A defect of purine nucleotide cycle in the skeletal muscle of hereditary dystrophic mice

The purine nucleotide cycle in the hind leg skeletal muscle of hereditary dystrophic mice ($\text{C57BL}\text{6J}\text{-}\text{dy}\text{dy}$) was investigated. The amount of adenine nucleotide produced from adenylosuccinate by the muscle extract in the dystrophic group was less than 3 % of that in the control group, while adenine nucleotide plus adenylosuccinate converted from IMP in the dystrophic group was about 70 % of that of the control group. Moreover, the activity of AMP deaminase of the dystrophic group was about 50 % of that of the control group. These results indicate that the purine nucleotide cycle is defective in the dystrophic muscle. This abnormality was suggested to be caused by the considerably low activity of adenylosuccinase.