title: Carnitine affects octanoate oxidation to carbon dioxide and dicarboxylic acids in colostrum-deprived piglets: in vivo analysis of mechanisms involved based on CoA- and carnitine-ester profiles.
abstract: Newborn, colostrum-deprived piglets (n = 21) were used to study the effects of L-carnitine supplementation on the in vivo oxidation of [1-14C]octanoate to CO2 and dicarboxylic acids. Pigs were fitted with arterial and bladder catheters and were infused with octanoate (supplying 35-100% of piglets' energy expenditure) and with or without valproate for a period of 24 h. After achieving steady-state octanoate oxidation, carnitine was coinfused [50 mumol/kg 0.75 prime plus 20 mumol/h.kg 0.75)], and deviations in the octanoate oxidation rate, dicarboxylic acid excretion rate, and carnitine metabolism were monitored. At the end of the 24-h infusion, samples of liver and muscle were analyzed for carnitine- and CoA-esters by HPLC. Carnitine stimulated octanoate oxidation by 7% (P < 0.05) and decreased dicarboxylic acid excretion by 45% (P < 0.05). Carnitine supplementation increased (P < 0.05) concentrations of carnitine and acetyl carnitine in hepatic tissue (three- and 55-fold, respectively) and plasma (seven- and 11-fold); whereas, muscle-carnitine concentration doubled upon carnitine supplementation, but acetyl carnitine concentration remained unaltered. Urinary excretion of acetyl and free carnitine also increased with carnitine supplementation, but accounted for < 10% of carnitine infused. Hepatic total CoA and CoA esters increased with carnitine supplementation, whereas muscle acetyl-CoA decreased. Valproate had only marginal effects on octanoate metabolism. These data confirm the hypothesis that carnitine effects the in vivo oxidation of octanoate in colostrum-deprived piglets and suggest that the effects may be mediated by aiding the export of excess acetyl groups from muscle or by enhancing uptake of octanoate into liver mitochondria.
authors.affiliation: Division of Nutritional Sciences, University of Illinois, Urbana 61801.
authors.forename: T A
authors.initials: TA
authors.lastname: van Kempen
authors.forename: J
authors.initials: J
authors.lastname: Odle
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002210:Caprylates / Q000008:administration & dosage / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism*; D002331:Carnitine / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D003065:Coenzyme A / Q000378:metabolism; D003126:Colostrum / Q000502:physiology*; D003998:Dicarboxylic Acids / Q000378:metabolism*; D005260:Female; D007261:Infusions, Intra-Arterial; D008099:Liver / Q000737:chemistry / Q000378:metabolism; D009132:Muscles / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D011247:Pregnancy; D013552:Swine; D013997:Time Factors; D014635:Valproic Acid / Q000494:pharmacology
chemical_list: D002210:Caprylates; D003998:Dicarboxylic Acids; D002245:Carbon Dioxide; D014635:Valproic Acid; D002331:Carnitine; D003065:Coenzyme A