Swelling activates chloride current and increases internal calcium in nonpigmented epithelial cells from the rabbit ciliary body
✍ Scribed by Lev M. Botchkin; Gary Matthews
- Publisher
- John Wiley and Sons
- Year
- 1995
- Tongue
- English
- Weight
- 936 KB
- Volume
- 164
- Category
- Article
- ISSN
- 0021-9541
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✦ Synopsis
Membrane current and (Ca], in rabbit nonpigmented ciliary body epithelial cells (NPE cells) were monitored with combined patch-clamp and fura-2 measurements during cell swelling induced by anisosrnotic conditions. In the presence of K-channel blockers, cell swelling produced an increase in membrane current, accompanied by an increase in [Cali. Structural changes in the cell, associated with mernbrane deformation, may be the cause of the increase in [Ca], 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 [Cali, there was no evidence that Ca was involved in the regulation of the CI conductance. Cell swelling activated the current even when [Cal, was strongly buffered at an elevated level ( S O 0 nM) or at a low level (-0) with internal Ca-BAPTAICs-BAPTA mixtures. In addition, CI conductance was unaffected when [Cali 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,-CAMP-S) and cAMP mimic 6,-CAMP-S). The data suggest independent involvement of CI conductance and internal Ca in the regulation of cell volume in NPE cells. @) 1YY5 wi1e.y-Liss, Inc