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Abstract:
The objective of this study was to examine the effect of neurotensin (NT) on pancreatic exocrine secretion in awake dogs (n = 5) with chronic gastric and pancreatic fistulas. Intravenous (IV) infusion of NT (1 microgram/kg/hr) alone significantly stimulated pancreatic secretion of protein and bicarbonate without causing release of secretin or cholecystokinin-33 (CCK-33). IV NT potentiated the secretory response of pancreatic bicarbonate to the intraduodenal (ID) infusion of HCl alone and to ID infusions of the amino acids, phenylalanine and tryptophan (AA) alone, as well as to an ID mixture of AA plus HCl. IV NT acted in an additive manner with ID AA, ID HCl, or ID AA plus HCl in the stimulation of pancreatic protein output. The addition of IV NT to each luminal secretagogue (ID AA, ID HCl, or ID AA plus HCl) failed to elevate plasma concentrations of CCK-33 or secretin over those observed during ID infusion of each secretagogue alone. ID corn oil (Lipomul) stimulated the simultaneous release of CCK-33, NT, and secretin significantly; IV infusion of NT (0.5 microgram/kg/hr) resulted in plasma NT levels that were similar to levels observed after ID Lipomul. These studies provide evidence that endogenous NT, CCK, and secretin may interact in the physiologic regulation of pancreatic exocrine secretion.