Binding properties of the novel, non-peptide CGRP receptor antagonist radioligand, [(3)H]BIBN4096BS

Eur J Pharmacol. 2002 May 10;442(3):187-93. doi: 10.1016/s0014-2999(02)01544-3.

Abstract

BIBN4096BS [[R-(R,(R*,S*)]-N-[2-[[5-amino-1-[[4-(4-pyridinyl)-1-piperazinyl]carbonyl] pentyl]amino]-1-[(3,5-dibromo-4-hydroxyphenyl)methyl]-2-oxoethyl]-4-(1,4-dihydro-2-oxo-3(2H)-quinazolinyl)-,1-Piperidinecarboxamide] is a selective calcitonin gene-related peptide (CGRP) receptor antagonist with a picomolar affinity to the CGRP receptor in human neuroblastoma SK-N-MC cells. Here, we describe the characterisation of the binding properties of the tritiated radioanalogue of BIBN4096BS in SK-N-MC cells as well as in marmoset tissue. [(3)H]BIBN4096BS showed reversible and saturable binding to SK-N-MC cells with a K(D) of 0.045 nM. In competition experiments, [3(H)]BIBN4096BS is concentration-dependently displaced from SK-N-MC cell membranes by BIBN4096BS as well as by the endogenous ligand CGRP and its analogues with the rank order of affinity BIBN4096BS>human alpha-CGRP=human beta-CGRP>[Cys(Et)(2,7)]human alpha-CGRP>adrenomedullin (high affinity site)=human alpha-CGRP-(8-37)=human beta-CGRP-(8-37)>calcitonin=amylin. In the marmoset cortex, saturable [(3)H]BIBN4096BS binding was observed with a K(D) of 0.077 nM. CGRP showed biphasic competition of [(3)H]BIBN4096BS binding, whilst BIBN4096BS monophasically displaced its radioanalogue with a K(i) of 0.099 nM. These data, using [(3)H]BIBN4096BS, confirm the high affinity of this novel antagonist for the primate CGRP receptor and demonstrate furthermore that this radioligand is a useful tool to study CGRP receptor pharmacology.

MeSH terms

  • Animals
  • Binding, Competitive
  • Brain / metabolism
  • Calcitonin Gene-Related Peptide / metabolism
  • Calcitonin Gene-Related Peptide Receptor Antagonists
  • Callithrix
  • Cerebral Cortex / metabolism
  • Dura Mater / metabolism
  • Female
  • Humans
  • Hydrogen-Ion Concentration
  • Iodine Radioisotopes
  • Kinetics
  • Male
  • Piperazines*
  • Piperidines / metabolism*
  • Piperidines / pharmacology
  • Quinazolines / metabolism*
  • Quinazolines / pharmacology
  • Radioligand Assay
  • Receptors, Calcitonin Gene-Related Peptide / metabolism*
  • Spleen / metabolism
  • Tritium
  • Tumor Cells, Cultured / metabolism

Substances

  • Calcitonin Gene-Related Peptide Receptor Antagonists
  • Iodine Radioisotopes
  • Piperazines
  • Piperidines
  • Quinazolines
  • Receptors, Calcitonin Gene-Related Peptide
  • Tritium
  • Calcitonin Gene-Related Peptide
  • olcegepant