Relaxant effects of pituitary adenylate cyclase activating polypeptide (PACAP) on epithelium-intact and -denuded guinea-pig trachea: a comparison with vasoactive intestinal peptide (VIP)

Neuropeptides. 1995 Sep;29(3):121-7. doi: 10.1016/0143-4179(95)90013-6.


The effect of pituitary adenylate cyclase activating peptide (PACAP 1-27) was examined on epithelium-intact and -denuded guinea-pig tracheal strips (GPT) and compared to vasoactive intestinal peptide (VIP) and salbutamol. PACAP (10(-11)-10(-8) moles) induced dose-dependent relaxations of the basal tone of both epithelium-intact and -denuded GPT. PACAP was approximately three times less potent than either VIP or salbutamol in relaxing epithelium-intact GPT. The relaxant effects of both peptides and salbutamol were markedly attenuated following removal of the epithelial layer. L-NAME (10(-4) M), a nitric oxide synthase inhibitor, did not affect the responses induced by either PACAP or VIP demonstrating that the relaxant effect is independent of nitric oxide synthesis. Phosphoramidon (5 x 10(-6) M) potentiated the relaxant responses of epithelium-intact GPT to both PACAP and VIP but did not affect the responses of epithelium-denuded GPT. PACAP and VIP also induced relaxations of the guinea-pig upper bronchus. In addition, PACAP (10(-6) M), as well as VIP, significantly inhibited the release of TxB2 induced by LTD4 (10(-7) M) from chopped guinea-pig lung suggesting that this newly isolated peptide, which has 68% homology with VIP, may possess anti-inflammatory action in the lung.

Publication types

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

MeSH terms

  • Adrenergic beta-Agonists / pharmacology*
  • Albuterol / pharmacology*
  • Animals
  • Arginine / analogs & derivatives
  • Arginine / pharmacology
  • Bronchi / drug effects
  • Cyclooxygenase Inhibitors / pharmacology
  • Epithelium / drug effects
  • Guinea Pigs
  • In Vitro Techniques
  • Leukotriene D4 / pharmacology
  • Muscle Relaxation / drug effects
  • Muscle Tonus / drug effects
  • Muscle, Smooth / drug effects*
  • NG-Nitroarginine Methyl Ester
  • Neuropeptides / pharmacology*
  • Pituitary Adenylate Cyclase-Activating Polypeptide
  • Thromboxane B2 / metabolism
  • Trachea / drug effects
  • Vasoactive Intestinal Peptide / pharmacology*


  • Adrenergic beta-Agonists
  • Cyclooxygenase Inhibitors
  • Neuropeptides
  • Pituitary Adenylate Cyclase-Activating Polypeptide
  • Vasoactive Intestinal Peptide
  • Thromboxane B2
  • Leukotriene D4
  • Arginine
  • Albuterol
  • NG-Nitroarginine Methyl Ester