Voltage-dependent K channels in protoplasts of trap-lobe cells of Dionaea muscipula

The outward rectification of the K⁺ current in mesophyll cell protoplasts from trap-lobes of Dionaea muscipula was studied with the patch-clamp technique. The rectification had instantaneous and time-dependent components. Changes in [K⁺]_i strongly affected the conductance voltage relation of the plasma membrane while changes in [K⁺]_o had little effect on the relation. Thus, the outward rectification depends on the membrane voltage and the concentration of intracellular K⁺. Corresponding single-channel activities were observed both in the intact membrane (cell-attached recording) and in excised patches. The single-channel conductance was about 3.3 pS with symmetrical solutions containing 30 mm K⁺.