Motility and hemodynamics of the canine gastrointestinal tract. Stimulation by pentagastrin, cholecystokinin and vasopressin.

Effects of pentagastrin (1-4096 ng/kg), cholecystokinin (1-4096 mU/kg, CCK) and vasopressin (.032-128 mU/kg) on gastrointestinal motility and blood flow, were determined by simultaneous measurement of blood flow (electromagnetic flow probes) to and motor activity (strain gages) of corpus, antrum, duodenum, jejunum, and colon of anesthetized dogs. Antral contractile amplitude was increased by pentagastrin at relatively low doses. Pentagastrin also increased corpus blood flow, corpus tone and antral blood flow. Gastric contractile frequency was least sensitive to pentagastrin. Corpus blood flow was decreased and small intestinal blood flow was increased by cholecystokinin at relatively low doses. CCK also increased small intestinal contractile amplitude and, at higher doses, antral contractile amplitude, and duodenal tone. Time-effect relation and sensitivity were different for the hemodynamic and motor responses to pentagastrin and to cholecystokinin. This shows the lack of correlation between vasoactive and motor-stimulating properties of these drugs. However, strong drug-induced contractions were shown to impede antral blood flow (pentagastrin and CCK) by about 35% and duodenal and jejunal blood flow (CCK) by resp. 70 and 60%. Vasopressin reduced blood flow to stomach and intestines by 50-80%, without affecting gastrointestinal motility.