Effects of dietary sunflowerseed oil and marine oil on platelet membrane fluidity, arterial thrombosis, and platelet responses in rats.

The relationships among platelet membrane fluidity, arterial thrombosis tendency, and platelet aggregation and prostanoid formation were investigated after feeding rats diets enriched in (n-6) or (n-3) polyunsaturated fatty acids. For at least 8 weeks, rats were fed a control diet containing 5 energy % (en%) sunflowerseed oil, a diet high in sunflowerseed oil (50 en%) which contains large amounts of 18:2(n-6), or a diet high in marine oil (5 en% sunflowerseed oil plus 45 en% sperm-whale oil) which contains considerable amounts of 20:5(n-3) and its desaturation and elongation products. Compared with the control diet, platelet membrane fluidity, measured by fluorescence polarization using platelets labelled with 1,6-diphenyl-1,3,5-hexatriene, was significantly increased upon feeding of the sunflowerseed-oil diet or the marine-oil diet. Both of these diets lowered arterial thrombosis tendency, measured by Hornstra's loop technique. Aggregation of platelets in whole blood activated with collagen tended to be higher upon sunflowerseed-oil feeding and lower in the marine-oil group. The concomitant formation of thromboxane A2 was not altered in the sunflowerseed-oil group, but was significantly reduced upon feeding the marine-oil diet. The results indicate that an increase in platelet membrane fluidity may be associated with a reduction in arterial thrombosis tendency. With the techniques used, no direct relationship could be observed among platelet membrane fluidity, platelet aggregation and platelet prostanoid production.