Document Detail

The Na+/H+ exchanger in immature and mature granulocytic HL-60 cells. Property changes induced by intracellular acidification and cell maturation.
MedLine Citation:
PMID:  2841335     Owner:  NLM     Status:  MEDLINE    
We have compared the properties of the Na+/H+ exchanger in two cell populations: growing promyelocytic HL-60 cells (immature) and HL-60 cells induced to mature into granulocytes by dimethyl sulfoxide. The exchanger was activated by intracellular acidification from pH 7.25 to pH 5.5. In both immature and mature granulocytic cells, this type of activation resulted in the expected increase in Vmax for Na+ uptake but also in an increase in KmNa. Maximum acidification caused an increase in Vmax of approximately 10-fold in both types of cells. The increase in KmNa was influenced by cell maturation. In immature cells, the KmNa was higher than in mature cells at all pH values tested, and this difference increased with acidification. Maximum acidification increased the KmNa from 15 +/- 4 to 124 +/- 17 mM in immature cells and from 10 +/- 3 to 43 +/- 20 mM in mature cells. Intracellular pH also influenced the pattern of inhibition of 22Na uptake by dimethylamiloride, a specific inhibitor of the exchanger. At intracellular pH 7.0 dimethylamiloride inhibition was mostly competitive in immature and competitive in mature cells. At lower intracellular pH, 5.9, the inhibition was mixed in both types of cells. Thus, the properties of the exchanger in granulocytic cells are influenced by the cell maturation stage and the intracellular pH.
M R Costa-Casnellie; G B Segel; M A Lichtman
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  263     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1988 Aug 
Date Detail:
Created Date:  1988-09-20     Completed Date:  1988-09-20     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  11851-5     Citation Subset:  IM    
Department of Medicine, University of Rochester Medical Center, New York 14642.
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MeSH Terms
Amiloride / analogs & derivatives,  pharmacology
Carrier Proteins / antagonists & inhibitors,  metabolism*
Dimethyl Sulfoxide / pharmacology
Fluorescent Dyes
Granulocytes / drug effects,  physiology*
Hydrogen-Ion Concentration
Sodium / metabolism
Sodium Radioisotopes
Sodium-Hydrogen Antiporter
Tumor Cells, Cultured
Grant Support
Reg. No./Substance:
0/Carrier Proteins; 0/Fluoresceins; 0/Fluorescent Dyes; 0/Sodium Radioisotopes; 0/Sodium-Hydrogen Antiporter; 1214-79-5/5-dimethylamiloride; 2609-46-3/Amiloride; 67-68-5/Dimethyl Sulfoxide; 695-53-4/Dimethadione; 7440-23-5/Sodium; 85138-49-4/2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein

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