Document Detail

Na+-inhibitory sites of the Na+/H+ exchanger are Li+ substrate sites.
MedLine Citation:
PMID:  15772122     Owner:  NLM     Status:  MEDLINE    
Amiloride-inhibitable Li+ influx in dog red blood cells is mediated by the Na+/H+ exchanger, NHE. However, there are substantial differences between the properties of Li+ transport and Na+ transport through the NHE. Li+ influx is activated by cell shrinkage, and Na+ influx is not, as we reported previously (Dunham PB, Kelley SJ, and Logue PJ. Am J Physiol Cell Physiol 287: C336-C344, 2004). Li+ influx is a sigmoidal function of its concentration, and Na+ activation is linear at low Na+ concentrations. Li+ does not inhibit its own influx; in contrast, Na+ inhibits Na+ influx. Li+ prevents this inhibition by Na+. Na+ is a mixed or noncompetitive inhibitor of Li+ influx, implying that both a Na+ and a Li+ can be bound at the same time. In contrast, Li+ is a competitive inhibitor of Na+ influx, suggesting Li+ binding at one class of sites on the transporter. Because the properties of Li+ transport and Na+ transport are different, a simple explanation is that Na+ and Li+ are transported by separate sites. The similarities of the properties of Li+ transport and the inhibition of Na+ transport by Na+ suggest that Li+ is transported by the Na+-inhibitory sites.
Philip B Dunham; Scott J Kelley; Paul J Logue; Michael J Mutolo; Mark A Milanick
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, P.H.S.     Date:  2005-03-16
Journal Detail:
Title:  American journal of physiology. Cell physiology     Volume:  289     ISSN:  0363-6143     ISO Abbreviation:  Am. J. Physiol., Cell Physiol.     Publication Date:  2005 Aug 
Date Detail:
Created Date:  2005-07-08     Completed Date:  2005-08-11     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  100901225     Medline TA:  Am J Physiol Cell Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  C277-82     Citation Subset:  IM    
Department of Biology, Syracuse University, 130 College Place, Syracuse, NY 13244-1220, USA.
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MeSH Terms
Amiloride / pharmacology
Binding Sites
Cell Size / drug effects
Diuretics / pharmacology
Erythrocytes / drug effects,  physiology*
Lithium / metabolism*
Sodium / metabolism*
Sodium-Hydrogen Antiporter / drug effects,  metabolism*
Grant Support
Reg. No./Substance:
0/Diuretics; 0/Sodium-Hydrogen Antiporter; 2609-46-3/Amiloride; 7439-93-2/Lithium; 7440-23-5/Sodium

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