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

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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)
JournalAmerican Journal of Physiology - Cell Physiology
Volume259
Issue number1 28-1
StatePublished - 1990
Externally publishedYes

Fingerprint

Bumetanide
Retinal Pigments
Retinal Pigment Epithelium
Cultured Cells
Cells
Ouabain
Stoichiometry
Osmolar Concentration
Anions
Cations
Epithelium
Tissue
Fluxes

Keywords

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

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology

Cite this

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title = "Na+-K+-Cl- cotransport in cultured cells derived from human retinal pigment epithelium",
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.",
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author = "Brian Kennedy",
year = "1990",
language = "English (US)",
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issn = "0363-6143",
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TY - JOUR

T1 - Na+-K+-Cl- cotransport in cultured cells derived from human retinal pigment epithelium

AU - Kennedy, Brian

PY - 1990

Y1 - 1990

N2 - 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.

AB - 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.

KW - bumetanide

KW - epithelial transport

KW - membrane transport

KW - sodium-potassium-chloride cotransport

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VL - 259

JO - American Journal of Physiology - Cell Physiology

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