ABNORMALITIES OF MUSCLE PROTEIN METABOLISM IN MICE WITH MUSCULAR DYSTROPHY *

Abstract

The metabolism of myosin and water-extractable proteins was studied in normal mice and in mice with hereditary muscular dystrophy. In the former the constancy of the radioactivity of myosin favored a life span for the myofibrils of approximately 20 days. The radioactivity of the water-extractable proteins decreased exponentially, due to turnover of these proteins. The results agree with those obtained previously in rats. In dystrophic mice the radioactivity of myosin increased for the first 4 days, then decreased without a plateau. The turnover of the water-extractable muscle proteins was highly accelerated. The results indicate a shorter life span of the muscle cell, or of a part of it, or more likely an acceleration of the turnover of the muscle proteins.