Harvey B J, Ehrenfeld J
Pflugers Arch. 1986 Apr;406(4):362-6. doi: 10.1007/BF00590937.
We have investigated the role of the electrogenic hydrogen ion pump in the regulation of intracellular sodium ion activity (aiNa) and intracellular pH (pHi) in frog skin epithelial cells using double-barreled ion sensitive microelectrodes. When Rana esculenta skin is mounted in an Ussing chamber and bathed in 1 mM Na2SO4 buffered to pH 7.34 with imidazole on the apical side and in normal Ringer on the serosal side, the apical addition of the carbonic anhydrase inhibitor ethoxzolamide (10(-4)M) blocks net H+ ion excretion and Na absorption, producing a depolarization of 25-30 mV of the apical membrane potential (psi mc). We demonstrate that these changes are accompanied by a fall in aiNa from 6.2 +/- 0.5 mmol/l to 3.4 +/- 0.6 mmol/l and an increase in pHi from 7.20 +/- 0.03 to 7.38 +/- 0.08 (n = 12 skins). Voltage clamping psi mc to its control value in the presence of ethoxzolamide restored aiNa but the pHi remained alkaline. Furthermore, the fall in aiNa produced by ethoxzolamide could be mimicked by voltage clamping psi mc towards the value of the Nernst potential for Na at the apical membrane. These results indicate that the maintenance of the cellular Na+ transport pool is dependent on a favourable electrical driving force and counter-current generated by an electrogenic H+ pump at the apical membrane. Addition of amiloride (10(-5) mol/l) or substitution of external Na+ by Mg2+ or K+ caused a hyperpolarization of psi mc and a fall in aiNa.2+ e
我们使用双管离子敏感微电极研究了蛙皮上皮细胞中电生性氢离子泵在调节细胞内钠离子活性（aiNa）和细胞内pH（pHi）方面的作用。当将食用蛙皮肤置于Ussing槽中，顶侧用1 mM Na2SO4（用咪唑缓冲至pH 7.34），浆膜侧用正常林格氏液灌注时，向顶侧添加碳酸酐酶抑制剂乙氧唑胺（10(-4)M）会阻断净氢离子排泄和钠吸收，导致顶膜电位（psi mc）去极化25 - 30 mV。我们证明这些变化伴随着aiNa从6.2±0.5 mmol/l降至3.4±0.6 mmol/l，以及pHi从7.20±0.03升至7.38±0.08（n = 12张皮肤）。在乙氧唑胺存在下将psi mc钳制在其对照值可恢复aiNa，但pHi仍保持碱性。此外，乙氧唑胺引起的aiNa下降可通过将psi mc钳制到顶膜钠能斯特电位值来模拟。这些结果表明，细胞内钠离子转运池的维持依赖于有利的电驱动力以及顶膜上电生性氢离子泵产生的逆流。添加氨氯吡脒（10(-5) mol/l）或用Mg2+或K+替代外部Na+会导致psi mc超极化和aiNa下降。
