title: Evidence for the distinct nature of F2-isoprostane receptors from those of thromboxane A2.
abstract: In rat glomeruli and mesangial cells, the thromboxane A2 (TxA2) mimetic, U-46,619, but not 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha), reduced glomerular inulin space and increased inositol 1,4,5-trisphosphate production, effects abolished by SQ-29,548. In competitive binding studies using 8-iso-[3H]PGF2alpha or [3H]SQ-29,548, mesangial cells displayed TxA2 binding sites but not ones for 8-iso-PGF2alpha. In contrast, rat aortic smooth muscle cells possessed specific binding sites for both TxA2 and 8-iso-PGF2alpha and displayed functional responses to both agonists, such as time- and dose-dependent activation of mitogen-activated protein kinases. In these cells, the mean dissociation constant value for the isoprostane receptor was 31.8 +/- 5.7 nM. When human TxA2 receptor cDNA was expressed in Xenopus oocytes injected with the Ca2+-specific photoprotein, aequorin, 8-iso-PGF2alpha gave much weaker responses than U-46,619. These studies provide the first radioligand binding characteristics of the F2-isoprostane receptor and demonstrate its specific and heterologous cellular localization. These studies support the distinct nature and biological significance of isoprostane receptors and provide a tool for their further molecular characterization.
authors.affiliation: Renal Division, Department of Medicine, Emory University and Veterans Affairs Medical Center, Atlanta, Georgia 30033, USA.
authors.forename: M
authors.initials: M
authors.lastname: Fukunaga
authors.forename: T
authors.initials: T
authors.lastname: Yura
authors.forename: R
authors.initials: R
authors.lastname: Grygorczyk
authors.forename: K F
authors.initials: KF
authors.lastname: Badr
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000331:Aequorin / Q000096:biosynthesis; D000818:Animals; D001011:Aorta / Q000201:enzymology; D001667:Binding, Competitive; D019086:Bridged Bicyclo Compounds, Heterocyclic; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D018076:DNA, Complementary; D015237:Dinoprost / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D004789:Enzyme Activation; D028441:F2-Isoprostanes; D005231:Fatty Acids, Unsaturated; D005920:Glomerular Mesangium / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D006834:Hydrazines / Q000378:metabolism; D007678:Kidney Glomerulus / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000201:enzymology; D009865:Oocytes / Q000187:drug effects / Q000502:physiology; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011982:Receptors, Prostaglandin / Q000187:drug effects / Q000502:physiology*; D017482:Receptors, Thromboxane / Q000187:drug effects / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000494:pharmacology; D014982:Xenopus laevis
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D018076:DNA, Complementary; D028441:F2-Isoprostanes; D005231:Fatty Acids, Unsaturated; D006834:Hydrazines; D011450:Prostaglandin Endoperoxides, Synthetic; D011982:Receptors, Prostaglandin; D017482:Receptors, Thromboxane; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; C034671:prostaglandin F2alpha receptor; C075750:8-epi-prostaglandin F2alpha; D000331:Aequorin; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; C045749:SQ 29548; D015237:Dinoprost; D017871:Calcium-Calmodulin-Dependent Protein Kinases