Regulation of intracellular pH in single rat zona glomerulosa cells.
The cytosolic pH (pHi) regulation of rat adrenal zona glomerulosa (ZG) cells was studied using single-cell spectrofluorimetry. Basal pHi was similar for cells incubated in the absence or presence of the HCO3(-)-CO2 buffering system. In the absence of HCO3-, inhibition of the Na(+)-H+ exchanger by dimethylamiloride (DMA) or removal of extracellular Na+ produced substantial acidification of basal pHi. In the presence of HCO3-, neither maneuver affected basal pHi. However, removing extracellular Cl- produced a prompt alkalinization not observed in the absence of HCO3-. Alkalinizing mechanisms were examined by monitoring pHi recovery from an acid load imposed by the NH4Cl pulse technique. In the absence of HCO3-, Na+ removal or DMA addition blocked greater than 80% of pHi recovery. In the presence of HCO3-, 34% of the pHi recovery rate was inhibited by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), 34% by DMA, and 72% by Na+ removal plus DIDS. Therefore both Na(+)-H+ and anion exchangers are active in these cells, working independently to maintain basal pHi. In the absence of HCO3-, Na(+)-H+ exchange is principally responsible for pHi recovery from an acid load. In HCO(3-)-containing medium, such recovery is shared by Na(+)-H+ and Cl(-)-HCO3- exchange.
Shepherd
R M
RM
Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
Williams
G H
GH
Quinn
S J
SJ
D000143:Acids / Q000494:pharmacology; D000818:Animals; D000838:Anions / Q000378:metabolism; D001639:Bicarbonates / Q000378:metabolism; D002021:Buffers; D002245:Carbon Dioxide / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002469:Cell Separation; D027963:Chloride-Bicarbonate Antiporters; D006859:Hydrogen / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000378:metabolism*; D007474:Ion Exchange; D051381:Rats; D017923:Sodium-Hydrogen Exchangers; D015384:Zona Glomerulosa / Q000166:cytology / Q000378:metabolism*
D000143:Acids; D000838:Anions; D001639:Bicarbonates; D002021:Buffers; D002352:Carrier Proteins; D027963:Chloride-Bicarbonate Antiporters; D017923:Sodium-Hydrogen Exchangers; D002245:Carbon Dioxide; D006859:Hydrogen