Figure 1.

Amount of the B₂ receptor radioligand [¹²⁵I]-HPP-Hoe140 bound to the thoracic spinal dorsal horn of SHR (n=4) and WKY (n=4) as a function of its concentration. Quantification was performed on 96 sections (24 sections per animal) for each concentration corresponding to 1056 sections for total and non-specific binding. Specific binding is calculated as the mathematical difference between total and non-specific binding (which persists in the presence of 1 μM of unlabelled ligand) and reflects the amount of radioligand bound to specific B₂ receptor binding sites (upper panel). The affinity of the binding, which is expressed as a dissociation constant (K_d), was calculated as the concentration of B₂ radioligand that results in 50% of maximal specific binding (lower panel).