AJP - Endocrinology and Metabolism, Vol 239, Issue 6 401-E406, Copyright © 1980 by American Physiological Society
Protein synthesis and degradation in skeletal muscle of normal and dystrophic hamsters
J. B. Li
Dystrophic hamsters (BIO 53.58) had lower body weights and gastrocnemius
muscle weights than normal hamsters (BIO RB). Dystrophic muscle contained
less protein than normal muscle. The proportion of collagenous to
noncollagenous protein remained unchanged. Loss of protein in the
dystrophic muscle was the result of an increase in the rate of protein
degradation. This was accompanied by higher activities of two lysosomal
proteases, cathepsins B and D. The net effect of the increase in protein
degradation was blunted by an increase in the rate of synthesis of total
protein and myosin. The faster rate of synthesis in dystrophic muscle was
partially due to an increase in the concentration of cellular RNA. Rates of
peptide-chain initiation and protein synthesis decreased in muscles of
normal hamsters perfused in the absence of insulin. In the presence of
insulin, these processes were maintained at higher rates. However, the rate
of protein synthesis in dystrophic muscle appeared less insulin-dependent
than normal muscle. Protein degradation was inhibited by insulin in both
types of muscle.
