Fig. 5.
Effects of NH3/NH4+ and MA/MA+ on pHi and Vm in H2O-injected oocytes. Exposure of control oocytes to NH3/NH4+ (5 mM) caused a small and slow decrease in pHi (dpHi/dt = −6 × 10−4 pH units/s) and depolarization of the cell membrane (segment ab). Both changes readily recovered upon removal of NH3/NH4+ from the bath (segment bc). However, exposure of the H2O-injected oocyte to MA/MA+ (5 mM) caused only a small increase in pHi and no depolarization (segment cd). Removal of MA/MA+ reversed these changes (segment de). Tracings are representative results from 13 experiments.