Distribution of binding sites for thromboxane A2 in the mouse kidney.

Academic Article

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, [125I]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.
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    Keywords

  • Alternative Splicing, Animals, Autoradiography, Binding Sites, Bridged Bicyclo Compounds, Heterocyclic, Fatty Acids, Unsaturated, Kidney, Male, Mice, Mice, Inbred C57BL, Polymerase Chain Reaction, RNA, Messenger, Receptors, Thromboxane, Thromboxane A2, Tissue Distribution, Transcription, Genetic
  • Digital Object Identifier (doi)

    Author List

  • Mannon RB; Coffman TM; Mannon PJ
  • Start Page

  • F1131
  • End Page

  • F1138
  • Volume

  • 271
  • Issue

  • 6 Pt 2