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This Article Full Text Full Text (PDF) All Versions of this Article: 582/3/1289    most recent jphysiol.2007.136614v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Frøsig, C. Articles by Richter, E. A. Search for Related Content PubMed PubMed Citation Articles by Frøsig, C. Articles by Richter, E. A. Related Collections Skeletal Muscle and Exercise

¹ Copenhagen Muscle Research Centre, Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
² James A. Haley Veterans Administration Hospital Research Service and Department of Internal Medicine, University of South Florida College of Medicine, Tampa Bay, FL, USA

We investigated if acute endurance-type exercise interacts with insulin-stimulated activation of atypical protein kinase C (aPKC) and insulin signalling to peptide chain elongation in human skeletal muscle. Four hours after acute one-legged exercise, insulin-induced glucose uptake was 80% higher (N = 12, P < 0.05) in previously exercised muscle, measured during a euglycaemic–hyperinsulinaemic clamp (100 µU ml^–1). Insulin increased (P < 0.05) both insulin receptor substrate (IRS)-1 and IRS-2 associated phosphatidylinositol (PI)-3 kinase activity and led to increased (P < 0.001) phosphorylation of Akt on Ser⁴⁷³ and Thr³⁰⁸ in skeletal muscle. Interestingly, in response to prior exercise IRS-2-associated PI-3 kinase activity was higher (P < 0.05) both at basal and during insulin stimulation. This coincided with correspondingly altered phosphorylation of the extracellular-regulated protein kinase 1/2 (ERK 1/2), p70S6 kinase (P70S6K), eukaryotic elongation factor 2 (eEF2) kinase and eEF2. aPKC was similarly activated by insulin in rested and exercised muscle, without detectable changes in aPKC Thr⁴¹⁰ phosphorylation. However, when adding phosphatidylinositol-3,4,5-triphosphate (PIP3), the signalling product of PI-3 kinase, to basal muscle homogenates, aPKC was more potently activated (P = 0.01) in previously exercised muscle. Collectively, this study shows that endurance-type exercise interacts with insulin signalling to peptide chain elongation. Although protein turnover was not evaluated, this suggests that capacity for protein synthesis after acute endurance-type exercise may be improved. Furthermore, endurance exercise increased the responsiveness of aPKC to PIP3 providing a possible link to improved insulin-stimulated glucose uptake after exercise.

(Received 21 May 2007; accepted after revision 24 May 2007; first published online 31 May 2007)
Corresponding author E. A. Richter: Copenhagen Muscle Research Centre, Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, 13, Universitetsparken, DK-2100, Copenhagen, Denmark. Email: erichter{at}ifi.ku.dk