A and B show the voltage protocol and the current response, respectively, of a protoplast when K+ was included as the monovalent cation in both pipette and bath solution. Note that the IV curve was strongly outward rectifying with K+ in the pipette medium ( Fig. 1E, solid squares); large outward currents carried by the Shaker-type outward-rectifying channel NtORK [15] were activated, whereas inward currents remained small.