Alterations in fatty acid oxidation in ischemic and reperfused myocardium

The focus of this review centered on describing the effects of excess fatty acids on myocardial recovery during reperfusion following ischemic stress. Effects on mechanical function were modest in our studies and are likely to remain difficult/impossible to measure due to the independent phenomenon of stunning which obfuscates and no doubt dominates the influences of other mechanical determinants. Mitochondria appear capable of again using long-chain fatty acids as a preferred substrate and in the presence of restored oxygen delivery can produce normal levels of CO2. These changes in oxidative metabolism are not mirrored by equal recoveries in mitochondrial energetics. Because of inefficiencies in electron transport and oxidative phosphorylation together with moderate uncoupling of electron transport from oxidative phosphorylation, ATP resynthesis is blunted. This explains in part the absolute decrease in contents of exchangeable nucleotides noted both in cytosol and mitochondria. Further impairments in recovery reside in the inability of the mitochondria to exchange adenine nucleotides into cytosol through the adenine nucleotide translocase antiport. These findings contribute to our understanding of mechanical stunning and may be of value in designing future strategies to optimize the handling of substrates during myocardial reperfusion.