title: Effects of exercise on mitochondrial content and function in aging human skeletal muscle.
abstract: Skeletal muscle mitochondria are implicated with age-related loss of function and insulin resistance. We examined the effects of exercise on skeletal muscle mitochondria in older (age = 67.3 +/- 0.6 years) men (n = 5) and women (n = 3). Similar increases in (p <.01) cardiolipin (88.2 +/- 9.0 to 130.6 +/- 7.5 microg/mU creatine kinase activity [CK]) and the total mitochondrial DNA (1264 +/- 170 to 1895 +/- 273 copies per diploid of nuclear genome) reflected increased mitochondria content. Succinate oxidase activity, complexes 2-4 of the electron transport chain (ETC), increased from 0.13 +/- 0.02 to 0.20 +/- 0.02 U/mU CK (p <.01). This improvement was more pronounced (p <.05) in subsarcolemmal (127 +/- 48%) compared to intermyofibrillar (56 +/- 12%) mitochondria. NADH oxidase activity, representing total ETC activity, increased from 0.51 +/- 0.09 to 1.00 +/- 0.09 U/mU CK (p <.01). In conclusion, exercise enhances mitochondria ETC activity in older human skeletal muscle, particularly in subsarcolemmal mitochondria, which is likely related to the concomitant increases in mitochondrial biogenesis.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.
authors.forename: Elizabeth V
authors.initials: EV
authors.lastname: Menshikova
authors.forename: Vladimir B
authors.initials: VB
authors.lastname: Ritov
authors.forename: Liane
authors.initials: L
authors.lastname: Fairfull
authors.forename: Robert E
authors.initials: RE
authors.lastname: Ferrell
authors.forename: David E
authors.initials: DE
authors.lastname: Kelley
authors.forename: Bret H
authors.initials: BH
authors.lastname: Goodpaster
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D001706:Biopsy; D002308:Cardiolipins / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003402:Creatine Kinase / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism*; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000502:physiology*; D010088:Oxidoreductases / Q000378:metabolism; D013053:Spectrophotometry
chemical_list: D002308:Cardiolipins; D004272:DNA, Mitochondrial; D010088:Oxidoreductases; C022691:succinate oxidase; D003402:Creatine Kinase