Fig. 6.

Investigating the effect of some A2A agonists at the A2B receptor. (A) Antagonist reversal of agonists at A2B using the endpoint cAMP assay. CHO-A2B cells were incubated with EC₉₀ (at A2B) concentrations of 3ab (red), 3cd (green), 3eg (blue), or 3ch (purple) for 2 hours at room temperature before addition of antagonist (2 μM ZM-241385) or vehicle for the indicated times. Data points represent antagonist-treated cAMP responses normalized to vehicle control at each time point. Best-fit lines represent nonlinear regression one-phase exponential decay from an average ± S.E.M. of three experiments performed in triplicate. (B) Sustained agonism at in CHO-A2B cells. Sustained cAMP responses were measured in washout experiments, measuring residual cAMP responses after pretreatment of CHO-A2B cells with EC₉₀ concentrations of 3ab, 3cd, 3eg, and 3ch. cAMP responses are normalized to acute responses (20× EC₉₀ of NECA) measured in parallel in the same population of pretreated cells. **P < 0.01; ***P < 0.001 as determined by repeated-measure ANOVA with Dunnett’s post-test compared with responses in vehicle control pretreated cells. Data represent an average of three experiments performed in triplicate.