Cytosolic pH regulation in mouse macrophages. Characteristics of HCO3(-)-dependent mechanisms.
Mechanisms regulating cytosolic pH (pHi) in adherent resident mouse macrophages have been characterized by use of the pH-sensitive fluorescent probe 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF). Na+/H+ exchange was activated after an acid load of the macrophage cytosol. However, when Na+/H+ exchange was the only pHi-regulatory mechanism operative, recovery did not proceed beyond a pHi of approx. 6.6. The mechanisms found to be operative at physiological pHi levels were alkalinizing Na(+)-dependent and acidifying Na(+)-independent Cl-/HCO3- exchangers and a H(+)-ATPase further characterized in the accompanying paper [Tapper & Sundler (1992) Biochem. J. 281, 245-250]. Acid extrusion via Na+/Cl-/HCO3- exchange was demonstrated by the dependence on external Na+ and HCO3- and on internal Cl- and by the sensitivity to 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulphonic acid (SITS) and 4,4'-di-isothiocyanatostilbene-2,2'-disulphonic acid (DIDS). By monitoring pHi changes upon Cl- removal and re-addition, the pH-dependence and sensitivity to SITS were found to differ for the alkalinizing and the acidifying Cl-/HCO3- exchangers.
Tapper
H
H
Department of Medical and Physiological Chemistry, Lund University, Sweden.
Sundler
R
R
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D005452:Fluoresceins; D005456:Fluorescent Dyes; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008264:Macrophages / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D006180:Proton-Translocating ATPases / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers
D001639:Bicarbonates; D002352:Carrier Proteins; D005452:Fluoresceins; D005456:Fluorescent Dyes; D017923:Sodium-Hydrogen Exchangers; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; D012964:Sodium; D006180:Proton-Translocating ATPases; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid