Lanthanum-inhabitable currents revealed both TRPV6-like and CaCC current components in the same single epididymal cell. (A) At least two constitutively active current components (blue and red arrows) in principal cells were inhibited in a time-dependent manner after the addition of 200 µM lanthanum (La³⁺) to the recording chamber solution. Currents were sampled at 5-s intervals from a holding potential of −60 to 60 mV. The pipette solution was potassium based with 0.1 mM EGTA, and the bathing solution was standard PSS. The dotted line indicates the zero current levels. (B) Current responses toward the voltage ramp applied from −120 to 100 mV from a holding potential of −60 mV confirmed that lanthanum had a faster inhibitory effect on the inward current at negative potentials (arrow) than the outward current at positive potentials (double arrows). (C) The current responses toward the 500-ms depolarizing episodes from −60 to 60 mV before and after the addition of 200 µM La³⁺. (D) Current–voltage plots for the current responses under control conditions or in the presence of lanthanum for a short period time (within ∼30 s) or after prolonged presence (>5 min). (E) Subtraction currents revealed that the current inhibited by the early presence of lanthanum was inwardly rectifying with a reversal potential at positive potential (subtraction early), whereas the total currents inhibited at the various voltages showed a linear relationship (subtraction prolonged). Error bars represent SEM. (F) Tracings showing the current responses toward the series of testing pulses between −120 and 60 mV in the early or prolonged presence or after wash-off of lanthanum.