title: Dietary (n-3) long-chain polyunsaturated fatty acids inhibit ischemia and reperfusion arrhythmias and infarction in rat heart not enhanced by ischemic preconditioning.
abstract: Ischemic 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)] tuna fish oil + 3% olive oil [(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-min regional ischemia and reperfused for 120 min. The IPC hearts were subjected to 3 cycles of 5-min 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 (10.9 +/- 0.6% ischemic zone, n = 6) than (n-6) PUFA (47.4 +/- 0.3%, n = 6) or SF (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%, n = 6). Heart function and infarct [(n-3) PUFA 9.6 +/- 0.1%, n = 6] did not differ among dietary IPC groups. Arrhythmias, significantly reduced by IPC in (n-6) PUFA and SF hearts, were significantly lower in (n-3) PUFA IPC hearts. Dietary fish oil induces a form of preconditioning, nutritional preconditioning, limiting ischemic cardiac injury, and myocardial infarction and endows cardioprotection as powerful as IPC, which provides no additional protection in (n-3) PUFA hearts.
authors.affiliation: School of Health Sciences, 4Smart Foods Centre, and 5Graduate School of Medicine, University of Wollongong, NSW 2522, Australia.
authors.forename: Grace G
authors.initials: GG
authors.lastname: Abdukeyum
authors.forename: Alice J
authors.initials: AJ
authors.lastname: Owen
authors.forename: Peter L
authors.initials: PL
authors.lastname: McLennan
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D003326:Coronary Circulation; D004195:Disease Models, Animal; D015525:Fatty Acids, Omega-3 / Q000627:therapeutic use*; D043371:Fatty Acids, Omega-6 / Q000627:therapeutic use*; D006321:Heart / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology; D019194:Ischemic Preconditioning / Q000379:methods*; D008297:Male; D009203:Myocardial Infarction / Q000517:prevention & control*; D017202:Myocardial Ischemia / Q000503:physiopathology; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000517:prevention & control*
chemical_list: D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6