Dawson J, Djamgoz M B
Department of Pure and Applied Biology, Imperial College, London.
J Exp Biol. 1988 May;136:417-32. doi: 10.1242/jeb.136.1.417.
Electrophysiological properties of skeletal body-wall muscles of prepupal Calliphora erythrocephala were investigated using double-barrelled intracellular ion-sensitive microelectrodes. The most realistic estimate of the intracellular K+ activity, obtained using K+-sensitive microelectrodes based on a neutral carrier, was 115 mmoll-1. The K+ equilibrium potential was consistently more negative than the prevailing resting potential, the average difference being -15 mV. The intracellular Na+ activity and the Na+ equilibrium potential were 7 mmoll-1 and +46 mV on average, respectively. The mean value of the intracellular Cl- activity was 40 mmoll-1, and this was apparently higher than that required for passive distribution of Cl-. However, when reversibly exposed to a Ringer containing no Cl-, cells could rapidly exchange most of their intracellular Cl-, although the resting membrane potentials were only transiently affected. It is concluded that an anionic interferent exists inside muscles, that this artefactually elevates the measured intracellular Cl- activities, and that Cl- makes no contribution to resting membrane electrogenesis.
使用双管细胞内离子敏感微电极研究了红头丽蝇蛹前期体壁骨骼肌的电生理特性。基于中性载体的钾敏感微电极测得的细胞内钾离子活性最实际的估计值为115 mmol·L⁻¹。钾离子平衡电位始终比主要的静息电位更负，平均差值为-15 mV。细胞内钠离子活性和钠离子平衡电位平均分别为7 mmol·L⁻¹和+46 mV。细胞内氯离子活性的平均值为40 mmol·L⁻¹，这明显高于氯离子被动分布所需的值。然而，当可逆地暴露于不含氯离子的林格氏液中时，细胞可以迅速交换其大部分细胞内氯离子，尽管静息膜电位仅受到短暂影响。结论是肌肉内部存在一种阴离子干扰物，这种假象会人为地提高测得的细胞内氯离子活性，并且氯离子对静息膜电产生没有贡献。
