Fig. 1.

Agonist inhibition of forskolin-stimulated cAMP accumulation in HEK293T cells expressing D_2L DAR. Cells were incubated for 10 min at 37°C in media containing 3 μM forskolin and increasing concentrations of agonists. After incubation, the cells were assayed for cAMP accumulation as described in the methods. The agonists MNPA (A), dopamine (B) and NPA (C) potently inhibited forskolin-stimulated cAMP accumulation (■). Addition of 1 μM (+)-butaclamol to the assays promoted a 300-1800-fold shift in the dose-response curves to lower potencies (□). All graphs are means ± SEM from 3-4 experiments performed in duplicate. Results are summarized in table I.