Cholinergic inhibition of meal stimulated plasma neurotensin like immunoreactivity in man.

Meal stimulated plasma neurotensin like immunoreactivity (NTLI) was compared during saline or atropine infusion in six volunteers over six hours. Plasma gastrin and pancreatic polypeptide were also measured to compare the timing of their release to that of NTLI. Like plasma gastrin and PP, plasma NTLI rose rapidly following the meal, rising from 27 +/- 7 pmol/l to a peak of 45 +/- 8 pmol/l at 20 minutes (p less than 0.05). Also, like that of pancreatic polypeptide, the release of NTLI was biphasic. Sixty minutes after the meal, plasma NTLI had returned to basal values, followed by a rise to a prolonged peak of 64 +/- 10 pmol/l between 90-180 minutes (p less than 0.05) returning once more to basal values by 240 minutes. Following atropine, basal plasma NTLI fell from 22 +/- 4 pmol/l to 11 +/- 2 pmol/l (p less than 0.05), but rose to basal levels 30-60 minutes after the meal, where it remained unaltered for the remainder of the study. We conclude that both basal and meal stimulated plasma NTLI are inhibited by cholinergic blockade. Further, the similar temporal relationship between plasma NTLI and pancreatic polypeptide in the late phase of the meal response, suggests that a component of NTLI may mediate part of the intestinal phase of pancreatic polypeptide release.