| Characteristics of Kcnn4 channels in the apical membranes of an intestinal epithelial cell line. | |
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MedLine Citation:
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PMID: 21868633 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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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. |
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Authors:
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Kanthesh M Basalingappa; Vazhaikkurichi M Rajendran; William F Wonderlin |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural Date: 2011-08-25 |
Journal Detail:
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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:
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Created Date: 2011-10-31 Completed Date: 2011-12-15 Revised Date: 2013-02-19 |
Medline Journal Info:
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Nlm Unique ID: 100901227 Medline TA: Am J Physiol Gastrointest Liver Physiol Country: United States |
Other Details:
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Languages: eng Pagination: G905-11 Citation Subset: IM |
Affiliation:
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Department of Biochemistry, West Virginia Univ. School of Medicine, Morgantown, 26506, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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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:
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DK-018777/DK/NIDDK NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Intermediate-Conductance Calcium-Activated Potassium Channels; 0/Kcnn4 protein, rat |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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