Changes in the rat skeletal muscle proteome induced by moderate-intensity endurance exercise

The adaptation of skeletal muscle to endurance exercise has not previously been investigated using proteomic techniques. Such work could improve our understanding and generate novel information regarding the effects of exercise. Plantaris muscles were investigated from rats exercised on treadmills at 70-75% peak oxygen uptake (V O(2)peak) for 30 min, 4 days per week for 5 weeks or sedentary controls. Analysis of 2-D gels matched 187 spots across control and exercised muscles and 80 proteins corresponding to 40 gene products were identified by MALDI-ToF MS. Exercise increased the animals' V O(2)peak by 14% and altered the expression of 15 spots consistent with a shift from glycolysis toward greater fatty-acid oxidation. The majority of differentially expressed gene products were present as multi-spot series of similar M(r) but different pI. Mitochondrial aconitase focused to 5 spots, 2 spots (pI 7.6 and 7.7) decreased (57%) whereas the pI 8.0 spot increased (51%) and was found to contain protein carbonyls. This adaptation may be related to exercise-induced oxidative stress and translocation of aconitase to mitochondrial DNA. In conclusion, proteomic techniques simultaneously demonstrated well-established effects, and identified novel changes not previously associated with the adaptation of muscle to exercise.