Guggino W B, London R, Boulpaep E L, Giebisch G
J Membr Biol. 1983;71(3):227-40. doi: 10.1007/BF01875464.
The transport of chloride across the Necturus proximal tubule cell was studied in the doubly-perfused kidney using conventional, chloride-sensitive and pH-sensitive microelectrodes. Lowering chloride activity in the basolateral solution results in a reduction in intracellular Cl- activity (aiCl). This reduction in aiCl is inhibited by removing either HCO-3 or Na+ from the perfusion solution, indicating that both HCO-3 and Na+ are required for Cl- movement across the basolateral cell membrane. Reducing either HCO-3 or Na+ in the basolateral solution causes an increase in aiCl. Thus changes in either Na+ or HCO-3 chemical gradients across the basolateral cell membrane significantly affect chloride movement. Changing intracellular pH by means of NH4Cl exposure results in an increase in aiCl followed by a sharp decrease when NH4Cl is removed. These changes in intracellular chloride do not occur in the absence of HCO-3. Likewise, the decrease in aiCl following NH4Cl treatment requires the presence of Na+ in the basolateral solution. We conclude that chloride is transported across the basolateral cell membrane in exchange for both Na+ and HCO-3. Our results also support the presence of a Na+/Cl- cotransport mechanism on the apical cell membrane.
利用传统的、对氯离子敏感和对pH敏感的微电极，在双灌注肾脏中研究了氯离子在美西螈近端肾小管细胞中的转运。降低基底外侧溶液中的氯离子活性会导致细胞内氯离子活性（aiCl）降低。从灌注溶液中去除HCO₃⁻或Na⁺会抑制aiCl的这种降低，这表明HCO₃⁻和Na⁺都是氯离子跨基底外侧细胞膜移动所必需的。降低基底外侧溶液中的HCO₃⁻或Na⁺会导致aiCl增加。因此，跨基底外侧细胞膜的Na⁺或HCO₃⁻化学梯度的变化会显著影响氯离子的移动。通过暴露于NH₄Cl来改变细胞内pH会导致aiCl增加，当去除NH₄Cl时aiCl会急剧下降。在没有HCO₃⁻的情况下不会发生这些细胞内氯离子的变化。同样，NH₄Cl处理后aiCl的降低需要基底外侧溶液中存在Na⁺。我们得出结论，氯离子通过与Na⁺和HCO₃⁻交换而跨基底外侧细胞膜转运。我们的结果也支持在顶端细胞膜上存在Na⁺/Cl⁻共转运机制。
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