Human myocardial beta-adrenoceptors: demonstration of both beta 1- and beta 2-adrenoceptors mediating contractile responses to beta-agonists on the isolated right atrium

Naunyn Schmiedebergs Arch Pharmacol. 1986 Feb;332(2):142-7. doi: 10.1007/BF00511404.


On the isolated electrically driven muscle strip of human right atrial appendages the beta-adrenoceptor subtypes mediating the positive inotropic effects of isoprenaline, dobutamine and procaterol were characterized using the beta 1-selective antagonist bisoprolol and the beta 2-selective antagonist ICI 118,551. The three agonists induced concentration-dependent increases in force of contraction with an order of potency: procaterol (pD2-value: 8.03) greater than isoprenaline (pD2-value: 7.73) greater than dobutamine (pD2-value: 5.44). In saturating concentrations all three agonists produced the same maximum of developed tension. ICI 118,551 (10(-9)--10(-7) mol/l) and bisoprolol (10(-9)--10(-7) mol/l) were nearly equipotent in antagonizing the positive inotropic effects of isoprenaline and dobutamine. However, the slopes of the Schild-plots for both antagonists against both agonists were significantly less than 1.0 indicating interaction with beta 1- and beta 2-adrenoceptors. On the other hand, ICI 118,551 (10(-10)--10(-8) mol/l) was approximately 100 times more potent than bisoprolol (10(-8)--10(-6) mol/l) in antagonizing the positive inotropic effect of the highly selective beta 2-agonist procaterol. In addition, the slopes of the Schild-plots for antagonism of ICI 118,551 and bisoprolol against procaterol were not significantly different from unity indicating interaction with a homogeneous class of beta-adrenoceptors. The pA2-value for ICI 118,551 was 9.49, for bisoprolol it amounted to 6.99.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic beta-Agonists / pharmacology*
  • Adult
  • Aged
  • Bisoprolol
  • Dobutamine / pharmacology
  • Dose-Response Relationship, Drug
  • Ethanolamines / pharmacology
  • Female
  • Heart Atria / drug effects
  • Humans
  • In Vitro Techniques
  • Isoproterenol / pharmacology
  • Male
  • Middle Aged
  • Myocardial Contraction* / drug effects
  • Myocardium / metabolism*
  • Procaterol
  • Propanolamines / pharmacology
  • Receptors, Adrenergic, beta / metabolism*
  • Stimulation, Chemical


  • Adrenergic beta-Agonists
  • Ethanolamines
  • Propanolamines
  • Receptors, Adrenergic, beta
  • Dobutamine
  • ICI 118551
  • Isoproterenol
  • Procaterol
  • Bisoprolol