Stuenkel E L, Machen T E, Williams J A
Department of Physiology, University of California, San Francisco 94143.
Am J Physiol. 1988 Jun;254(6 Pt 1):G925-30. doi: 10.1152/ajpgi.1988.254.6.G925.
The mechanisms underlying regulation of intracellular pH (pHi) by rat pancreatic duct cells were studied by use of the pH-sensitive, fluorescent, cytoplasmically trapped dye 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF). Cells exhibited a mean pHi of 7.18 +/- 0.14 in bicarbonate-buffered medium, as calculated from the BCECF fluorescence ratio. Removal of extracellular Na (Nao) caused an intracellular acidification that was rapidly reversed by Na replacement and occurred independently of Clo. Amiloride (10(-3) M) reversibly blocked Na-dependent recovery after Na-free-induced acidification. These results demonstrate the presence of a Na+-H+ exchange mechanism in pancreatic duct cells. Replacement of Clo with gluconate caused an intracellular alkalinization that was reversed by replacement of Cl. Application of the disulfonic stilbene derivatives, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) and dihydro-DIDS (2 X 10(-4) M), resulted in block of both Cl-dependent recovery from Na-gluconate and the onset of alkalinization of transition from NaCl to Na-gluconate. Chloride-dependent alteration of pHi occurred independently of Nao. These results demonstrate the presence of an anion exchange mechanism consistent with Cl--HCO3- exchange. Thus pancreatic duct cells contain both Na+-H+ and Cl--HCO3- exchangers.
利用对pH敏感的、荧光的、捕获于细胞质中的染料2'，7'-双（羧乙基）-5（6）-羧基荧光素（BCECF），研究了大鼠胰腺导管细胞调节细胞内pH（pHi）的机制。根据BCECF荧光比率计算，细胞在碳酸氢盐缓冲培养基中的平均pHi为7.18±0.14。去除细胞外Na（Nao）会导致细胞内酸化，这种酸化在Na重新加入后迅速逆转，且其发生与Cl⁻无关。氨氯吡咪（10⁻³ M）可逆性地阻断了无Na诱导酸化后依赖Na的恢复。这些结果证明胰腺导管细胞中存在Na⁺-H⁺交换机制。用葡萄糖酸盐替代Cl⁻会导致细胞内碱化，而Cl⁻重新加入后这种碱化会逆转。应用二磺酸芪衍生物4,4'-二异硫氰酸芪-2,2'-二磺酸（DIDS）和二氢-DIDS（2×10⁻⁴ M），会阻断从葡萄糖酸钠中依赖Cl⁻的恢复以及从NaCl转变为葡萄糖酸钠时碱化的开始。pHi的Cl⁻依赖性改变独立于Nao发生。这些结果证明存在一种与Cl⁻-HCO₃⁻交换一致的阴离子交换机制。因此，胰腺导管细胞同时含有Na⁺-H⁺和Cl⁻-HCO₃⁻交换体。
