Greater basal skeletal muscle AMPKα phosphorylation in men than in women: Associations with anaerobic performance

Objectives: This study was designed to investigate the association of gender, fibre type composition, and anaerobic performance with the basal skeletal muscle signalling cascades regulating muscle phenotype. Design: Muscle biopsies were obtained from 25 men and 10 women all young and healthy. Methods. Protein phosphorylation of Thr(172)AMPK alpha, Ser(221)ACC beta, Thr(286)CaMKII as well as total protein abundance of PGC-1 alpha, SIRT1, and CnA were measured by Western blot and anaerobic performance by the Wingate test. Results: Percent type I myosin heavy chain (MHC I) was lower in men (37.1 +/- 10.4 vs. 58.5 +/- 12.5, P<.01). Total, free testosterone and free androgen index were higher in men (11.5, 36.6 and 40.6 fold, respectively, P<.01). AMPK alpha phosphorylation was 2.2-fold higher in men compared to women (P<.01). Total Ser(221)ACC beta and Thr(286)CaMKII fractional phosphorylation tended to be higher in men (P=.1). PGC1-alpha and SIRT1 total protein expression was similar in men and women, whereas CnA tended to be higher in men (P=.1). Basal AMPK alpha phosphorylation was linearly related to the percentage of MHC I in men (r=0.56; P<.01), but not in women. No association was observed between anaerobic performance and basal phosphorylations in men and women, analysed separately. Conclusion: In summary, skeletal muscle basal AMPK alpha phosphorylation is higher in men compared to women, with no apparent effect on anaerobic performance.