HISTOCHEMICAL AND ULTRASTRUCTURAL STUDIES OF ENZYMES, PARTICULARLY IN CARBOHYDRATE METABOLISM OF THE BOVINE HEART CONDUCTION SYSTEM

Abstract

The enzymes relating to phosphoric acid metabolism, oxido-reduction system, and carbohydrate metabolism were histochemically demonstrated in the Purkinje cells, RBB, LBB, HIS, and A-V node. Generally, the enzyme activity in the tissue cells of the conduction system was lower than in the tissue cells of the heart muscle. Only the case, phosphorylase, was the activity of the conduction system higher than that of the heart muscle. The polyglucose particles synthesized by phosphorylase and brancher were larger and more numerous under the electronmicroscopic level in the CS. The activities of glucose-phosphate isomerase, phosphoglucomutase, and ribose-5-phosphate isomerase were newly demonstrated in CS and HM. The activities of LDH, G-6-P DH, and R-5-P isomerase in the CS were the same as or slightly lower than their activities in the HM. The activities of G-6-P and SDH in the CS were apparently lower than those in the HM, as previous reports were already indicated. Acid-P and Alk-P activities were very slight or almost negative in both CS and HM. The author presumes that higher phosphorylase activity and considerable ATP, G-6-P DH, and R-5-P isomerase activities in the CS are related to anaerobic metabolism and to the chemical energy from ATP and NADPH.