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Swelling activates chloride current and increases internal calcium in nonpigmented epithelial cells from the rabbit ciliary body
Author(s) -
Botchkin Lev M.,
Matthews Gary
Publication year - 1995
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041640209
Subject(s) - dids , swelling , biophysics , chloride channel , patch clamp , bapta , chemistry , ionophore , conductance , calcium , intracellular , membrane , microbiology and biotechnology , biochemistry , biology , medicine , pathology , receptor , mathematics , organic chemistry , combinatorics
Membrane current and [Ca] i in rabbit nonpigmented ciliary body epithelial cells (NPE cells) were monitored with combined patch‐clamp and fura‐2 measurements during cell swelling induced by anisosmotic conditions. In the presence of K‐channel blockers, cell swelling produced an increase in membrane current, accompanied by an increase in [Ca] i. Structural changes in the cell, associated with membrane deformation, may be the cause of the increase in [Ca] i during swelling. The conductance activated by swelling was permeable to CI: it was dependent on the CI concentration gradient across the cell membrane, and it was blocked by the CI‐channel blockers DIDS, SITS, NPPB, and DIOA. Although swelling increased both CI current and [Ca] i , there was no evidence that Ca was involved in the regulation of the CI conductance. Cell swelling activated the current even when [Ca] i was strongly buffered at an elevated level (500 nM) or at a low level (∼0) with internal Ca‐BAPTA/Cs‐BAPTA mixtures. In addition, CI conductance was unaffected when [Ca] i was increased with a Ca ionophore. There was also no evidence that cAMP participates in the regulation of the CI conductance: swelling activation of the current occurred in the presence of cAMP inhibitor (R p ‐cAMP‐S) and cAMP mimic (S p ‐cAMP‐S). The data suggest independent involvement of CI conductance and internal Ca in the regulation of cell volume in NPE cells. © 1995 Wiley‐Liss, Inc.