Development of computer-assisted simulation procedure to analyze receptor modulatory processes

Experimentally induced changes in neurotransmitter receptors have been analyzed by means of a computer assisted simulation procedure over a wide range of free ligand concentrations. This approach allows to evaluate, for a given range of ligand concentrations, the relative influence of simultaneous variations in binding parameters (i.e. dissociation constant or Kd and in maximal number of binding sites or Bm) and to predict the net and final effect of the experimental condition on the receptor-mediated transmission line. The function representing the changes in bound values versus the respective free ligand concentrations, has been studied analytically on the basis of all the possible values that the percent changes in both Kd and Bm parameters induced by a given experimental condition can assume. A well characterized change in the pattern of bound radioligand could in this way be defined. This approach, developed to show in an immediate and clear way treatment-induce changes in receptor populations or to fit directly rough experimental data expressed as differences in bound values versus free ligand concentrations, seems to be an useful complement to the widely used saturation analysis of binding data.