title: Muscle mitochondrial oxidative phosphorylation activity, but not content, is altered with abdominal obesity in sedentary men: synergism with changes in insulin sensitivity.
abstract: BACKGROUND
  Abdominal obesity is a major risk factor for muscle insulin resistance. Mitochondria may play a key role in this etiology.
  
  
  OBJECTIVE
  Changes in muscle mitochondrial content and function were examined according to abdominal obesity and insulin sensitivity in men.
  
  
  METHODS
  The descriptive MitHyCal study was conducted on the general population of Clermont-Ferrand, France.
  
  
  METHODS
  Forty-two healthy sedentary men (41.7 +/- 4.3 yr) were divided into four groups according to waist circumference: 87 cm or less (group 1, n = 10); 88-93 cm (group 2, n = 12); 94-101 cm (group 3, n = 10); and 102 cm or greater (group 4, n = 10).
  
  
  METHODS
  Plasma metabolic check-up was performed, and insulin sensitivity index was calculated from glucose and insulin responses to a 3-h oral glucose tolerance test. Muscle biopsies were obtained to assess mitochondrial content, oxidative phosphorylation activity, and superoxide anion (reactive oxygen species) production.
  
  
  METHODS
  Assessment of muscle mitochondrial content and function was planned before data collection began.
  
  
  RESULTS
  Abdominal obesity was negatively correlated to insulin sensitivity index (r = -0.39; P < 0.01), and only group 4 was insulin-resistant (P < 0.05). There were no between-group differences in muscle mitochondrial content and maximal activity of key oxidative enzymes. In contrast, muscle mitochondrial ADP-stimulated respiration rate was 24% higher in groups 2 and 3 compared to groups 1 and 4 (P < 0.05). Mitochondrial ATP and reactive oxygen species production rates were 27 and 48% lower in group 4 than in group 1 (P < 0.05).
  
  
  CONCLUSIONS
  Abdominal obesity is associated with alterations in intrinsic muscle mitochondrial function but not content. These adaptations mainly result in reduced mitochondrial ATP production rate in response to insulin resistance.
authors.affiliation: Institut National de la Recherche Agronomique, Unité Mixte de Recherche 1019, Centre de Recherche en Nutrition Humaine Auvergne, F-63000 Clermont-Ferrand, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Chanseaume
authors.forename: Valentin
authors.initials: V
authors.lastname: Barquissau
authors.forename: Jérôme
authors.initials: J
authors.lastname: Salles
authors.forename: Julien
authors.initials: J
authors.lastname: Aucouturier
authors.forename: Véronique
authors.initials: V
authors.lastname: Patrac
authors.forename: Christophe
authors.initials: C
authors.lastname: Giraudet
authors.forename: Céline
authors.initials: C
authors.lastname: Gryson
authors.forename: Pascale
authors.initials: P
authors.lastname: Duché
authors.forename: Yves
authors.initials: Y
authors.lastname: Boirie
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Chardigny
authors.forename: Béatrice
authors.initials: B
authors.lastname: Morio
mesh_terms: D050153:Abdominal Fat / Q000502:physiology*; D015502:Absorptiometry, Photon; D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D001706:Biopsy; D001823:Body Composition / Q000502:physiology; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D017931:DNA Primers / Q000235:genetics; D004032:Diet; D005951:Glucose Tolerance Test; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism*; D009043:Motor Activity / Q000502:physiology*; D009765:Obesity / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption / Q000502:physiology; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055105:Waist Circumference
chemical_list: D017931:DNA Primers; D012313:RNA; D004247:DNA