Hydroxylated 22-carbon fatty acids in platelet and vascular smooth muscle function: interference with TXA2/PGH2 receptors.

Sub-micromolar levels of the lipoxygenase products of n-3 fatty acids specifically antagonize both the contractile effects of thromboxane (U46619) and its platelet aggregating effect. In addition, OH-22:6n3 inhibits thromboxane-induced decreases in cerebral blood flow of the rat. Analysis of binding parameters indicates these derivatives induce a marked decrease in the affinity of the TXA2/PGH2 receptor for thromboxane with a mild change in the number of receptor sites. The 22-carbon n-3 hydroxy fatty acids are the most potent biological antagonists of thromboxane in comparison to the n-6 hydroxy fatty acids and their parent fatty acids. Dietary permutations modify the hydroxy fatty acid profile and correlate with changes in thromboxane-mediated responses.