Kleinman J G, Brown W W, Ware R A, Schwartz J H
Am J Physiol. 1980 Nov;239(5):F440-4. doi: 10.1152/ajprenal.1980.239.5.F440.
Cell pH (pHc) was examined by the [14C]DMO technique in suspensions of proximal tubule fragments from rabbit renal cortex. In buffer with 10 mM HCO3(-), pHc was more alkaline than external pH (pHe) at values of the latter < 7.4. Maximal cell-to-extracellular pH gradients (delta pH) occurred at pHe = 6.8 and below. At pHe > 7.4, pHc was more acid than pHe was. However, pHc was always more alkaline than the electrochemical equilibrium pH. At pHe congruent to 7.0, 60 min of deoxygenation decreased delta pH from 0.22 +/- 0.02 to 0.05 +/- 0.01. Reoxygenation restored delta pH to control values. Incubation with ouabain abolished the delta pH. Both the carbonic anhydrase inhibitor, acetazolamide, and the anion transport inhibitor, 4-acetamido-4'-isothiocyano-2,2'-disulfonic stilbene (SITS), increased delta pH. The studies demonstrate relative intracellular alkalinity in proximal tubule. A fall in pHc occurs with maneuvers that interfere with H+ pumping out of the cells. A rise in pHc occurs with maneuvers that interfere with the disposition of intracellular alkali: slowing of HCO3(-) generation with acetazolamide or blocking of HCO3(-) exit with SITS. The results support a H+-secretory model of proximal tubule acid transport that is dependent on maintenance and dispersal of intracellular alkalinity.
采用[¹⁴C]二甲基氧（DMO）技术检测了兔肾皮质近端小管片段悬液中的细胞pH值（pHc）。在含有10 mM HCO₃⁻的缓冲液中，当外部pH值（pHe）< 7.4时，pHc比外部pH值更偏碱性。最大细胞与细胞外pH梯度（δpH）出现在pHe = 6.8及以下。当pHe > 7.4时，pHc比pHe更偏酸性。然而，pHc始终比电化学平衡pH更偏碱性。在pHe约为7.0时，60分钟的脱氧处理使δpH从0.22±0.02降至0.05±0.01。再给氧可使δpH恢复到对照值。用哇巴因孵育可消除δpH。碳酸酐酶抑制剂乙酰唑胺和阴离子转运抑制剂4-乙酰氨基-4'-异硫氰基-2,2'-二磺酸芪（SITS）均可增加δpH。这些研究表明近端小管存在相对的细胞内碱化。干扰H⁺泵出细胞的操作会导致pHc下降。干扰细胞内碱处置的操作会导致pHc上升：乙酰唑胺减缓HCO₃⁻生成或SITS阻断HCO₃⁻流出。结果支持近端小管酸转运的H⁺分泌模型，该模型依赖于细胞内碱化的维持和分布。
