Figure 4.
Activation of GIRK channels in HEK cells stably transfected with human D2long and GIRK2 channel subunit by quinpirole. (A) Representative channel activation profile for quinpirole using D2long/GIRK2 HEK cells. The concentration of quinpirole is presented as nanomolar. (B) Composite dose response curve for the activation of GIRK2 channels (current amplitude) as a function of quinpirole concentration. GIRK current amplitude is normalized to the maximal current (assigned as 100%). Each point is the mean value for n ≥ 3 ± SEM. Curve shown is the best fit of the data to the logistic equation (see Methods). An EC50 value of 38 ± 4 nM was determined with a Hill coefficient of 1.1, indicating a simple one site interaction for channel activation.