Relative anion permeabilities and concentrations in leaf cells of Pisum sativum determined using electrical measurements and the Goldman equation

The electrical potential difference across the tonoplast ofpalisade mesophyll cells of leaves of Pisum sativum was 6.6± 0.8 mv (positive in the vacuole). The potential acrossthe plasmalemma depended on the particular anion accompanyingpotassium in the external solution. Assuming that the plasmalemmapotentials were diffusion potentials that could be analyzedusing the Goldman equation, the permeabilities of pyruvate,formate, .butyrate, acetate and bicarbonate into the cells werecalculated to be large compared with that of potassium, whilethe chloride permeability was relatively low. The upper limitsfor concentrations in the cytoplasm of palisade mesophyll cellsin pea leaves were as follows: potassium, 98 mM total monovalentorganic acids, 0.4 mM and bicarbonate, 0.2 mM. (Received March 3, 1971; )