Figure 10.

Selectivity of the SV current in quinoa mesophyll vacuoles to Na⁺ and K⁺. Typical whole-vacuole current recordings are shown. SV currents were activated by a prepulse to +140 mV, followed by a series of test steps to less positive voltages, resulting in a complete or partial closure of SV channels (tail currents). Vacuole (pipette solution) contains 500 mm NaCl, and bath contains 100 mm KCl. Reversal potential (approximately 50 mV) is indicated by the arrowhead. At right is a summary of tail current I/V relationships obtained with a standard 100 mm KCl bath and either 500 mm (n = 8) or 100 mm (n = 4) NaCl in the pipette (vacuolar side).