Figure 10.

Displacement of [³H]S1P by COA-Cl in receptor ligand-binding competition assay using membrane preparation derived from S1P₁-overexpressing chem-1 cells. The figure shows the results of receptor ligand-binding competition assay in which [³H]S1P was bound to membrane preparation derived from chem-1 cells overexpressing S1P₁. Increasing concentrations of COA-Cl, unlabeled S1P, or unlabeled adenosine were included along with [³H]S1P (A−C, respectively). In each panel, 100% and 0% correspond to the [³H]S1P binding values obtained in the presence of the vehicle and excess S1P, respectively (n = 6−9). (D) Degrees of [³H]S1P binding obtained in the presence of the vehicle, COA-Cl (500 μmol/L), S1P (10 μmol/L) and adenosine (2.5 mmol/L). COA-Cl displaced [³H]S1P but adenosine did not.