Dose-Dependent Increase in Concentrations of Gastric Inhibitory Polypeptide and Pancreatic Polypeptide after Small Amounts of Glucose Intraduodenally in Man

Abstract

Nine healthy volunteers were infused intraduodenally with 100 ml isotonic solutions of 1, 2.5, and 5 g glucose for 15 min at 1-h intervals. The gastric inhibitory polypeptide (GIP) concentration in plasma did not increase after 1 g of glucose, whereas after 2.5 g of glucose the GIP concentration increased from 32.1 (23.2-68.4) to 53.9 (30.0-63.0) pM and after 5 g from 36.8 (18.0-54.7) to 78.5 (46.9-163) pM. The serum concentration of pancreatic polypeptide (PP) increased only after 5 g, from 19.3 (14.8-29.1) to 28.8 (15.3-45.3) pM. This shows that the plasma concentration of GIP increases dose-dependently after small doses of duodenal glucose and that glucose really is a duodenal stimulus for an increase in serum PP concentration.

Key-words:

• Entero-insular axis
• gastric inhibitory polypeptide
• glucose
• insulin
• pancreatic polypeptide
• response, dose-dependent