PH-DEPENDENT TRANSPORT OF PROCAINAMIDE IN CULTURED RENAL EPITHELIAL MONOLAYERS OF OK CELLS - CONSISTENT WITH NONIONIC DIFFUSION
PH-DEPENDENT TRANSPORT OF PROCAINAMIDE IN CULTURED RENAL EPITHELIAL MONOLAYERS OF OK CELLS - CONSISTENT WITH NONIONIC DIFFUSION
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DOI：
10.1111/j.1476-5381.1995.tb16392.x
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发表时间：
1995-09-01
影响因子：
7.3
通讯作者：
BROWN, CDA
中科院分区：
文献类型：
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作者：
DUDLEY, AJ;BROWN, CDA
1以前的研究表明普鲁卡因胺是有机阳离子/质子反向转运的底物。为了更详细地研究普鲁卡因酰胺通量和质子通量之间的耦合，我们研究了细胞外普鲁卡因酰胺添加对培养的肾OK细胞单层细胞内pH值的影响。使用BCECF作为探针监测细胞内pH值。2顶端添加普鲁卡因酰胺（10 mM）可引起细胞内pH值显著碱化。基底外侧添加普鲁卡因酰胺在提高细胞内pH值方面同样有效。在另外两种肾细胞系中发现了类似的碱化作用：MDCK菌株1和LLCPK（1）。3相反，四乙基铵和N-甲基烟酰胺，有机阳离子/质子反向转运的原型底物对细胞内pH没有影响。4在生理pH值下，普鲁卡因胺以中性弱碱（B）及其共轭弱酸（BH+）的形式存在。为了测试哪种普鲁卡因酰胺导致碱化，进行了[B]保持恒定而[BH+]在1.15 mM至7.25 mM范围内变化的实验。结果表明，中性弱碱（B）是渗透性物质。5普鲁卡因酰胺从普鲁卡因酰胺负载细胞单层流出导致细胞内pH显著酸化。与普鲁卡因酰胺摄取一样，这一结果可归因于中性弱碱的移动。普鲁卡因胺对细胞内pH的这些影响与普鲁卡因胺的非离子扩散一致，而不是普鲁卡因胺与细胞内pH的相互作用。有机阳离子/质子反向转运体。此外，结果表明有机阳离子/质子反向转运在OK细胞中不高表达。
1 Previous studies suggest that procainamide is a substrate for organic cation/proton antiport. In order to study the coupling between procainamide flux and proton flux in greater detail we investigated the effects of extracellular procainamide addition upon intracellular pH in cultured monolayers of renal OK cells. Intracellular pH was monitored by use of BCECF as a probe.2 Apical addition of procainamide (10 mM) caused a significant aIkalinisation of intracellular pH. Basolateral addition of procainamide was equally effective in raising intracellular pH. A similar alkalinisation was found in two other renal cell lines: MDCK strain 1 and LLCPK(1).3 In contrast, both tetraethylammonium and N-methylnicotinamide, archetypal substrates for organic cation/proton antiport were without effect upon intracellular pH.4 At physiological pH values, procainamide exists as a neutral weak base (B) and its conjugate weak acid (BH+). To test which species of procainamide was responsible for the alkalinisation, experiments in which [B] was kept constant whilst [BH+] was varied from 1.15 mM to 7.25 mM were performed. The results suggested that the neutral weak base (B) was the permeant species.5 Procainamide efflux from procainamide-loaded cell monolayers resulted in a significant acidification of intracellular pH. As with procainamide uptake, this result could be ascribed to the movement of neutral weak base.6 These effects of procainamide upon intracellular pH are consistent with nonionic diffusion of procainamide rather than an interaction of procainamide with the organic cation/proton antiporter. In addition, the results suggest that organic cation/proton antiport is not highly expressed in OK cells.