Document Detail


Effect of coupling on volume-regulatory response of ciliary epithelial cells suggests mechanism for secretion.
MedLine Citation:
PMID:  10362607     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The ciliary epithelium of the eye secretes the aqueous humor. It is a double epithelium arranged so that the apical surfaces of the nonpigmented ciliary epithelial (NPCE) and pigmented ciliary epithelial (PCE) cells face each other and the basolateral membranes face the inside of the eye and the blood, respectively. We have investigated the volume responses of both single cells and coupled pairs from this tissue to osmotic challenge. Both NPCE and PCE cells undergo regulatory volume increase (RVI) and decrease (RVD) when exposed to hyper- and hyposmotic solution, respectively. In hyposmotic solution single cells swell and return to their original volumes within approximately 3 min. In nonpigmented cells RVD could be inhibited by blockers of volume-activated Cl- channels [tamoxifen (100%) > quinidine (87%) > DIDS (84%) > 5-nitro-2-(3-phenylpropylamino)benzoic acid (80%) > SITS (58%)] and K+ channels [Ba2+ (31%)]. However, in PCE cells these inhibitors and additionally tetraethylammonium and Gd3+ were without effect. Only bumetanide, an inhibitor of Na+-K+-2Cl- cotransport, was found to have any effect on RVD in PCE cells. NPCE-PCE cell coupled pairs also underwent RVD, but with altered kinetics. The onset of RVD of the PCE cell in a pair occurred approximately 80 s before that of the NPCE cell, and the peak swell was reduced. This is consistent with fluid movement from the PCE to the NPCE cell. The effect of the volume-activated Cl- channel inhibitor tamoxifen was to eliminate this difference in the times of onset of RVD in coupled cell pairs and to inhibit RVD in both the NPCE and PCE cells partially. On the basis of these observations we suggest that fluid is transferred from the PCE to the NPCE cell in coupled pairs during cell swelling and the subsequent RVD. Furthermore, we speculate that reciprocal RVI-RVD could underlie aqueous humor secretion.
Authors:
V E Walker; J W Stelling; H E Miley; T J Jacob
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American journal of physiology     Volume:  276     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1999 Jun 
Date Detail:
Created Date:  1999-07-29     Completed Date:  1999-07-29     Revised Date:  2010-08-25    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  C1432-8     Citation Subset:  IM    
Affiliation:
School of Molecular and Medical Biosciences, University of Wales, Cardiff CF1 3US, United Kingdom.
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MeSH Terms
Descriptor/Qualifier:
Animals
Body Fluids / secretion*
Cattle
Chloride Channels / antagonists & inhibitors
Ciliary Body / cytology*,  drug effects,  secretion*
Epithelial Cells / cytology,  drug effects,  secretion
Fluorescent Dyes
Injections
Isoquinolines
Potassium Channel Blockers
Tamoxifen / pharmacology
Temperature
Grant Support
ID/Acronym/Agency:
//Wellcome Trust
Chemical
Reg. No./Substance:
0/Chloride Channels; 0/Fluorescent Dyes; 0/Isoquinolines; 0/Potassium Channel Blockers; 10540-29-1/Tamoxifen; 77944-88-8/lucifer yellow
Comments/Corrections
Comment In:
Am J Physiol. 1999 Nov;277(5 Pt 1):C1019   [PMID:  10610621 ]

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


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