Glycogen Content and Activities of Key Glycolytic Enzymes in Muscle Biopsies from Control Subjects and Patients with Chronic Alcoholic Skeletal Myopathy

Abstract

The capacity for glycolysis in muscle biopsies obtained from long-term heavy alcohol drinking patients was compared with tissue from control subjects by assay in vitro of the total activities of glycogen phosphorylase, phosphofructokinase and fructose 1,6-bisphosphatase, key regulatory enzymes in the anaerobic glycolytic pathway. Biopsies from 13 of 22 patients had type II fiber atrophy, and the activities of all 3 enzymes were reduced in these biopsies, when expressed in terms of DNA content, the most striking reduction being in phosphofructokinase activity. The amount of glycogen in the tissue correlated closely with these enzyme activities and was slightly lower in the most atrophic tissue, when expressed in terms of DNA content. The activities of acid and neutral .alpha.-glucosidases were similar in biopsies from control subjects and patients with various severities of alcohol myopathy. The reduced activities are consistent with a reduced proportion of type II fiber muscle mass in these patients, and there may be a reduced capacity for glycolysis with resultant reduced lactate production. Whether the changes in enzyme activities are primary to the selective atrophy remains to be established.