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Occupancy of P2 purinoceptors with unique properties modulates the function of human platelets
Journal article   Peer reviewed

Occupancy of P2 purinoceptors with unique properties modulates the function of human platelets

G Soslau, I Brodsky and J Parker
Biochimica et biophysica acta, v 1177(2), pp 199-207
06 Jun 1993
DOI: https://doi.org/10.1016/0167-4889(93)90041-m
PMID: 7684612
Featured in Collection :   UN Sustainable Development Goals @ Drexel

Abstract

Receptors, Purinergic - physiology Receptors, Purinergic - chemistry Prostaglandin Endoperoxides, Synthetic - antagonists & inhibitors Iloprost - pharmacology 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid Humans Collagen - antagonists & inhibitors Adenosine - pharmacology Adenosine Triphosphate - analogs & derivatives Adenosine Triphosphate - pharmacology Dose-Response Relationship, Drug Adenosine Triphosphate - antagonists & inhibitors Signal Transduction - drug effects Receptors, Purinergic - drug effects Platelet Aggregation Inhibitors - pharmacology Theophylline - pharmacology Cell Membrane - metabolism Platelet Aggregation - drug effects Cyclic AMP - metabolism Adenosine - antagonists & inhibitors GTP-Binding Proteins - metabolism
This report demonstrates that platelets possess P2 purinoceptors with unique properties that distinguish them from the ADP (P2T) receptor. Extracellular ATP, and its poorly hydrolyzable analogues, inhibit collagen- and U46619 (a thromboxane mimetic)-induced platelet aggregations. Adenosine deaminase was without effect on ATP action while reversing the inhibitory effect of adenosine. A unique aspect of the P2 receptor is the sensitivity to UTP and CTP and insensitivity to GTP. The rank order of inhibition by beta gamma-methylene ATP, alpha beta-methylene ATP > ATP indicates that a P2x-like receptor is present on the platelet membrane. This conclusion is further supported by the nearly complete desensitization to ATP by pre-exposure of platelets to alpha beta-methylene-ATP. However, unlike previously described P2x purinoceptors, the inhibition of platelet aggregation by extracellular ATP appears to result, at least in part, from the ATP-induced increase of intracellular cyclic AMP levels apparently coupled through a Gs protein. The combined addition of iloprost (0.14 to 1.39 nM) and ATP (18 microM) or ATP (20-40 microM) and the phosphodiesterase inhibitor theophylline (0.5 to 1 mM) synergistically inhibited platelet aggregation implying a common interactive site with adenylate cyclase. This is further substantiated by the ability of the adenylate cyclase inhibitor, 2',5'-dideoxyadenosine, to abrogate the inhibitory effects of ATP. The protein kinase A (PKA) inhibitor H1004 blocks ATP inhibition of platelet aggregation while the protein kinase C inhibitor H7 did not. This implies that the generation of cyclic AMP, with the subsequent activation of PKA and phosphorylation of selected proteins is required, in part, for the action of ATP.

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Web of Science research areas
Biochemistry & Molecular Biology
Biophysics
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