Determining K+ channel activation curves from K+ channel currents
Determining K+ channel activation curves from K+ channel currents
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DOI：
10.1007/s002490000091
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发表时间：
2000-01-01
影响因子：
2
通讯作者：
Clay, JR
中科院分区：
文献类型：
--
作者：
Clay, JR
一般认为钾离子通道具有与驱动力（V - E-K）线性相关的电流-电压（IV）关系，其中V为膜电位，E-K为钾离子平衡电位。因此，K+通道的激活曲线通常是通过用（V - E-K）归一化宏观K+电流的电压箝位族来测量的，其中V是电压箝位序列中每个连续步骤的电位。然而，对于许多类型的K+通道，IV关系实际上对驱动力具有非线性依赖，这在Goldman-Hodgkin-Katz关系中得到了很好的描述。当在归一化过程中使用GHK对（V - E-K）的依赖关系时，得到了一个非常不同的激活曲线的电压依赖关系，可以更准确地反映通道门控的这一特征。将这一过程应用于最近发表的结果，获得了对快速失活的I-A通道Kv1.4和Kv4.2的电压依赖性的新见解。
Potassium ion channels are generally believed to have current-voltage (IV) relations which are linearly related to driving force (V - E-K), where V is membrane potential and E-K is the potassium ion equilibrium potential. Consequently, activation curves for K+ channels have often been measured by normalizing voltage-clamp families of macroscopic K+ currents with (V - E-K), where V is the potential of each successive step in the voltage clamp sequence. However, the IV relation for many types of K+ channels actually has a non-linear dependence upon driving force which is well described by the Goldman-Hodgkin-Katz relation. When the GHK dependence on (V - E-K) is used in the normalization procedure, a very different voltage dependence of the activation curve is obtained which may more accurately reflect this feature of channel gating. Novel insights into the voltage dependence of the rapidly inactivating I-A channels Kv1.4 and Kv4.2 have been obtained when this procedure was applied to recently published results.