THE NATURE OF THE M BAND ENZYME IN RAT VENTRICULAR MUSCLE

The types of cardiac cholinesterases (1) and the responses of the myocardium to acetylcholine (2, 3) differ in various species and at various sites in the heart. It has not been possible to explain the differing physiological responses in terms of the types of cholinesterases present (1-3). A comparative study of the histochemical localization at the ultrastructural level of cholinesterase activity in cardiac muscle, correlated with biochemical and physiological findings, might shed some light on the