Fig. 8.

Correlation of the negative logarithm of hA₁R ligands’ association rates (pk _on, a) and dissociation rates (pk _off, b) determined by SPA (x-axis) and filtration assay (y-axis). Agonists: CCPA, NECA, and LUF5834; antagonist: DPCPX. Correlation of the negative logarithm of hA₁R ligands’ kinetic K _D (pK _D) determined by SPA (y-axis) and filtration (x-axis). For (partial) agonists LUF5834, CCPA, and NECA, only the low affinity state of the receptor was taken into account due to the presence of 1 mM GTP in the competition association experiments (c). Correlation of the negative logarithm of hA₁R ligands’ affinity (pK _i) from displacement studies of specific [³H]-DPCPX binding from hA₁R membranes and the negative logarithm of hA₁R ligands’ kinetic K _D (pK _D) determined by SPA (d) and filtration (e). For (partial) agonists LUF5834, CCPA and NECA, only the low affinity state of the receptor was taken into account due to the presence of 1 mM GTP in the competition association experiments