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Characterization of cell volume‐sensitive chloride currents in freshly prepared and cultured pancreatic acinar cells from early postnatal rats
Author(s) -
Schmid Andreas,
Blum Robert,
Krause Elmar
Publication year - 1998
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1998.453bb.x
Subject(s) - dids , chloride channel , chemistry , biophysics , chloride , reversal potential , channel blocker , intracellular , depolarization , membrane potential , niflumic acid , patch clamp , biochemistry , membrane , biology , calcium , receptor , organic chemistry
1 In freshly prepared and cultured exocrine pancreatic acinar cells from 5‐ to 7‐day‐old rats a chloride‐selective membrane conductance could be activated by intracellular application of GTPγS (40–100 μM), by application of positive pressure (5 cmH 2 O) to the pipette interior or by challenging the cells with a hyposmolar bath solution. Hyperosmolar bath solutions inhibited the cell volume‐sensitive chloride currents. 2 The anion permeability sequence of the cell volume‐sensitive chloride conductance was I − > Cl − ≈ Br − > F − > methanesulphonate − > glutamate − . I − had a higher permeability but lower conductance than Cl − . The permeability ratio for P glutamate / P Cl was 0.12. 3 The cell volume‐sensitive chloride conductance showed outward rectification. Membrane depolarization to high positive voltages (≥+60 mV) caused a time‐dependent decay in outward currents. 4 DIDS (4,4′‐diisothiocyanatostilbene‐2,2′‐disulphonic acid) and SITS (4‐acetamido‐4′‐isothiocyanatostilbene‐2,2′‐disulphonic acid) reversibly inhibited the cell volume‐sensitive chloride current in a voltage‐dependent manner. NPPB (5‐nitro‐2‐(3‐phenylpropylamino)‐benzoic acid), quinidine, quinine and tamoxifen caused voltage‐independent current inhibition. 5 Combined fura‐2 and whole‐cell current measurements showed that activation of the cell volume‐sensitive chloride current does not involve cytosolic Ca 2+ signals. Furthermore, there is no evidence that Ca 2+ ‐activated chloride currents play a significant role in cultured pancreatic acinar cells from 5‐ to 7‐day‐old rats. 6 Polymerase chain reaction followed by DNA sequence analysis indicated the presence of mRNA homologous to the ClC‐3 chloride channel in pancreatic tissue from 5‐day‐old rats.