The administration of dietary fish oil to animals also led to the incorporation of omega-3 fatty acids into vascular and endothelial cell lipids, with an increase in EPA and DHA and decreases in arachidonic and linoleic acids, which are similar to the findings reported in platelets. However, the functional effects of the accumulation of omega-3 fatty acids in endothelial cell membranes are less clear than in platelets. The addition of purified EPA and DHA to cultured endothelial cells led to a decrease in cellular production of prostaglandin 6-keto-Flfll after stimulation with agonists. Aortic vascular rings from rats fed fish oil elaborated decreased amounts of PGI2without detectable synthesis of PGI3. However, perfused human umbilical vasculature converted C-EPA to a substance that decomposed to C-delta 17-6-keto-Fla, a breakdown product of PGI3. fully
The recent availability of techniques to measure the metabolites of PGI2 and PGI3 (PGI-M) in urine has allowed assessment of the daily endogenous production of these metabolites in humans ingesting fish oil. Studies in normal subjects fed fish oil showed that urinary PGI2-M did not decrease significantly, and small amounts of PGI3-M appeared.
In addition to the effects on platelet and vascular function, other alterations of hemostasis that have been reported after fish oil feeding include an elevation in the plasma levels of antithrombin III and tPA and reduced fibrinolytic enzyme inhibitors. The viscosity whole blood and erythrocyte membranes have been found to be decreased as well.’
Use of Fish Oil in Experimental and Clinical Vascular Disease
The possibility that dietary fish oil may have a salutary effect on platelet-vessel interactions in atherosclerotic vascular disease has been examined. Hay et al showed that the administration of 3.5 g/day of EPA (as fish oil) for 5 weeks to 13 patients with severe ischemic heart disease lengthened the platelet survival time by 10% and produced a significant fall in the platelet specific protein (3-thromboglobulin (BTG) and in platelet factor 4 (PF4). Fisher et al observed a similar effect in a hyperlipidemic population with large-vessel atherosclerosis and a shortened baseline platelet survival.