Changes in nuclear protein composition in response to chronic electrical stimulation of skeletal muscle

The adaptive response of skeletal muscle to increased functional demand involves phenotypic changes that affect contractile properties, energy metabolism and calcium kinetics. Some of these changes are known to be initiated at a pre-translational level, but the underlying regulatory mechanisms have not yet been identified. In this study we used chronic electrical stimulation (10 Hz, continuous) to initiate fast-to-slow muscle fibre-type transformation, and two-dimensional electrophoresis (2-DE) to assess changes in nuclear protein composition after 24 and 72 h. We report an early and sustained increase in the level of a 3 kDa protein in stimulated fast muscle (n = 6). The presence of the same protein in control slow muscle is consistent with a possible functional role in the determination of the slow phenotype.