Transport ATPases of Cardiac Sarcolemma in 20, 25‐Diazacholesterol Induced Myopathy

. 20, 25-Diazacholesterol, known to induce myotonia in skeletal muscle, also affects cardiac muscle as can be concluded from the development of cardiomegaly. At the same time (Na+, K+) ATPase of cardiac sarcolemmal membranes of the 20, 25-diazacholesterol treated rats showed an increased activity as compared with control animals (91 % and 46 % stimulation respectively). The Ca++ stimulated ATPase showed the same tendency (96 % and 64 % stimulation). In the plasma of the treated rats creatine phosphokinase activity was found to be elevated whereas the amount of protein-bound iodine was decreased, a finding that is common in myotonic dystrophy.