Endocrine pancreatic control of the release of gastric inhibitory polypeptide. A possible physiological role for C-peptide.

Intravenous infusion in anaesthetized rats of rat II C-peptide at a dose which produced circulating levels of 22.8 +/- 1.8 nmol/l after 30 min, resulted in a significant reduction (141 +/- 7 to 50 +/- 4 pmol/l, p < 0.001, mean +/- SEM) in the immunoreactive gastric inhibitory polypeptide response to an intestinal perfusion with a fat emulsion. Immunoreactive insulin levels were unchanged from basal in this study. It is suggested that C-peptide must be considered as a candidate for the endocrine pancreatic factor which exerts a negative feedback upon gastric inhibitory polypeptide release.