Energy metabolism in the ischemic heart.

A reduction in myocardial oxygen supply during ischemia, not only leads to reduced aerobic ATP production but does not stimulate glycolytic ATP synthesis. The residual aerobically synthesized ATP comes primarily from continued inefficient (i.e., compared to glucose in terms of moles of ATP produced per mole of O2 consumed) oxidation of fatty acids. This leads to elevated tissue levels of long chain fatty acyl-CoA and fatty acyl-carnitine. Both are potentially cell damaging metabolic intermediates. Restriction of glycolysis is due to inhibition of glyceraldehyde-3-phosphate dehydrogenase by accumulated metabolites, such as H+, lactate and NADH. The reduced production of ATP leads to decreased levels of high energy phosphate stores which in turn may impair myocardial mechanical function.