Differential effects of adenine nucleotide analogues on shape change and aggregation induced by adenosine 5′‐diphosphate (ADP) in human platelets

Abstract

1 Adenosine 5'-diphosphate (ADP) induces human blood platelets to aggregate and change shape, and it has been suggested that these two responses are mediated by more than one subtype of ADP receptor. 2 The structure-activity relationships for several analogues of adenine nucleotides in causing aggregation and shape change were measured and compared in washed platelets using an aggregometer. ADP and its analogues 2-methylthioadenosine 5'-diphosphate (2-methylthio-ADP), adenosine 5'(a,b-methylene)diphosphonate (AMPCP), S P -adenosine 5'-O-(1-thiodiphosphate) (AD-P aS) and adenosine 5'-O-(2-thiodiphosphate) (ADPbS) were used as agonists. Adenosine 5'-triphosphate (ATP) and its analogues, P 1 , P 5 -diadenosine pentaphosphate (Ap 5 A), adenosine (5'-(a,b-methylene)triphosphonate (AMPCPP), 2-methylthioadenosine 5'-triphosphate (2-methylthio-ATP) and uridine 5'-triphosphate (UTP), as well as the trypanocidal drug suramin, were used as antagonists. 3 In general, the structure-activity relationships for both responses were similar, but for some analogues di erences were observed. ADPaS and ADPbS were much more potent agonists relative to ADP for shape change than for aggregation and indeed ADPaS antagonized ADP-induced aggregation with an apparent pK B value of 5.5+0.1. 2-Methylthio-ATP also had di erent e ects in aggregation and shape change, being a much higher a nity antagonist of aggregation than of shape change with an apparent pK B value of 7.0+0.2 for aggregation and 5.2+0.2 for shape change. 4 These results support the suggestion that these two responses are mediated by multiple ADP receptors on human platelets, and are consistent with shape change being mediated via one receptor (the P2Y 1 receptor) with aggregation requiring the activation of two receptors (the P2Y 1 and another P2Y receptor).

Alterations of Adenine Nucleotide Metabolism and Function of Blood Platelets in Patients With Diabetes

“…This could explain why in diabetic patients strongest correlations were revealed between ATP, but not ADP, platelet levels and different platelet activities (Tables 4 and 5). That suramin, a nonspecific purinergic receptor antagonist (15,16), inhibited thrombinevoked platelet activation and aggregation indicates that ATP/ADP released from activated platelets exert their effects through purinergic receptors (Fig. 2) (29).…”

“…Reagents and materials. Reagents for ATP/ADP, acetyl-CoA assays, and suramin, a nonselective purinergic receptors antagonist (15,16), were supplied by Sigma Chemicals (Poznań , Poland); thrombin was from Bio-Med (Lublin, Poland); Commassie Brillant Blue G-250 was from Bio-Rad (Munchen, Germany); and glycine-proline-arginine-proline-NH 2 (GPRP) tetrapeptide was from Bachem (Bubendorf, Switzerland). All other chemicals were of analytical grade.…”

Adenine triphosphate nucleotides are antagonists at the P2Y12 receptor

“…The main objective of our work was to re-examine the effects of adenine triphosphate nucleotides at this receptor, since in several recent studies ATP and its triphosphate analogues were found to be full agonists at native or heterologously expressed P2Y 12 [11,[17][18][19], which does not fit the data previously obtained in blood platelets. Thus, ATP and its adenine triphosphate analogues 2MeSATP and 2ClATP have been shown to be antagonists of ADP-induced adenylyl cyclase inhibition in platelets, a response mediated solely by activation of the P2Y 12 receptor [22][23][24].…”

Nucleotide receptors: an emerging family of regulatory molecules in blood cells

“…210,211 According to this proposal, the P2T AC receptor would coincide with the platelet P2Y ADP (written in italics to signify that it is not yet cloned) receptor of the nomenclature established by IUPHAR. 2,27 Development of selective platelet P2 receptor antagonists has progressed further than in other cell types, and some have already reached clinical applications.…”