Binding of KRH-594, an antagonist of the angiotensin II type 1 receptor, to cloned human and rat angiotensin II receptors

Fundam Clin Pharmacol. 2002 Aug;16(4):317-23. doi: 10.1046/j.1472-8206.2002.00076.x.

Abstract

We studied the binding properties of KRH-594, a new selective antagonist of angiotensin II (AII) type 1 (AT1) receptors, to rat liver membranes and to recombinant AT1 and AT2 receptors. Preincubation of rat liver membranes with KRH-594 produced maximal inhibition of [125I]-AII binding when the preincubation time was 1-2 h. Preincubation with KRH-594 for 2 h decreased the B(max) value and increased the Kd value. For human AT1, human AT2, rat AT1A and rat AT1B receptors, the Ki values for KRH-594 were 1.24, 9360, 0.67, and 1.02 nm, respectively. The rank order of K1 values for human AT1 receptors was KRH-594 >> EXP3174 > candesartan = AII. The order of specificities for human AT1 and AT2 receptors was candesartan > EXP3174 > KRH-594. Although a 2-h preincubation of human AT2 receptors with KRH-594 (30 microM) or CGP 42112 (a selective AT2 receptor antagonist; 0.3 nM) inhibited binding of [125I]-AII, the suppression by KRH-594 was not significant. These results indicate that KRH-594 binds potently to AT1 receptors in an insurmountable manner, and that at a very high dose (30 microM) it may also bind to AT2 receptors, but in a surmountable manner.

Publication types

  • Comparative Study

MeSH terms

  • Angiotensin II / antagonists & inhibitors*
  • Angiotensin Receptor Antagonists*
  • Animals
  • Benzimidazoles / pharmacology
  • Biphenyl Compounds
  • COS Cells
  • Chlorocebus aethiops
  • Dose-Response Relationship, Drug
  • Humans
  • Imidazoles / pharmacology
  • In Vitro Techniques
  • Liver / drug effects
  • Liver / metabolism
  • Losartan / pharmacology
  • Membranes
  • Oligopeptides / pharmacology
  • Radioligand Assay
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, Angiotensin, Type 1
  • Receptor, Angiotensin, Type 2
  • Receptors, Angiotensin / genetics
  • Receptors, Angiotensin / metabolism
  • Tetrazoles / pharmacology*
  • Thiadiazoles / pharmacology*
  • Time Factors
  • Transfection

Substances

  • Angiotensin Receptor Antagonists
  • Benzimidazoles
  • Biphenyl Compounds
  • Imidazoles
  • KRH 594
  • Oligopeptides
  • Receptor, Angiotensin, Type 1
  • Receptor, Angiotensin, Type 2
  • Receptors, Angiotensin
  • Tetrazoles
  • Thiadiazoles
  • Angiotensin II
  • CGP 42112A
  • losartan carboxylic acid
  • Losartan
  • candesartan