Light‐dependent rubidium uptake into isolated mesophyll protoplasts from leaves of Pisum sativum

A method is described for the isolation of large amounts of physiologically active protoplasts from leaves of Pisum sativum L. Rubidium uptake was determined after separation of the intact protoplasts from the loading medium by rapid centrifugation through a phthalate step gradient. In freshly isolated mesophyll protoplasts of Pisum sativum, rubidium uptake was carbonylcyanide‐p‐trifluoromethoxyphenylhydrazone reduced by metabolic inhibitors such as 5 μM, 0.1 mW cyanide, 2 μM DCMU and 5 mM arsenate and by dark incubation. Reduction of rubidium uptake by inhibition of aerobic respiration or the photosynthetic electron transport system demonstrates that both processes play a role in the energy supply for membrane transport in these protoplasts.