Levels of 3-Nitrotyrosine (3-NT), copper/zinc (SOD1), and manganese (SOD2) superoxide dismutase in muscle homogenates from aged and aged-trained mice. A, C and E) Representative immunoblots showing levels of 3-NT (A), SOD1 (C), and SOD2 (E) in hind limb muscle homogenates. B, D and F) Relative band densities of 3-NT (B), SOD1 (D), and SOD2 (F) normalized to GAPDH. Data are shown as mean ± SEM; n = number of mice; *p < 0.05 as evaluated by two-tailed unpaired Student’s t-test.