Author:

Keywords:

Adaptor Proteins, Signal Transducing, Adult, Animals, Cell Line, Exercise, Fasting, Humans, Male, Mice, Mitogen-Activated Protein Kinase 1, Mitogen-Activated Protein Kinase 3, Muscle Contraction, Myoblasts, Skeletal, Phosphoproteins, Phosphorylation, Protein Kinase Inhibitors, Proto-Oncogene Proteins c-akt, Quadriceps Muscle, Ribosomal Protein S6 Kinases, 70-kDa, Signal Transduction, p38 Mitogen-Activated Protein Kinases, Science & Technology, Life Sciences & Biomedicine, Physiology, Sport Sciences, cell signaling, protein synthesis, resistance exercise, MAPK, p70s6k, P70 S6 KINASE, P38 MAP KINASE, PROTEIN-SYNTHESIS, AMINO-ACIDS, CREATINE SUPPLEMENTATION, 4E-BP1 PHOSPHORYLATION, ACTIVATION, INCREASE, CONTRACTION, PATHWAYS, Cell Cycle Proteins, 1106 Human Movement and Sports Sciences, 3202 Clinical sciences, 3208 Medical physiology, 4207 Sports science and exercise

Abstract:

We analysed the effects of resistance exercise upon the phosphorylation state of proteins associated with adaptive processes from the Akt/PKB (protein kinase B) and the mitogen-activated protein kinase (MAPK) pathways. Nine healthy young men (21.7 +/- 0.55 year) performed 10 sets of 10 leg extensions at 80% of their 1-RM (repetition maximum). Muscle biopsies were taken from the vastus lateralis at rest, within the first 30 s after exercise and at 24 h post-exercise. Immediately post exercise, the phosphorylation states of Akt/PKB on Thr308 and Ser473 and 4E-BP1 on Thr37/46 (eukaryotic initiation factor 4E-binding protein 1) were decreased (-60 to -90%, P < 0.05). Conversely, the phosphorylation of p70(s6k) (p70 ribosomal S6 kinase) on Thr421/Ser424 was increased more than 20-fold (P < 0.05), and this was associated with a 10- to 50-fold increase in the phosphorylation of p38 and ERK1/2 (extracellular signal-regulated kinase) (P < 0.05). Twenty-four hours post-exercise the phosphorylation state of Akt/PKB on Thr308 was depressed, whereas the phosphorylation of p70(s6k) on Thr421/Ser424 and sarcoplasmic ERK1/2 were elevated. The present results indicate that high-intensity resistance exercise in the fasted state inhibits Akt/PKB and 4E-BP1 whilst concomitantly augmenting MAPK signalling and p70(s6k) on Thr421/Ser424.