Document Detail


Regulation of intracellular pH in Calu-3 human airway cells.
MedLine Citation:
PMID:  11790817     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The Calu-3 human cell line exhibits features of submucosal gland serous cells and secretes HCO(3)(-). The aim of this study was to identify the HCO(3)(-) transporters present in these cells by studying their role in the regulation of intracellular pH (pH(i)). Calu-3 cells were grown on coverslips, loaded with the pH-sensitive fluorescent dye BCECF, and their fluorescence intensity monitored as an indication of pH(i). Cells were acidified with NH(4)Cl (25 mM, 1 min) and pH(i) recovery recorded. In the absence of HCO(3)(-), initial recovery was 0.208 +/- 0.016 pH units min(-1) (n = 37). This was almost abolished by removal of extracellular Na(+) and by amiloride (1 mM), consistent with the activity of a Na(+)-H(+) exchanger (NHE). In the presence of HCO(3)(-) and CO(2), recovery (0.156 +/- 0.018 pH units min(-1)) was abolished (reduced by 91.8 +/- 6.7 %, n = 7) by removal of Na(+) but only attenuated (by 63.3 +/- 5.8 %, n = 9) by amiloride. 4,4-Dinitrostilbene-2,2-disulfonic acid (DNDS) inhibited recovery by 45.8 +/- 5.0 % (n = 7). The amiloride-insensitive recovery was insensitive to changes in membrane potential, as confirmed by direct microelectrode measurements, brought about by changing extracellular [K(+)] in the presence of either valinomycin or the K(+) channel opener 1-EBIO. In addition, forskolin (10 microM), which activates the cystic fibrosis transmembrane conductance regulator Cl(-) conductance in these cells and depolarises the cell membrane, had no effect on recovery. Removal of extracellular Cl(-) trebled pH(i) recovery rates, suggesting that an electroneutral, DNDS-sensitive, Cl(-)-HCO(3)(-) exchanger together with a NHE may be involved in pH(i) regulation and HCO(3)(-) secretion in these cells. RT-PCR detected the expression of the electrogenic Na(+)-HCO(3)(-) cotransporter NBC1 and the Cl(-)-HCO(3)(-) exchanger (AE2) but not the electroneutral Na(+)-HCO(3)(-) cotransporter NBCn1.
Authors:
S K Inglis; L Finlay; S J Ramminger; K Richard; M R Ward; S M Wilson; R E Olver
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of physiology     Volume:  538     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  2002 Jan 
Date Detail:
Created Date:  2002-01-15     Completed Date:  2002-04-16     Revised Date:  2014-02-19    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  527-39     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Amiloride / pharmacology
Bicarbonates / pharmacology
Buffers
Carbon Dioxide / pharmacology
Cell Line
Cell Membrane / physiology
Colforsin / pharmacology
HEPES / pharmacology
Homeostasis
Humans
Hydrogen / metabolism*
Hydrogen-Ion Concentration
Intracellular Membranes / metabolism*
Membrane Potentials / physiology
Respiratory System / cytology,  drug effects,  metabolism*
Serous Membrane / cytology,  drug effects,  metabolism*
Sodium / physiology
Sodium-Hydrogen Antiporter / antagonists & inhibitors,  physiology
Solutions
Stilbenes / pharmacology
Grant Support
ID/Acronym/Agency:
G84/5902//Medical Research Council
Chemical
Reg. No./Substance:
0/Bicarbonates; 0/Buffers; 0/Sodium-Hydrogen Antiporter; 0/Solutions; 0/Stilbenes; 128-42-7/4,4'-dinitro-2,2'-stilbenedisulfonic acid; 142M471B3J/Carbon Dioxide; 1F7A44V6OU/Colforsin; 7DZO8EB0Z3/Amiloride; 7YNJ3PO35Z/Hydrogen; 9NEZ333N27/Sodium; RWW266YE9I/HEPES
Comments/Corrections

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