Dietary Fish Oil Mimics the Cardio‐Protective Effect of Ischemic Preconditioning in Isolated Rat Heart

Abstract

Cardio protective actions of n-3 polyunsaturated fatty acids (PUFA) suggest a preconditioning-like effect. We investigated whether modification of membrane composition by dietary fish oil protects the heart during ischemia/reperfusion compared to ischemic preconditioning. Rats were fed diets with fish oil (n-3 PUFA), sunflower seed oil (n-6 PUFA) or saturated fat (beef tallow) (SF) for 6 weeks. Isovolumic isolated perfused hearts were reperfused for 120min after 30min regional ischemia, with or without ischemic preconditioning (3x 5min cycles of global ischemia). The n-3 PUFA hearts had lower coronary flow (CF), heart rate (HR) and end diastolic pressure (EDP) at rest. In reperfusion they had less arrhythmia, better developed pressure recovery, and maximum relaxation rate, and HR, CF and EDP stayed lower. Ischemic preconditioning reduced CF, HR and EDP at rest, reduced EDP rise in ischemia and improved developed pressure recovery and reduced arrhythmia. Preconditioning was effective only in SF and n-6 PUFA hearts. Therefore, prefeeding with n-3PUFA provided cardio protection, improving recovery, reducing stunning and arrhythmia while ischemic preconditioning provided similar but no additional protection. We conclude that dietary fish oil produces a preconditioning-like effect that is not subject to desensitisation with long-term feeding. DHA rich tuna fish oil was a gift of NuMega Lipids Australia.