TY - JOUR
T1 - Perfused rat intrahepatic bile ducts secrete and absorb water, solute, and ions
AU - Masyuk, Anatoly I.
AU - Gong, Ai Yu
AU - Kip, Sertac
AU - Burke, Michael J.
AU - LaRusso, Nicholas F.
N1 - Funding Information:
Supported by grant DK24031 (to N.F.L.) from the National Institutes of Health and by the Mayo Foundation.
PY - 2000
Y1 - 2000
N2 - Backgrounds & Aims: We report a novel approach to study biliary water, bile acid, and HCO3 - transport: the microperfusion of intrahepatic bile duct units (IBDUs) isolated from normal rat liver. Methods: To study water transport, IBDUs were perfused in vitro with a membrane-impermeant fluorescent volume marker, fluorescein sulfonate; net water movement (Jv) and osmotic water permeability (Pf) were then calculated. To study solute transport, IBDUs were perfused with taurocholic acid (TCA) and bile acid uptake was calculated from the concentrations of TCA in the perfused and collected solutions. To study ion transport, IBDUs were perfused with the cell-impermeant pH-sensitive dye BCECF dextran; luminal pH was determined from fluorescence excitation ratios. Results: When inward (secretory) or outward (absorptive) osmotic gradients were established across IBDUs, water movement was observed from bath to lumen (i.e., secretion) and from lumen to bath (i.e., absorption). The perfused IBDUs absorbed TCA in a saturable, sodium-dependent manner; in addition, TCA absorption was blocked in a dose-dependent fashion by S0960, a specific inhibitor of the Na+/bile acid cotransporter. Addition of forskolin to HCO3 --containing (but not HCO3 --free) bath buffer resulted in lumen alkalinization reflecting HCO3 - transport into the lumen of perfused IBDUs. Conclusions: The results provide direct functional evidence that intrahepatic bile ducts both secrete and absorb water in response to osmotic gradients, actively absorb bile acid, and transport HCO3 -.
AB - Backgrounds & Aims: We report a novel approach to study biliary water, bile acid, and HCO3 - transport: the microperfusion of intrahepatic bile duct units (IBDUs) isolated from normal rat liver. Methods: To study water transport, IBDUs were perfused in vitro with a membrane-impermeant fluorescent volume marker, fluorescein sulfonate; net water movement (Jv) and osmotic water permeability (Pf) were then calculated. To study solute transport, IBDUs were perfused with taurocholic acid (TCA) and bile acid uptake was calculated from the concentrations of TCA in the perfused and collected solutions. To study ion transport, IBDUs were perfused with the cell-impermeant pH-sensitive dye BCECF dextran; luminal pH was determined from fluorescence excitation ratios. Results: When inward (secretory) or outward (absorptive) osmotic gradients were established across IBDUs, water movement was observed from bath to lumen (i.e., secretion) and from lumen to bath (i.e., absorption). The perfused IBDUs absorbed TCA in a saturable, sodium-dependent manner; in addition, TCA absorption was blocked in a dose-dependent fashion by S0960, a specific inhibitor of the Na+/bile acid cotransporter. Addition of forskolin to HCO3 --containing (but not HCO3 --free) bath buffer resulted in lumen alkalinization reflecting HCO3 - transport into the lumen of perfused IBDUs. Conclusions: The results provide direct functional evidence that intrahepatic bile ducts both secrete and absorb water in response to osmotic gradients, actively absorb bile acid, and transport HCO3 -.
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U2 - 10.1053/gast.2000.20248
DO - 10.1053/gast.2000.20248
M3 - Article
C2 - 11113089
AN - SCOPUS:0034465189
SN - 0016-5085
VL - 119
SP - 1672
EP - 1680
JO - Gastroenterology
JF - Gastroenterology
IS - 6
ER -