Biochemical changes in progressive muscular dystrophy. XV. Distribution of radioactive glutamate and proximate composition of various components of skeletal muscle and liver in vitamin E-deficient dystrophic rabbits and 129/ReJ (dy/dy) mice.

The proximate composition of skeletal muscle and liver and the incorporation of radioactive glutamate into their various components were investigated in vitamin E-deficient rabbits and genetically dystrophic (dy/dy) mice during various stages of the disease. Total fat content in skeletal muscle was decreased in the early phase and increased in the terminal stage of both types of dystrophy. This component altered only in the liver of dystrophic mice, showing a reduction in the mild stage but returning later to normal values. Carbohydrate content was diminished in the skeletal muscle of both species at each stage of the disease. In the liver, however, it was elevated considerably in vitamin E-deficient rabbits, but was depressed in dystrophic mice. Protein content was decreased in the skeletal muscle of both dystrophic models. Similar results were obtained for amino acids, except that they were increased in the terminal stages of nutritional dystrophy. Analogous values were recorded for hepatic amino acids in nutritionally-induced and hereditary dystrophy (in rabbits and mice respectively). Incorporation of C14-glutamate into various components of skeletal muscle and liver in both models revealed divergent responses, depending upon the nature of the dystrophy, and the component in which incorporation was measured. These data indicate a rapid turnover of C14-glutamate in the skeletal muscle and liver of vitamin E-deficient and genetically dystrophic animals. Also, it is clear that the changes in the various components of skeletal muscle and liver, as well as the pattern of C14-glutamate incorporation, are different in the two types of dystrophy.