Age related atrophy and muscle damage pose significant challenges to rehabilitation and quality of life in the elderly. These age-related changes involve oxidative damage to muscle proteins (e.g. carbonylation). It has been demonstrated that carbonyl levels increase in skeletal muscle with aging, but the exact distributions within the muscle, the differences between muscle types, or how different individuals accumulate carbonylated proteins are unknown. This thesis describes the development of technologies to investigate carbonylation levels at different morphological compartments of muscle tissue, different muscle types (i.e., slow- and fast-twitch), and different age groups.

Three technologies were developed and tested. Immunofluorescence imaging was used to localize and semi-quantitate carbonyls in various microsctructures of rat skeletal muscle. Capillary sieving electrophoresis with laser induced fluorescence detection (CSE-LIF) was used for detection and quantitation of carbonylated proteins. Quantitative proteomics following carbonylated protein enrichment was used for identification and quantitation of carbonylated proteins.

Fluorescence microscopy imaging, despite that this technique is only semi-quantitative, demonstrated that carbonylation exists cross the entire muscle tissue; and that, with aging, there appears to be more damage in the connective tissue than in other muscle regions. Slightly more carbonylation was observed in SSM than in IFM in both muscle types.

The CSE-LIF method, with a limit of detection of 0.15 fmol carbonyls, demonstrated that total protein carbonylation is higher in old than in young animals, for both muscle types. In addition, carbonylation is higher in fast- than in slow-twitch muscle for the two age groups considered in this study. Principal component analysis (PCA) classified the carbonyl profiles into four distinct sample groups of different age- and muscle-types. Additionally, PCA predicted that most age-related or muscle-type-related changes in the protein carbonylation occur at low molecular weight ranges.

The quantitative proteomic method revealed 78 and 38 carbonylated proteins in fast and slow-twitch muscles, respectively. Additionally, 16 mitochondrial proteins were identified with significant change in carbonylation status with age. Ingenuity pathway analysis was used to assign biological relevance to these proteins (e.g. carbonylation of proteins involved in fatty acid metabolism and citric acid cycle).