Activation and inactivation of single calcium channels in snail neurons.
Activation and inactivation of single calcium channels in snail neurons.
复制标题
蜗牛神经元中单个钙通道的激活和失活。
DOI：
10.1085/jgp.83.5.751
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
Wilson,DL
中科院分区：
文献类型：
--
作者：
Brown,AM;Lux,HD;Wilson,DL
通过对蜗牛神经元单个钙通道行为的研究，探讨了钙电流的激活和失活特性。采用了上一篇文章中描述的方法。此外，零相位数字滤波器已被纳入改善延迟的分析到第一次打开，或等待时间。结果表明，随着时间的推移，单通道打开的概率减小。这在29℃时尤为明显，并与宏观电流中观察到的失活相平行。观察到单个通道的事实意味着有大量的通道从“未激活”状态重新打开。在18℃时发生小的去极化，几乎没有失活。从这些测量中，分析了单通道打开、关闭和等待时间的直方图，以估计三状态激活模型的速率常数。发现了两个与模型严重不符的地方。首先，20 mV的等待时间分布比单通道关闭时间分析获得的参数预测的要慢。其次，等待时间直方图的峰值时间和大小与三状态模型不一致。结果表明，激活至少涉及四种状态。一些四态模型可以从进一步的考虑中消除。然而，一个全面的钙通道动力学模型必须等待进一步的测量。
Activation and inactivation properties of Ca currents were investigated by studying the behavior of single Ca channels in snail neurons. The methods described in the previous paper were used. In addition, a zero-phase digital filter has been incorporated to improve the analysis of latencies to first opening, or waiting times. It was found that a decrease in the probability of single channel opening occurred with time. This was especially marked at 29 C and paralleled the inactivation observed in macroscopic currents. The fact that a single channel was observed means that there is a significant amount of reopening from the" inactivated" state. Small depolarizations at 18 C showed little inactivation. From these measurements, histograms ofsingle channel open, closed, and waiting times were analyzed to estimate the rate constants of a three-state model of activation. Two serious discrepancies with the model were found. First, waiting time distributions at-20 mV were slower than those predicted by parameters obtained from an analysis of the single channel closed times. Second, it was shown that the time and the magnitude of the peak of the waiting time histogram were inconsistent with a three-state model. It is concluded that a minimum of four states are involved in activation. Some fourstate models may be eliminated from further consideration. However, a comprehensive model of Ca channel kinetics must await further measurements.