Greater Basal Skeletal Muscle AMPKα Phosphorylation in Men Than in Women: Associations with Anaerobic Performance.

Abstract 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 Thr172AMPKα, Ser221ACCβ, Thr286CaMKII as well as total protein abundance of PGC-1α, 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). AMPKα phosphorylation was 2.2-fold higher in men compared to women (P < .01). Total Ser221ACCβ and Thr286CaMKII fractional phosphorylation tended to be higher in men (P = .1). PGC1-α and SIRT1 total protein expression was similar in men and women, whereas CnA tended to be higher in men (P = .1). Basal AMPKα 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 AMPKα phosphorylation is higher in men compared to women, with no apparent effect on anaerobic performance.