Figure 7. Time course of fast erg current deactivation.

E-4031-sensitive currents measured in a rhombencephalon neurone and erg currents following heterologous expression of erg1a, erg1b, erg2 and erg3 channels in CHO cells were recorded with the pulse protocol as described in Figs 2 and 6. The deactivating erg currents elicited by the test pulses between −70/−80 mV and −120 mV were fitted with a single exponential function to the fast decaying part of the curves (dotted lines in A and B) yielding the time constant τ_fast. Example traces elicited by the test pulse to −100 mV of native (A) and heterologously expressed currents (B). C, mean values of time constants τ_fast of deactivation plotted against the test potential for erg currents in rhombencephalon neurones (•; n= 24), as well as for erg1a (○; n= 6), erg1b (▵; n= 8), erg2 (▿; n= 10) and erg3 (□; n= 5) currents measured in CHO cells. Asterisks indicate significance against τ_fast of rhombencephalic erg (*P≤ 0.05; **P≤ 0.01; ***P≤ 0.001).