Figure 1. E-4031-insensitive currents are not a main target for TRH in perforated-patch clamped GH3 cells studied in high-K+, low-Ca2+ extracellular solutions.
Current recordings from two representative cells showing high and low proportions of E-4031-insensitive inward current components are shown in A and B. The E-4031 sensitivity of currents recovered following TRH-induced inhibition after a prolonged period of TRH washout is illustrated in C. Currents were recorded in response to the voltage protocol shown in A. A and B, upper panel, currents under control conditions, after blockade of r-ERG channels with 5 μm E-4031, and 3 min after adding 100 nm TRH in the continuous presence of the inhibitor. Lower panel, E-4031-sensitive and TRH-sensitive currents obtained by subtracting the traces in the presence of E-4031 or TRH + E-4031 from control currents. C, current traces in the upper panel correspond to those recorded before adding TRH (Control), after 2 min of TRH treatment, following a 15 min period of washout with hormone-free medium, and in the presence of 5 μm E-4031. E-4031-sensitive currents obtained by subtracting the trace in the presence of E-4031 from those without inhibitor are shown in the lower panel. Zero current level is indicated with dashed lines on the non-subtracted current records.