Beta-adrenergic control of motility in the rat colon. I. Evidence for functional separation of the beta 1- and beta 2-adrenoceptor-mediated inhibition of colon activity

Gastroenterology. 1986 Feb;90(2):400-7. doi: 10.1016/0016-5085(86)90939-x.


The beta-adrenoceptor-mediated inhibitory response in isolated rat colon strips of beta-adrenoceptor agonists (isoproterenol, terbutaline, prenalterol) in the absence and presence of the selective beta-adrenoceptor antagonists metoprolol (beta 1) and IPS 339 (beta 2) demonstrates that both beta 1- and beta 2-adrenoceptors are involved in the inhibition of colonic motility. Neuronal blockade induced by tetrodotoxin suppressed the relatively high (68%) maximal response of prenalterol (partial beta-adrenoceptor agonist) to 23%. The concentration-response curves for terbutaline (beta 2-selective agonist) and isoproterenol (nonselective agonist) were not influenced by tetrodotoxin. The results thus indicate that the beta-adrenergic inhibition of spontaneous activity in the rat colon strip may be mediated at two functional levels within the colon wall: either by beta 2-adrenoceptors in the smooth muscle layer or by beta 1-adrenoceptors in the intramural ganglionic plexuses, which by neuronal elements are coupled to the effector smooth muscle.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic beta-Agonists / pharmacology
  • Adrenergic beta-Antagonists / pharmacology
  • Animals
  • Colon / physiology*
  • Gastrointestinal Motility*
  • Isoproterenol / pharmacology
  • Male
  • Metoprolol / pharmacology
  • Muscle, Smooth / drug effects
  • Muscle, Smooth / physiology*
  • Practolol / analogs & derivatives
  • Practolol / pharmacology
  • Prenalterol
  • Propanolamines / pharmacology
  • Rats
  • Rats, Inbred Strains
  • Receptors, Adrenergic, beta / drug effects
  • Receptors, Adrenergic, beta / physiology*
  • Sympathectomy
  • Terbutaline / pharmacology
  • Tetrodotoxin / pharmacology


  • Adrenergic beta-Agonists
  • Adrenergic beta-Antagonists
  • Propanolamines
  • Receptors, Adrenergic, beta
  • Tetrodotoxin
  • IPS 339
  • Metoprolol
  • Isoproterenol
  • Prenalterol
  • Terbutaline
  • Practolol