The effects of dietary mackerel oil on the recovery of cardiac function after acute ischaemic events in the pig.

To investigate the effects of fish oil nutrition on cardiac haemodynamics and the biochemical response to ischaemia-reperfusion, young pigs (5 weeks old) were fed a 9% lard fat diet or a mixed diet of 4.5% mackerel oil and 4.5% lard fat for 16 weeks. In the mackerel oil fed pigs plasma cholesterol and triglyceride levels decreased by 22% and 58% (both p less than 0.05), respectively, while levels in the animals which received only lard fat did not change. The n-6 fatty acids present in cardiac and platelet membrane phospholipids underwent a partial replacement by n-3 fatty acids in the mackerel oil fed pigs. Under anaesthesia, multiple coronary artery occlusions (5 min) were interrupted by 10 min of reperfusion. The extent of recovery of cardiac function and reduction of adenine nucleotide levels were similar for both dietary groups. The incidence of reperfusion arrhythmias was significantly lower and the reactive hyperaemic responses were of longer duration in the mackerel oil fed animals. These effects cannot be explained by diet-induced alterations in thromboxane B2/6-keto-PGF1 alpha ratio, although a marked reduction in absolute levels of both prostaglandins was seen in the mackerel oil fed pigs (p less than 0.05). In conclusion, dietary fish oil caused changes in membrane fatty acid composition and plasma prostaglandin levels, although these did not affect alterations of cardiac performance during and after short periods of ischaemia.