Electrophysiological characterization of volume-activated chloride currents in mouse cholangiocyte cell line.
Recent electrophysiological and radioisotope efflux studies have demonstrated various Cl(-) channels in cholangiocytes including volume-activated Cl(-) channels (VACC). Because VACCs play prominent roles in many vital cellular functions and physiology in cholangiocytes, we have examined their electrophysiological characteristics in mouse cholangiocytes to provide an important framework for studying in the future. The present study is to characterize VACCs expressed in the mouse bile duct cell (MBDC) line, conditionally immortalized by SV40 virus. Conventional whole cell patch-clamp techniques were used to study the electrophysiological characteristics of VACC in MBDC. When the MBDCs were exposed to hypotonic solution, they exhibited an outwardly rectified current, which was significantly inhibited by replacing chloride in the bath solution with gluconate or glutamate and by administration of classic chloride channel inhibitors 5-nitro-2-(3-phenylpropylamino)-benzoate, glybenclamide, DIDS, and tamoxifen. These inhibitory effects were reversible with washing them out from the bath solution. Moreover, the ion selectivity of the volume-activated channel to different anions indicates that it is more permeable to SCN(-) > I(-) >/= Cl(-) > F(-) >/= acetate >/= glutamate >/= gluconate. These electrophysiological characteristics demonstrate that the volume-activated current observed is a VACC. In addition, the VACC in MBDC has electrophysiological characteristics similar to those of the VACC in human cholangiocarcinoma cell line. The present study is the first to characterize the VACC in mouse cholangiocyte and will provide an important framework for further studies to examine and understand the role of the VACC in biliary secretion and ion-transport physiology.
Chen
Biyi
B
Department of Medicine, Division of Gatroenterology/Hepatology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Nicol
Grant
G
Cho
Won Kyoo
WK
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D001652:Bile Ducts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002460:Cell Line; D002586:Cesium / Q000494:pharmacology; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism; D004558:Electric Stimulation; D004594:Electrophysiology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism; D005942:Gluconates / Q000378:metabolism; D007038:Hypotonic Solutions; D007150:Immunohistochemistry; D007552:Isotonic Solutions; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D009578:Nitrobenzenes / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D013539:Simian virus 40
D018118:Chloride Channels; D002712:Chlorides; D005942:Gluconates; D007038:Hypotonic Solutions; D007552:Isotonic Solutions; D009578:Nitrobenzenes; D002586:Cesium; C047633:5-(4-nitrophenyl)-2,4-pentadienal; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; C030691:gluconic acid