| Calcium-dependent chloride channels in endosomes from rabbit kidney cortex. | |
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MedLine Citation:
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PMID: 8166237 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Ion channels in endosomal membranes from rabbit kidney cortex were studied after reconstitution into planar lipid bilayers. The most frequently observed ion channel was anion selective (PCl/PK = 13) and had a single-channel conductance of 116 pS when the cis and trans solutions contained 410 and 150 mM KCl, respectively, and a conductance of 90 pS in symmetrical 150 mM KCl solutions. The anion selectivity sequence of the channel was NO3- > F- > Br- > Cl- >> I-. The activity of the channel was voltage dependent such that hyperpolarization of the cis, or cytoplasmic, surface of the channel increased the open probability (Po). The activity of the channel was also highly dependent on the calcium activity of the cis but not the trans solution. Channels were fully active (Po > 0.7) at Ca2+ concentration > 1 microM, but channel activity was completely absent (Po < 0.001) at Ca2+ concentration < 250 nM. The effects of calcium on Po were not voltage dependent. The Cl(-)-channel blocker 2-[(2-cyclopentyl-6,7-dichloro-2,3-dihydro-2-methyl-1-oxo-1H-inden -5- yl)oxy]-acetic acid (IAA-94/95) produced a concentration-dependent reversible flickering block of the endosomal channel with a Ki of 15 microM. 4,4'-Dinitrostilbene-2,2'-disulfonic acid, a disulfonic stilbene, also produced a flickering block of the channel with a Ki of approximately 5 microM. Because endosomal Cl- channels are believed to facilitate endosomal acidification, we tested the effects of IAA-94/95 and deletion of Ca2+ on the rate of acidification of intact endosomes. Because neither maneuver affected acidification, we conclude that the 116-pS channel does not participate in endosomal acidification. This channel may be involved in other endosomal processes, e.g., cell volume regulation and control of membrane trafficking. |
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Authors:
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W B Reeves; R W Gurich |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: The American journal of physiology Volume: 266 ISSN: 0002-9513 ISO Abbreviation: Am. J. Physiol. Publication Date: 1994 Mar |
Date Detail:
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Created Date: 1994-05-20 Completed Date: 1994-05-20 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0370511 Medline TA: Am J Physiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: C741-50 Citation Subset: IM |
Affiliation:
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Division of Nephrology, University of Arkansas for Medical Sciences, Little Rock. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Acids
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metabolism Adenosine Triphosphate / pharmacology Animals Calcium / pharmacology* Chloride Channels / metabolism* Cyclic AMP-Dependent Protein Kinases / pharmacology Female Glycolates / pharmacology Ion Channel Gating / drug effects Kidney Cortex / metabolism* Organelles / metabolism* Rabbits Stilbenes / pharmacology |
| Grant Support | |
ID/Acronym/Agency:
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5R29-DK-39331/DK/NIDDK NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Acids; 0/Chloride Channels; 0/Glycolates; 0/Stilbenes; 128-42-7/4,4'-dinitro-2,2'-stilbenedisulfonic acid; 54197-05-6/MK 473; 56-65-5/Adenosine Triphosphate; 7440-70-2/Calcium; EC 2.7.11.11/Cyclic AMP-Dependent Protein Kinases |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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