Fig. 4

MtDNA copy number measured by real-time PCR in vastus lateralis muscle of control and COPD subjects. a Lower mtDNA copy number in homogenate muscle samples of COPD (1.9 ± 0.45, n = 15) compared to controls (5.1 ± 1.1, n = 13; *P < 0.05). b MtDNA copy number in single COX-normal (COX⁺/SDH⁺; n = 12 fibers per group) and COX-deficient (COX⁻/SDH⁺; n = 13 fibers per group) muscle fibers, demonstrating an upregulation of mtDNA copy number in COX-deficient fibers of controls (5.3 ± 0.89 compared to 2.4 ± 0.42 in COX-normal) but not in COPD muscle (1.1 ± 0.23 in COX-deficient fibers compared to 0.78 ± 0.14 in COX-normal). Graphs show mean ± SEM (*P < 0.05)