title: Trans-stimulation effect on H(+)-organic cation antiport system in rat renal brush-border membranes.
abstract: Trans-stimulation effect on tetraethylammonium (an organic cation) transport was examined in rat renal brush-border membrane vesicles. The uptake of [14C]tetraethylammonium at pH 6.0-8.5 was stimulated by preloading the membrane vesicles with unlabeled tetraethylammonium. When the uptake was measured in preloaded membrane vesicles in the presence of carbonyl cyanide p-trifluoromethoxyphenylhydrazone, stimulation was observed at high pH but not at low pH. These results suggest that the mechanisms of the trans-stimulation effect on organic cation transport are different depending on the pH. When pH is low, the trans-stimulation is due to generation of an outward H+ gradient, which in turn stimulates [14C]tetraethylammonium uptake by H(+)-[14C]tetraethylammonium exchange. In contrast, when pH is high, the stimulation is due to direct exchange of tetraethylammonium for [14C]tetraethylammonium.
authors.affiliation: Department of Pharmacy, Kyoto University Hospital, Faculty of Medicine, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Katsura
authors.forename: H
authors.initials: H
authors.lastname: Maegawa
authors.forename: Y
authors.initials: Y
authors.lastname: Tomita
authors.forename: M
authors.initials: M
authors.lastname: Takano
authors.forename: K
authors.initials: K
authors.lastname: Inui
authors.forename: R
authors.initials: R
authors.lastname: Hori
mesh_terms: D000818:Animals; D001692:Biological Transport; D002250:Carbon Radioisotopes; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007672:Kidney Cortex / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000378:metabolism
chemical_list: D002250:Carbon Radioisotopes; D013757:Tetraethylammonium Compounds; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D019789:Tetraethylammonium