title: Evidence against a sexual dimorphism in glucose and fatty acid metabolism in skeletal muscle cultures from age-matched men and post-menopausal women.
abstract: OBJECTIVE
  In vivo whole body differences in glucose/lipid metabolism exist between men and women. Thus, we tested the hypothesis that intrinsic sex differences exist in skeletal muscle gene expression and glucose/lipid metabolism using cultured myotubes.
  
  
  METHODS
  Myotube cultures were prepared for gene expression and metabolic studies from vastus lateralis skeletal muscle biopsies obtained from age-matched men (n = 11; 59 +/- 2 years) and post-menopausal women (n = 10; 60 +/- 1 years).
  
  
  RESULTS
  mRNA expression of several genes involved in glucose and lipid metabolism was higher in skeletal muscle biopsies from female vs. male donors, but unaltered between the sexes in cultured myotubes. Basal and insulin-stimulated glucose uptake, as well as glucose incorporation into glycogen, was similar in myotube cultures derived from male vs. female donors. In males vs. females, insulin increased glucose uptake (1.3 +/- 0.1 vs. 1.5 +/- 0.1-fold respectively) and incorporation into glycogen (2.3 +/- 0.3 vs. 2.0 +/- 0.3-fold respectively) to the same extent. Basal fatty acid oxidation and rate of uptake/accumulation was similar between sexes. In response to the 5'AMP-activated protein kinase activator AICAR, lipid oxidation was increased to the same extent in myotubes established from male vs. female donors (1.6 +/- 0.6 vs. 2.0 +/- 0.3-fold respectively). Moreover, the AICAR-induced rate of uptake/accumulation was similar between sexes.
  
  
  CONCLUSIONS
  Differences in metabolic parameters and gene expression profiles between age-matched men and post-menopausal women noted in vivo are not observed in cultured human skeletal muscle cells. Thus, the sexual dimorphism in glucose and lipid metabolism is likely a consequence of systemic whole body factors, rather than intrinsic differences in the skeletal muscle proper.
authors.affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Rune
authors.forename: F
authors.initials: F
authors.lastname: Salehzadeh
authors.forename: F
authors.initials: F
authors.lastname: Szekeres
authors.forename: I
authors.initials: I
authors.lastname: Kühn
authors.forename: M E
authors.initials: ME
authors.lastname: Osler
authors.forename: L
authors.initials: L
authors.lastname: Al-Khalili
mesh_terms: D018929:Cell Culture Techniques; D005227:Fatty Acids / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D020869:Gene Expression Profiling; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D017698:Postmenopause; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012727:Sex Characteristics
chemical_list: D005227:Fatty Acids; D012333:RNA, Messenger; D005947:Glucose