Fatty acid composition and lipoxygenase metabolism in blood cells of the lesser spotted dogfish, Scyliorhinus canicula.

1. The fatty acid composition of erythrocytes and leucocytes of the elasmobranch, Scyliorhinus canicula, was determined so as to indicate substrate availability for eicosanoid formation. 2. Leucocytes showed a greater degree of fatty acid unsaturation than the erythrocytes, with particularly high levels of docosahexaenoic acid (22:6,n-3). 3. The major eicosanoid precursors, arachidonic acid (20:4,n-6) and eicosapentaenoic acid (20:5,n-3), represented 13.9% and 5.2% of the total fatty acid, respectively, in erythrocytes compared with 10.7% and 6% in leucocytes. 4. Whole blood and isolated leucocytes were stimulated with calcium ionophore, A23187 and the resulting lipoxygenase products separated by reverse phase high performance liquid chromatography. 5. The main lipoxygenase products formed were 6-trans-leukotriene B4, 6-trans-12-epi-leukotriene B4, 5(S),6(R) dihydroxyeicosatetraenoic acid and 5- and 15-hydroxyeicosatetraenoic acid. 6. No leukotriene B4, leukotriene B5, or lipoxins were detected.