The potential of using receptor-ligand dissociation rates as a model f
or investigating molecular changes in receptors was tested using the d
issociation of[H-3]citalopram, [H-3]paroxetine and [H-3]imipramine fro
m the brain 5-HT transporter of four different species (mouse, rat, pi
g and man). Since the dissociation rates of each of the three ligands
differed in most of the species investigated, receptor-ligand dissocia
tion rate constants would seem to be a sensitive measure of receptor c
onformation. The model could be useful in the search of structural var
iation in receptors whether attributable to genetic factors or to post
translational modification.