Document Detail

Whole-cell patch clamping of isolated fiber cells confirms that spatially distinct Cl- influx and efflux pathways exist in the cortex of the rat lens.
MedLine Citation:
PMID:  19279312     Owner:  NLM     Status:  MEDLINE    
PURPOSE: To test the hypothesis that lens fiber cells use different combinations of transport proteins to mediate Cl influx and efflux in order to regulate their steady state volume. METHODS: Cells were isolated from rat lenses by enzymatic dissociation in the presence of Gd(3+), and short and long fiber cells were assigned to peripheral efflux and deeper influx zones, respectively. Electrical properties were of isolated cells, and whole lenses were analyzed by using whole-cell patch clamping and intracellular microelectrodes, respectively, before and after exposure to hyposmotic challenge and/or the addition of [(dihydronindenyl)oxy] alkanoic acid (DIOA). RESULTS: Cells from the influx zone were dominated by an outwardly rectifying Cl(-) conductance, and exposure to hyposmotic challenge increased this conductance. Cells isolated from the efflux zone were dominated by K(+) conductance(s) with only a minimal contribution from the Cl(-) conductance. Exposure of cells that exhibited a minimal baseline Cl(-) conductance to hyposmotic challenge caused swelling and a transient increase in Cl(-) current. In other cells that initially lacked a Cl(-) conductance, hyposmotic challenge caused swelling, but no increase in outward current. However, the subsequent addition of DIOA exacerbated swelling and activated a Cl(-) current. Under isosmotic conditions, addition of DIOA also induced cell swelling and the transient activation of a Cl(-) current. In whole lenses, exposure to hyposmotic challenge increased the contribution of an anion conductance to the membrane potential. CONCLUSIONS: In peripheral cells, Cl(-) efflux is primarily mediated by potassium chloride cotransporters (KCCs) and its activity can be upregulated by hyposmotic challenge. In addition, these cells also contain a Cl(-) channel that exhibits a variable baseline activity level and that can be recruited to effect regulatory volume decrease if the KCC transporters are inhibited.
Kevin F Webb; Paul J Donaldson
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-03-11
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  50     ISSN:  1552-5783     ISO Abbreviation:  Invest. Ophthalmol. Vis. Sci.     Publication Date:  2009 Aug 
Date Detail:
Created Date:  2009-07-29     Completed Date:  2009-08-11     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3808-18     Citation Subset:  IM    
Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand.
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MeSH Terms
Biological Transport, Active / physiology
Carboxylic Acids / pharmacology
Chloride Channels / metabolism*
Chlorides / metabolism*
Indenes / pharmacology
Ion Transport
Lens Cortex, Crystalline / cytology,  drug effects,  metabolism*
Osmotic Pressure
Patch-Clamp Techniques
Rats, Wistar
Reg. No./Substance:
0/((dihydroindenyl)oxy)alkanoic acid; 0/Carboxylic Acids; 0/Chloride Channels; 0/Chlorides; 0/Indenes

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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