Erythrocyte membrane cation-stimulated ATPase activities in myotonic muscular dystrophy

The cation-stimulated ATPase activities of erythrocyte membranes from patients with myotonic muscular dystrophy (MyD) were compared with the activities in age- and sex-matched controls. The enzymes included ouabain-sensitive ATPase, Mg2+-ATPase and Ca2+ + Mg2+-ATPase. Sampling and processing of the materials from patients with MyD and controls were simultaneously done in each experiment. The enzyme activities were varied with or without EGTA in the reaction medium, or with different temperatures for membrane storage, but no significant differences between MyD and control were observed in any conditions. The present study indicates no specific abnormality of the cation-stimulated ATPase activities of erythrocyte membranes in MyD.