Depolarization removes the gating effect of extracellular Ca²⁺ by preventing Ca²⁺ influx through the open pore. (A and B) In the presence of 32 µM ADPR macroscopic TRPM2 currents at various test potentials (bars below traces) were activated by exposure to 125 µM of intracellular Ca²⁺ and closed by its sudden removal. Colored smooth lines are fitted single exponentials and time constants are in milliseconds. Pipette [Ca²⁺] was ∼4 µM in A and 1 mM in B. (C) Closing rates (mean ± SEM) in zero [Ca²⁺]_i and ∼4 µM (black circles) or 1 mM (red circles)of free Ca²⁺ in the pipette solution, obtained as the reciprocals of current decay time constants (see A and B, respectively), are plotted against membrane potential.