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Nutrient Physiology, Metabolism, and Nutrient-Nutrient Interactions

(n-3) Long Chain PUFA Dose-Dependently Increase Oxygen Utilization Efficiency and Inhibit Arrhythmias after Saturated Fat Feeding in Rats¹

² Department of Surgery, Monash University, and Department of Cardiothoracic Surgery, Alfred Hospital, Melbourne, Australia; and ³ Division of Medical Sciences, Graduate School of Medicine, University of Wollongong, Australia

^* To whom correspondence should be addressed. Email: salvatore.pepe{at}med.monash.edu.au.

Fish oil (FO) modifies cardiac membrane phospholipid fatty acid composition to confer increased efficiency of oxygen utilization and antiarrhythmic effects. We tested the capacity of low-dose increments of FO, rich in (n-3) PUFA, to reverse the detrimental pro-arrhythmic and inefficient oxygen usage effects of dietary saturated fat (SAT) [including high ratio of (n-6) PUFA:(n-3) PUFA] during ischemia and reperfusion. Wistar rats were fed an SAT-enriched diet (15.3% fat, including 12% SAT, added by weight) for 6 wk and were then divided into 4 groups (n = 10/group) fed that diet or a 12% fat diet containing 3, 6, or 12% FO in place of SAT for 6 wk. Paced (300/min), erythrocyte-perfused isolated working hearts were subjected to low coronary flow ischemia (15 min) and were then reperfused. At normoxic baseline, external work capacity increased marginally at 6 and 12% FO; however, marked dose-related reductions in oxygen consumption were evident due to FO-dependent reduction in oxygen-energy utilization efficiency and associated reductions in coronary flow and oxygen extraction. Postischemic recovery resulted in lower oxygen consumption, greater oxygen-energy utilization efficiency, reduced coronary release of creatine kinase, and reduced incidence of arrhythmias in all FO groups compared with the SAT group. FO at a dose as low as 3% of total fat dietary supplement effectively reversed the high oxygen requirements and pro-arrhythmic effects of a SAT-rich diet even with continued consumption of SAT (9%) in this ex vivo animal model.