Sa. Grubman et al., REGULATION OF INTRACELLULAR PH BY IMMORTALIZED HUMAN INTRAHEPATIC BILIARY EPITHELIAL-CELL LINES, The American journal of physiology, 266(6), 1994, pp. 70001060-70001070
We have produced continuous cell lines using retroviral transduction o
f SV40 large T antigen into human intrahepatic biliary epithelial (IBE
) cells from three different normal individuals. These IBE cell Lines
grow in a hormone-supplemented medium in the presence of NIH/3T3 fibro
blast coculture. These cells maintain their epithelial appearance and
are positive for the biliary-specific markers cytokeratins 7 and 19 an
d gamma-glutamyl transpeptidase while being negative for the hepatocyt
e markers albumin and asialoglycoprotein receptor. To evaluate ion tra
nsport pathways in IBE cell lines, we utilized intracellular pH (pH(i)
) measurements obtained using the intracellular fluorescent indicator
2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein. In the absence of H
CO3--CO2, an amiloride-sensitive Na+-H+ exchanger participated in the
regulation of basal pH(i). In the presence of HCO3-CO2, a 4,4'-diisoth
iocyanostilbene-2,2'-disulfonic acid (DIDS)-sensitive, Na-, Cl-, and H
CO3--dependent acid extrusion mechanism accounted for similar to 60% o
f pH(i) recovery from acidic pH(i); this mechanism is most consistent
with the presence of a Na-dependent Cl--HCO3- exchanger (Na+HCO3-Cl-H). Under basal conditions, Cl- depletion revealed a DIDS-sensitive alk
alinization consistent with a Na-independent Cl--HCO3- exchanger. Thes
e model systems will allow the opportunity to study the normal mechani
sms of IBE function and to study the pathobiology of IBE processes in
disease states.