Transient K current in the somatic membrane of cultured central neurons of embryonic rat.
Transient K current in the somatic membrane of cultured central neurons of embryonic rat.
复制标题
培养的胚胎大鼠中枢神经元体膜中的瞬时 K 电流。
DOI：
10.1152/jn.1992.68.5.1708
复制
发表时间：
1992
影响因子：
2.5
通讯作者：
Nonner,W
中科院分区：
文献类型：
--
作者：
Rizzo,MA;Nonner,W
1. 在高压钳下记录胚胎大鼠培养的海马、纹状体和脊髓神经元的体细胞K电流，并用密封移液管切除膜球（“泡”）。2. 在300毫秒的去极化过程中，泡中的体细胞K电流受到快速和几乎完全失活的影响，而全细胞K电流则包含大量维持的成分。气泡和全细胞电流的大小和动力学性质在整个记录期间是稳定的。3. 体细胞A电流的稳态失活与电压密切相关，在激活电流的电压水平附近完全失活，而在+90 mV的去极化期间，峰值电导不饱和。激活以延迟开始。半激活次数随去极化而减少，半失活次数随去极化变化不大。失活后的恢复时间呈s型曲线，一半时间约为50 ms。在单个神经元之间，激活和失活的半倍变化超过一个数量级。失活和峰值电导的中点电位在大约40 mV的范围内变化。海马、纹状体和脊髓神经元参数范围重叠。5. 个体体细胞膜在其4-氨基吡啶阻滞、电流波动和电流动力学中显示出K通道异质性的迹象。另一方面，建立不同程度的稳态失活或从完全失活中恢复的条件脉冲后引发的电流具有重叠的时间过程。6. 这些体细胞A通道的特征与报道的爪蟾卵母细胞中表达的RCK4、Raw3和mShal产物的特征进行了比较。虽然原生通道和克隆通道的电压依赖性和大多数动力学特性的范围是兼容的，但这三个克隆通道从失活中恢复的速度要慢得多。此外，与RCK4和Raw3通道不同，原生通道的失活在亚细胞片段中切除后是稳定的。
1. Somatic K currents of cultured hippocampal, striatal, and spinal cord neurons of embryonic rat were recorded under voltage clamp in membrane spheres ("blebs") excised by means of a tight-seal pipette. 2. The somatic K current in blebs was subject to rapid and near complete inactivation during 300-ms depolarizations, whereas whole-cell K currents included a substantial maintained component. Size and kinetic properties of bleb and whole-cell currents were stable throughout the recording period. 3. The steady-state inactivation of somatic A current was steeply voltage dependent and complete near voltage levels that activated current, whereas peak conductances did not saturate during depolarizations up to +90 mV. Activation started with a delay. Half-times of activation decreased with depolarization, but half-times of inactivation varied little with depolarization. Recovery from inactivation followed a sigmoidal time course with half-times of approximately 50 ms. 4. Half-times of activation and inactivation varied over more than an order of magnitude between individual neurons. Midpoint potentials of inactivation and peak conductance varied over approximately 40 mV. The parameter ranges of hippocampal, striatal, and spinal cord neurons overlapped. 5. Individual soma membranes revealed signs of K channel heterogeneity in their 4-aminopyridine block, current fluctuations, and current kinetics. On the other hand, currents elicited after conditioning pulses that established varied degrees of steady-state inactivation or of recovery from full inactivation had superimposable time courses. 6. The described characteristics of the somatic A channels are compared with those reported for the RCK4, Raw3, and mShal products expressed in Xenopus oocytes. Whereas the ranges of voltage dependencies and of most kinetic characteristics are compatible among native and cloned channels, these three cloned channels recover much more slowly from inactivation. In addition, inactivation in native channels, unlike that in RCK4 and Raw3 channels, was stable after excision in a subcellular fragment.