Erythrosin B as an effective inhibitor of electrogenic H⁺ extrusion

In 24‐h‐genninaled radish seedlings erythrosin B (EB), an effective inhibitor of microsomal as well as of partially purified vanadate‐sensitive ATPase markedly inhibited the basal and the FC‐stimulated proton extrusion, and induced a rapid depolarization of FC‐hyperpolarized trans‐membrane electric potential (PD) without causing any significant change of ATP level. The effects of EB on H + extrusion were partially additive with those of vanadatc, another inhibitor of plasma membrane H + ‐ATPase. These effects are interpreted as due to a direct inhibition by EB on plasma membrane H + ‐ATPase involved in H + electrogenic transport in the higher plants.