Cytoplasmic pH modulates the activity of the plasma membrane electron transport system in Ehrlich ascites tumour cells

We report evidence for a modulation of Ehrlich cell plasma membrane redox activity by cytoplasmic pH. When Ehrlich cells were submitted to treatments leading to a slight decrease of cytoplasmic pH, there was a significant inhibition of plasma membrane ferricyanide reductase activity. However, those treatments which produced a slight alkalinization of the cytoplasm enhanced the activity of the plasma membrane redox system. Since it has been shown previously that plasma membrane redox activity controls cytoplasmic pH, it seems that plasma membrane redox activity and cytoplasmic pH mutually modulate each other.