Kinetics of Carnitine Palmitoyltransferase-I in Liver and Skeletal Muscle of Young Pigs

North Carolina State University Swine Nutrition Research from 2001. 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). CPT-I activities in liver and skeletal muscle mitochondria were determined, and enzyme kinetic constants (Vmax & Km for carnitine) were estimated. Kinetics of CPT-I in muscle were not affected by diet (P >0.1; carnitine Km = 480 44mol/L). In contrast, the Km for carnitine in liver was increased from 164 to 216 20 mol/L by dietary L-carnitine supplementation (P < 0.01) and from 169 to 211 20 mol/L by high protein feeding (P < 0.05). Because tissue carnitine concentrations were within the range of the respective Kms 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.