Fig. 2.

Changes in the intracellular cAMP level after stimulation of dopamine D₂ receptor with rotigotine. HEK293 cells transiently transfected with Gα-mCitrine and D₂R-mCherry or Gα-mCitrineβ₁γ₂ and D₂R-mCherry were prestimulated with 1 μM of forskolin to enhance the basal levels of cAMP. After 5 min, rotigotine was added at a final concentration of 1 μM and the cells were incubated with the agonist for 10 min. In the case of Gαs, the prestimulation step with the use of forskolin was omitted. After stimulation, the cells were harvested and their intracellular cAMP concentration was determined. Data are presented as percentage of the cAMP levels in controls (nontransfected cells), and an appropriate control was used in every experiment. Control 1—Gαi; Control 2—Gαs. Error bars represent SEM; n = 4 experiments were performed in duplicates; unpaired T-test was used to evaluate the differences between samples. Comparison with adequate control: *p < 0.05 and ***p < 0.001; comparison within Gαi: ^#p < 0.05, ^##p < 0.005, and ^###p < 0.001