Aminotransferase Activity in Denervation Atrophy of the Amphibian Skeletal Muscle

Abstract

The activity levels and some properties of aspartate aminotransferase and alanine aminotransferase of normal and denervated frog skeletal muscle were investigated. In general, the denervated muscle showed significant decrement in the activities of the two aminotransferases. But the peripheral nerve section did not induce any change in the aminotransferase levels of fiver, kidney, heart and serum of frog. In the skeletal muscle, the two aminotransferases were found to exist in two different isozymes, one being associated with the mitochondria and the other with the soluble fraction. The mitochondrial component of both the enzymes was relatively cationic in nature when compared to the soluble fraction. The denervated muscle showed a considerable decrease in both the isozymes of the two aminotransferases. The thermostability of both the enzymes was considerably lowered in the denervated muscle. No elevation of either aminotransferase activity was observed in the denervated skeletal muscle following addition of a heat-denatured serum, while a marked elevation was observed in the normal muscle. The enzymes of denervated muscle showed altered sensitivities towards their inhibitors. The results of the present study suggest that denervation induces quantitative as well as qualitative changes in the aminotransferases of frog skeletal muscle.