Voltage-dependent gating of gap junction channels in embryonic chick ventricular cell pairs.
Voltage-dependent gating of gap junction channels in embryonic chick ventricular cell pairs.
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胚胎鸡心室细胞对间隙连接通道的电压依赖性门控。
DOI：
10.1152/ajpcell.1990.258.4.c662
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Veenstra,RD
中科院分区：
文献类型：
--
作者：
Veenstra,RD
研究了 7 日龄胚胎鸡心室酶解后的配对肌细胞中宏观间隙连接电导 (Gj) 对跨接电压 (Vj) 的依赖性。两个细胞的膜电压由整个细胞配置中单独的膜片钳电路独立控制。在七个不同细胞对的记录中发现了两种独特的单一连接电导。较大通道的平均电导为 166 +/- 37 pS（n = 6 对），而第二个通道的平均电导为 58 +/- 10 pS（n = 3）。瞬时 Gj 在 -100 至 +100 mV 的 Vj 范围内保持线性，而当电压超过 +/- 30 mV 时，稳态 Gj 下降。 Gj 的衰减和恢复阶段都遵循指数时间进程，恢复时间常数比失活慢四倍，在 80 mV 时需要 1.1 s。归一化稳态 Gj-Vj 曲线可由二态玻尔兹曼分布定义，假设有效门控电荷为 1.72，半失活电压为 45 mV，残余电压不敏感 Gj 为最大值的 27%。单通道记录显示，Vj 步长达到 80 mV 时 160 pS 通道关闭，五个此类记录的总体平均值产生指数衰减的结电流，时间常数为 184 ms。单通道电流-电压关系在整个 Vj 范围内保持线性，斜率为 145 pS。结果支持这样的假设：160-pS 间隙连接通道群体由跨接点电位门控。
The dependence of macroscopic gap junctional conductance (Gj) on transjunctional voltage (Vj) was studied in paired myocytes after enzymatic dissociation of 7-day-old embryonic chick ventricles. The membrane voltage of both cells was independently controlled by separate patch-clamp circuits in the whole cell configuration. Two distinctive unitary junctional conductances were identified in recordings from seven different cell pairs. The larger channel had a mean conductance of 166 +/- 37 pS (n = 6 pairs), whereas a second channel averaged 58 +/- 10 pS (n = 3). Instantaneous Gj remained linear over a Vj range of -100 to +100 mV, whereas the steady-state Gj declined when voltages exceeded +/- 30 mV. Both decay and recovery phases of Gj follow exponential time courses, with the recovery time constant being four times slower than inactivation, requiring 1.1 s at 80 mV. The normalized steady-state Gj-Vj curve could be defined by a two-state Boltzmann distribution, assuming an effective gating charge of 1.72, a half-inactivation voltage of 45 mV, and a residual voltage-insensitive Gj of 27% of maximum. Single-channel recordings revealed closure of 160-pS channels on a Vj step to 80 mV, and the ensemble average of five such records produced an exponentially decaying junctional current with a time constant of 184 ms. The single-channel current-voltage relationship remains linear with a slope of 145 pS over the entire Vj range. The results support the hypothesis that a population of 160-pS gap junction channels is gated by transjunctional potentials.