Contemporary events have greatly stimulated investigation of the physiology and biochemistry of the heart, as well as increasing interest in cardiac surgery and congenital and coronary artery disease.
Analytical electrolyte data on the heart are voluminous, but little is to be found on the complete histochemical characterization of this tissue.1 In fact, almost nothing has been done histochemically on the canine heart, the commonest source of cardiac research.
Histochemical changes in various parts of the heart following experimental coronary artery occlusion in both young and adult dogs have been studied by Hastings, Blumgart, Lowry, and Gilligan,2 and Lowry et al.3 Their analytical data were expressed on a fat-free, blood-free basis; their calculated data were made using an assumed value for the connective tissue mass. We have actually determined the connective tissue mass for all of the tissues presented here. Brodie4 did histochemical studies on a variety