title: 2-Alkylthio-substituted platelet P2Y12 receptor antagonists reveal pharmacological identity between the rat brain Gi-linked ADP receptors and P2Y12.
abstract: The Gi-linked platelet ADP receptor, now designated as P2Y12, accounts for ADP-induced inhibition of adenylyl cyclase in platelets and certain clonal rat cell lines. The pharmacology of this receptor is well characterized. Based on the functional approach of [35S]GTPgammaS autoradiography, we recently disclosed the widespread presence of Gi-linked ADP receptors in the rat nervous system. Based on initial pharmacological analysis, these receptors were strikingly similar with P2Y12. Here, we extend this analysis by comparing the potencies of six 2-alkylthio-substituted ATP analogues, including the adenosine-aspartate conjugate 2-hexylthio-AdoOC(O)Asp2 and five AR-C compounds (AR-C67085, AR-C69931, AR-C78511, AR-C69581, AR-C70300) with wide range of affinities towards P2Y12, in reversing 2-methylthio-ADP stimulated G protein activity in rat brain sections and human platelet membranes. Closely matching pIC50 values (r2=0.99) revealed pharmacological similarity between the two receptors with one exception: AR-C67085 more avidly recognized the platelet P2Y12. Further analysis of the rat brain pIC50 data against those available for three of the AR-C compounds in reversing P2Y12-mediated adenylyl cyclase inhibition in rat platelets (r2=0.96) and rat C6 glioma cells (r2=1.00) demonstrated that the three P2Y receptors are pharmacologically indistinguishable. We conclude that the rat brain Gi-linked ADP receptors, as revealed using [35S]GTPgammaS autoradiography, correspond to P2Y12.
authors.affiliation: Department of Physiology, University of Kuopio, P.O. Box 1627, 70211 Kuopio, Finland.
authors.forename: Kati S
authors.initials: KS
authors.lastname: Vasiljev
authors.forename: Asko
authors.initials: A
authors.lastname: Uri
authors.forename: Jarmo T
authors.initials: JT
authors.lastname: Laitinen
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D001345:Autoradiography; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008565:Membrane Proteins; D058919:Purinergic P2 Receptor Antagonists; D011869:Radioligand Assay; D051381:Rats; D017208:Rats, Wistar; D018048:Receptors, Purinergic P2; D058925:Receptors, Purinergic P2Y12
chemical_list: D008565:Membrane Proteins; C548576:P2RY12 protein, human; C553058:P2ry12 protein, rat; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D058925:Receptors, Purinergic P2Y12; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D000255:Adenosine Triphosphate; D019206:GTP-Binding Protein alpha Subunits, Gi-Go