Na+-K+-Cl- cotransport in cultured cells derived from human retinal pigment epithelium

B. G. Kennedy

Research output: Contribution to journalArticle

25 Scopus citations

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 K(I)) = 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.

Original languageEnglish (US)
Pages (from-to)C29-C34
JournalAmerican Journal of Physiology - Cell Physiology
Volume259
Issue number1 28-1
StatePublished - Aug 14 1990
Externally publishedYes

Keywords

  • bumetanide
  • epithelial transport
  • membrane transport
  • sodium-potassium-chloride cotransport

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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