Potential involvement of a propranolol-insensitive atypical beta-adrenoceptor the vasodilator effect of cyanopindolol in the human pulmonary artery

J Physiol Pharmacol. 2006 Sep;57(3):317-28.


The aim of our study was to examine whether non beta(1)-/beta(2)-adrenoceptors participate in the relaxation of the human pulmonary artery. For this purpose the vasodilatory effect of the non-conventional partial beta-adrenoceptor agonist cyanopindolol was examined. Cyanopindolol (1-300 microM), studied in the presence of the beta(1)-/beta(2)-adrenoceptor antagonist propranolol, relaxed the human pulmonary artery preconstricted with serotonin 1 microM in a concentration-dependent manner (maximally by about 80%). This effect was diminished by bupranolol 10 microM (an antagonist of beta(1)-beta(3)-adrenoceptors and the low affinity state of the beta(1)-adrenoceptor) and CGP 20712 10 microM (known to antagonize the low-affinity state of the beta(1)-adrenoceptor at high concentrations). In further experiments, the effect of beta-adrenoceptor ligands on the serotonin-induced vasoconstriction was examined. The concentration-response curve for serotonin was not affected by cyanopindolol 30 microM, bupranolol 10 microM and CGP 20712 10 microM but shifted to the right by cyanopindolol 100 and 300 microM; the serotonin 5-HT(2A) receptor antagonist ketanserin 0.3 microM abolished the maximum contraction elicited by serotonin. In conclusion, the present study reveals that the vasodilatory effect of cyanopindolol in the human pulmonary artery consists of two components, i.e. activation of a propranolol-insensitive atypical beta-adrenoceptor and antagonism against 5-HT(2A) receptors.

MeSH terms

  • Adrenergic beta-Antagonists / pharmacology*
  • Analysis of Variance
  • Bupranolol / pharmacology
  • Dose-Response Relationship, Drug
  • Female
  • Humans
  • Imidazoles / pharmacology
  • In Vitro Techniques
  • Male
  • Middle Aged
  • Pindolol / analogs & derivatives*
  • Pindolol / pharmacology
  • Pulmonary Artery / drug effects*
  • Pulmonary Artery / physiology
  • Receptor, Serotonin, 5-HT2A / drug effects
  • Receptor, Serotonin, 5-HT2A / physiology
  • Receptors, Adrenergic, beta-1 / drug effects
  • Receptors, Adrenergic, beta-2 / drug effects
  • Serotonin 5-HT2 Receptor Antagonists
  • Vasoconstriction / drug effects
  • Vasodilation / drug effects*
  • Vasodilation / physiology
  • Vasodilator Agents / pharmacology*


  • Adrenergic beta-Antagonists
  • Imidazoles
  • Receptor, Serotonin, 5-HT2A
  • Receptors, Adrenergic, beta-1
  • Receptors, Adrenergic, beta-2
  • Serotonin 5-HT2 Receptor Antagonists
  • Vasodilator Agents
  • cyanopindolol
  • Bupranolol
  • Pindolol
  • CGP 20712A