Figure 10.

Screening for off-target effects of SK609 at high concentration (100 μM) on a panel of 128 GPCRs using the DiscoveRx β-arrestin recruitment assay. (A) Screening at 100 μM of SK609 in both agonist (light blue bars) and antagonist mode (dark blue bars) resulted in ~70 receptors that had an effect (nonzero value). SK609 has an agonist effect at D2R and D3R and antagonist activity at adrenergic, cannabinoid receptor-1, and 5HT2A receptors at a concentration of 100 μM. Several other hits were found to be false positives. (B) Dose–response curves of SK609 and SK213 for antagonizing isoproterenol-induced β-arrestin-2 recruitment at the β₂-adrenergic receptor. CHO-K1 cells stably expressing β₂-adrenergic receptor were plated at 10 000 cells/well in a 96-well plate and incubated for 48 h, pretreated with vehicle or indicated concentrations of SK609 or SK213 for 30 min, and subsequently treated with vehicle or 300 nM of isoproterenol (EC₈₀) for 90 min. Following stimulation, signal was detected using the PathHunter detection reagents following the manufacturer’s protocol. Each value represents mean ± SEM of three independent experiments performed in duplicate and represented as percent of control (300 nM of isoproterenol).