FIG. 1. Plasma concentrations of GLP-1 (A), glucose (C), insulin (D), glucagon (E), C-peptide (F), PP (G), and GIP (H), and gastric emptying (B) after instilling two liquid test meals (amino acids and sucrose) via a nasogastric tube into the stomach at 0 and 240 min in nine healthy young volunteers during the intravenous infusion of GLP-1 (0.8 pmol · kg⁻¹ ⋅ min⁻¹) or placebo. Mean ± SEM. P values were calculated by repeated-measures ANOVA. *Significant (P < 0.05) differences at specific time points between experiments with placebo and GLP-1. †Significant difference from the corresponding time point after the first meal during the exogenous administration of GLP-1. FIG. 1. Plasma concentrations of GLP-1 (A), glucose (C), insulin (D), glucagon (E), C-peptide (F), PP (G), and GIP (H), and gastric emptying (B) after instilling two liquid test meals (amino acids and sucrose) via a nasogastric tube into the stomach at 0 and 240 min in nine healthy young volunteers during the intravenous infusion of GLP-1 (0.8 pmol · kg−1 ⋅ min−1) or placebo. Mean ± SEM. P values were calculated by repeated-measures ANOVA. *Significant (P < 0.05) differences at specific time points between experiments with placebo and GLP-1. †Significant difference from the corresponding time point after the first meal during the exogenous administration of GLP-1. More