Oberleithner H
Pflugers Arch. 1985 Jul;404(3):244-51. doi: 10.1007/BF00581246.
Chronic exposure to high potassium (K+ adaptation) stimulates H+ net secretion in the diluting segment of the frog kidney. In order to investigate the cellular mechanism of the H+ secretory process intracellular pH (pHi) measurements were performed in cells of the diluting segment of the isolated doubly-perfused kidney of K+ adapted Rana esculenta. pHi changes were monitored by pH-sensitive microelectrodes while the tubule lumen was rapidly perfused with various solutions. With control solutions (extracellular pH = 7.80) pHi averaged 7.60 +/- 0.05. Luminal application of furosemide (5 X 10(-5) mol/l) or reduction of luminal Cl- (from 104 mmol/l to 9 mmol/l) hyperpolarized the cell membrane potentials but pHi was not altered. Reduction of luminal Na+ (from 98 mmol/l to 3 mmol/l) depolarized the cell membrane potentials but pHi remained constant. Complete removal of luminal Na+, however, led to a significant decrease of pHi from 7.61 +/- 0.08 to 7.18 +/- 0.08. Luminal application of amiloride (1 X 10(-3) mol/l) also decreased pHi significantly (delta pHi = 0.15 +/- 0.02). The results indicate that an amiloride-sensitive H+ extrusion mechanism exists in the luminal cell membrane of the K+ adapted frog diluting segment. The data are consistent with Na+/H+ exchange which maintains a constant pHi even at extreme experimental conditions.
长期暴露于高钾环境（钾适应）会刺激蛙肾稀释段的氢离子净分泌。为了研究氢离子分泌过程的细胞机制，我们对经钾适应的食用蛙分离的双灌注肾稀释段细胞进行了细胞内pH值（pHi）测量。在用pH敏感微电极监测pHi变化的同时，用各种溶液快速灌注肾小管管腔。使用对照溶液（细胞外pH = 7.80）时，pHi平均为7.60±0.05。管腔内应用呋塞米（5×10⁻⁵mol/L）或降低管腔氯离子浓度（从104mmol/L降至9mmol/L）会使细胞膜电位超极化，但pHi未改变。降低管腔钠离子浓度（从98mmol/L降至3mmol/L）会使细胞膜电位去极化，但pHi保持恒定。然而，完全去除管腔钠离子会导致pHi从7.61±0.08显著降低至7.18±0.08。管腔内应用氨氯地平（1×10⁻³mol/L）也会使pHi显著降低（ΔpHi = 0.15±0.02）。结果表明，在经钾适应的蛙稀释段管腔细胞膜中存在一种氨氯地平敏感的氢离子外排机制。这些数据与钠/氢交换一致，即使在极端实验条件下，钠/氢交换也能维持恒定的pHi。
