EFFECTS OF VASOACTIVE INTESTINAL POLYPEPTIDE ON BLOOD-FLOW, MOTILITY AND FLUID TRANSPORT IN THE GASTRO-INTESTINAL TRACT OF THE CAT

The effect of close intra-arterial infusions of vasoactive intestinal polypeptide (VIP) on gastric motility, intestinal fluid transport and colonic motility were studied in the cat. Regional blood flow was followed in all experiments. In the stomach VIP produced a gastric relaxation and a blood flow increase. The motility response was similar to that seen when eliciting the vago-vagal reflex relaxation by distending the esophagus. In the small intestine a hyperemia and a decrease of net H2O uptake was seen. When infusing small amounts of VIP a decrease of net water uptake was seen without any change of intestinal blood flow. Large amounts of VIP produced a transient secretory state in the small intestine. In the colon a hyperemia was seen immediately upon starting infusion of the drug. After 2-3 min of infusion a contraction of the colon was apparent. The administration of atropine to the animal did not significantly affect any of the responses produced by VIP. VIP may be a gastrointestinal tract neurotransmitter.