Fig. 1.

Effect of intravenous infusion of GIP(1-39), Ex-4, or GLP-2 on duodenal HCO₃⁻ secretion in rats. Duodenal HCO₃⁻ secretion was measured as total CO₂ output using flow-through pH and CO₂ electrodes. Vehicle, GIP(1-39) (0.1–1 nmol/kg/h) (A and B), Ex-4 (0.1–1 nmol/kg/h) (C and D), or GLP-2 (0.01–1 nmol/kg/h) (E and F) was intravenously infused. A, C, and E, total CO₂ output over the time course. Each data point represents mean ± S.E.M. (n = 6 rats). *, p < 0.05 versus vehicle group. B, D, and F, total HCO₃⁻ output during the challenge period. Each data point represents mean ± S.E.M. (n = 6). *, p < 0.05 versus vehicle group, †, p < 0.05 versus 0.1 group (B and D) or 0.01 group (F).