Volume 118, Issue 1, Pages 101-107 (January 2000) HCO3− secretion in the rat colonic crypt is closely linked to Cl− secretion  John P. Geibel*,‡, Satish Singh‡,§, Vazhaikkurichi M. Rajendran§, Henry J. Binder‡,§  Gastroenterology  Volume 118, Issue 1, Pages 101-107 (January 2000) DOI: 10.1016/S0016-5085(00)70418-5 Copyright © 2000 American Gastroenterological Association Terms and Conditions

Fig. 1 Effect of several secretogogues on net bicarbonate movement in isolated, perfused colonic crypt. After completion of a control period (2), either 0.5 mmol/L DBcAMP (▨), 60 nmol/L VIP (■), or 100 nmol/L ACh (▩) was added to the bath solution. Positive numbers represent net absorption, negative ones net secretion. Gastroenterology 2000 118, 101-107DOI: (10.1016/S0016-5085(00)70418-5) Copyright © 2000 American Gastroenterological Association Terms and Conditions

Fig. 2 Bicarbonate movement in isolated, perfused colonic crypt. After completion of a control period (2), (A) 60 nmol/L VIP (▩) or (B) 0.5 mmol/L DBcAMP (▨) was added to the bath solution. The experiments indicated as 22 mmol/L HCO3− contained 22 mmol/L HCO3− with 5% CO2; those indicated as 0 mmol/L HEPES contained 32 mmol/L HEPES-replaced HCO3−. Positive numbers represent net absorption, negative ones net secretion. Numbers in parentheses represent numbers of crypts studied in each experiment. Gastroenterology 2000 118, 101-107DOI: (10.1016/S0016-5085(00)70418-5) Copyright © 2000 American Gastroenterological Association Terms and Conditions

Fig. 2 Bicarbonate movement in isolated, perfused colonic crypt. After completion of a control period (2), (A) 60 nmol/L VIP (▩) or (B) 0.5 mmol/L DBcAMP (▨) was added to the bath solution. The experiments indicated as 22 mmol/L HCO3− contained 22 mmol/L HCO3− with 5% CO2; those indicated as 0 mmol/L HEPES contained 32 mmol/L HEPES-replaced HCO3−. Positive numbers represent net absorption, negative ones net secretion. Numbers in parentheses represent numbers of crypts studied in each experiment. Gastroenterology 2000 118, 101-107DOI: (10.1016/S0016-5085(00)70418-5) Copyright © 2000 American Gastroenterological Association Terms and Conditions

Fig. 3 Effect of HCO3−/CO2 on net fluid movement in isolated, perfused colonic crypt. The experiments indicated as 22 mmol/L HCO3− contained 22 mmol/L HCO3− with 5% CO2; in those indicated as 0 mmol/L HCO3−, 32 mmol/L HEPES replaced 22 mmol/L HCO3−. In the top panel, 0.5 mmol/L DBcAMP (▨) was added to bath solution; in the bottom panel, 100 nmol/L VIP (■) was added to bath solution. 2, Control. Positive numbers represent net absorption, negative ones net secretion. Numbers in parentheses represent numbers of crypts studied in each experimental group. Gastroenterology 2000 118, 101-107DOI: (10.1016/S0016-5085(00)70418-5) Copyright © 2000 American Gastroenterological Association Terms and Conditions

Fig. 4 Role of lumen and bath Cl− on DBcAMP-induced net fluid and bicarbonate secretion in isolated, perfused colonic crypt. After completion of a control period (2) with a lumen solution containing 131.2 mmol/L Cl−, 0.5 mmol/L DBcAMP (▨) was added to bath solution; Cl− was replaced by gluconate in both the lumen Cl− (■) and bath Cl− (▩) experiments. Positive numbers represent net absorption, negative ones net secretion. Numbers in parentheses represent numbers of crypts studied in each experiment. Gastroenterology 2000 118, 101-107DOI: (10.1016/S0016-5085(00)70418-5) Copyright © 2000 American Gastroenterological Association Terms and Conditions

Fig. 5 Effect of transport inhibitors on HCO3− and fluid movement. Fluid and HCO3− secretion was stimulated by bath 0.5 mmol/L DBcAMP (2). In the lumen DIDS experiment (▨), 100 μmol/L DIDS was added to lumen; in the bath bumetanide experiment (■), 100 nmol/L bumetanide was added to the bath solution; and in the lumen NPPB experiment (▩), 10 μmol/L NPPB was added to lumen solution. Positive numbers represent net absorption, negative numbers net secretion. Numbers in parentheses represent numbers of crypts studied in each experiment. Gastroenterology 2000 118, 101-107DOI: (10.1016/S0016-5085(00)70418-5) Copyright © 2000 American Gastroenterological Association Terms and Conditions