Developmental cardiac metabolism in health and disease.

Cardiac metabolism changes in response to oxygen and substrate availability during development. The fetus is relatively more dependent on anaerobic glycolysis, using glucose as its major substrate during hypoxia, lactate when well-oxygenated. The mature heart is almost exclusively aerobic, with nonesterified fatty acids as the predominant substrate. During hypoxia and ischemia, shifting the heart to carbohydrate metabolism has oxygen-sparing effects. Blocking lipolysis or carnitine palmityl transferase activity prevents accumulation of potentially toxic long-chain esters during hypoxia/ischemia, thereby reducing the risk of electrophysiologic disturbance and membrane disruption. Knowledge of developmental cardiac metabolism may aid in the development of therapeutic strategies to preserve the myocardium during hypoxia and ischemia.