1-(m-chlorophenyl)-biguanide, a potent high affinity 5-HT3 receptor agonist

Eur J Pharmacol. 1990 Jun 21;182(1):193-7. doi: 10.1016/0014-2999(90)90513-6.


1-(m-Chlorophenyl)-biguanide (mCPBG) was examined and compared with three 5-HT3 receptor agonists in three 5-HT3 receptor models. mCPBG inhibited [3H]GR67330 binding to 5-HT3 receptors with high affinity (IC50 1.5 nM). mCPBG depolarized the rat vagus nerve with an EC50 one tenth of that for 5-HT (0.05 vs. 0.46 microM); the maximum depolarization was approximately half that for 5-HT. The mCPBG depolarization was potently blocked by the selective 5-HT3 antagonist, ondansetron (pKB 8.6 +/- 0.1). In anaesthetised cats, mCPBG potently evoked the Bezold-Jarisch reflex which was blocked by low doses of ondansetron (10 micrograms/kg i.v.). It is concluded that mCPBG is a potent, high affinity 5-HT3 receptor agonist.

MeSH terms

  • Anesthesia
  • Animals
  • Biguanides / pharmacology*
  • Binding, Competitive / drug effects
  • Cats
  • Heart Rate / drug effects
  • Imidazoles / pharmacology
  • In Vitro Techniques
  • Male
  • Ondansetron
  • Rats
  • Receptors, Serotonin / drug effects*
  • Reflex / drug effects
  • Vagus Nerve / drug effects
  • Vagus Nerve / metabolism


  • Biguanides
  • Imidazoles
  • Receptors, Serotonin
  • Ondansetron
  • 1-(3-chlorophenyl)biguanide
  • phenyl biguanide