Intracellular pH regulation in rainbow trout (Oncorhynchus mykiss) hepatocytes: the activity of sodium/proton exchange is oxygen-dependent.
We studied pH regulation in freshly isolated rainbow trout hepatocytes using microspectrofluorometry with the fluorescent dye BCECF. In accordance with earlier data on rainbow trout hepatocytes, ion substitution (N-methyl D-glucamine for sodium and gluconate for chloride) and transport inhibitor [10 microM M methyl isobutyl amiloride (MIA) to inhibit sodium/proton exchange and 100 microM DIDS to inhibit bicarbonate transport] studies in either Hepes-buffered or bicarbonate/carbon dioxide-buffered media (extracellular pH 7.6) indicated a role for sodium/proton exchange, sodium-dependent bicarbonate transport, and sodium-independent anion exchange in the regulation of hepatocyte pH. In Hepes-buffered medium, the activity of the sodium/proton exchanger (i.e. proton extrusion inhibited by MIA) was greater at 1% than at 21% oxygen. The oxygen dependency of the sodium/proton exchange is not caused by hydroxyl radicals, which appear to mediate the oxygen sensitivity of potassium-chloride cotransport in erythrocytes.
Tuominen
A
A
Department of Biology, University of Turku, 20014 Turku, Finland.
Rissanen
E
E
Bogdanova
A
A
Nikinmaa
M
M
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000584:Amiloride / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D017920:Antiporters / Q000378:metabolism; D001639:Bicarbonates / Q000037:antagonists & inhibitors; D002478:Cells, Cultured; D005452:Fluoresceins; D005456:Fluorescent Dyes; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007424:Intracellular Fluid / Q000378:metabolism*; D017686:Oncorhynchus mykiss / Q000378:metabolism*; D010100:Oxygen / Q000494:pharmacology*; D011522:Protons; D027982:Sodium-Bicarbonate Symporters / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
D017920:Antiporters; D001639:Bicarbonates; D005452:Fluoresceins; D005456:Fluorescent Dyes; D011522:Protons; D027982:Sodium-Bicarbonate Symporters; D017923:Sodium-Hydrogen Exchangers; D000584:Amiloride; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; C056369:5-(N-methyl-N-isobutyl)amiloride; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D010100:Oxygen