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 language | English |
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Pages (from-to) | 117-123 |
Number of pages | 7 |
Journal | Ophthalmic Research |
Volume | 29 |
Issue number | 3 |
DOIs | |
State | Published - 1 Jan 1997 |
Keywords
- Bovine retinal pigment epithelial cells
- Bumetanide
- Cation chromatography
- Na/K-ATPase
- Na/K/7Cl-cotransporter Rubidium uptake methods
- Ouabain