Effects of membrane potential on the voltage dependence of motility-related charge in outer hair cells of the guinea-pig
Effects of membrane potential on the voltage dependence of motility-related charge in outer hair cells of the guinea-pig
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DOI：
10.1111/j.1469-7793.1998.225bz.x
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发表时间：
1998-07-01
影响因子：
5.5
通讯作者：
Takahashi, S
中科院分区：
文献类型：
--
作者：
Santos-Sacchi, J;Kakehata, S;Takahashi, S
1. 对豚鼠分离的外毛细胞（OHC）进行全细胞电压钳位，以研究初始电压对运动相关门控电流的电压依赖性的影响，或者等效地，对膜电容的电压依赖性的影响。2．预脉冲传递导致与运动相关的门控电流大小发生变化，这主要是由于峰值电容电压 (V(pkCm)) 的变化引起的。去极化使 V(pkCm) 向超极化方向移动，而超极化则相反。 -80 mV 下长期保持电位（> 2 分钟）的 -120 和 +40 mV 预脉冲状态之间的平均偏移为 14.67 +/- 0.95 mV（n = 10；平均值 +/- S.E.M）3。初始膜电位的影响呈 S 形，V(pkCm) 每 e 倍变化的电压依赖性为 23 mV，并且 OHC 静息电位的生理范围内具有最大斜率。这表明细胞已做好对静息电位变化做出最大反应的准备。4．与运动相关的门控电流动力学相比，预脉冲效应的动力学较慢。使用两个电压正弦曲线对膜电容 (C(m)) 进行高分辨率测量表明，V(pkCm) 的变化会引起 C(m) 随由两个指数 (tau(0), 0.070 +/- 0.003 s; tau(1), 1.28 +/- 0.07 s; A(0), 1.54 +/- 0.13 pF; A(1), 1.51 +/- 0 .3 pF；表示 +/- S.E.M.；步长为 +50 至 -80 mV）。前脉冲效应的恢复表现出相似的时间过程。5．预脉冲效应对细胞内酶消化、快速细胞内钙缓冲液和细胞内压力具有抵抗力。通过建模，我指出这种效应可以通过侧膜中分子马达产生的固有电压感应张力来解释。
1. Isolated outer hair cells (OHCs) from the guinea-pig were whole-cell voltage clamped to study the influence of initial voltage on the voltage dependence of motility-related gating current or, equivalently, on the voltage dependence of membrane capacitance.2. Prepulse delivery caused changes in the magnitude of motility-related gating: currents, which are due predominantly to shifts in the voltage at peak capacitance (V(pkCm)) Depolarization shifts V(pkCm) in the hyperpolarizing direction, and hyperpolarization does the opposite. The mean shift between -120 and +40 mV prepulse states with long-term holding potentials (> 2 min) at -80 mV was 14.67 +/- 0.95 mV (n = 10; mean +/- S.E.M).3. The effect of initial membrane potential is sigmoidal, with a voltage dependence of 23 mV per e-fold change in V(pkCm), and maximum slope within the physiological range of OHC resting potentials. This indicates that the cell is poised to respond maximally to changes in resting potential.4. The kinetics of prepulse effects are slow compared with motility-related gating current kinetics. High-resolution measurement of membrane capacitance (C(m)) using two voltage sinusoids indicates that shifts in V(pkCm) induce C(m) changes with time courses fitted by two exponentials (tau(0), 0.070 +/- 0.003 s; tau(1), 1.28 +/- 0.07 s; A(0), 1.54 +/- 0.13 pF; A(1), 1.51 +/- 0 .3 pF; means +/- S.E.M.; n = 22; step from +50 to -80 mV). Recovery of prepulse effects exhibits a similar time course.5. Prepulse effects are resistant to intracellular enzymatic digestion, to fast intracellular calcium buffers, and to intracellular pressure. Through modelling, me indicate hom the effect may be explained by an intrinsic voltage-induced tension generated by the molecular motors residing in the lateral membrane.