Synthetic GLP-1 lowers postprandial (pp) glycemia by stimulating insulin, inhibiting glucagon, and delaying gastric emptying. However, the effects of the endogenous peptide are largely unknown. Using the specific GLP-1 receptor antagonist exendin(9-39)amide (Ex(9-39)) the investigators recently showed that GLP-1 released during intestinal meal perfusion acts as an incretin hormone and as an enterogastrone. As the relative contributions of these effects to controll postprandial glycemia are unclear, the investigators used Ex(9-39) to investigate the mechanisms of action of GLP-1 after an oral meal in humans.

Two experiments were performed in random order in 12 healthy subjects. After a 50-min basal period subjects ingested a 412 kcal mixed semisolid meal containing 30g oatmeal, labelled with 99mTc-Sn-colloid. Gastric emptying was measured by high-resolution scintigraphy until 210 min after meal ingestion. Saline (SAL) or Ex(9-39) at 900 pmol/kg/min was intravenously infused during the two experiments. In addition, in 6 of the 12 subjects gastric motility was measured by antroduodenal manometry and gastric barostat. AUC: pp incremental area under the curve. Lag period (LP): time to 10% emptying.

Inclusion Criteria:

• Healthy subject
• >=18 years of age
• No medication

Exclusion Criteria:

• Acute disease
• Metabolic disease
• On medication
• Pregnancy, breast feeding
• Gastrointestinal surgery
• Dyspeptische Symptome (Völlegefühl, Blähungen, abdominelle Schmerzereignisse, Übelkeit, Erbrechen, Sodbrennen)
• Teilnahme an einer klinischen Studie in den vergangenen 6 Monaten