title: Characterization of the prostanoid TP receptor population in human nonpregnant myometrium.
abstract: We have used both functional and binding studies to fully characterize the prostanoid TP receptor in the myometrium from nonpregnant human donors. Both U-46,619 and I-BOP produced concentration-dependent contraction of human myometrial strips in vitro (pEC50 = 6.9 +/- 0.6; and 7.8 +/- 0.5, respectively). U-46,619-induced contractions were attenuated by the TP receptor antagonists: ICI 192,605 (pKB = 9.2 +/- 0.3); ICI D1,542 (pKB = 9.1 +/- 0.3); L670,596 (pKB = 8.6 +/- 0.3); GR 32,191 (pKB = 8.6 +/- 0.2); SQ 29,548 (pKB = 8.2 +/- 0.5); ONO 3,708 (pKB = 8.1 +/- 0.3) and BM 13,505 (pKB = 7.4 +/- 0.2). The binding of [125I]-BOP to human myometrial membranes was saturable, selective and displaceable. Equilibrium binding of [125I]-BOP identified one class of sites, Kd = 3.4 nM (pKd = 8.7 +/- 0.4) and a maximum binding of 323.1 +/- 361.5 fmol/mg protein. The addition of the nonhydrolyzable GTP analog GTP gamma S (100 microM) to the assay had no effect on [125I]-BOP binding. The Kd determined kinetically was 4.1 +/- 0.2 nM. TP receptor antagonists competed for [125I]-BOP binding: ICI D1,542 (pIC50 = 8.3 +/- 0.4); L670,596 (pIC50 = 7.9 +/- 0.1); ICI 192,605 (pIC50 = 7.2 +/- 0.1); ONO 3,708 (pIC50 = 7.2 +/- 0.04); SQ 29,548 (pIC50 = 7.2 +/- 0.1); GR 32,191 (pIC50 = 7.0 +/- 0.2); BM 13,505 (pIC50 = 6.8 +/- 0.1). The rank order of potency for the seven TP receptor antagonists in displacing [125I]-BOP from its binding site was correlated (r = 0.75) with the rank order of potency in inhibiting U-46,619-induced contraction of myometrial strips. Ligands selective for other prostanoid receptors were unable to significantly displace [125I]-BOP binding. These results are consistent with the notion that the human myometrial TP receptor is pharmacologically similar to the low affinity TP receptor in human platelets.
authors.affiliation: Department of Obstetrics and Gynecology, McMaster University, Hamilton, Ontario, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Senchyna
authors.forename: D J
authors.initials: DJ
authors.lastname: Crankshaw
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000328:Adult; D001667:Binding, Competitive; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D005260:Female; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008875:Middle Aged; D009215:Myometrium / Q000737:chemistry*; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D017482:Receptors, Thromboxane / Q000032:analysis*; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D005231:Fatty Acids, Unsaturated; D011450:Prostaglandin Endoperoxides, Synthetic; D017482:Receptors, Thromboxane; C061750:7-(3-(3-hydroxy-4-(4'-iodophenoxy)-1-butenyl)-7-oxabicyclo(2.2.1)heptan-2-yl)-5-heptenoic acid; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid