MRS2279 diammonium is a selective and high affinity P2Y1 receptor antagonist, with a K i value of 2.5 nM and an IC 50 value of 51.6 nM. MRS2279 diammonium competitively inhibits ADP-promoted platelet aggregation with an pK b value of 8.05 In Vitro MRS2279 diammonium antagonizes 2-MeSADP-stimulated inositol phosphate formation in turkey erythrocyte membranes with a pK b value of 7.75. MRS2279 diammonium shows high affinity competitive antagonism to human P2Y1 receptor with a pK b value of 8.10 in 1321N1 human astrocytoma cells. MRS2279 diammonium shows specific effect for the P2Y1 receptor, but shows no effect on activation of the human P2Y2, P2Y4, P2Y6, or P2Y11 receptors by their cognate agonists. MRS2279 diammonium shows no ability to block the capacity of ADP to act through the Gi/adenylyl cyclase linked P2Y receptor of platelets to inhibit cyclic AMP accumulation. MCE has not independently confirmed the accuracy of these methods. They are for reference only. In Vivo MRS2279 diammonium (2 μL, 1 nM; intracerebroventricular injection; 30 min prior to mechanical ventilation) reduces mouse brain injury induced by mechanical ventilation in high-pressure ventilation mice. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:P2Y1 Receptor 51.6 nM (IC 50 )