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. 2019 Mar 20;316(6):C792–C804. doi: 10.1152/ajpcell.00010.2019

Fig. 5.

Fig. 5.

Time-dependent decay in currents is associated with changes in thiocyanate equilibrium potential (ESCN). A: tail currents recorded in a C57BL/6J mouse retinal pigment epithelial (RPE) cell in the presence of 500 µM external thiocyanate (SCN−) elicited by stepping the membrane voltage to 0 mV after depolarizing the membrane potential to +50 mV for different durations from a holding potential of −60 mV. The horizontal interrupted line marks the steady-state current at 0 mV and the short horizontal unbroken line the zero-current potential. The pipette and bath solutions contained 140 mM Cl− and 145.6 mM Cl−, respectively. The red traces are best fits of the tail currents to a double-exponential function. Tail currents following brief depolarizations had a fast inward component followed by a slow outward component. Inset: amplitudes of the slow and fast components of tail current plotted as a function of the duration of the voltage step to +50 mV. The slow component of tail currents was outward for depolarizing voltage steps of short duration and inward for voltage steps of longer duration. The reversal in tail current polarity indicates that the time-dependent decay in outward current is associated with the intracellular accumulation of SCN−. Results are representative of experiments in 6 cells from 2 C57BL/6J mice. B: tail currents recorded in a C57BL/6J mouse RPE cell in the presence of 500 µM external SCN− elicited by stepping the membrane voltage to −90 mV after hyperpolarizing the membrane potential to −120 mV for different durations from a holding potential of 0 mV. The pipette and bath solutions contained 140 mM Cl− and 145.6 mM Cl−, respectively. The horizontal interrupted line marks the steady-state current at −90 mV and the short horizontal unbroken line the zero-current potential. The red traces are best fits of the tail currents to a double-exponential function. Inset: amplitudes of the slow and fast components of tail current plotted as a function of the duration of the voltage step to −120 mV. The slow component was inward for hyperpolarizing voltage steps of short duration and outward for voltage steps of long duration. The reversal in tail current polarity indicates that the time-dependent decay in inward current is associated with the depletion of intracellular SCN−. Results are representative of experiments in 7 cells from 2 C57BL/6J mice.