Functional evidence of atypical beta 3-adrenoceptors in the human colon using the beta 3-selective adrenoceptor antagonist, SR 59230A

Br J Pharmacol. 1996 Apr;117(7):1374-6. doi: 10.1111/j.1476-5381.1996.tb15294.x.


The role of beta 3-adrenoceptors in human colonic circular smooth muscle was assessed in vitro by use of the beta 3-selective antagonist SR 59230A. Isoprenaline, in the presence of the selective beta-adrenoceptor antagonists CGP 20712A (beta 1) and ICI 118551 (beta 2), both at 0.1 microM, concentration-dependently relaxed the preparation (pEC50 = 5.22). This effect was potently and competitively antagonized by SR 59230A with a pA2 of 8.31, while its R,R enantiomer SR 59483A gave an apparent pKB of 6.21. Relaxation was likewise produced by CGP 12177A (pEC50 = 6.05), but not by BRL 37344. Although only one of these beta 3-selective agonists was effective, the remarkably high potency of SR 59230A as a stereospecific antagonist of non-beta 1 non-beta 2 relaxation of human colonic muscle by isoprenaline provides strong functional evidence of beta 3-adrenoceptors in that tissue.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic beta-Agonists / pharmacology
  • Adrenergic beta-Antagonists / pharmacology*
  • Aged
  • Colon
  • Female
  • Humans
  • In Vitro Techniques
  • Isoproterenol / pharmacology
  • Male
  • Middle Aged
  • Muscle Relaxation / drug effects
  • Muscle, Smooth / drug effects
  • Muscle, Smooth / metabolism*
  • Propanolamines / pharmacology*
  • Receptors, Adrenergic, beta / metabolism*
  • Receptors, Adrenergic, beta-3
  • Stereoisomerism


  • 3-(2-ethylphenoxy)-1-(1,2,3,4-tetrahydronaphth-1-ylamino)-2-propanol oxalate
  • Adrenergic beta-Agonists
  • Adrenergic beta-Antagonists
  • Propanolamines
  • Receptors, Adrenergic, beta
  • Receptors, Adrenergic, beta-3
  • Isoproterenol