Effect of xenopsin on blood flow, hormone release, and acid secretion

We investigated the effects of the neurotensin analogue xenopsin on regional blood flow, central hemodynamics, and stimulated acid secretion in awake conscious dogs. Organ blood flow, estimated using the radioactive microsphere technique, was significantly increased during the xenopsin infusion to the adrenals, pancreas, and ileum. There was no change in mean arterial pressure or cardiac output (measured by thermodilution). Along with changes in blood flow, there was a significant increase in the hormone output from the pancreas. These included rises in plasma pancreatic polypeptide, insulin, and glucagon. There also was a rise in plasma cortisol levels during the infusion. Substance P levels rose slowly but significantly during the xenopsin infusion. There was no change in plasma gastrin levels. Xenopsin produced a significant inhibition of tetragastrin-stimulated gastric acid output. Thus, xenopsin appears to have region-specific influence on blood flow that correlates with region-specific hormonal secretion. In addition, xenopsin, like its mammalian analogue neurotensin, is an inhibitor of stimulated gastric acid secretion. A mammalian xenopsin-like peptide may well be involved in the modulation of gastrointestinal function.