DISTRIBUTION AND KINETICS OF MEMBRANE DIELECTRIC POLARIZATION .1. LONG-TERM INACTIVATION OF GATING CURRENTS
DISTRIBUTION AND KINETICS OF MEMBRANE DIELECTRIC POLARIZATION .1. LONG-TERM INACTIVATION OF GATING CURRENTS
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DOI：
10.1085/jgp.79.1.21
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发表时间：
1982-01-01
影响因子：
3.8
通讯作者：
FERNANDEZ, JM
中科院分区：
文献类型：
--
作者：
BEZANILLA, F;TAYLOR, RE;FERNANDEZ, JM
通过减去在非常正或非常负的电势下记录的电容性电流的线性分量来测量门控电流。当膜去极化几分钟，复极化到通常的保持电位（HP）--70 mV，持续1 ms，然后脉冲到0 mV时，在2- 4 ms内转移的电荷约为保持在--70 mV的相同脉冲期间转移的电荷的50%。发现这种电荷减少（称为门控电流的缓慢失活）与电荷-电位（Q-V）曲线向更超极化电位的偏移一致。当HP为0 mV时，可移动的总电荷与HP为-70 mV时的总电荷相同。在去极化保持电位下，ON门控电流快分量的时间常数小于-70 mV。当HP为-70 mV，50 ms持续时间的预脉冲为0 mV时，Q-V曲线也向更超极化的电位移动（电荷固定），但效果不如保持在0 mV时明显。当HP为0 mV时，预脉冲至-70 mV持续50 ms使Q-V曲线部分后移，表明门控电荷的快速失活可以在缓慢失活的情况下恢复。由门控粒子与快速失活粒子和慢速失活粒子相互作用组成的物理模型再现了大部分实验结果。
Gating currents were measured by subtracting the linear component of the capacitative current recorded at very positive or very negative potentials. When the membrane is depolarized for a few minutes, repolarized to the usual holding potential (HP) of --70 mV for 1 ms, and then pulsed to 0 mV, the charge transferred in 2--4 ms is approximately 50% of that which was transferred during the same pulse holding at --70 mV. This charge decrease, called slow inactivation of the gating current, was found to be consistent with a shift of the charge vs. potential (Q-V) curve to more hyperpolarized potentials. When the HP is 0 mV, the total charge available to move is the same as the total charge available when the HP is --70 mV. The time constants of the fast component of the ON gating current are smaller at depolarized holding potentials than at --70 mV. When the HP is --70 mV and a prepulse of 50 ms duration is given to 0 mV, the Q-V curve is also shifted to more hyperpolarized potentials (charge immobilization), but the effect is not as pronounced as the one obtained by holding at 0 mV. When the HP is 0 mV, a prepulse to --70 mV for 50 ms partially shifts back the Q-V curve, indicating that fast inactivation of the gating charge may be recovered in the presence of slow inactivation. A physical model consisting of a gating particle that interacts with a fast inactivating particle, and a slow inactivating particle, reproduces most of the experimental results.