title: Lipid oxidation fuels recovery from exhaustive exercise in white muscle of rainbow trout.
abstract: The oxidative utilization of lipid and carbohydrate was examined in white muscle of rainbow trout (Oncorhynchus mykiss) at rest, immediately after exhaustive exercise, and for 32-h recovery. In addition to creatine phosphate and glycolysis fueling exhaustive exercise, near maximal activation of pyruvate dehydrogenase (PDH) at the end of exercise points to oxidative phosphorylation of carbohydrate as an additional source of ATP during exercise. Within 15 min postexercise, PDH activation returned to resting values, thus sparing accumulated lactate from oxidation. Glycogen synthase activity matched the rate of glycogen resynthesis and represented near maximal activation. Decreases in white muscle free carnitine, increases in long-chain fatty acyl carnitine, and sustained elevations of acetyl-CoA and acetyl carnitine indicate a rapid utilization of lipid to supply ATP for recovery. Increases in malonyl-CoA during recovery suggest that malonyl-CoA may not regulate carnitine palmitoyltransferase-1 in trout muscle during recovery, but instead it may act to elongate short-chain fatty acids for mitochondrial oxidation. In addition, decreases in intramuscular triacylglycerol and in plasma nonesterified fatty acids indicate that both endogenous and exogenous lipid fuels may be oxidized during recovery.
authors.affiliation: Department of Biology, McMaster University, Hamilton, Ontario L8S 4K1, Canada. richarjg@mcmaster.ca
authors.forename: Jeff G
authors.initials: JG
authors.lastname: Richards
authors.forename: George J F
authors.initials: GJ
authors.lastname: Heigenhauser
authors.forename: Chris M
authors.initials: CM
authors.lastname: Wood
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D050260:Carbohydrate Metabolism; D004734:Energy Metabolism / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006006:Glycogen Synthase / Q000378:metabolism; D019344:Lactic Acid / Q000097:blood; D015227:Lipid Peroxidation / Q000502:physiology*; D008316:Malonyl Coenzyme A / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D017686:Oncorhynchus mykiss; D010725:Phosphocreatine / Q000378:metabolism; D005082:Physical Exertion / Q000502:physiology*; D011767:Pyruvate Decarboxylase / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism
chemical_list: D005230:Fatty Acids, Nonesterified; D014280:Triglycerides; D010725:Phosphocreatine; D019344:Lactic Acid; D000249:Adenosine Monophosphate; D008316:Malonyl Coenzyme A; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D006006:Glycogen Synthase; D011767:Pyruvate Decarboxylase