Chaplain R A
J Membr Biol. 1975;21(3-4):335-51. doi: 10.1007/BF01941075.
Recording from the dendrite membrane indicated a resting potential of minus-51.6 mV, which was reduced by inhibition of the Na+/K+ pump. Voltage clamp at rest revealed a small inward current between minus-50 and minus-80 mV and a larger outward current at clamp potentials of minus-40 to +30 mV. Using ramp-changes of muscle tension as stimuli a time-variant tension-induced inward current (TIC) became apparent, the amplitude of which decreased towards larger depolarizing voltages until at +18 mV the current reversed the direction. The time course of the conductance changes corresponds to similar phases in the generator potential. The outward current only responded to fast reductions in tension, decreasing transiently. A contribution of the active Na+/K+ pump to the hyperpolarizing potential response is suggested by the effects of K-removal or Na-substitution by Li+. In Na-free choline chloride media the generator potential and the TIC was depressed by 70-85%. Additional removal of Ca-2+ abolished the TIC. In contrast, lowering the Ca-2+ level in presence of Na+ decreased the membrane resistance and markedly enhanced the TIC (maximally eightfold at 10-minus 5M Ca-2+) while 75-150 mM Ca-2+ or intracellular application of a Ca-ionophore had the reverse effect.
对树突膜的记录显示静息电位为 -51.6 mV，抑制 Na+/K+ 泵会使其降低。静息时的电压钳显示在 -50 至 -80 mV 之间有一个小的内向电流，在钳制电位为 -40 至 +30 mV 时有一个较大的外向电流。以肌肉张力的斜坡变化作为刺激，时变张力诱导的内向电流（TIC）变得明显，其幅度朝着更大的去极化电压减小，直到在 +18 mV 时电流方向反转。电导变化的时间进程与发生器电位的相似阶段相对应。外向电流仅对张力的快速降低有反应，短暂减小。K+ 去除或 Li+ 替代 Na+ 的效应表明活性 Na+/K+ 泵对超极化电位反应有贡献。在无 Na+ 的氯化胆碱介质中，发生器电位和 TIC 降低了 70 - 85%。额外去除 Ca2+ 消除了 TIC。相反，在存在 Na+ 的情况下降低 Ca2+ 水平会降低膜电阻并显著增强 TIC（在 10 - 5M Ca2+ 时最大增强八倍），而 75 - 150 mM Ca2+ 或细胞内应用钙离子载体则有相反的效果。
