title: Oxidation of 1-14C-ascorbic acid in the guinea pig: effect of the route of administration.
abstract: Twenty-four hours after the administration of (1-14C)-ascorbic acid to guinea pigs by oral, intraperitoneal or intracardiac routes, 14CO2 expired levels were 22.6 plus or minus 1.8, 17.6 plus or minus 1.4 and 14.4 plus or minus 0.6 percent, respectively, of the administered radioactive doses. Whole blood concentrations of ascorbic acid were 80.2 plus or minus 2 micrograms per ml and, in general they were inversely related to expired 14CO2 production, which in turn reflects the degree of ascorbic acid catabolism in ascorbic acid adequate animals. Regardless of the route of (1-14C)-ascorbic acid administration, there was a biphasic pattern of 14CO2 evolution; the first peak occurs at two hours and the second peak at five hours after administration of the doses. Thin layer chromatography analysis of (1-14C)-ascorbic acid verified the reagent's purity. In vitro isolated stomach content and intestinal content experiments illustrated that at least 1-2% of the expired 14CO2 might also result from enterohepatic circulation of the label.
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000097:blood*; D004386:Duodenum / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism; D006168:Guinea Pigs; D006321:Heart; D007274:Injections, Intraperitoneal; D008297:Male; D010084:Oxidation-Reduction
chemical_list: D001205:Ascorbic Acid