Figure 5.

A D₁R agonist and an antagonist modulated hyperpolarization-activated cyclic nucleotide-gated (HCN) currents in a bipolar cell. (A) Voltage steps (lower panel) evoked inward currents in a type 5-2 bipolar cell. Steady-state currents (*) and tail currents (arrow). (B) HCN currents were evoked in a type 5-2 bipolar cell. SKF increased the HCN steady-state current, whereas SCH decreased the current. (C) The tail current was also increased by SKF38393 (red). SCH23390 decreased the tail current (blue) in the same cell. (D) A summary graph shows that SKF increased the HCN tail current in four bipolar cells (p < 0.05), and SCH decreased the current (p < 0.01, *p < 0.05.). (E) In five bipolar cells, SKF and SCH did not change the HCN tail current (p > 0.1).