AJP - Cell Physiology, Vol 262, Issue 1 C182-C190, Copyright © 1992 by American Physiological Society
Regulation of intracellular pH in single rat zona glomerulosa cells
R. M. Shepherd, G. H. Williams and S. J. Quinn
Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
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.
