Figure 3.

Time course for rat heart (rH1) sodium channel block by U-50,488H. Oocytes were held at −120 mV and currents were evoked by depolarizations to −10 mV every 6 s in the absence (A) and presence (B) of U-50,488H. At the time indicated by the bar, 300 μM U-50,488H was added to the solution perfusing the cell. Maximal rH1 sodium current amplitude is shown plotted against time. Current traces are shown under control conditions (A, control), at the time maximal block was attained with U-50,488H (B, 300 μM), and 5 min after removal of U-50,488H from the bath solution and recovery of pre-drug current amplitude (C, wash). The inset in the upper panel depicts the time course for 1000 μM lidocaine block of the rH1 sodium current under identical experimental conditions. Note the prolonged time scale required for current recovery from block