title: Effect of vasoactive intestinal polypeptide on the release of serotonin from the in vitro vascularly perfused small intestine of guinea pig.
abstract: Isolated segments of the guinea pig small intestine were vascularly perfused and the release of endogenous serotonin (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) into the portal vein was measured. All test substances were intraarterially perfused. Vasoactive intestinal polypeptide (VIP, 1 pmol/l-100 nmol/l) inhibited the spontaneous release of 5-HT and 5-HIAA. The maximal inhibitory effect (about 60%) was seen at 100 pmol/l. The effect of VIP on the spontaneous release of 5-HT and 5-HIAA was not changed in the presence of 1 mumol/l tetrodotoxin (TTX). Raising intraluminal pressure by 500 Pa for 5 min increased the release of 5-HT and 5-HIAA by about 25%. Raising the intraluminal pressure in the presence of VIP reduced the release of 5-HT and 5-HIAA by about 75%. In the presence of TTX (1 mumol/l), raising intraluminal pressure also caused a decrease of the release of 5-HT and 5-HIAA which was unaffected by the additional presence of VIP. The fluid volume expelled during peristaltic activity was not affected by VIP, but reduced by about 90% in the presence of TTX. In conclusion the results demonstrate a direct inhibitory effect of VIP on the release of 5-HT from the enterochromaffin cells. In addition, VIP appears to interfere with the neuronally mediated stimulation of 5-HT release during peristaltic activity.
authors: Department of Pharmacology, University of Mainz, Federal Republic of Germany.
authors: H
authors: H
authors: Schwörer
authors: K
authors: K
authors: Racké
authors: H
authors: H
authors: Kilbinger
mesh_terms: D000818:Animals; D006168:Guinea Pigs; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D066298:In Vitro Techniques; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*
chemical_list: D012701:Serotonin; D014660:Vasoactive Intestinal Peptide; D013779:Tetrodotoxin; D006897:Hydroxyindoleacetic Acid