Reversible, highly localized alterations in fatty acid metabolism in the chronically ischemic canine myocardium

Acute myocardial ischemia is accompanied by a marked decrease in the oxidation of fatty acids. Whether similar changes occur during chronic ischemia was studied in 13 beagles. In 10 dogs, an ameroid constrictor was implanted about the left circumflex artery; 3 others served as sham-operated controls. Mitochondrial and peroxisomal fatty acid oxidation of (1-14C)oleate were measured and compared in affected (posterobasal left ventricular endocardial [posterior LV endo]) and unaffected (anteroapical LV epicardial [anterior LV epi]) tissues of control and experimental dogs. Five experimental and 3 control dogs were killed after 3 weeks. The posterior LV endo sections of experimental dogs at 3 weeks showed increased fatty acid oxidation due to peroxisomal (KCN-insensitive) beta oxidation (p less than 0.01). The anterior LV epi sections showed no difference in fatty acid oxidation between sham-operated and experimental dogs. Five dogs were studied after 3 months; fatty acid oxidation of the posterior LV endo section was normal. Thus, under a slowly evolving state of myocardial ischemia, highly localized and reversible adaptive changes in fatty acid oxidation occur that enable the affected tissue to cope with a fatty acid load. When collateralization is accomplished, fatty acid metabolism reverts to normal.