title: Platelet endoperoxide/thromboxane A2 (PGH2/TXA2) receptors in patients with myeloproliferative disorders.
abstract: In patients with myeloproliferative disorders (MPD) an altered sensitivity of platelets to antiaggregatory prostaglandins and to the endoperoxide analogue U 46619 has been found. In this study we examined U 46619-induced platelet aggregation and binding of the endoperoxide/thromboxane A2 (TXA2) receptor antagonist SQ 29548 in 11 patients with MPD and 11 healthy controls. Although platelet responsiveness to U 46619 was significantly enhanced (p less than 0.05) in MPD, binding affinity and binding capacity of the corresponding endoperoxide/TXA2 receptor were not altered (Bmax 0.67 +/- 0.20 vs. 0.58 +/- 0.14 pmol/10(9) platelets, Kd 0.41 +/- 0.11 vs. 0.55 +/- 0.09 nM). These data exclude the possibility that changes in the presentation of endoperoxide/TXA2 receptors are responsible for the enhanced platelet sensitivity to endoperoxides found in MPD.
authors.affiliation: Medizinische Klinik, Universität Tübingen, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Faul
authors.forename: W
authors.initials: W
authors.lastname: Renn
authors.forename: K
authors.initials: K
authors.lastname: Jaschonek
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000328:Adult; D000368:Aged; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D019086:Bridged Bicyclo Compounds, Heterocyclic; D005231:Fatty Acids, Unsaturated; D005260:Female; D006801:Humans; D006834:Hydrazines / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D009196:Myeloproliferative Disorders / Q000097:blood*; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D011982:Receptors, Prostaglandin / Q000187:drug effects / Q000378:metabolism*; D017482:Receptors, Thromboxane
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D005231:Fatty Acids, Unsaturated; D006834:Hydrazines; D010975:Platelet Aggregation Inhibitors; D011450:Prostaglandin Endoperoxides, Synthetic; D011982:Receptors, Prostaglandin; D017482:Receptors, Thromboxane; C055662:prostaglandin endoperoxide receptor; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; C045749:SQ 29548