A new chromatographic method for measurement of rubidium transport activities in cultured bovine retinal pigment epithelial cells

Julie Y. Crider, Gary W. Williams, Thomas Yorio, Najam A. Sharif, Brenda W. Griffin

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4 Scopus citations

Abstract

A new method for measuring cellular rubidium (Rb+) uptake activities based on cation chromatography was developed and compared with the standard technique, uptake of the radioisotope 86Rb+, using cultured bovine retinal pigment epithelial (RPE) cells. The Rb+ response was strictly linear from 0.25 nmol (detection limit) to 25 nmol. The Na+/K+-ATPase inhibitor ouabain inhibited Rb+ uptake with IC50 values of 128.7 ± 23.5 nM (n = 8; radioactive method) and 56.6 ± 9.3 nM (n = 9; non-radioactive method, p < 0.01). The latter value is identical to the IC50 value of 54.4 ± 16.2 nM (n = 3) for ouabain binding to the intact RPE cells. Ouabain and bumetanide, an inhibitor of the Na+/K+/Cl cotransporter, each inhibited Rb+ uptake maximally by 66 and 30%, respectively. This new technique allows sensitive measurement of intracellular Rb+, as well as K+ and Na+, and, thus, should prove useful for studying the effects of pharmacologic agents and simulated disease conditions on cation transport and cation balance in RPE and other cell types.

Original languageEnglish
Pages (from-to)117-123
Number of pages7
JournalOphthalmic Research
Volume29
Issue number3
DOIs
StatePublished - 1 Jan 1997

Keywords

  • Bovine retinal pigment epithelial cells
  • Bumetanide
  • Cation chromatography
  • Na/K-ATPase
  • Na/K/7Cl-cotransporter Rubidium uptake methods
  • Ouabain

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