 1993 Wiley‐Liss, Inc.