Figure 6.
Involvement of Ih in dopaminergic modulation of sAHP. A, Cell-attached recordings showing that D2 receptor activation with quinpirole (20 μm) reduced spontaneous firing, accompanied by an increase in irregularity. B, After TTX treatment (1 μm), application of quinpirole reduced the depolarizing sag during hyperpolarizing pulses and the subsequent rebound depolarization (top), and prolonged sAHP (arrows, bottom). C, Group data showing that, in the presence of TTX, quinpirole significantly increased sAHP duration, but was ineffective on sAHP amplitude and time-to-peak. D, A neuron was treated first with ZD7288 (30 μm) and then with dopamine (50 μm). Dopamine was unable to further prolong sAHP when Ih was mostly blocked (arrows). E, Histogram showing the changes of sAHP in the presence of ZD7288 alone or ZD7288 plus dopamine. The effects of dopamine on sAHP duration were completely occluded by ZD7288. *p < 0.01.