Myocardial function, ischaemia and n-3 polyunsaturated fatty acids: a membrane basis
Long-chain omega-3 polyunsaturated fatty acids (n-3 PUFA) are selectively incorporated into cardiac cell membranes from the diet in a dose-related manner. Regular intake can slow the heart rate, reduce myocardial oxygen consumption, and increase coronary reserve. These properties contribute to preconditioning-like effects of resistance to myocardial ischemic damage and improved post-ischaemic recovery. These effects can be demonstrated in isolated hearts independently of effects of n-3 PUFA on neural or blood parameters. The enrichment of myocardial membranes with n-3 PUFA also reduces vulnerability to cardiac arrhythmias, particularly ventricular fibrillation during myocardial ischemia and reperfusion, and attenuates heart failure and cardiac hypertrophy. n-3 PUFA concentrations can increase from 7% to 15% in the myocardial membranes of rats (mainly in the form of docosahexaenoic acid (22:6n-3, DHA) with dietary intakes of only 0.3% fish oil, equivalent to two meals of salmon per week in the human diet. Dietary fish oil produces changes in cardiac function that might contribute to cardiovascular health benefits in humans and does so by modifying cardiac membranes within a dose range achievable in the human diet.