Document Detail


Characteristics of Kcnn4 channels in the apical membranes of an intestinal epithelial cell line.
MedLine Citation:
PMID:  21868633     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Intermediate-conductance K(+) (Kcnn4) channels in the apical and basolateral membranes of epithelial cells play important roles in agonist-induced fluid secretion in intestine and colon. Basolateral Kcnn4 channels have been well characterized in situ using patch-clamp methods, but the investigation of Kcnn4 channels in apical membranes in situ has been hampered by a layer of mucus that prevents seal formation. In the present study, we used patch-clamp methods to characterize Kcnn4 channels in the apical membrane of IEC-18 cells, a cell line derived from rat small intestine. A monolayer of IEC-18 cells grown on a permeable support is devoid of mucus, and tight junctions enable selective access to the apical membrane. In inside-out patches, Ca(2+)-dependent K(+) channels observed with iberiotoxin (a Kcnma1/large-conductance, Ca(2+)-activated K(+) channel blocker) and apamin (a Kcnn1-3/small-conductance, Ca(2+)-activated K(+) channel blocker) present in the pipette solution exhibited a single-channel conductance of 31 pS with inward rectification. The currents were reversibly blocked by TRAM-34 (a Kcnn4 blocker) with an IC(50) of 8.7 ± 2.0 μM. The channels were not observed when charybdotoxin, a peptide inhibitor of Kcnn4 channels, was added to the pipette solution. TRAM-34 was less potent in inhibiting Kcnn4 channels in patches from apical membranes than in patches from basolateral membranes, which was consistent with a preferential expression of Kcnn4c and Kcnn4b isoforms in apical and basolateral membranes, respectively. The expression of both isoforms in IEC-18 cells was confirmed by RT-PCR and Western blot analyses. This is the first characterization of Kcnn4 channels in the apical membrane of intestinal epithelial cells.
Authors:
Kanthesh M Basalingappa; Vazhaikkurichi M Rajendran; William F Wonderlin
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2011-08-25
Journal Detail:
Title:  American journal of physiology. Gastrointestinal and liver physiology     Volume:  301     ISSN:  1522-1547     ISO Abbreviation:  Am. J. Physiol. Gastrointest. Liver Physiol.     Publication Date:  2011 Nov 
Date Detail:
Created Date:  2011-10-31     Completed Date:  2011-12-15     Revised Date:  2013-06-27    
Medline Journal Info:
Nlm Unique ID:  100901227     Medline TA:  Am J Physiol Gastrointest Liver Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  G905-11     Citation Subset:  IM    
Affiliation:
Department of Biochemistry, West Virginia Univ. School of Medicine, Morgantown, 26506, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Cell Line
Cell Membrane / metabolism*
Epithelial Cells / cytology,  metabolism*
Intermediate-Conductance Calcium-Activated Potassium Channels / metabolism*
Intestinal Mucosa / cytology,  metabolism*
Intestines / cytology,  metabolism*
Membrane Potentials / physiology
Rats
Grant Support
ID/Acronym/Agency:
DK-018777/DK/NIDDK NIH HHS
Chemical
Reg. No./Substance:
0/Intermediate-Conductance Calcium-Activated Potassium Channels; 0/Kcnn4 protein, rat
Comments/Corrections

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