title: Kinetics of carnitine palmitoyltransferase-I are altered by dietary variables and suggest a metabolic need for supplemental carnitine in young pigs.
abstract: To examine the kinetics of carnitine palmitoyltransferase-I (CPT-I) and the influence of dietary variables, young pigs (18 kg, n = 20) were fed corn-soybean meal diets supplemented with 40 g soy oil/kg and containing either 136 or 180 g crude protein/kg and either 0 or 500 mg/kg L-carnitine (2 x 2 factorial design). Diets were offered for 10 d (85% of ad libitum); CPT-I activities in liver and skeletal muscle mitochondria were determined, and enzyme kinetic constants (V:(max) and K:(m) for carnitine) were estimated. Kinetics of CPT-I in muscle were not affected by diet (P: > 0.1; carnitine K:(m) = 480 +/- 44 micromol/L). In contrast, the K:(m) for carnitine in liver was increased from 164 to 216 +/- 20 micromol/L by dietary L-carnitine supplementation (P: < 0.01) and from 169 to 211 +/- 20 micromol/L by high protein feeding (P: < 0.05). Dietary L-carnitine increased muscle and liver free carnitine concentrations by 72 and 158% over control concentrations (770 and 80 micro;mol/kg wet muscle and liver, respectively). Because tissue carnitine concentrations were within the range of the respective K:(m) for both liver and muscle tissue, it is inferred that alteration of tissue carnitine concentrations via dietary supplementation could modulate CPT-I activity in young pigs.
authors.affiliation: Department of Animal Science, North Carolina State University, Raleigh, NC 27695-7621, USA.
authors.forename: K
authors.initials: K
authors.lastname: Heo
authors.forename: X
authors.initials: X
authors.lastname: Lin
authors.forename: J
authors.initials: J
authors.lastname: Odle
authors.forename: I K
authors.initials: IK
authors.lastname: Han
mesh_terms: D000818:Animals; D002331:Carnitine / Q000008:administration & dosage* / Q000031:analogs & derivatives* / Q000378:metabolism; D002334:Carnitine O-Palmitoyltransferase / Q000378:metabolism*; D004032:Diet; D019587:Dietary Supplements; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology; D008930:Mitochondria, Liver / Q000201:enzymology; D018482:Muscle, Skeletal / Q000378:metabolism / Q000648:ultrastructure; D013024:Soybean Oil; D013025:Glycine max; D013552:Swine / Q000502:physiology*; D003313:Zea mays
chemical_list: C116917:acylcarnitine; D013024:Soybean Oil; D002334:Carnitine O-Palmitoyltransferase; D002331:Carnitine