Electrical properties of parenchymal cell membranes in the oat coleoptile.

Parenchymal cells of oat (Avena sativa) coleoptiles had an osmotic concentration of 410 mM (determined by plasmolysis); of this only 22 mM was K(+) and 1 mM Na(+) (flame photometry). Cells were impaled with micropipette electrodes. Iontophoretic injection of the dye Niagara sky-blue from the micropipette showed that the tip of the electrode penetrated the vacuole. When sections of tissue were immersed in a solution of 22 mM KCl, 1 mM CaCl2, and 50 mM glucose, average membrane potential was found to be 38.5 mV inside negative specific membrane resistance was ∼510 Ω cm(2), and specific membrane capacitance, ∼2 μf cm(-2). The cell membranes showed <25% retification and no electrical excitability. Electrotonic coupling of adjacent cells could not be demonstrated.