Evidence for the distinct nature of F 2-isoprostane receptors from those of thromboxane a 2

Megumu Fukunaga, Takafumi Yura, Ryszard Grygorczyk, Kamal F. Badr

Research output: Contribution to journalArticlepeer-review

Abstract

-In rat glomeruli and mesangial cells, the thromboxane A 2 (TxA 2) mimetic, U-46,619, but not 8-iso-prostaglandin F (8-isoPGF ), reduced glomerular inulin space and increased inositol 1,4,5-trisphosphate production, effects abolished by SQ29,548. In competitive binding studies using 8-iso-[ 3H]PGF or [ 3H]SQ-29,548, mesangial cells displayed TxA 2 binding sites but not ones for 8-iso-PGF . In contrast, rat aortic smooth muscle cells possessed specific binding sites for both TxA 2 and S-iso-PGF 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 TxA 2 receptor cDNA was expressed in Xenopus oocytes injected with the Ca 2+-specific photoprotein, aequorin, 8-iso-PGF gave much weaker responses than U-46,619. These studies provide the first radio-ligand binding characteristics of the F 2-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.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume272
Issue number4 PART 2
StatePublished - 1997
Externally publishedYes

Keywords

  • Binding characteristics
  • Mitogen-activated protein kinases
  • Signal transduction mechanism

ASJC Scopus subject areas

  • Physiology (medical)

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