title: Modulation of Na-H antiporter activity in human lymphoblasts by altered membrane cholesterol.
abstract: The effects of changes in membrane cholesterol on Na-H antiporter activity in culture human lymphoblasts are described. Lymphoblast cholesterol alteration was achieved with liposomes of phosphatidylcholine (cholesterol depletion) or phosphatidylcholine plus cholesterol (cholesterol enrichment). Lymphoblast intracellular pH (pHi) was examined by fluorimetry using cells loaded with the pH-sensitive dye 2',7'-bis(2-carboxyethyl)5(6)-carboxyfluorescein, and the Na-dependent proton efflux rate at a pHi of 6.0 was taken as the maximum velocity of the Na-H antiporter. Lymphoblast membrane cholesterol depletion activated the Na-H antiporter, and enrichment of membrane cholesterol caused inhibition of the antiporter activity. This study demonstrates that in situ modification of membrane cholesterol can modulate the activity of the Na-H antiporter.
authors.affiliation: Department of Clinical Pharmacology, University of Oxford, United Kingdom.
authors.forename: C E
authors.initials: CE
authors.lastname: Poli de Figueiredo
authors.forename: L L
authors.initials: LL
authors.lastname: Ng
authors.forename: J E
authors.initials: JE
authors.lastname: Davis
authors.forename: F J
authors.initials: FJ
authors.lastname: Lucio-Cazana
authors.forename: J C
authors.initials: JC
authors.lastname: Ellory
authors.forename: B M
authors.initials: BM
authors.lastname: Hendry
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008081:Liposomes; D008214:Lymphocytes / Q000166:cytology / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers
chemical_list: D002352:Carrier Proteins; D008081:Liposomes; D017923:Sodium-Hydrogen Exchangers; D002784:Cholesterol