FIGURE 1. Three-compartment ligand-receptor model used for analysis of CGP 12177 time–concentration curves obtained with PET. All transfer probabilities of ligand between compartments are linear, except for binding probability, which depends on local association rate constant (kon), on local free ligand concentration (F*(t)/VR), and on local concentration of unoccupied receptor sites (B'max-B*(t)). PET experimental data correspond to sum of labeled ligand in 2 tissue compartments and of fraction FV of blood concentration. B and B* = unlabeled and labeled bound ligand concentrations, respectively; B'max = receptor concentration; Ca* and F* = free ligand concentration in blood and tissue, respectively; k1 and k2 = rate constants; kon and koff = association and dissociation rate constants, respectively.
