| Volume-sensitive Cl-dependent K transport in human erythrocytes. | |
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MedLine Citation:
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PMID: 2447785 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Passive K fluxes, measured with 86Rb, were investigated in osmotically swollen human erythrocytes. K influx and efflux increased progressively with increased hypotonicity up to 167 mosmol/kg. No increase in K flux was seen when NO3 or methylSO4 were substituted for Cl. Substitution of choline or N-methylglucamine for external Na reduced the K flux in swollen cells by only 22%, compared with a 60% reduction in euvolumic cells. However, the magnitude of this Na-dependent component was slightly, but significantly, higher in swollen cells. The presence of Na-dependent K influx in swollen cells was confirmed by measurements of Na influx demonstrating a K-dependent Na influx of similar magnitude in isovolumic and swollen cells. The volume-sensitive K flux was inhibited by bumetanide, but significantly less so than was Cl-dependent flux in isovolumic cells (half-maximal inhibition at 1.0 X 10(-4) vs. 5.8 X 10(-7) M). Kinetic analysis revealed that Cl-dependent K influx had a lower affinity for external K in swollen cells than in euvolumic cells (Km was 29.8 vs. 6.1 mM). The increased K flux in swollen cells was found to be transient, decreasing substantially and reverting back to a predominantly Na-dependent and more bumetanide-sensitive form after 2 h. The results indicate that swelling of human erythrocytes activates a transient Cl-dependent K flux that differs significantly from that in isovolumic cells in that it is less Na dependent, less sensitive to bumetanide, and has a lower affinity for K. Na-K cotransport is either unaffected or slightly increased in swollen cells. The altered flux in swollen cells would thermodynamically favor a volume-regulatory KCl efflux. |
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Authors:
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W C O'Neill |
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Publication Detail:
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Type: In Vitro; Journal Article; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: The American journal of physiology Volume: 253 ISSN: 0002-9513 ISO Abbreviation: Am. J. Physiol. Publication Date: 1987 Dec |
Date Detail:
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Created Date: 1988-01-27 Completed Date: 1988-01-27 Revised Date: 2007-11-14 |
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: C883-8 Citation Subset: IM |
Affiliation:
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Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30303. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Biological Transport
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drug effects Bumetanide / pharmacology Chlorides / blood* Erythrocytes / cytology, physiology* Humans Ion Channels / physiology Potassium / blood* Sodium / blood Stilbenes / pharmacology Water-Electrolyte Balance |
| Grant Support | |
ID/Acronym/Agency:
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DK-01473/DK/NIDDK NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Chlorides; 0/Ion Channels; 0/Stilbenes; 128-42-7/4,4'-dinitro-2,2'-stilbenedisulfonic acid; 28395-03-1/Bumetanide; 7440-09-7/Potassium; 7440-23-5/Sodium |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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