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This Article Accepted manuscript (PDF) All Versions of this Article: JOE-08-0122v1 198/2/375    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Kelly, K. Articles by Turcotte, L. PubMed PubMed Citation Articles by Kelly, K. Articles by Turcotte, L.

K Kelly, Kinesiology, University of Southern California, Los Angeles, 90089, United States
C Sung, Physiology and Biophysics, University of Southern California, Los Angeles, United States
M Abbott, Biological Sciences, University of Southern California, Los Angeles, United States
L Turcotte, Kinesiology, University of Southern California, Los Angeles, United States

Correspondence: Karen Kelly, Email: karenkelly012{at}hotmail.com

Abstract

Insulin is important in the regulation of muscle metabolism. However, its role in the regulation of muscle long-chain fatty acid (LCFA) metabolism, independently of glucose, is not clear. To determine whether insulin regulates LCFA metabolism independently of glucose and if so, via which signaling pathway, L6 myotubes were incubated, in the presence or absence of insulin (100 nM), and with either an inhibitor of PI3K (Wortmannin,W; 50 nM), PKB/Akt (A, 10 µM), or aPKC- (mP, 100 µM). LCFA kinetic parameters were measured via incubation with [1-14C]palmitate. Basal LCFA uptake was found to increase linearly with time (1 to 60 min) and concentration (50-750 µM). LCFA uptake increased in the presence of insulin and was maximal at 10 nM (P<0.05). Wortmannin prevented the insulin-induced increase in LCFA uptake and decrease in LCFA oxidation. While mP abolished the insulin-induced increase in LCFA uptake, it did not prevent the insulin-induced decrease in LCFA oxidation. None of the variables were affected by Akt inhibition. These results suggest a direct effect of insulin on LCFA metabolism in muscle cells and suggest that downstream of PI3K, aPKC- but not PKB/Akt mediates the effects of insulin on LCFA uptake but not oxidation.