Glutathione peroxidase activity and glutathione concentration in genetically dystrophic mice

The present studies were conducted to determine whether inherited muscular dystrophy in the 129/ReJ-dy mouse was associated with differences in specific activity, substrate availability, or apparent Km of glutathione peroxidase. The results indicate that glutathione peroxidase is elevated in skeletal muscle of mice with genetic muscular dystrophy when the activity is expressed on a protein basis. This elevation precedes the development of severe paralysis since muscles from the fore legs showed increased enzyme activity as early as the more severely affected hind legs. There was no difference in glutathione peroxidase activity in tissues other than skeletal muscle. GSH concentration was elevated in muscle and normal in other tissues of dystrophic mice, showing that adequate substrate was available to the enzyme. The apparent Km for cumene hydroperoxide was also similar for muscle of normal and dystrophic mice. This report provides further evidence that mice with dystrophia muscularis have a functional glutathione peroxidase system in all tissues including skeletal muscle, and that a defect in this in vivo protective system is apparently not a contributing factor in the pathology of the disease.