Long-term dietary fish oil supplementation protects against ischemia-reperfusion-induced myocardial dysfunction in isolated rat hearts.

Dietary fish oil has been shown to exert protective effects against arrhythmias and myocardial infarction after coronary artery occlusion. However, the effects of fish oil on ischemia-reperfusion-induced cardiac dysfunction are not known. This study was designed to examine if long-term dietary fish oil protects against a rise in coronary perfusion pressure and myocardial contractile dysfunction following ischemia and reperfusion. Fifteen Sprague-Dawley rats (age 7 to 9 weeks) were fed fish oil-rich chow for 4 to 5 weeks and 11 rats from the same batch were fed ordinary chow. Three fish oil-fed rats were also fed ad libitum indomethacin for the last 2 days. Isolated hearts from both groups were perfused on a Langendorff apparatus and were subjected to 25 minutes of global ischemia and 20 minutes of reperfusion. Myocardial phospholipid acid content was also measured. After 4 to 5 weeks of dietary fish oil supplementation, myocardial content of long-chain polyunsaturated fatty acid (PUFA) (C20-C22) and omega-3 PUFA was increased and that of omega-6 PUFA was decreased in the fish oil-fed group (all p < 0.01). Following global ischemia and reoxygenation, there was a reduction in the force of cardiac contraction and an increase in coronary perfusion pressure. However, reduction in the force of cardiac contraction was less in the hearts of fish oil-fed rats than in the control hearts (49 +/- 9% vs 63 +/- 5%, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)