Control of Cl− influx inChara by internal pH

Abstract

Summary. The possible regulation of CI influx in Chara by the cytoplasmic C1-concentration and cytoplasmic pH was investigated using both intact and intracellularly perfused cells. In perfused cells C1-influx was sensitive to changes in the internal C1-concentration but only when the concentration was less than 1 mM.In intact cells the metabolic inhibitors, CCCP, DCMU, and oligomycin which inhibit C1-influx also reduced the cytoplasmic pH. A correlation between ATP concentration and cytoplasmic pH was shown to apply when the ATP concentration was lowered using these inhibitors. The possible relationships between ATP status, cytoplasmic pH, and C1-influx are discussed.

Kinetic response of H+-coupled transport to extracellular pH: Critical role of cytosolic pH as a regulator

“…[Below pHo = 6, pHc is not detectably pHo dependent.] The second observation is that C1-influx in Chara is an acutely sensitive function of pH~ (Sanders, 1980c;Reid & Walker, 1984). Indeed, C1-influx titrates as though 2 H + were dissociating from sites with pKos = 7.85.…”