Secretion of neurotensin and its effects on the jejunum in the dog.

The triple-lumen perfusion technique was used to assess the effect of neurotensin on the canine jejunum; net water and electrolyte fluxes were measured during intravenous infusion of neurotensin and during preceding and succeeding control infusions of sodium chloride. A pharmacologic dose of neurotensin (70 pmol X kg-1 X min-1) converted basal net jejunal water and electrolyte absorption to net secretion (p less than 0.02); 3.2 pmol X kg-1 X min-1 of the peptide significantly inhibited net water and electrolyte absorption (p less than 0.05), and induced a transient but consistent increase in jejunal transmural potential difference; however, 1.3 pmol X kg-1 X min-1 had no significant effect on net jejunal water and electrolyte fluxes. Neurotensin (1.3 pmol X kg-1 X min-1) induced a rise in plasma neurotensinlike immunoreactivity which was greater than the increment occurring after a normal meal, but which could be reproduced in the same animals by infusion of oleic acid into the ileum. This latter stimulus, however, had no effect on jejunal potential difference, or net water and electrolyte fluxes. These observations do not support a hormonal role for neurotensin in the postprandial regulation of intestinal function in the dog, although they do not rule out the possibility of physiologic paracrine activity.