Na+-dependent fluid absorption in intact perfused rat colonic crypts John P. Geibel, Vazhaikkurichi M. Rajendran, Henry J. Binder  Gastroenterology  Volume 120, Issue 1, Pages 144-150 (January 2001) DOI: 10.1053/gast.2001.20890 Copyright © 2001 American Gastroenterological Association Terms and Conditions

Fig. 1 Effect of inhibition of Cl− secretion on net fluid absorption in isolated, perfused colonic crypt. Net fluid movement was determined in the presence of either 50 or 100 μmol/L bath bumetanide, an inhibitor of Na-K-2Cl cotransport. *P < 0.01, **P < 0.001; compared with control. Results are mean ± SEM. Number in parentheses represents the number of animals studied in each experiment. □, Control; ▨, 50 μmol/L bumetanide; ■, 100 μmol/L bumetanide. Gastroenterology 2001 120, 144-150DOI: (10.1053/gast.2001.20890) Copyright © 2001 American Gastroenterological Association Terms and Conditions

Fig. 2 Role of lumen Na+ on fluid absorption (Jv) in isolated, perfused colonic crypt. (A) Control perfusion contained 140 mmol/L Na+, whereas in the Na+-free experiment, lumen Na+ was replaced by 140 mmol/L NMDG. *P < 0.001 compared with 140 mmol/L Na+ control. (B) Effect of 1 μmol/L EIPA, an amiloride analogue that selectively inhibits Na+-H exchange, on net fluid movement. Control solution contained 50 mmol/L Na+. **P < 0.001 compared with 50 mmol/L Na+ control. Results are mean ± SEM. Number in parentheses represents the number of animals studied in each experiment. Gastroenterology 2001 120, 144-150DOI: (10.1053/gast.2001.20890) Copyright © 2001 American Gastroenterological Association Terms and Conditions

Fig. 3 Effect of lumen and bath Cl− on net fluid absorption in the presence or absence of bath Cl− in the isolated, perfused colonic crypt. Either lumen or bath Cl− was selectively replaced by cyclamate. *P < 0.001 compared with lumen Cl−-Ringer. **P < 0.05 compared with lumen and bath Cl−-Ringer. Results are mean ± SEM. Number in parentheses represents the number of animals studied in each experiment. □, Lumen Cl−-Ringer; ▨, lumen Cl−-free Ringer. Gastroenterology 2001 120, 144-150DOI: (10.1053/gast.2001.20890) Copyright © 2001 American Gastroenterological Association Terms and Conditions

Fig. 4 Effect of Cl− transport inhibitors on net fluid absorption in isolated, perfused colonic crypt. DIDS is an inhibitor of anion exchange at 100 μmol/L, but of Cl− channels at 500 μmol/L.10 NPPB is an inhibitor of Cl− channels at a dose of 10 μmol/L. *P < 0.001. **P < 0.05. †P < 0.001. Results are mean ± SEM. Number in parentheses represents the number of animals studied in each experiment. □, Control; ▩, lumen NPPB; ▨, lumen DIDS (100 μmol/L); ▩, lumen DIDS (500 μmol/L). Gastroenterology 2001 120, 144-150DOI: (10.1053/gast.2001.20890) Copyright © 2001 American Gastroenterological Association Terms and Conditions

Fig. 5 Effect of acetazolamide on net fluid absorption in isolated, perfused colonic crypt. Cl− was present in the studies shown in the left 2 histograms, but was replaced by cyclomate in both lumen and bath in the studies presented in the right 2 histograms. *P < 0.001 compared with Cl−-free Ringer control. Results are mean ± SEM. Number in parentheses represents the number of animals studied in each experiment. □, Cl−-Ringer; ■, Cl−-free Ringer; ▨, acetazolamide. Gastroenterology 2001 120, 144-150DOI: (10.1053/gast.2001.20890) Copyright © 2001 American Gastroenterological Association Terms and Conditions