Sarcolemmal ATPase Activities in Normal and BIO 14.6 Dystrophic Hamster Skeletal Muscle

Abstract

Increased Na+–K+-ATPase activities are observed in skeletal muscle sarcolemmal fractions of genetically dystrophic hamsters in advanced disease stages. A decline with age is seen in Na+–K+-ATPase activities in normal hamsters, which is not paralleled by the Na+–K+-ATPase activities in dystrophic animals. In young animals the sarcolemmal ATPase activities of normal and dystrophic muscle are indistinguishable. The data therefore do not support the membrane hypothesis of muscular dystrophy. Freezing decreases Mg2+-ATPase and increases Na+–K+-ATPase activities. Heparin has no effect on freshly isolated sarcolemmal ATPases, but partially prevents the freezing effect. The response to freezing and/or to heparin is indistinguishable between preparations from normal and dystrophic muscle.