The role of prostanoid receptors in mediating the effects of PGE2 on human platelet function

The effects of prostaglandin E2 (PGE2) on platelet function are believed to be the result of opposing mechanisms that lead to both enhancement and inhibition of platelet function. Enhancement of platelet function is known to be via EP3 receptors linked to Gi and inhibition of adenylyl cyclase. However, the receptors involved in inhibition of platelet function have not been fully defined. Here we have used measurements of platelet aggregation, calcium signaling and P-selectin expression to assess platelet function induced by platelet activating factor (PAF), thrombin receptor activating peptide (TRAP-6) and the thromboxane A2 mimetic U46619 respectively, to determine the effects of PGE2 and of selective prostanoid receptor agonists on platelet function. Their effects on vasodilator-stimulated phosphoprotein (VASP) phosphorylation were also determined. We also assessed the ability of selective prostanoid receptor antagonists to modify the effects of PGE2. The agonists and antagonists used were iloprost (IP ...