源自人视网膜色素上皮的培养细胞中的钠钾氯协同转运体

Na(+)-K(4)-Cl- cotransport in cultured cells derived from human retinal pigment epithelium.

作者信息

Kennedy B G

机构信息

Department of Physiology, Northwest Center for Medical Education, Indiana University School of Medicine, Gary 46408.

出版信息

Am J Physiol. 1990 Jul;259(1 Pt 1):C29-34. doi: 10.1152/ajpcell.1990.259.1.C29.

DOI:10.1152/ajpcell.1990.259.1.C29

PMID:2372049

Abstract

Unidirectional fluxes of Rb+ and Cl- were measured in cultured human retinal pigment epithelium (HRPE) to characterize the Na(+)-K(+)-Cl-cotransport system in this epithelial tissue. In HRPE, the ouabain-sensitive fraction of Rb+ influx comprises 65% of the total Rb+ influx. Bumetanide [inhibition constant (KI) = 160 nM] inhibited the residual ouabain-insensitive fraction of Rb+ influx by 70%. The bumetanide-sensitive fraction of Rb+ influx was dependent on the presence of both extracellular Na+ and Cl-. Cl- influx was similarly inhibited by bumetanide and also dependent on extracellular Na+ and Rb+. The stoichiometry of bumetanide-sensitive Cl- influx to Rb+ influx was 2:1. Elevation of extracellular osmolarity (by 30%) caused a 2.5-fold increase in Na(+)-K(+)-Cl- cotransport activity in cultured HRPE. The present study provides direct evidence for the occurrence of Na(+)-K(+)-Cl- cotransport-mediated cation and anion transport in HRPE.

摘要

在培养的人视网膜色素上皮细胞（HRPE）中测量了Rb⁺和Cl⁻的单向通量，以表征该上皮组织中的Na⁺-K⁺-Cl⁻共转运系统。在HRPE中，哇巴因敏感的Rb⁺内流部分占总Rb⁺内流的65%。布美他尼[抑制常数（KI）=160 nM]抑制了Rb⁺内流中剩余的哇巴因不敏感部分的70%。布美他尼敏感的Rb⁺内流部分依赖于细胞外Na⁺和Cl⁻的同时存在。Cl⁻内流同样受到布美他尼的抑制，并且也依赖于细胞外Na⁺和Rb⁺。布美他尼敏感的Cl⁻内流与Rb⁺内流的化学计量比为2:1。细胞外渗透压升高（30%）导致培养的HRPE中Na⁺-K⁺-Cl⁻共转运活性增加2.5倍。本研究为HRPE中发生Na⁺-K⁺-Cl⁻共转运介导的阳离子和阴离子转运提供了直接证据。