title: Multispecific anion exchange in basolateral (sinusoidal) rat liver plasma membrane vesicles.
abstract: The mechanisms and driving forces for hepatic uptake of sulfate were investigated in basolateral (sinusoidal) rat liver plasma membrane vesicles. A transmembrane pH difference (pH 8.0 inside, 6.0 outside) stimulated sulfate uptake above equilibrium ("overshoot"). This pH gradient-stimulated sulfate uptake was saturable with increasing concentrations of sulfate and could be inhibited by probenecid, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), carbonyl cyanide p-(trifluoromethoxy)-phenylhydrazone, and nigericin. At low buffer concentrations and pH 6.0 an inwardly directed sodium gradient also stimulated sulfate uptake. This sodium-dependent sulfate uptake could be inhibited by amiloride and DIDS, indicating indirect coupling of sodium and sulfate flux through concomitant sodium-proton and sulfate-hydroxyl exchange. Cisinhibition of initial pH gradient-stimulated sulfate uptake, as well as transstimulation of sulfate uptake under pH-equilibrated conditions (pH 7.5 inside and outside), were observed with sulfate, thiosulfate, oxalate, and succinate, but not with chloride, bicarbonate, acetate, lactate, pyruvate, p-aminohippurate, citrate, glutamate, aspartate, and taurocholate. Furthermore, cholate and sulfobromophthalein exhibited competitive inhibition of pH gradient-stimulated sulfate uptake. In addition, an inside-to-outside hydroxyl gradient also stimulated uptake of cholate and this pH gradient-sensitive portion of cholate uptake was inhibited by extravesicular sulfate. In contrast to basolateral membranes, no evidence for multispecific sulfate-hydroxyl exchange was found in canalicular plasma membrane vesicles.
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D000838:Anions; D001667:Binding, Competitive; D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D019826:Cholic Acid; D002793:Cholic Acids / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009550:Nigericin / Q000494:pharmacology; D011339:Probenecid / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000494:pharmacology; D013431:Sulfates / Q000378:metabolism*; D013448:Sulfobromophthalein / Q000494:pharmacology
chemical_list: D000838:Anions; D002793:Cholic Acids; D013431:Sulfates; D013448:Sulfobromophthalein; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D000584:Amiloride; D012964:Sodium; D019826:Cholic Acid; D011339:Probenecid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D009550:Nigericin