The effect of acute ethanol administration on the clearance of 3H-PteGlu by the rat kidney

Abstract

Studies of the renal clearance of folic acid in primates demonstrate net reabsorption of folate by a saturable system. The acute administration of ethanol to rats causes a significant increase in urinary folate excretion. The mechanism for this effect is not known and thus the effect of acute ethanol administration on the urinary clearance of folate was studied in rats. 3H-PteGlu was administered to male Sprague-Dawley rats via continuous intravenous infusion in doses ranging from 0.1 to 15,800 nmol/kg b. wt. and the urinary clearance relative to 14C-inulin was determined. Clearance ratios of 3H-folate to 14C-inulin indicate that folate is reabsorbed from the tubular fluid at physiological doses of 3H-PteGlu and possibly secreted at pharmacological doses of 3H-PteGlu. The effect of acute ethanol administration on the folate/inulin clearance ratio was assessed at each dose of 3H-PteGlu. At plasma ethanol levels in the range of 150–200 mg/dl, the urinary clearance of 3H-folate with respect to inulin was increased at a folate dose of 30 nmol/kg b. wt.