Document Detail

Sodium-dependent activity of aquaporin-1 in rat glioma cells: a new mechanism of cell volume regulation.
MedLine Citation:
PMID:  18795320     Owner:  NLM     Status:  MEDLINE    
Cell volume controls many functions and is itself regulated. To study cell volume regulations, the mean volume of C6-BU-1 rat glioma cells was electronically measured under isotonic and anisotonic conditions. Two isotonic solutions were used containing either normal (solution 1) or low (solution 2) NaCl. Anisotonicity was induced by changing NaCl or sucrose concentrations in solutions 1 and 2, respectively. The cells behaved like perfect osmometers when the tonicity was increased. In contrast, just after hypotonic challenges, the cell volume was smaller than that predicted by a perfect osmometer. This deviation reveals a new mechanism, which we call the volume increase limitation (VIL). When hypotonicity was induced by decreasing NaCl, a classical slow regulatory volume decrease (RVD) was also observed in addition to VIL. The cells expressed aquaporin-1 sensitive to HgCl(2) and decreased by siRNA, which both reduced fast volume changes. In this study, we show that: (1) RVD is proportional to the change in external Cl(-) concentration and is inhibited by Cl(-) channel and K(+)-Cl(-) cotransporter blockers; (2) cell swelling due to the influx of H(2)O through aquaporins shows rectification with decreasing osmolarity and is sensitive to the internal Na(+) concentration; (3) VIL is linearly related with hypotonicity and is abolished in solutions 1 and 2 by the Na(+) ionophore monensin and in solution 1 by the Na(+)-K(+) ATPase inhibitor ouabain. These results suggest that VIL is triggered by the decrease in internal Na(+) caused by hyponatrema and cell swelling. In addition to RVD, VIL should protect cells during hyposmotic stress.
Béatrice Rouzaire-Dubois; Gilles Ouanounou; Seana O'Regan; Jean-Marc Dubois
Publication Detail:
Type:  Journal Article     Date:  2008-09-16
Journal Detail:
Title:  Pflügers Archiv : European journal of physiology     Volume:  457     ISSN:  1432-2013     ISO Abbreviation:  Pflugers Arch.     Publication Date:  2009 Mar 
Date Detail:
Created Date:  2009-02-09     Completed Date:  2009-07-24     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0154720     Medline TA:  Pflugers Arch     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  1187-98     Citation Subset:  IM    
CNRS, Institut de Neurobiologie Alfred Fessard-FRC, Gif-sur-Yvette, France.
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MeSH Terms
Aquaporin 1 / biosynthesis,  metabolism*
Cell Size / drug effects*
Chlorides / pharmacology
Glioma / metabolism
Hypotonic Solutions
Ion Channels / physiology
Isotonic Solutions
Mercuric Chloride / pharmacology
Osmolar Concentration
RNA, Small Interfering / pharmacology
Sodium / metabolism*
Tumor Cells, Cultured
Reg. No./Substance:
0/Chlorides; 0/Hypotonic Solutions; 0/Ion Channels; 0/Isotonic Solutions; 0/RNA, Small Interfering; 146410-94-8/Aquaporin 1; 7440-23-5/Sodium; 7487-94-7/Mercuric Chloride

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

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