Platelet aggregation by ADP plays a major role in the development and extension of arterial thrombosis. The antithrombotic thienopyridine compounds ticlopidine and clopidogrel have proved useful tools to investigate the mechanisms of ADP-induced platelet activation. In essence, although clopidogrel has been shown to completely and selectively block ADP-induced platelet aggregation, G protein activation and inhibition of adenylyl cyclase, this drug does not affect shape change and Ca2+ influx. Binding studies, using the non-hydrolysable ligand [33P]2MeSADP, have shown that human platelets contain about 600 high-affinity binding sites for 2MeSADP (K(d) ~ 5 nM). These sites present pharmacological characteristics of a P(2T) receptor. Clopidogrel treatment reduces the number of sites by 70% on rat platelets (from 1200 to 450) and leaves the residual binding sites resistant to clopidogrel. Moreover, patients with congenital impairment of ADP-induced platelet aggregation but normal shape change display very low levels of [33P]2MeSADP binding sites. The current data thus strongly suggest the presence of two ADP receptors, one responsible for shape change and rapid Ca2+ influx and the other a Gi protein-coupled receptor responsible for Ca2+ mobilization from internal stores, inhibition of adenylyl cyclase and platelet aggregation.
Purinoceptors on blood platelets: further pharmacological and clinical evidence to suggest the presence of two ADP receptors / C. Gachet, M. Cattaneo, P. Ohlmann, B. Hechler, A. Lecchi, J. Chevalier, D. Cassel, P. Mannucci, J. Cazenave. - In: BRITISH JOURNAL OF HAEMATOLOGY. - ISSN 0007-1048. - 91:2(1995), pp. 434-444.
|Titolo:||Purinoceptors on blood platelets: further pharmacological and clinical evidence to suggest the presence of two ADP receptors|
|Parole Chiave:||purinoceptors; ADP; 2MESADP; thienopyridine; thrombosis|
|Settore Scientifico Disciplinare:||Settore MED/09 - Medicina Interna|
|Data di pubblicazione:||1995|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1111/j.1365-2141.1995.tb05319.x|
|Appare nelle tipologie:||01 - Articolo su periodico|