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DYSREGULATION OF MUSCLE LIPID METABOLISM IN RATS SELECTIVELY BRED FOR LOW AEROBIC RUNNING CAPACITY
Running Head: Lipid metabolism and exercise capacity Fiona J. Spargo1, Sean L. McGee2, Nick Dzamko3, Matthew J. Watt3, Bruce E. Kemp3, Steven L. Britton4, Lauren G. Koch4, Mark Hargreaves2, John A. Hawley1
1
Exercise Metabolism Laboratory, RMIT University, Victoria, Australia
2
Department of Physiology, University of Melbourne, Victoria, Australia
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4
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St Vincent’s Institute of Medical Research and the Department of Medicine, Fitzroy, Victoria, Australia Physical Medicine and Rehabilitation, University of Michigan, Ann Arbor, Michigan, US
Address correspondence to: John A. Hawley, Ph.D. Exercise Metabolism Group School of Medical Sciences
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2 ABSTRACT As substrate for evaluation of metabolic diseases we developed novel rat models that contrast for endurance exercise capacity. Through two-way artificial selection we created rodent phenotypes of intrinsically low- (LCR) and high-capacity runners (HCR) that also differ markedly for cardiovascular and metabolic disease risk factors. Here we determined skeletal muscle proteins with putative roles in lipid and carbohydrate metabolism to better understand the mechanisms underlying differences in whole-body substrate handling between phenotypes. Animals (generation 16) differed for endurance running capacity by 295%. LCR had higher resting plasma glucose (6.58 ±0.45 vs. 6.09 ±0.45 mmol/L), insulin (0.48 ±0.03
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vs. 0.32 ±0.02 ng/mL), non-esterified fatty acid (NEFA; 0.57 ±0.14 v 0.35 ±0.05 mM) and triglyceride (TG; 0.47 ±0.11 vs. 0.25 ±0.08 mmol/L) concentrations (all P
