Differential effects of dietary fatty acids on the accumulation of arachidonic acid and its metabolic conversion through the cyclooxygenase and lipoxygenase in platelets and vascular tissue.

Semisynthetic diets containing either corn oil (CO) or butter (B) (11 and 2.2 en % as linoleic acid, respectively) were fed to male rabbits for periods of 3 weeks and 3 months. The CO diet, in respect to the B diet, induced higher levels of linoleic acid (LA) and lower levels of arachidonic acid (AA) in platelet phospholipids, lower levels of AA in aortic phosphatidylinositol (PI) and accumulation of both LA and AA in liver lipids. The thresholds for aggregation with AA, but not with collagen, were higher in the CO group and the formation of thromboxane B2 (TXB2) from [14C] AA, but not from endogenous substrate after collagen stimulation, was lower in the same group. Formation of PGE2-like material by incubated aortas was higher in the B group. In the CO group, platelet cyclooxygenase appeared to be selectively depressed. The correlations among diet-induced fatty acid changes in platelet and aortic lipids, platelet aggregation and thromboxane and prostacyclin formation are discussed.