Intracellular pH regulation by a Na+/H+ exchanger in cultured bovine trabecular cells.
Intracellular pH (pHi) of cultured bovine trabecular cells was measured using video-imaging techniques with a pH-sensitive intracellular fluorescent dye, BCECF. In bicarbonate-rich Ringer at pH 7.4, pHi was 7.29 +/- 0.03 (+/- SEM, n = 12 monolayers, 120 cells sampled). Exposure to 20 mM NH4Cl immediately alkalinized pHi: replacement with a Na(+)-rich solution acidified pHi before recovery to resting levels. When NH4Cl was replaced by a low Na+ solution, acidification was sustained but pHi recovery occurred after Na(+)-rich solution. A pHi of 7.11 +/- 0.02 (n = 2 monolayers, 20 cells) occurred in pH 6.8 and pHi was 7.72 +/- 0.03 (n = 2 monolayers, 20 cells) in pH 8.0. Amiloride (1 mM) acidified pHi but DIDS (1 mM) treatment, HCO3(-)-free condition, 1 mM ouabain, 50 mM K+, and 2 mM BaCl2 failed to change pHi. Hydrogen peroxide (1 mM) acidified pHi but no change occurred with 50 microM. Trabecular cells possess an Na+/H+ exchanger similar to that in other cell types.
Chu
T C
TC
Department of Ophthalmology, Medical College of Georgia, Augusta.
Keith
C
C
Green
K
K
D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D002352:Carrier Proteins / Q000502:physiology*; D002417:Cattle; D002478:Cells, Cultured; D005452:Fluoresceins / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007091:Image Processing, Computer-Assisted; D007424:Intracellular Fluid / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers; D014129:Trabecular Meshwork / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D002352:Carrier Proteins; D005452:Fluoresceins; D017923:Sodium-Hydrogen Exchangers; D000643:Ammonium Chloride; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; D006861:Hydrogen Peroxide