| Regulatory volume decrease in the presence of HCO3- by single osteosarcoma cells UMR-106-01. | |
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MedLine Citation:
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PMID: 1325445 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The technique for the simultaneous recording of cell volume changes and pHi in single cells was used to study the role of HCO3- in regulatory volume decrease (RVD) by the osteosarcoma cells UMR-106-01. In the presence of HCO3-, steady state pHi is regulated by Na+/H+ exchange, Na+ (HCO3-)3 cotransport and Na(+)-independent Cl-/HCO3- exchange. Following swelling in hypotonic medium, pHi was reduced from 7.16 +/- 0.02 to 6.48 +/- 0.02 within 3.4 +/- 0.28 min. During this period of time, the cells performed RVD until cell volume was decreased by 31 +/- 5% beyond that of control cells (RVD overshoot). Subsequently, while the cells were still in hypotonic medium, pHi slowly increased from 6.48 +/- 0.02 to 6.75 +/- 0.02. This increase in pHi coincided with an increase in cell volume back to normal (recovery from RVD overshoot or hypotonic regulatory volume increase (RVI)). The same profound changes in cell volume and pHi after cell swelling were observed in the complete absence of Cl- or Na+, providing HCO3- was present. On the other hand, depolarizing the cells by increasing external K+ or by inhibition of K+ channels with quinidine, Ba2+ or tetraethylammonium prevented the changes in pHi and RVD. These findings suggest that in the presence of HCO3-, RVD in UMR-106-01 cells is largely mediated by the conductive efflux of K+ and HCO3-. Removal of external Na+ but not Cl- prevented the hypotonic RVI that occurred after the overshoot in RVD. Amiloride had no effect, whereas pretreatment with 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) strongly inhibited hypotonic RVI. Thus, hypotonic RVI is mediated by a Na+(out)-dependent, Cl(-)-independent and DIDS-inhibitable mechanism, which is indicative of a Na+(HCO3-)3 cotransporter. This is the first evidence for the involvement of this transporter in cell volume regulation. The present results also stress the power of the new technique used in delineating complicated cell volume regulatory mechanisms in attached single cells. |
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Authors:
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R A Star; B X Zhang; P A Loessberg; S Muallem |
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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, P.H.S. |
Journal Detail:
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Title: The Journal of biological chemistry Volume: 267 ISSN: 0021-9258 ISO Abbreviation: J. Biol. Chem. Publication Date: 1992 Sep |
Date Detail:
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Created Date: 1992-10-07 Completed Date: 1992-10-07 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 2985121R Medline TA: J Biol Chem Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 17665-9 Citation Subset: IM |
Affiliation:
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Department of Medicine, University of Texas Southwestern Medical Center, Dallas 75235-9040. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Bicarbonates / pharmacology* Carrier Proteins / metabolism Cell Line Hydrogen-Ion Concentration Kinetics Osteosarcoma / metabolism*, pathology Potassium Chloride / pharmacology Quinidine / pharmacology Rats Sodium / metabolism Sodium-Bicarbonate Symporters Sodium-Hydrogen Antiporter Tumor Cells, Cultured |
| Grant Support | |
ID/Acronym/Agency:
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AR39245/AR/NIAMS NIH HHS; DK38938/DK/NIDDK NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Bicarbonates; 0/Carrier Proteins; 0/Sodium-Bicarbonate Symporters; 0/Sodium-Hydrogen Antiporter; 56-54-2/Quinidine; 7440-23-5/Sodium; 7447-40-7/Potassium Chloride |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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