Mechanisms of pH recovery from intracellular acid loads in the leech connective glial cell.
We used double-barrelled, neutral carrier, pH-sensitive microelectrodes to study the mechanisms by which the intracellular pH (pHi) is regulated in the connective glial cells of the medicinal leech. In HEPES-buffered, nominally CO2/HCO3(-)-free solutions the recovery of pHi from intracellular acidosis is Na(+)-dependent and reduced by at least half in the presence of amiloride, suggesting the action of Na+:H+ exchange. The rate of pHi recovery by this mechanism can be increased by raising the extracellular buffering power or by increasing extracellular pH. The presence of CO2/HCO3(-)-greatly increases the rate of pHi recovery from intracellular acidosis. This CO2/HCO3(-)-stimulated recovery is also dependent on external Na+, largely Cl(-)-independent, inhibited by DIDS, and accompanied by membrane hyperpolarization. This is consistent with it being mediated by the electrogenic cotransport of Na+ and HCO3- into the cells. A Cl(-)-dependent component to Na(+)- and HCO3(-)-dependent regulation is most easily explained by the added presence of a Na(+)-dependent exchange of HCO3- and Cl-.
Szatkowski
M
M
Institut für Zoologie, Universität Düsseldorf, Germany.
Schlue
W R
WR
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000138:Acidosis / Q000378:metabolism; D000143:Acids / Q000378:metabolism*; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D003238:Connective Tissue / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007865:Leeches / Q000378:metabolism*; D008839:Microelectrodes; D009457:Neuroglia / Q000378:metabolism*
D000143:Acids; D001639:Bicarbonates; D002712:Chlorides; D002245:Carbon Dioxide; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid