title: Stimulatory effect of ethanol on weak organic acid uptake in rat renal tubules.
abstract: Ethanol at relatively low concentrations (10-40 mM) significantly stimulated the uphill uptake of a weak organic acid, fluorescein, in the superficial proximal tubules of rat renal cortex slices, but it did not affect the rate of glucose production from lactate or pyruvate in rat renal cortex fragment suspension. In a low Na+ medium, ethanol failed to stimulate fluorescein uptake, although under the conditions employed in the present study, the baseline weak organic acid uptake was not dependent on external Na+. The stimulation of fluorescein uptake by ethanol (20 mM) was abolished by an inhibitor of alcohol dehydrogenase (EC 1.1.1.1), pyrazole (1 mM), or an inhibitor of aldehyde dehydrogenase (EC 1.2.1.3), cyanamide (0.3 mM), suggesting that oxidation of ethanol mediated its effect on the uptake. Among gluconeogenesis inhibitors tested, only D-malate (2 mM) abolished the stimulatory effect of ethanol, while the rest either did not affect (quinolinate) or even slightly augmented (alpha-cyano-4-hydroxycinnamate and phenylpyruvate) it. The effect of ethanol was markedly increased by an inhibitor of the tricarboxylic acid cycle, fluoroacetate. It was concluded that the stimulation by ethanol of weak organic acid uptake in rat renal tubules was mediated by the production of acetate.
authors.affiliation: Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St Petersburg.
authors.forename: A A
authors.initials: AA
authors.lastname: Nikiforov
authors.forename: I B
authors.initials: IB
authors.lastname: Ostretsova
mesh_terms: D000426:Alcohol Dehydrogenase / Q000494:pharmacology; D000444:Aldehyde Dehydrogenase / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D003373:Coumaric Acids / Q000494:pharmacology; D003484:Cyanamide / Q000494:pharmacology; D000431:Ethanol / Q000378:metabolism / Q000494:pharmacology*; D019793:Fluorescein; D005452:Fluoresceins / Q000378:metabolism*; D005943:Gluconeogenesis / Q000187:drug effects; D066298:In Vitro Techniques; D007687:Kidney Tubules, Proximal / Q000187:drug effects* / Q000378:metabolism; D007773:Lactates / Q000494:pharmacology; D019344:Lactic Acid; D008293:Malates / Q000494:pharmacology; D008297:Male; D010667:Phenylpyruvic Acids / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D017378:Quinolinic Acid / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
chemical_list: D003373:Coumaric Acids; D005452:Fluoresceins; D007773:Lactates; D008293:Malates; D010667:Phenylpyruvic Acids; D011720:Pyrazoles; C007175:alpha-cyano-4-hydroxycinnamate; D019344:Lactic Acid; D000431:Ethanol; C031280:pyrazole; D003484:Cyanamide; C030298:malic acid; D000426:Alcohol Dehydrogenase; D000444:Aldehyde Dehydrogenase; D017378:Quinolinic Acid; D019793:Fluorescein; C031606:phenylpyruvic acid