Protein Turnover of Rat Skeletal Muscle After Denervation

Summary

Protein synthesis and protein breakdown of the soleus and extensor digitorum longus muscles were studied in vitro during the early stages of denervation atrophy. 24 hr after nerve section significant increases in rates of protein breakdown were found in both types of muscle. These changes in degradative rates were maintained throughout the 10 days of denervation studied and correlated with the net loss of protein from the atrophying muscle During the first 2 days of denervation significant decreases in rates of protein synthesis also correlated with the muscle wasting. However, these early effects of denervation upon rates of protein synthesis were not maintained at later time points, and were in fact reversed i.e. increased at 7 to 10 days. Both muscles responded in a parallel fashion, although the onset of atrophy occurred more rapidly and to a greater extent in the soleus. Myofibrillar and soluble proteins prepared from normal and denervated muscles were equally susceptible to in vitro degradation by pronase.