Fig. 5.
D2R interacts with the HCN channel to modulate the onset frequency. A Ih of fan cells is almost completely blocked by 10 µmol/L ZD7288 and subsequent additional application of 10 µmol/L quinpirole fails to modulate it. C The onset frequency of fan cells decreases during bath application of 10 µmol/L ZD7288 and subsequent additional application of 10 µmol/L quinpirole has no effect. B, D Ih amplitude at −120 mV and onset frequency in pre-drug, ZD7288, and ZD7288 + quinpirole. ** vs pre. E Ih of fan cells is up-regulated by 1 mmol/L 8-Br-cAMP (cAMP) and subsequent additional application of 10 µmol/L quinpirole fails to decrease it. G The onset frequency of fan cells increases during bath application of 1 mmol/L 8-Br-cAMP and subsequent additional application of 10 µmol/L quinpirole has no effect. F, H Ih amplitude at −120 mV and onset frequency in pre-drug, 8-Br-cAMP, and 8-Br-cAMP + quinpirole. *, ** vs pre. *P < 0.05, **P < 0.01.