Distribution of binding sites for thromboxane a2 in the mouse kidney

Roslyn B. Mannon, Thomas M. Coffman, Peter J. Mannon

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Thromboxane A2 (TxA2) is a potent vasoconstrictor eicosanoid that has been implicated in the pathogenesis of both human and experimental renal diseases. The biological actions of TxA2 in the kidney are mediated through specific cell-surface receptors. In this report, we characterize the distribution of thromboxane receptors (TxR) within the normal mouse kidney by receptor autoradiography. With the iodinated TxR agonist [125I]BOP, TxA2 binding sites were detected throughout the kidney. Competitive inhibition curves of whole kidney binding demonstrated a half-maximal inhibitory concentration of 6.5 nM. When Scatchard analysis was performed on anatomically discrete regions, the [125I]BOP binding in the medulla was best fit by a one-site model, with a dissociation constant (Kd) of 8.2 ± 2.2 nM. In contrast, [126I]BOP binding in the cortex was better described by a two-site model, with estimated Kd of 262 ± 16 pM for a higher affinity site and 16.9 ± 1.3 nM for a lower affinity site. These sites do not appear to represent receptor isoforms that arise from alternative splicing of mRNA. The lower affinity binding sites may represent a novel TxR or an alternative affinity state for the previously characterized high-affinity binding site.

Original languageEnglish (US)
Pages (from-to)F1131-F1138
JournalAmerican Journal of Physiology
Volume271
Issue number6 PART 2
DOIs
StatePublished - 1996

Keywords

  • Eicosanoid
  • Glomerulus
  • Medulla
  • Receptor autoradiography

ASJC Scopus subject areas

  • Physiology (medical)

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