title: Relationships between mitochondrial content and bioenergetics with obesity, body composition and fat distribution in healthy older adults.
abstract: BACKGROUND
  Mitochondrial function declines with age; however, the relationship between adiposity and mitochondrial function among older adults is unclear. This study examined relationships between skeletal muscle mitochondrial content and electron transport chain complex 2 driven respiration with whole body and thigh composition, body fat distribution, and insulin sensitivity in older adults.
  
  
  METHODS
  25 healthy, sedentary, weight-stable men (N = 13) and women (N = 12) >65 years of age, with a BMI range of 18-35 kg/m(2), participated in this study. Vastus lateralis biopsies were analyzed for citrate synthase (CS) activity and succinate mediated respiration of isolated mitochondria. Whole body and thigh composition were measured by DXA and CT. HOMA-IR was calculated using fasting glucose and insulin as an estimate of insulin sensitivity.
  
  
  RESULTS
  Similar to reports in middle-aged adults, skeletal muscle CS activity was negatively correlated with BMI (R = -0.43) in our cohort of older adults. Higher total and thigh adiposity were correlated with lower CS activity independent of BMI (R = -0.50 and -0.71 respectively). Maximal complex 2 driven mitochondrial respiration was negatively correlated with lower body adiposity in males (R = -0.66). In this cohort of non-diabetic older adults, both HOMA-IR and insulin were positively correlated with CS activity when controlling for BMI (R = 0.57 and 0.66 respectively).
  
  
  CONCLUSIONS
  Adiposity and body composition are correlated with skeletal muscle mitochondrial content and electron transport chain function in healthy, sedentary, community dwelling, older adults. Specific relationships of mitochondrial bioenergetics with gender and insulin sensitivity are also apparent.
  
  
  BACKGROUND
  ClinicalTrials.gov identifier NCT01049698.
authors.affiliation: Sticht Center on Aging & Department of Internal Medicine, Section on Gerontology and Geriatrics, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA.
authors.forename: Manish S
authors.initials: MS
authors.lastname: Bharadwaj
authors.affiliation: Sticht Center on Aging & Department of Internal Medicine, Section on Gerontology and Geriatrics, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Tyrrell
authors.affiliation: Department of Biostatistical Sciences, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA.
authors.forename: Iris
authors.initials: I
authors.lastname: Leng
authors.affiliation: Sticht Center on Aging & Department of Internal Medicine, Section on Gerontology and Geriatrics, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA.
authors.forename: Jamehl L
authors.initials: JL
authors.lastname: Demons
authors.affiliation: Sticht Center on Aging & Department of Internal Medicine, Section on Gerontology and Geriatrics, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA.
authors.forename: Mary F
authors.initials: MF
authors.lastname: Lyles
authors.affiliation: Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37203 USA.
authors.forename: J Jeffrey
authors.initials: JJ
authors.lastname: Carr
authors.affiliation: Sticht Center on Aging & Department of Internal Medicine, Section on Gerontology and Geriatrics, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA.
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Nicklas
authors.affiliation: Sticht Center on Aging & Department of Internal Medicine, Section on Gerontology and Geriatrics, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA.
authors.forename: Anthony J A
authors.initials: AJ
authors.lastname: Molina
keywords: Adiposity; Aging; Mitochondria; Muscle; Obesity