title: Medium-chain fatty acids but not L-carnitine accelerate the kinetics of [14C]triacylglycerol utilization by colostrum-deprived newborn pigs.
abstract: The effect of L-carnitine on in vivo fatty acid utilization was determined using colostrum-deprived newborn piglets fed emulsified triglycerides (TG) composed of [1-14C]octanoate (tri-8:0) or [1-14C]octadecanoate (tri-18:1). A soy protein-based liquid diet devoid of L-carnitine was fed piglets for 1 d to allow development of fatty acid-metabolizing enzymes and intestinal fat digestion and absorption before assessment of in vivo fat utilization. The radiolabeled TG were fed in isoenergetic amounts (97.7 kJ/kg(0.75)), with or without L-carnitine (1 mmol/kg(0.75)) as 30% (v/v) emulsions, using polyoxyethylene sorbitan monooleate as an emulsifier. Expired CO(2) was quantified and specific radioactivity (Bq/micromol) was determined at 20-min intervals over 24 h. The rate (mmol ATP.kg(-0.75).min(-1)) and extent (mol ATP/kg(0.75)) of TG oxidative utilization (i.e., composite of digestion, absorption and oxidation) were calculated from the kinetics of 14CO(2) expiration. The maximal rate and extent of tri-8:0 oxidation were three and fourfold greater than those of tri-18:1, respectively (P < 0.001), and tri-18:1 delayed the time to reach 10 and 50% of maximal oxidation rate by 1.2 and 1.9 h (P < 0.01, respectively), regardless of supplemental carnitine. Collectively, these findings quantify the accelerated oxidation of medium-chain vs. long-chain triglycerides, but fail to support a need for supplemental carnitine to maximize fat oxidation in colostrum-deprived piglets.
authors.affiliation: Department of Animal Science, North Carolina State University, Raleigh 27695-7621, USA.
authors.forename: Kinam N
authors.initials: KN
authors.lastname: Heo
authors.forename: Xi
authors.initials: X
authors.lastname: Lin
authors.forename: In K
authors.initials: IK
authors.lastname: Han
authors.forename: Jack
authors.initials: J
authors.lastname: Odle
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002331:Carnitine / Q000494:pharmacology*; D003126:Colostrum / Q000502:physiology*; D005227:Fatty Acids / Q000737:chemistry* / Q000494:pharmacology*; D007413:Intestinal Mucosa / Q000378:metabolism; D007700:Kinetics; D010084:Oxidation-Reduction / Q000187:drug effects; D013552:Swine; D014280:Triglycerides / Q000378:metabolism*
chemical_list: D002250:Carbon Radioisotopes; D005227:Fatty Acids; D014280:Triglycerides; D002331:Carnitine