Figure 7.

Shifting SV activation to physiological vacuolar potentials and changing rectification property. A and B, Whole-vacuolar SV currents (A) and current-voltage relationship (B). The pipette solution contained 20 mm KCl, 2 mm EGTA, and 5 mm HEPES-Tris, pH 7.0. The bath contained 200 mm KCl, 10 mm CaCl₂, 2 mm MgCl₂, and 20 HEPES-Tris, pH 8.0. Similar currents were recorded in seven of nine vacuoles. C, Under the same conditions as in A, time-dependent inward SV currents were recorded occasionally (n = 2 of 9 vacuoles) at negative membrane potentials (C). D, Current-voltage relationship of vacuoles showing bi-directional SV currents. This behavior was observed in two of nine vacuoles recorded under these conditions. As symbolized in C, ○ and ● show the time-dependent peak and steady-state amplitudes of SV currents, respectively.