Activities of enzymes in cardiac energy metabolism

Abstract
The activities of enzymes of fat and carbohydrate energy metabolism were determined in hearts from a number of species. Activities of citrate synthase and 3-hydroxyacyl CoA dehydrogenase were lower in hearts from ectothermic animals than rats or pigeons. However, activities of hexokinase and phosphofructokinase in the ectothermic hearts were equal to or greater than the activities in the endothermic hearts. It thus appears that the hearts from the ectothermic species have a greater dependence upon a glucose-based metabolism than hearts from endothermic animals.