Docosahexaenoic acid and docosapentanoic acid incorporation into human platelets after 24 and 72 hours: inhibitory effects on platelet reactivity.

Short-term in vitro platelet membrane lipid enrichment studies and feeding trials of human subjects with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have shown a decreased reactivity in the platelet response to collagen. In this study, exogenous albumin-bound n-3 polyunsaturated fatty acids (PUFAs), namely EPA, DHA and docosapentanoic acid (DPA) were added to platelet suspensions and maintained at 22 degrees C for 24 and 72 hours. Subsequently, the aggregation response to agonist stimulation and the morphological appearance of the platelets were evaluated. A significant enrichment of platelet phospholipids (PL) in n-3 fatty acids occurred upon incubation with n-3 PUFAs in vitro, which was accompanied by a decrease in the aggregation response to collagen and preservation of platelet morphology compared with non-supplemented control platelet preparations. The inhibitory effect of the n-3 PUFAs appeared to be surface mediated in the case of DHA and DPA because the platelet response to agonist returned when the fatty acids were removed by washing. The platelet aggregation response after storage at 22 degrees C was also evaluated in platelet suspensions collected from healthy individuals before and after 42 days of dietary supplementation with seal oil, rich in DPA and DHA. Unlike the in vitro supplementation, in vivo modification and enrichment of platelet PLs by ingestion of seal oil did not appear to improve platelet function during storage relative to the placebo group.