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Hyposmotically activated chloride channels in cultured rabbit non‐pigmented ciliary epithelial cells
Author(s) -
Shi Chanjuan,
Ryan Jennifer S.,
French Andrew S.,
CocaPrados Miguel,
Kelly Melanie E. M.
Publication year - 1999
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.1469-7793.1999.00057.x
Subject(s) - dids , niflumic acid , patch clamp , chloride channel , biophysics , chemistry , conductance , reversal potential , biochemistry , biology , membrane , receptor , mathematics , combinatorics
1 We used whole‐cell patch‐clamp recording techniques and noise analysis of whole‐cell current to investigate the properties of hyposmotic shock (HOS)‐activated Cl − channels in SV40‐transformed rabbit non‐pigmented ciliary epithelial (NPCE) cells. 2 Under conditions designed to isolate Cl − currents, exposure of cells to hyposmotic external solution reversibly increased the whole‐cell conductance. 3 The whole‐cell current activated with a slow time course (> 15 min), exhibited outward rectification and was Cl − selective. 4 The disulphonic stilbene derivatives 4,4′‐diisothiocyanatostilbene‐2,2′‐disulfonic acid (DIDS, 0·5 mM), 4‐acetamido‐4′‐isothiocyanatostilbene‐2,2′‐disulfonic acid (SITS, 0·5 mM) and 4,4′‐dinitrostilbene‐2,2′‐disulfonic acid (DNDS, 0·5 mM) produced a voltage‐sensitive block of HOS‐activated Cl − current at depolarized potentials, whereas niflumic acid produced a voltage‐independent block of the current. 5 Under Ca 2+ ‐free conditions, HOS stimulation still reversibly activated the Cl − current, but the amplitude of current was reduced and the time course of current activation was slower compared with control ( P < 0·05 ). 6 The non‐specific kinase inhibitor H‐7 (100 μM), upregulated HOS‐activated Cl − current amplitude in all cells tested ( P < 0·05 ). 7 Noise analysis of whole‐cell Cl − current indicated that cell swelling activated a high density of small conductance Cl − channels (< 1 pS). 8 We conclude that HOS primarily activates a high density of volume‐sensitive small conductance Cl − channels in rabbit NPCE cells, and that Ca 2+ and phosphorylation are involved in channel regulation.