Phosphodiesters in muscular dystrophies.

Phosphorus nuclear magnetic resonance studies of various normal and dystrophic muscles have demonstrated differences in phosphodiester contents. Dystrophic chicken pectoralis muscle contains elevated levels of the diester SEP, and Duchenne dystrophic human leg muscle lacks the diester GPC. It is shown that SEP may be characteristic of slow fiber types, indicating imcomplete maturation of the dystrophic pectoralis muscle. The activities of SEP-metabolizing enzymes have been determined in microsomes of pectoralis muscle, kidney, and intestinal mucosa of normal and dystrophic chickens. There was little difference between normal and dystrophic values of SEP phosphodiesterase and SEP synthase in kidney and mucosa. Dystrophic pectoralis muscle microsomes possessed significantly elevated levels of both enzymes. The increase in SEP synthase activity of dystrophic muscle may explain the increase in the SEP level if the phosphodiesterase is regulated in vivo. It is shown that human muscle disease processes may raise, leave unchanged, or lower GPC levels. In certain diseases when GPC is markedly elevated, such as Werdnig-Hoffmann, or depressed, such as Duchenne muscular dystrophy, it may serve as a marker.