Pituitary adenylate cyclase-activating polypeptide relaxes rat gastrointestinal smooth muscle

Z. Mungan, A. Arimura, Atilla Ertan, W. J. Rossowski, D. H. Coy

Research output: Contribution to journalArticle

53 Scopus citations

Abstract

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a new member of the secretin/glucagon peptides family, being most homologous to vasoactive intestinal peptide (VIP). The present study was designed to investigate a possible effect of PACAP on the rat gastrointestinal smooth muscle in vitro. We demonstrated that 1) PACAP reduced basal smooth-muscle contractions in all portions of the gastrointestinal tract, but the effect of VIP was region-specific. The inhibitory effect of PACAP in mid-colon was approximately 100 times greater than that of VIP. 2) PACAP significantly inhibited smooth-muscle contractions induced by acetylcholine or carbachol. The inhibitory effect of PACAP was not affected by hexamethonium and was additive to the inhibitory effect of atropine and pirenzepine. 3) PACAP inhibited smooth-muscle contractions induced by substance P, cholecystokinin, and galanin, even after atropine treatment. Although the exact mechanism of the inhibitory action of PACAP remains to be clarified, PACAP appears to exert its effect in the rat at a site other than muscarinic receptors, probably through a direct effect on gastrointestinal smooth muscle in vitro.

Original languageEnglish (US)
Pages (from-to)375-380
Number of pages6
JournalScandinavian Journal of Gastroenterology
Volume27
Issue number5
DOIs
StatePublished - Jan 1 1992

Keywords

  • Pituitary adenylate cyclase-activating polypeptide
  • Rat GI tract
  • Smooth-muscle contraction
  • Vasoactive intestinal polypeptide

ASJC Scopus subject areas

  • Gastroenterology

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