FIGURE 2.

Pancreatic ductal HCO₃^- and fluid secretion in AQP1 knock out mice. (A) Traditional PCR shows the presence of AQP1 mRNA both in the isolated pancreatic ducts (PD) and in the total pancreas (TP). As positive control, kidney was used (K). (B) Pancreatic ductal fluid secretion was measured on isolated pancreatic ducts from wild type (WT, black line) and AQP1 knock out (KO, red line) mice. Changes in the relative luminal volume of the ducts was measured by videomicroscopy and analyzed by Scion Image software. (C) Changes in the relative luminal volume of the pancreatic ducts of AQP1 WT and KO mice measured at the final time point (40 min). Data are shown as means ± SEM. n = 4–8 ducts/groups. ^∗p ≤ 0.05 vs. WT. (D) Reconstructed images of the duodenal filling before (1) and after (2) secretin stimulation. Yellow color shows the presence of fluid. Red arrows indicate excreted volume in the small bowel after stimulation with secretin. In the case of KO mice, the secretin-stimulated fluid secretion significantly decreased. (E) In vivo pancreatic fluid secretion was measured as total excreted volume (TEV) using small animal magnetic resonance imaging. Raw data were acquired in axial and coronar view. Data are shown as means ± SEM. n = 4 animals/groups. ^∗p ≤ 0.05 vs. WT. (F) Representative experimental traces show pancreatic ductal HCO₃^- secretion in AQP1 WT (black line) and AQP1 KO (red line) mice. (G) Base flux [–J(B^-/min)] was calculated from the ΔpH/Δt obtained by linear regression analysis of pH_i measurements made over the first 60 s after readdition of extracellular Cl^-. Means ± SEM are from 20 ROIs of four ducts. ^∗p ≤ 0.05 vs. WT.