Kavalali E T, Plummer M R
Department of Biological Sciences, Rutgers University, Piscataway, New Jersey 08855-1059, USA.
J Neurosci. 1996 Feb 1;16(3):1072-82. doi: 10.1523/JNEUROSCI.16-03-01072.1996.
Neuronal voltage-gated calcium channels provide a pathway for calcium influx that is required for processes ranging from intracellular signaling to alterations in cellular excitability. In hippocampal neurons, we have characterized a subtype of dihydropyridine-sensitive L-type calcium channels (Lp channel) that shows multiple kinds of voltage-dependent potentiation of its activity. One type of potentiation is elicited by low-voltage stimuli (-10 mV) and can be seen in dual-pulse protocols in which a transient hyperpolarization is interposed between conditioning and test pulses. The second type of potentiation is elicited by much higher voltages (+60 mV) and is selectively deactivated at hyperpolarized voltages. We have compared these types of potentiation in the Lp channel, the "standard" L-type channel, and the cardiac L-type channel. Our results show that the high-voltage potentiation is common to all three channel types. The low-voltage form of potentiation, however, is unique to the Lp channel. Thus, the Lp channel shows two kinds of potentiation that differ in their voltage dependence and rate of decay. Therefore, calcium channel plasticity in the hippocampus has a variety of forms distinguished by their stimulus requirements and duration.
神经元电压门控钙通道为钙内流提供了一条途径，而钙内流是从细胞内信号传导到细胞兴奋性改变等一系列过程所必需的。在海马神经元中，我们已经鉴定出一种对二氢吡啶敏感的L型钙通道亚型（Lp通道），该通道表现出多种其活性的电压依赖性增强。一种增强类型由低电压刺激（-10 mV）引发，并且可以在双脉冲实验方案中观察到，在该方案中，在条件刺激脉冲和测试脉冲之间插入一个短暂的超极化。第二种增强类型由高得多的电压（+60 mV）引发，并且在超极化电压下选择性失活。我们已经比较了Lp通道、“标准”L型通道和心脏L型通道中的这些增强类型。我们的结果表明，高电压增强在所有三种通道类型中都很常见。然而，低电压形式的增强是Lp通道所特有的。因此，Lp通道表现出两种在电压依赖性和衰减速率上不同的增强。因此，海马体中的钙通道可塑性具有多种形式，这些形式因其刺激要求和持续时间而有所区别。
