Characteristics of tricyclic antidepressant binding sites associated with murine lymphocytes from spleen.

A single population of high affinity, saturable, tricyclic antidepressant (3-H-desipramine) binding sites has been identified on the membranes of murine lymphocytes. There are approximately 300 binding sites per cell and the apparent dissociation constant (Kd) for these binding sites is about 0.4 nM. Competition studies between the radiolabeled ligand in concentrations near the Kd and other members of the class of tricyclic antidepressants indicate that binding is competitive, reversible, and does not display interactions characteristic of cooperativity.