Calcium-activated chloride conductance in a pancreatic adenocarcinoma cell line of ductal origin (HPAF) and in freshly isolated human pancreatic duct cells.
Using the whole-cell patch-clamp technique, a calcium-activated chloride conductance (CACC) could be elicited in HPAF cells by addition of 1 microM ionomycin to the bath solution (66 +/- 22 pA/pF;Vm + 60 mV) or by addition of 1 microM calcium to the pipette solution (136 +/- 17 pA/pF; Vm + 60 mV). Both conductances had similar biophysical characteristics, including time-dependent inactivation at hyperpolarising potentials and a linear/slightly outwardly rectifying current/voltage (I/V) curve with a reversal potential (Erev) close to the calculated chloride equilibrium potential. The anion permeability sequence obtained from shifts in Erev was I > Br >/= Cl. 4,4'-Diisothiocyanatostilbene disulphonic acid (DIDS, 500 microM) caused a 13% inhibition of the current (Vm + 60 mV) while 100 microM glibenclamide, 30 nM TS-TM-calix[4]arene and 10 microM tamoxifen, all chloride channel blockers, had no marked effects (8%, -6% and -2% inhibition respectively). Niflumic acid (100 microM) caused a voltage-dependent inhibition of the current of 48% and 17% (Vm +/- 60 mV, respectively). In freshly isolated human pancreatic duct cells (PDCs) a CACC was elicited with 1 microM calcium in the pipette solution (260 +/- 62 pA/pF; Vm + 60 mV). The presence of this CACC in human PDCs could provide a possible therapeutic pathway for treatment of pancreatic insufficiency of the human pancreas in cystic fibrosis.
Winpenny
J P
JP
Department of Physiological Sciences, The Medical School, University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.
Harris
A
A
Hollingsworth
M A
MA
Argent
B E
BE
Gray
M A
MA
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000200:Action Potentials; D000230:Adenocarcinoma / Q000503:physiopathology*; D000838:Anions; D002118:Calcium / Q000494:pharmacology*; D002614:Chelating Agents / Q000494:pharmacology; D018118:Chloride Channels / Q000032:analysis / Q000502:physiology*; D004533:Egtazic Acid / Q000494:pharmacology; D004553:Electric Conductivity; D006801:Humans; D007454:Iodides / Q000378:metabolism; D015759:Ionomycin / Q000494:pharmacology; D008297:Male; D010183:Pancreatic Ducts / Q000737:chemistry / Q000503:physiopathology*; D010190:Pancreatic Neoplasms / Q000503:physiopathology*; D014407:Tumor Cells, Cultured
D000838:Anions; D002614:Chelating Agents; D018118:Chloride Channels; D007454:Iodides; D004533:Egtazic Acid; D015759:Ionomycin; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D002118:Calcium