Figure 4.

Averaged current–voltage (I–V) relationships of I_K(DR) taken with or without roxadustat addition. In these experiments, the examined cells were maintained at −50 mV and a series of voltage pulses from −60 to +50 mV in 10-mV increments were applied at a rate of 0.1 Hz. (A) Representative I_K(DR) traces obtained in the absence (upper) and presence (lower) of 3 μM roxadustat. The upper part indicates the voltage protocol applied and the arrowhead shown in the left inside each panel is the zero current level. Calibration mark in the right lower corner applies to all panels. (B) Averaged I–V relationships of I_K(DR) in the control (i.e., in the absence of roxadustat). Current amplitudes at different levels of voltage were measured at the beginning (■) and end (□) of voltage steps. (C) Averaged I–V relationships of I_K(DR) in the presence of 3 μM roxadustat. Current amplitudes at different levels of command steps were measured at the beginning (●) and end (○) of voltage steps. Each point shown in (B) and (C) indicates the mean ± SEM (n = 9). The vertical dashed line shown in (C) indicates considerable difference between peak and late I_K(DR) as cells were exposed to 3 μM roxadustat.