Research Paper Volume 1, Issue 6 pp 557—572

Figure 2. Muscle creatine kinase (CKm) is differentially 3-nitrotyrosine modified during aging. Quadriceps muscle extracts (30 ?g) from six young (3-6 months), six middle-aged (12-14 months) and five aged (20-24 months) old mice were resolved by SDS PAGE and transferred to a PVDF membrane. (A) Immunoblots probed with a monoclonal anti-3-nitrotyrosine antibody reveal a nitrated 45 kDa protein in middle aged and aged samples. (B) The immunoblots in (A) were reprobed with an anti-creatine kinase type M antibody which identifies the levels of CKm in the samples applied to the gels in (A). (C) Densitometric analysis demonstrates the progressive increase in nitration in the aging muscle samples. The highest level of nitration is seen in the aged muscle samples relative to the young samples. Error bars depicted on the figure represent calculated standard errors of mean. p < 0.05 in both cases.