Figure 7.
Nicotine reduces Ih similarly to ZD 7288. A, Continuous recordings of current responses evoked by hyperpolarizing voltage steps (from −60 to −120 mV, 1 s duration) repetitively delivered at 0.1 Hz, in the absence and presence of ZD 7288 (100 μm; black bar). Individual responses obtained before and during ZD 7288 from the trace on the left (asterisks) are shown on the right with an expanded timescale. B, Current responses evoked by hyperpolarizing voltage steps (10 mV increments) from a holding potential of −50 to −120 mV in the absence (Control) or presence of ZD 7288 (100 μm). C, Current–voltage relationship for the cell shown in B. Con, Control. D, Each symbol represents I–V slope (measured between −90 and −120 mV) of individual cells obtained in the absence (open circles) or presence (filled circles) of ZD 7288. Bigger symbols represent averaged values. E, Activation curves of nicotine-sensitive (gray circles; n = 6) and ZD 7288-sensitive (black circles; n = 9) responses obtained by subtracting tail currents recorded in the presence of nicotine (Nic) or ZD 7288 from their respective controls. ***p < 0.001.