Rouzaire-Dubois B, Dubois J M
Laboratoire de Neurobiologie cellulaire et moléculaire, CNRS, F-91198 Gif-sur-Yvette Cedex, France.
Pflugers Arch. 1997 Nov;434(6):750-5. doi: 10.1007/s004240050461.
The contribution of an electrogenic proton pump to the membrane potential of neuroblastoma x glioma hybrid NG 108-15 cells was determined with whole-cell voltage and current recordings and cell volume measurements with the preparation bathed in symmetrical 140 mM KCl solutions. The effects of the K+ channel blockers tetraethylammonium and 4-aminopyridine and of the H+-ATPase inhibitor bafilomycin A1 on the membrane potential and input resistance revealed that the membrane potential is generated by an outward H+ pump current of 5-15 pA in equilibrium with an inward passive current. This conclusion is supported by both current- and voltage-clamp results obtained when the preparation was bathed in a Na+-containing external solution after K+ channel blockade with Cs+ in the pipette. Additional support was obtained by measurement of the volume of cells incubated in solutions containing 140 mM KCl. Tetraethylammonium induced a bafilomycin-sensitive increase in inward K+ current and an increase in cell volume of 76% which we believe to be a consequence of the K+ influx. Finally, comparison of membrane potentials obtained in experiments using Na+-containing external, and K+-containing pipette solutions and after K+ channel blockade with Cs+ in the pipette also showed that, under normal physiological conditions, the resting membrane potential is essentially determined by an electrogenic H+ pump.
利用全细胞电压和电流记录以及在对称的140 mM KCl溶液中孵育的标本进行细胞体积测量，确定了生电质子泵对神经母细胞瘤x胶质瘤杂交NG 108 - 15细胞膜电位的贡献。钾通道阻滞剂四乙铵和4 -氨基吡啶以及H⁺ - ATP酶抑制剂巴弗洛霉素A1对膜电位和输入电阻的影响表明，膜电位由5 - 15 pA的外向H⁺泵电流产生，该电流与内向被动电流达到平衡。当用Cs⁺阻断移液管中的钾通道后，将标本置于含钠的外部溶液中孵育时获得的电流钳和电压钳结果均支持这一结论。通过测量在含140 mM KCl的溶液中孵育的细胞体积，获得了额外的支持。四乙铵诱导内向钾电流增加，且对巴弗洛霉素敏感，细胞体积增加76%，我们认为这是钾离子内流的结果。最后，比较在使用含钠外部溶液和含钾移液管溶液的实验中以及在移液管中用Cs⁺阻断钾通道后获得的膜电位，也表明在正常生理条件下，静息膜电位基本上由生电H⁺泵决定。
