LHRH AND GTP-GAMMA-S MODIFY CALCIUM CURRENT ACTIVATION IN BULLFROG SYMPATHETIC NEURONS
LHRH AND GTP-GAMMA-S MODIFY CALCIUM CURRENT ACTIVATION IN BULLFROG SYMPATHETIC NEURONS
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DOI：
10.1016/0896-6273(90)90035-e
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发表时间：
1990-07-01
期刊：
影响因子：
16.2
通讯作者：
JONES, SW
中科院分区：
文献类型：
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作者：
ELMSLIE, KS;ZHOU, W;JONES, SW
LHRH（鸡II型促黄体生成素释放激素）部分降低钙电流，并减慢青蛙交感神经元中部分剩余电流的激活动力学。通过用GTP-γ-S进行细胞内透析来模拟LHRH的作用。强烈的去极化可以暂时逆转LHRH或GTP-γ-S的作用：激活动力学恢复正常，电流幅度增加（易化）。易化发展迅速（>+ 30 mV时π= 4-6 ms），衰减较慢（− 80 mV时t1 2= 60 ms）。LHRH中的尾电流比对照组小且快，并且这些效应被易化部分逆转。这些结果可以用一个模型来解释，在这个模型中，一小部分通道被转换成“不情愿”的门控模式，在这种模式下，开放需要更强的去极化。如果这种机制是突触前抑制的根源，我们的研究结果预测，抑制发射器释放将被克服在爆发的高频活动。
LHRH (chicken II luteinizing hormone-releasing hormone) partially reduces calcium currents and slows the activation kinetics of part of the remaining current in frog sympathetic neurons. The effects of LHRH are mimicked by intracellular dialysis with GTP-γ-S. A strong depolarization can temporarily reverse the effects of LHRH or GTP-γ-S: activation kinetics return to normal, and the amplitude of the current is increased (facilitation). Facilitation develops rapidly (π= 4–6 ms at>+ 30 mV) and decays more slowly (t 1 2= 60 ms at− 80 mV). Tail currents in LHRH are smaller and faster than in the control, and these effects are partially reversed by facilitation. These results can be explained by a model in which a fraction of the channels is shifted into a “reluctant” gating mode, where opening requires stronger depolarization. If this mechanism is at the root of presynaptic inhibition, our results predict that inhibition of transmitter release would be overcome during bursts of high frequency activity.