title: Skeletal muscle mitochondrial DNA content in exercising humans.
abstract: Several weeks of intense endurance training enhances mitochondrial biogenesis in humans. Whether a single bout of exercise alters skeletal muscle mitochondrial DNA (mtDNA) content remains unexplored. Double-stranded mtDNA, estimated by slot-blot hybridization and real time PCR and expressed as mtDNA-to-nuclear DNA ratio (mtDNA/nDNA) was obtained from the vastus lateralis muscle of healthy human subjects to investigate whether skeletal muscle mtDNA changes during fatiguing and nonfatiguing prolonged moderate intensity [2.0-2.5 h; approximately 60% maximal oxygen consumption (Vo(2 max))] and short repeated high-intensity exercise (5-8 min; approximately 110% Vo(2 max)). In control resting and light exercise (2 h; approximately 25% Vo(2 max)) studies, mtDNA/nDNA did not change. Conversely, mtDNA/nDNA declined after prolonged fatiguing exercise (0.863 +/- 0.061 vs. 1.101 +/- 0.067 at baseline; n = 14; P = 0.005), remained lower after 24 h of recovery, and was restored after 1 wk. After nonfatiguing prolonged exercise, mtDNA/nDNA tended to decline (n = 10; P = 0.083) but was reduced after three repeated high-intensity exercise bouts (0.900 +/- 0.049 vs. 1.067 +/- 0.071 at baseline; n = 7; P = 0.013). Our findings indicate that prolonged and short repeated intense exercise can lead to significant reductions in human skeletal muscle mtDNA content, which might function as a signal stimulating mitochondrial biogenesis with exercise training.
authors.affiliation: Department of Biochemistry, Molecular and Cell Biology, University of Zaragoza, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Marcuello
authors.forename: J
authors.initials: J
authors.lastname: González-Alonso
authors.forename: J A L
authors.initials: JA
authors.lastname: Calbet
authors.forename: R
authors.initials: R
authors.lastname: Damsgaard
authors.forename: M J
authors.initials: MJ
authors.lastname: López-Pérez
authors.forename: C
authors.initials: C
authors.lastname: Díez-Sánchez
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism; D004247:DNA / Q000037:antagonists & inhibitors / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D052097:Quadriceps Muscle / Q000378:metabolism*; D013997:Time Factors
chemical_list: D004272:DNA, Mitochondrial; D004247:DNA