The effect of endogenous eicosapentaenoic acid on PMN leukotriene and PAF biosynthesis

Caseinate elicited peritoneal PMNs were obtained from rats fed Menhaden fish oil or control rat chow. Total polyeneoic fatty acids were measured and compared with PAF and leukotriene biosynthesis after stimulation with the calcium ionophore A23187. PAF was measured by acetate incorporation and its molecular species were measured by GCNICIMS after conversion to the PFB-diglyceride. Eicosapentaenoic acid enrichment lowered the total amount of leukotriene B4 but increased the amount of LTB5 proportionally to the increase in the fatty acid. Although concentrations of 20:5 exceeded those of 20:4, PAF biosynthesis was not inhibited nor were the relative amounts of its molecular species dramatically altered.