Figure 2. 1 μg of membranes prepared from CHO cells stably expressing D2 receptors were incubated with indicated concentrations of [³H]spiperone in the absence (total binding) or presence of 1000-fold excess unlabeled haloperidol (nonspecific binding, NSB). Binding was terminated by rapid filtration. Specific binding was defined by subtracting NSB from total binding. Data were fit to one-site binding equation using a non-linear regression method.

Figure 3. 1 μg of membranes prepared from CHO cells stably expressing D2 receptors were incubated with indicated concentrations of haloperidol in the presence of 1nM [3H]haloperidol. Binding was terminated by rapid filtration. Data were fit to one-site competition equation using a non-linear regression method.

Figure 1: Dopamine-induced concentration-dependent stimulation of intracellular calcium mobilization in CHO-K1/D2/Gα15 cells. The cells were loaded with Calcium-4 prior to stimulation with a D2 receptor agonist, dopamine. The intracellular calcium change was measured by FLIPR^TETRA. The relative fluorescent units (RFU) were normalized and plotted against the log of the cumulative doses of dopamine (Mean ± SD, n = 2). The EC₅₀ of dopamine on D2 expressing CHO-K1/Gα15 cells was 18.8 nM.
Note:
1. EC₅₀ value is calculated with four parameter logistic equation:
Y=Bottom + (Top-Bottom)/ (1+10^ ((LogEC₅₀-X)*HillSlope))
X is the logarithm of concentration.
Y is the response and starts at Bottom and goes to Top with a sigmoid shape.