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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.

Original publication

DOI

10.1007/s004240050586

Type

Journal article

Journal

Pflugers Arch

Publication Date

05/1998

Volume

435

Pages

796 - 803

Keywords

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid, Action Potentials, Adenocarcinoma, Anions, Calcium, Chelating Agents, Chloride Channels, Egtazic Acid, Electric Conductivity, Humans, Iodides, Ionomycin, Male, Pancreatic Ducts, Pancreatic Neoplasms, Tumor Cells, Cultured