Fig. 6.

Effect of luminal perfusion of PA1 on $\mathrm{HC}{\mathrm{O}}_{\mathrm{3}}^{\mathrm{-}}$ secretion and serotonin (5-HT) release in portal vein (PV) in rat duodenum. The duodenal loop was perfused with pH 7.0 Krebs buffer with or without PA1 (1 µM or 0.1 mM) in vivo. IND (5 mg/kg sc) was pretreated 1 h before the experiments. A: duodenal $\mathrm{HC}{\mathrm{O}}_{\mathrm{3}}^{\mathrm{-}}$ secretion was measured with flow-through pH and CO₂ electrodes and expressed as total CO₂ output. B: during luminal perfusion of PA1 (1 µM or 0.1 mM), PV blood was collected and 5-HT levels were measured. Each data point is expressed as the mean ± SE (n = 5 or 6). P < 0.05 vs. pH 7.0 Krebs group (*) and PA1 (1 µM) group (†).