Skeletal muscle mitochondrial DNA content in exercising humans.
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.
Marcuello
A
A
Department of Biochemistry, Molecular and Cell Biology, University of Zaragoza, Spain.
González-Alonso
J
J
Calbet
J A L
JA
Damsgaard
R
R
López-Pérez
M J
MJ
Díez-Sánchez
C
C
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
D004272:DNA, Mitochondrial; D004247:DNA