Long- and medium-chain fatty acid oxidation is increased in exercise-trained human skeletal muscle

• Published in: Metabolism, clinical and experimental Vol. 51; no. 4; pp. 460 - 464
• Main Authors: Jong-Yeon, Kim, Hickner, Robert C., Dohm, G.Lynis, Houmard, Joseph A.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.04.2002; Elsevier
• Subjects: Adult; Biological and medical sciences; Caprylates - metabolism; Carbon Dioxide - analysis; Carnitine - pharmacology; Carnitine Acyltransferases - metabolism; Carnitine O-Palmitoyltransferase - metabolism; Citrate (si)-Synthase - metabolism; Diabetes. Impaired glucose tolerance; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Exercise - physiology; Fatty Acids, Nonesterified - metabolism; Female; Fundamental and applied biological sciences. Psychology; Humans; Male; Medical sciences; Muscle, Skeletal - metabolism; Oxidation-Reduction; Palmitic Acid - metabolism; Regression Analysis; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports; Physical exercise; Human; Long chain; Label; Medium chain; Striated muscle; Fatty acids; Carnitine; Mitochondria; Preparation; Production; Endurance; Oxidation; Sedentary
• ISSN: 0026-0495; 1532-8600
• DOI: 10.1053/meta.2002.31326

The purpose of this study was to test the hypothesis that skeletal muscle fatty acid oxidation is enhanced by increased entry into the mitochondria with exercise training. Muscle was obtained from young ([ap ] 24 years) sedentary (n = 13) and endurance-trained (n = 10) volunteers and oxidation studied by measuring 14CO 2 production from labeled medium-chain (MCFA) or long-chain (LCFA) fatty acids in muscle homogenate preparations. LCFA (palmitate) oxidation was ( P [lt ] .05) approximately 34% higher in the trained than sedentary subjects (26.9 [plusmn] 3.0 v 17.8 [plusmn] 1.3 nmol CO 2/g [middot] h). MCFA (octanoate) oxidation was also about 26% higher ( P [lt ] .05) in the trained subjects (21.7 [plusmn] 2.1 v 16.1 [plusmn] 2.0 nmol CO 2/g [middot] h). To examine the roles of carnitine-mediated transport and mitochondrial content, we also measured carnitine palmitoyltransferase I (CPT1), carnitine octanoyl transferase (COT), and citrate synthase (CS) activities. CPT1 and CS activity were significantly ( P [lt ] .05) higher ([ap ]25%) in the endurance-trained subjects; there was no difference in COT activity. These data suggest that adaptations at the level of CPT1 and processes distal to this step may contribute to increases in LCFA or MFCA oxidation with exercise training. In contrast, carnitine-mediated transport (COT) does not appear to contribute to an enhancement in MCFA oxidation with exercise training.