ABSTRACT
This chapter elaborates on the alterations of carbohydrate, fatty acid, and ketone energy metabolism in the myocardium of streptozotocin (STZ) diabetic animals. The cellular energy currency, ATP, is regenerated from ADP and inorganic phosphate primarily via mitochondrial oxidative phosphorylation. Before launching into a description of the intricacies of the mechanisms regulating myocardial energy metabolism, it is important to address a few basic concepts concerning the experimental conditions used for studying cellular energy metabolism in STZ diabetic animals. The content of glycogen in the heart is highly dependent on diet, feeding state, and the metabolic flux of glycogen synthesis, while breakdown is dependent upon substrate availability and hormonal stimulation. Lactate is a major source of pyruvate formation under well-perfused conditions in vivo, and under some conditions lactate uptake can exceed glycolysis as a source of pyruvate. Pyruvate decarboxylation is the key irreversible step in carbohydrate oxidation and is catalyzed by pyruvate dehydrogenase (PDH).
