title: Intracellular pH regulation in cultured microglial cells from mouse brain.
abstract: Intracellular pH (pHi) and the mechanisms of pHi regulation have been investigated in cultured microglial cells from mouse brain using the pH-sensitive fluorescent dye 2',7'-bis-(2-carboxyethyl)-5-(6)-carboxyfluorescein (BCECF). Cells were acidified by a pulse of NH4+ (4-5 min; 20 mM) and the subsequent pHi recovery from an acidification was studied. In HCO3(-)-free saline, pH regulation was dependent on extracellular [Na+] and sensitive to amiloride, indicating the involvement of the Na+/H+ exchanger. In HCO3(-)-containing solution 2 mM amiloride slowed but did not block pHi recovery; the recovery however was dependent on extracellular [Na+] and sensitive to 0.3 mM DIDS, suggesting the presence of Na+/HCO3 cotransporter and/or Na(+)-dependent Cl-/HCO3-exchanger. The involvement of a Na-dependent Cl-/HCO3-exchanger was inferred from the observation that removal of Cl- or application of 1 mM furosemide decreased but did not block the recovery rate. Increasing [K+]0 resulted in an alkalinization by a process that was neither HCO3- nor Na(+)-dependent, nor DIDS- and amiloride-inhibitable. In conclusion, microglial cells express a distinct set of pH regulatory carriers which control for a defined level of pHi. An increase in [K+]0 can offset this level.
authors.affiliation: Max Delbrück Center for Moleculare Medicine, Cellular Neuroscience, Berlin-Buch, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Faff
authors.forename: C
authors.initials: C
authors.lastname: Ohlemeyer
authors.forename: H
authors.initials: H
authors.lastname: Kettenmann
mesh_terms: D000143:Acids / Q000378:metabolism; D000818:Animals; D017920:Antiporters / Q000378:metabolism*; D001639:Bicarbonates / Q000378:metabolism*; D001921:Brain / Q000166:cytology / Q000502:physiology*; D002478:Cells, Cultured; D027963:Chloride-Bicarbonate Antiporters; D002712:Chlorides / Q000378:metabolism*; D003600:Cytosol / Q000502:physiology; D005452:Fluoresceins; D005456:Fluorescent Dyes; D006863:Hydrogen-Ion Concentration; D051379:Mice; D008815:Mice, Inbred Strains; D017628:Microglia / Q000502:physiology* / Q000648:ultrastructure; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*; D012996:Solutions
chemical_list: D000143:Acids; D017920:Antiporters; D001639:Bicarbonates; D027963:Chloride-Bicarbonate Antiporters; D002712:Chlorides; D005452:Fluoresceins; D005456:Fluorescent Dyes; D017923:Sodium-Hydrogen Exchangers; D012996:Solutions; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein