Villegas J, Villegas R, Giménez M
J Gen Physiol. 1968 Jan;51(1):47-64. doi: 10.1085/jgp.51.1.47.
The effects on the Schwann cell electrical potential of external ionic concentrations and of K-strophanthoside were investigated. Increasing (K)(o) depolarized the cell. The potential is related to the logarithm of (K)(o) in a quasi-linear fashion. The linear portion of the curve has a slope of 45 mv/ten-fold change in (K)(o). Diminutions of (Na)(o) and (Cl)(o) produced only small variations in the potential. Calcium and magnesium can be replaced by 44 mM calcium without altering the potential. Increase of (Ca)(o) to 88 mM produced about 10 mv hyperpolarization. The cell was hyperpolarized by 11 mv and 4 mv within 1 min after applying K-strophanthoside at concentrations of 10(-3) and 10(-5)M, respectively. No variations of cellular potassium, sodium, or chloride were observed 3 min after applying the glycoside. The hyperpolarization caused by 10(-3)M K-strophanthoside was not observed when (K)(o) was diminished to 1 or 0.1 mM or was increased to 30 mM. At a (K)(o) of 30 mM, 10(-2)M strophanthoside was required to produce the hyperpolarizing effect. In high calcium, the cell was further hyperpolarized by the glycoside. The initial hyperpolarization caused by the glycoside was followed by a gradual depolarization and a decrease of the cellular potassium concentration. The results indicate that the Schwann cell potential of about -40 mv is due to ionic diffusion, mainly of potassium, and to a cardiac glycoside-sensitive ion transport process.
研究了细胞外离子浓度和毒毛花苷 K 对雪旺氏细胞电位的影响。增加细胞外钾离子浓度会使细胞去极化。电位与细胞外钾离子浓度的对数呈准线性关系。曲线的线性部分斜率为 45 mV/细胞外钾离子浓度十倍变化。降低细胞外钠离子和氯离子浓度只会使电位产生微小变化。钙和镁可以被 44 mM 的钙替代而不改变电位。将细胞外钙离子浓度增加到 88 mM 会产生约 10 mV 的超极化。分别施加浓度为 10⁻³ 和 10⁻⁵ M 的毒毛花苷 K 后 1 分钟内，细胞分别超极化 11 mV 和 4 mV。施加糖苷 3 分钟后未观察到细胞内钾、钠或氯离子的变化。当细胞外钾离子浓度降至 1 或 0.1 mM 或升至 30 mM 时，未观察到 10⁻³ M 毒毛花苷 K 引起的超极化。在细胞外钾离子浓度为 30 mM 时，需要 10⁻² M 的毒毛花苷才能产生超极化作用。在高钙环境下，糖苷会使细胞进一步超极化。糖苷引起的初始超极化之后是逐渐去极化和细胞内钾离子浓度降低。结果表明，约 -40 mV 的雪旺氏细胞电位是由于离子扩散（主要是钾离子）以及对强心苷敏感的离子转运过程所致。
