Dietary linoleic acid affects phospholipid fatty acid composition in heart and eicosanoid production by cardiomyocytes from atlantic salmon ( Salmo salar)

1. 1. Atlantic salmon post-smolts were fed practical-type diets containing linoleic acid at 10, 25 or 45% of total dietary fatty acids for a period of 20 weeks. 2. 2. As dietary linoleic acid was increased, individual phospholipids of heart contained increased levels of 18:2n-6, 20:2n-6, 20:3n-6 and 20:4n-6 and reduced levels of 20:5n-3. The ratio of n-3/n-6 polyunsaturated fatty acids in heart phospholipids decreased and the ratio of 20:4n-6/20:5n-3 increased. 3. 3. An increased production of thromboxane B 2 occurred in isolated cardiac myocytes from fish given the highest dietary linoleic acid but the production of 6-keto prostaglandin F 1α was not significantly affected, nor was the activity of heart sarcoplasmic reticulum Ca 2+-Mg 2+ ATPase (EC 3.6.1.4).