Background: In the thrombotic process of acute coronary syndromes, the pathophysiological role of thromboxane A2 via cyclooxygenase is well established; however, the role of 12-HETE via 12-lipoxygenase is little known. Therefore, we used OPC-29030, a novel specific inhibitor of 12-HETE synthesis, to test whether platelet-derived 12-HETE is involved in mediating cyclic flow variations (CFVs) and platelet aggregation in stenosed and endothelium-injured canine coronary arteries.
Methods and results: After developing CFVs, dogs received a vehicle or OPC-29030 intravenously. Plasma and intraplatelet 12-HETE levels increased after CFVs. OPC-29030 but not vehicle reduced CFVs, which was associated with decreases in plasma and intraplatelet 12-HETE levels. Cessation of OPC-29030 restored CFVs in association with increases in plasma and intraplatelet 12-HETE levels. ADP and U46619 induced ex vivo platelet 12-HETE production and aggregation. After OPC-29030 administration, the ADP- and U46619-induced increases in ex vivo platelet 12-HETE production and aggregation were inhibited significantly. Platelet aggregation was linearly correlated with platelet 12-HETE production. OPC-29030 suppressed activation of human platelet glycoprotein IIb/IIIa.
Conclusions: OPC-29030 reduced intraplatelet 12-HETE levels, resulting in the inhibition of coronary thrombosis in vivo in dogs. OPC-29030 inhibited human platelet glycoprotein IIb/IIIa activation in vitro. Thus, platelet-derived 12-HETE may play an important role in mediating thrombotic process.