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Spatially distinct Cl‐ influx and efflux pathways interact to maintain lens cell volume
Author(s) -
Webb Kevin Francis,
Chee Kaa Sandra Nardia,
Kistler Joerg,
Donaldson Paul James
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a964-c
Subject(s) - efflux , microbiology and biotechnology , biophysics , chemistry , lens (geology) , homeostasis , lens fiber , cell , conductance , biology , biochemistry , paleontology , mathematics , nucleus , combinatorics
The unique transparency of the ocular lens is a consequence its cellular architecture. Failure of volume homeostasis leads to a swelling of fiber cells that distorts this architecture and results in lens cataract. Like other cell types, the lens uses a variety of Cl‐ channels and transporters to regulate its volume. However in contrast to other tissues, these volume regulatory processes appear to be spatially segregated in the lens between cells at different stages of differentiation. Utilizing a novel preparation of viable lens fiber cells, we have used whole cell patch clamping to compared the volume regulatory mechanisms of fiber cell isolated from the zones of influx and efflux. Under isotonic conditions short peripheral fiber cells (<50 μm) from the zone of ion efflux tended to have a minimal Cl‐ conductance, but upon exposure to a hyposmotic solution were capable of a regulatory volume decrease that was inhibited by DIOA. Interestingly, exposure of short fiber cells to hyposmotic solutions plus DIOA caused cell swelling and the subsequent activation of a Cl‐ conductance. In contrast longer fiber cells (>120 μm) were dominated by an outwardly rectifying Cl‐ conductance which was blocked by NPPB. Since fiber cells are connected by gap junctions it is expected that these spatially distinct Cl‐ influx and efflux pathways produce a circulating flux of ions which plays a key role in tissue homeostasis. These transport processes may also be targeted pharmacologically to modulate lens cell volume in potential therapeutic interventions. This work was supported by the Health Research Council of New Zealand, the Maurice and Phyllis Paykel Trust and the University of Auckland Research Committee.