 they competitively inhibit the binding of TXA2 to its thromboxane receptor, α isoform.Contrastingly, 15-lipoxgenase-derived epoxyalcohol and trihydroxy metabolites of arachidonic acid viz., 15-hydroxy-11,12-epoxyeicosatrienoic acid, 13-hydroxy-14,15-epoxy-eicosatrienoic acid (a 14,15-HxA4 isomer), and 11,12,15-trihydroxyeicosatrienoic acid dilate rabbit aorta by an Endothelium-derived hyperpolarizing factor (EDHF) mechanism, i.e.they form in the vessels endothelium, move to underlying smooth muscles, and trigger a response of Hyperpolarization (biology)-induced relaxation by binding to and thereby opening their apamin-sensitive small conductance (SK) Calcium-activated potassium channel#SK channels.