Use of an electrochemical technique to study plasmamembrane redox reactions in cultured cells of Daucus carota L.

By exploiting the electron transfer reactions of ferricyanide-ferrocyanide at a gold electrode, an electrochemical technique was devised and successfully employed for the measurement of extracellular ferricyanide reduction or ferrocyanide oxidation by carrot (Daucus carota L.) cells grown in suspension culture. This technique eliminated problems of cell damage and insensitivity encountered when these activities are measured spectrophotometrically in magnetically stirred cell suspensions. Cells harvested from the mid-exponential phase of culture growth catalysed a rapid reduction of ferricyanide which was accompanied by H(+) extrusion and was stimulated by ethanol. These cells also oxidised ferrocyanide, which was not associated with H(+) extrusion. These observations can be explained on the basis of a plasmamembrane located, H(+)-translocating redox system. The electrochemical technique is a useful method of studying this system.