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[RC] Mitochondria - Ridecamp Guest

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Authors A Marcuello, J GonzalezAlonso, JAL Calbet, R Damsgaard, MJ LopezPerez, 
C DiezSanchez
Title   Skeletal muscle mitochondrial DNA content in exercising humans
Full source     Journal of Applied Physiology, 2005, Vol 99, Iss 4, pp 1372-1377

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; similar to 60% maximal oxygen consumption ((V) over dot o(2max))] and short 
repeated high-intensity exercise (5-8 min; similar to 110% (V) over dot 
o(2max)). In control resting and light exercise (2 h; similar to 25% (V) over 
dot o(2max)) 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 It 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.


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