Uptake and effect on arachidonic acid oxygenation of some icosaenoic acids in human platelets.

8,11,14-icosatrienoic (DHLA), 5,8,11,14,17-icosapentaenoic (EPA) acids (the monoenoic and trienoic prostaglandin precursors, respectively) and 5,8,11-icosatrienoic acid (20:3n-9) were pre-coated onto albumin and then incorporated into platelet lipids. Around 80% of the total incorporation concerned their acylation into phospholipids and a few percentage was oxygenated through the cyclooxygenase and/or lipoxygenase pathways, simulating therefore the in vivo situation. Such modified platelets normally oxygenated exogenous arachidonic acid (AA) while (only when enriched with DHLA or EPA) they produced less oxygenated derivatives of AA under thrombin stimulation. This indicates that endogenous AA liberation was decreased in both DHLA and EPA-rich platelets, which might be related to the formation of inhibitory prostaglandins from these polyunsaturated fatty acids.