Dietary (n-3) Long-Chain Polyunsaturated Fatty Acids Inhibit lschemia and Reperfusion Arrhythmias and Infarction in Rat Heart Not Enhanced by lschemic Preconditioning.

lschemic preconditioning (IPC) and (n-3) PUFA are both cardioprotective. This study compared effects of dietary fish oil, IPC, and their interactions on heart function and injury during myocardial ischemia and reperfusion. Male Wistar rats were fed diets containing 10% wt:wt fat comprising either 7% high-docosahexaenoic acid (DHA( [22:6(n-3)1 tuna fish oil + 3% olive oil L(n-3) PUFA]; 5% sunflower seed oil + 5% olive oil [(n-6) PUFA]; or 7% beef tallow + 3% olive oil [saturated fat (SF)] for 6 wk. In control experiments, isolated perfused hearts were subjected to 30-mm regional ischemia and reperfused for 120 mm. The (PC hearts were subjected to 3 cycles of 5-mm global ischemia before the ischemia and reperfusion. Control (n-3) PUFA hearts had significantly lower heart rate, coronary flow, end diastolic pressure, maximum relaxation rate, and ischemic and reperfusion arrhythmias. In reperfusion, they had greater developed pressure and maximum relaxation rate and smaller infarct 110.9 ± 0.6% ischemic zone, n= 61 than (n-6) PUFA (47.4 ± 0.3%, n= 61 orSF (50.3 ± 0.3%, n= 6). Compared with control, IPC significantly improved heart function and reduced infarct in (n-6( PUFA (11.8 ± 0.4%, n = 6) and SF hearts (13.1 ± 0.1 0/s, n = 61. Heart function and infarct ](n-3) PUFA 9.6 ± 0.1%, n = 6] did not differ among dietary PC groups. Arrhythmias, significantly reduced by IPC in (n-6) PUFA and SF hearts, were significantly lower in (n-3) PUFA (PC hearts. Dietary fish oil induces a form of preconditioning, nutritional preconditioning, limiting ischemic cardiac injury, and myocar- dial infarction and endows cardioprotection as powerful as PC, which provides no additional protection in (n-3) PUFA hearts. [ABSTRACT FROM AUTHOR]