MYOFIBRILLAR PROTEIN-DEGRADATION AND MUSCLE PROTEINASES IN NORMAL AND DIABETIC RATS

In diabetic rats, the overall activities of alkaline proteinases and aminopeptidases in skeletal muscle are increased two- to three-fold. The elevation of proteolytic activities may be responsible for the massive breakdown of myofibrillar proteins indicated by a five-fold increase of 3-methylhistidine excretion into urine. Insulin treatment of the diabetic rats results in the normalization of both muscle proteolytic activities as well as the 3-methylhistidine excretion. Our data suggest that in diabetic rats the enhanced muscle protein catabolism is effected by the increased activities of alkaline proteinases and aminopeptidases and that insulin is a regulatory hormone of protein catabolism. © 1979.