UNIT 1.35 In Vitro Binding of [3H]PSB-0413 to P2Y12 Receptors

The P2Y12 /ADP receptor plays a central role in platelet activation. Characterization of this receptor is mandatory for studying disorders associated with a P2Y12 receptor defect and for evaluating P2Y12 receptor agonists and antagonists. In the absence of suitable anti-P2Y12 antibodies, radioligand binding assays are the only way to conduct such studies. While various radioligands were employed in the past for this purpose, none were found to be suitable for routine use. Described in this unit are protocols for quantitatively and qualitatively assessing P2Y12 receptors with [3H]PSB-0413, a selective antagonist for this site. The saturation and competition assays described herein make possible the determination of P2Y12 receptor density on cells, as well as the potencies and affinities of test agents at this site. © 2015 by John Wiley & Sons, Inc. Keywords: P2Y12; binding; blood platelets; radioligand; ADP