Use of Radiolabeled 2-Methylthio-ADP to Study P2Y Receptors on Platelets and Cell Lines

The use of radioactive 2-methylthio-ADP (2MeS-ADP) to study ADP receptors on platelets was first developed by MacFarlane et al. ( 1 ) in 1983. However, this technique may not have initially been pursued by many groups because of the relative paucity of studies into platelet ADP receptors and the absence of a commercially available radiolabeled ligand. From 1992 to 1994, a few papers described the use of 2MeS-ADP to demonstrate the antagonistic activity of clopidogrel on the platelet ADP receptor ( 2 – 4 ) and the presence of ADP receptors on megakaryocytoblastic cells ( 5 ). Since these initial reports, several groups have published studies describing the binding characteristics of 2MeS-ADP on platelets ( 6 , 7 ). Two different teams provided evidence for a defect of ADP receptor numbers in platelets from patients with a low sensitivity to ADP ( 8 , 9 ). Consequently, a variety of antiplatelet compounds have been evaluated as antagonists on platelet ADP receptors ( 10 – 13 ). A recent study has demonstrated the ability of P2Y 12 to bind 2MeS-ADP, supporting its identity as the previously named P2T AC or low-affinity platelet ADP receptor ( 14 ). These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.