Pharmacological parameters for SCH-442416 binding to A2AR, A1R-A2AR and A2AR-D2R CHO cells.

Competition experiments of [3H]ZM-241385 (2 nM) binding versus increasing concentrations of SCH-442416 were performed as indicated in Methods in membrane preparations from CHO cells expressing A2AR or A1R and A2AR or A2AR and D2R. Results were fitted assuming that receptors (also when heteromerizing) form homodimers, and cooperativity (DCB ≠ 0, fitting to eq. 2; Materials and Methods) or non-cooperativity (DCB = 0, fitting to eq. 3; Materials and Methods) of SCH-442416 binding was statistically tested (F test). KDB1 and KDB2 are, respectively, the equilibrium dissociation constants of the first and second binding of B (SCH-442416) to the dimer. DCB is the “dimer cooperativity” index for the binding of the ligand B, and B50 is the concentration providing half saturation for B. Data are mean ± S.E.M. values of three experiments.**: pDB2 and B50 values in A2R and A1R-A2AR cells; Kruskal-Wallis, followed by Dunn's test.