Changes in fatty acid composition of cardiac lipids accompanying myocardial necrosis.

Administration of isoproterenol induces changes in phospholipids of heart muscle membranes. Longer and more unsaturated fatty acids replace shorter and less unsaturated fatty acids. Dietary polyunsaturated fatty acids, i.e., C22:6, replace C18:2 and C20:4 in phospholipids of heart muscle. Increased sensitivity to isoproterenol and increased myocardial cell damage is accompanied by a relative increase in long chain polyunsaturated fatty acids in phospholipids of heart muscle. Development of myocardial necrosis increases with a progressive replacement of C18:2 and C20:4 by C22:6. Alterations in fatty acid composition of membrane phospholipids and consequent changes in membrane properties may play an important role in myocardial cell damage. Myocardial damage following administration of isoproterenol is increased when there is enhanced intramyocardial lipolysis and an increased amount of polyunsaturated fatty acids in membrane phospholipids. Mocardial damage is decreased when there is reduced intramyocardial lipolysis and the membrane response makes the membranes less permeable and more stable.