Abstract 217: The P2Y12 Antagonists, 2MeSAMP and AR-C69931MX, Inhibit Platelet Activation Through the P2Y12/Gi-Dependent Mechanism
Objective— ADP is an important physiological agonist that induces integrin activation and platelet aggregation through it receptors the P2Y1 (Gq-coupled) and P2Y12 (Gi-coupled). P2Y12 plays a critical role for platelet activation and thrombosis. Adenosine-based P2Y12 antagonists, 2-methylthioadenosine 5’-monophosphate triethylammonium salt (2MeSAMP) and AR-C69931MX are widely used to demonstrate the role of P2Y12. AR-C69931MX (Cangrelor) is also under clinical trials for thrombotic diseases. However, a recent study reported that both 2MeSAMP and AR-C69931MX raise intra-platelet cAMP levels and inhibit aggregation through a P2Y12-independent mechanism. The present work, by using P2Y12 deficient mice, sought to clarify previous conflicting reports and to elucidate the mechanisms by which 2MeSAMP and AR-C69931MX inhibit platelet activation and thrombosis.
Methods and Results— We show that 2MeSAMP and AR-C69931MX inhibited aggregation and ATP release in platelets from wild type but not in P2Y12 deficient mice. 2MeSAMP and AR-C69931MX neither raised intracellular cAMP levels nor induced VASP phosphorylation in both mouse and human platelets. Furthermore, unlike the activators (PGI2 and forskolin) of the cAMP pathway, 2MeSAMP and AR-C69931MX failed to inhibit platelet aggregation, calcium mobilization, Akt phosphorylation, and Rap1b activation in P2Y12 deficient platelets. In addition, while injection of AR-C69931MX inhibited thrombus formation in a FeCl3-induced thrombosis model in wild type mice, it failed to affect thrombus formation in P2Y12 deficient mice.
Conclusion— These data together demonstrate that 2MeSAMP and AR-C69931MX inhibit platelet function through the P2Y12-dependent mechanism both in vitro and in vivo.
- © 2012 by American Heart Association, Inc.