[Potentiometric study of redox systems of human erythrocytes using potassium ferricyanide].

It was shown that the rate of potassium ferricyanide reduction in erythrocyte suspension recorded potentionmetrically depends on the activity of redox systems of erythrocytes. The rate of this process is increased after an addition of glucose, methylene blue and ascorbate. A sharp decline of the level of reducing equivalents in the hexose monophosphate pathway by tretbutylhydroperoxide stops the ferricyanide reduction. It is concluded that the hexose monophosphate shunt is a source of reducing equivalents for ferricyanide reduction. Ascorbic acid and methylene blue act as "carriers" of the reducing equivalents across the membrane and provide for the reduction of ferricyanide, i.e. compound, which does not penetrate the cell.