Potassium and Chloride Effluxes during Excitation of Characeae Cells

概要

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Action potentials of intact and tonoplast-free Characeae cells were studied in relation to the effluxes of K^+ and Cl^-. K^+ efflux was monitored by atomic absorption spectroscopy or direct measurement of ^<42>K efflux. Cl^- efflux was monitored by the Ag-AgCl electrode method. A large K^+ efflux was always observed during excitations irrespective of whether the cell was intact or tonoplast-free. In tonoplast-free cells, the permeability of the plasma membrane for K^+ at the plateau of the prolonged action potential was almost the same as that in the resting state. In many cases, Cl^- efflux was also observed during excitations of intact cells although some cells showed action potentials without a detectable increase in Cl^- efflux. Almost all tonoplast-free cells generated action potentials with no associated increase in Cl^- efflux. These results indicate that some ion other than Cl^- carries inward current which balances the outward current carried by K^+. Calcium ion is discussed as the most probable candidate.
日本植物生理学会の論文