Low J C, Yamada M, Djamgoz M B
Imperial College of Science, Technology and Medicine, Department of Biology, London, U.K.
Vision Res. 1991;31(3):437-49. doi: 10.1016/0042-6989(91)90096-n.
Passive membrane properties and electromotive force of light modulated currents of L-, R/G-type and rod-driven horizontal cells were studied by voltage-clamp using double-barrelled micro-electrodes whilst perfusing with 5 microM dopamine to uncouple the gap junctions. Input impedances of horizontal cells in darkness were 31 +/- 1.4 M omega (mean +/- SE, n = 63); the resting potentials were -37 +/- 1.3 mV. Current-voltage relationships had regions of both inward and outward rectification and a region of negative resistance was commonly observed. Reversal potentials of light modulated currents were estimated on average to be -7 +/- 4 mV (n = 14), which is consistent with the involvement of K+ and Na+ and/or Ca2+ gradients. Importantly in R/G cells both depolarizing and hyperpolarizing components of the response had essentially the same reversal potential.
使用双管微电极通过电压钳研究了L型、R/G型和视杆驱动的水平细胞的被动膜特性以及光调制电流的电动势，同时灌注5微摩尔多巴胺以解开缝隙连接。黑暗中水平细胞的输入阻抗为31±1.4兆欧（平均值±标准误，n = 63）；静息电位为-37±1.3毫伏。电流-电压关系既有内向整流区域也有外向整流区域，并且通常观察到负电阻区域。光调制电流的反转电位平均估计为-7±4毫伏（n = 14），这与钾离子、钠离子和/或钙离子梯度的参与一致。重要的是，在R/G细胞中，反应的去极化和超极化成分基本上具有相同的反转电位。
