Specific high affinity [3H]imipramine binding sites in rat lung are associated with a non-neuronal uptake site for...

[3H]Imipramine binds to rat lung membranes. The binding is saturable, of high affinity and sodium-dependent. Drug displacement studies indicate that the binding site in rat lung is similar to that already described in the brain cortex. Tricyclic antidepressants inhibited [3H]imipramine binding in the lung in the low nanomolar range and through a competitive interaction. Serotonin and non-tricyclic serotonin uptake blockers inhibited [3H]imipramine binding in lung in a complex manner. Our results support the view that [3H]imipramine binding and the serotonin recognition site of the transporter are related but not identical.