Phosphorylase in Skeletal Muscle of Normal and Selected Lines of Dystrophic Chickens

Phosphorylase activity was assayed in pectoralis (white) and adductor (red) muscles of normal chicks and three selected lines of chicks with hereditary muscular dystrophy. Activity is higher than normal in the adductor of all lines of dystrophic chicks. The adductor is relatively spared by the dystrophic process. In the pectoralis muscle activity is also higher than in normal muscle prior to the onset of degenerative changes, but falls with progression of the myopathy. It is suggested that quantitatively higher levels of energy-producing enzymes in dystrophic muscle may promote fiber hypertrophy and ultimately initiate fiber degeneration.