Ochi R, Hashimoto K
Pflugers Arch. 1978 Dec 15;378(1):1-7. doi: 10.1007/BF00581951.
Electrotonic potentials produced by rectangular hyperpolarizing current pulses were recorded intracellularly at various distances from guinea-pig papillary muscles and the results were analyzed according to the single-dimensional cable model. In normal Tyrode solution the space constant (lambda) was 0.62 +/- 0.12 mm (mean and S.D., nine preparations) and the time constant (tau) was 4.0 +/- 0.8 ms. Procaine (1 mg/ml) increased lambda to 1.20 +/- 0.29 mm and tau to 19.7 +/- 4.7 ms by increasing the membrane resistance, while the membrane capacity was only slightly increased and little change was observed in the internal longitudinal resistance. The dose-response relationship revealed that procaine inhibited the resting membrane conductance almost completely in a one-to-one manner with the dissociation constant of about 1 mM. It was suggested that potassium conductance predominant in the resting membrane conductance in guinea-pig papillary muscle was depressed by procaine and that electrical coupling is well maintained even when the membrane resistivity of apposed normal ordinary membrane at intercalated disks becomes high.
通过矩形超极化电流脉冲产生的电紧张电位在豚鼠乳头肌不同距离处进行细胞内记录，并根据一维电缆模型对结果进行分析。在正常的台氏液中，空间常数（λ）为0.62±0.12毫米（平均值和标准差，9个标本），时间常数（τ）为4.0±0.8毫秒。普鲁卡因（1毫克/毫升）通过增加膜电阻使λ增加到1.20±0.29毫米，τ增加到19.7±4.7毫秒，而膜电容仅略有增加，内部纵向电阻几乎没有变化。剂量反应关系表明，普鲁卡因以一对一的方式几乎完全抑制静息膜电导，解离常数约为1毫摩尔。提示豚鼠乳头肌静息膜电导中占主导地位的钾电导被普鲁卡因抑制，并且即使闰盘处相邻正常普通膜的膜电阻率升高，电耦合仍能良好维持。
