FIGURE 7.

Inhibition of TRPML^Va current by trivalent cations. A, representative time courses of currents at −100 mV and +100 mV recorded using voltage ramps by whole-cell recording of an HEK293 cell expressing TRPML^Va. The cell was exposed to normal Tyrode's NMDG, pH 4.6 Tyrode's, and pH 4.6 Tyrode's solution containing 1 and 10 mm FeCl₃ as indicated, showing concentration dependent inhibition by Fe³⁺. B, I-V curves obtained by voltage ramps under conditions shown in A. C and D, similar to A and B, but pH 7.2 Tyrode's solution was used, and 1 mm LaCl₃ and 1 mm GdCl₃ in the pH 7.2 Tyrode's were applied as shown. E and F, I-V curves obtained by voltage ramps from whole-cell recording of two different TRPML^Va-transfected cells exposed to pH 4.6 Tyrode's solution without or with 1 mm LaCl₃ (E), or GdCl₃ (F). G, summary data (means ± S.E.) for % inhibition by La³⁺ and Gd³⁺ (both at 1 mm) of whole-cell currents at −100 mV in HEK293 cells that expressed either TRPML^Va or hTRPML1^Va. The extracellular solution had pH either at 4.6 or 7.2 as indicated.