Changes in the Synthesis of Total Proteins Induced by Chronic Electrical Stimulation of Skeletal Muscle

Rates of protein synthesis were measured by constant infusion of H-tyrosine in control fast and slow muscles of the rabbit hind limb and in fast muscles subjected to chronic electrical stimulation. Slow muscle had synthesis rates more than twice those of fast muscle, and its RNA content was 20% higher. Stimulation of fast muscle brought about a striking phasic increase, lasting several weeks, in protein synthetic rates, RNA content and RNA activity. There was indirect evidence for an accompanying increase in the rate of protein degradation. In the long term, synthesis rates stabilized at levels similar to those found in slow muscle. These results provide evidence of an overall increase in protein turnover that is significant in relation to both experimental and therapeutic applications of chronic electrical stimulation.