title: Mitochondrial mass and activity as a function of body composition in individuals with spinal cord injury.
abstract: Spinal cord injury (SCI) is accompanied by deterioration in body composition and severe muscle atrophy. These changes put individuals at risk for insulin resistance, type II diabetes, and cardiovascular disease. To determine the relationships between skeletal muscle mitochondrial mass, activity, and body composition, 22 men with motor complete SCI were studied. Body composition assessment was performed using dual-energy X-ray absorptiometry and magnetic resonance imaging. Skeletal muscle biopsies were obtained from the vastus lateralis muscle to measure citrate synthase (CS) and complex III (CIII) activity. CS activity was inversely related to %body fat (r= -0.57,P= 0.013), %leg fat (r= -0.52,P= 0.027), %trunk fat (r= -0.54,P= 0.020), and %android fat (r= -0.54,P= 0.017). CIII activity was negatively related to %body fat (r= -0.58,P= 0.022) and %leg fat (r= -0.54,P= 0.037). Increased visceral adipose tissue was associated with decreased CS and CIII activity (r= -0.66,P= 0.004;r= -0.60,P= 0.022). Thigh intramuscular fat was also inversely related to both CS and CIII activity (r= -0.56,P= 0.026;r= -0.60,P= 0.024). Conversely, lean mass (r= 0.75,P= 0.0003;r= 0.65,P= 0.008) and thigh muscle cross-sectional area (CSA;r= 0.82,P= 0.0001;r= 0.84;P= 0.0001) were positively related to mitochondrial parameters. When normalized to thigh muscle CSA, many body composition measurements remained related to CS and CIII activity, suggesting that %fat and lean mass may predict mitochondrial mass and activity independent of muscle size. Finally, individuals with SCI over age 40 had decreased CS and CIII activity (P= 0.009;P= 0.004), suggesting a decrease in mitochondrial health with advanced age. Collectively, these findings suggest that an increase in adipose tissue and decrease in lean mass results in decreased skeletal muscle mitochondrial activity in individuals with chronic SCI.
authors.affiliation: Spinal Cord Injury and Disorders, Hunter Holmes McGuire VA Medical Center, Richmond, Virginia.|Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia.
authors.forename: Laura C
authors.initials: LC
authors.lastname: O'Brien
authors.affiliation: Spinal Cord Injury and Disorders, Hunter Holmes McGuire VA Medical Center, Richmond, Virginia.
authors.forename: Rodney C
authors.initials: RC
authors.lastname: Wade
authors.affiliation: Spinal Cord Injury and Disorders, Hunter Holmes McGuire VA Medical Center, Richmond, Virginia.
authors.forename: Liron
authors.initials: L
authors.lastname: Segal
authors.affiliation: Department of Medicine, Division of Cardiology, Pauley Heart Center Virginia Commonwealth University, Richmond, Virginia.
authors.forename: Qun
authors.initials: Q
authors.lastname: Chen
authors.affiliation: Department of Surgery, Hunter Holmes McGuire VA Medical Center, Richmond, Virginia.|Department of Surgery, Virginia Commonwealth University, Richmond, Virginia.
authors.forename: Jeannie
authors.initials: J
authors.lastname: Savas
authors.affiliation: Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia.|Department of Medicine, Division of Cardiology, Pauley Heart Center Virginia Commonwealth University, Richmond, Virginia.|Medical Service, Hunter Holmes McGuire VA Medical Center, Richmond, Virginia.|Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Lesnefsky
authors.affiliation: Spinal Cord Injury and Disorders, Hunter Holmes McGuire VA Medical Center, Richmond, Virginia ashraf.gorgey@va.gov.|Physical Medicine and Rehabilitation, Virginia Commonwealth University, Richmond, Virginia.
authors.forename: Ashraf S
authors.initials: AS
authors.lastname: Gorgey
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000201:enzymology; D000293:Adolescent; D000328:Adult; D001823:Body Composition; D002950:Citrate (si)-Synthase / Q000378:metabolism; D014450:Electron Transport Complex III / Q000378:metabolism; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000201:enzymology; D013119:Spinal Cord Injuries / Q000000981:diagnostic imaging / Q000378:metabolism*; D055815:Young Adult
chemical_list: D002950:Citrate (si)-Synthase; D014450:Electron Transport Complex III
keywords: Body composition; Mitochondria; metabolism; skeletal muscle; spinal cord injuries