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.
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.
van Kempen
T A
TA
Division of Nutritional Sciences, University of Illinois, Urbana 61801.
Odle
J
J
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
D002210:Caprylates; D003998:Dicarboxylic Acids; D002245:Carbon Dioxide; D014635:Valproic Acid; D002331:Carnitine; D003065:Coenzyme A