Fig. 3.

NE 52-QQ57 is a novel GPR4 antagonist working in a physiological range of pH.

A. NE 52-QQ57 (formula above the bar chart) inhibits GPR4-mediated cAMP accumulation but its potency depends on proton concentration (pH). Plotted are mean % changes ± s.e.m. (n = 5 of triplicates) where % change is calculated as (with drug – baseline)/(baseline x 100) for every triplicate. Inhibition by NE 52-QQ57 becomes less effective as pH decreases. Significant differences are shown by repeated measures one-way ANOVA with Tukey's multiple comparisons post hoc test (** - p < 0.01).

B. Concentration-response curve for NE 52-QQ57 at pH 7.4. Calculated IC₅₀ is 26.8 nM. Data represent mean ± s.e.m. of triplicates. Log −10 corresponds to zero concentration of the drug.