[Development of subsensitivity to imipramine in the system of reverse serotonin uptake by thrombocytes in patients with endogenous depression].

The inhibitory effect of imipramine (IC50) on [3H]serotonin uptake and its kinetic parameter (V400) were measured in platelets of 9 patients with unipolar and 6 with bipolar affective disorder. The IC50 and V400 values in depressed patients were significantly higher (p less than 0.002) than these found in the control group. Treatment with antidepressants significantly decreased the IC50 values. The results support the hypothesis postulating that depression is related to a decreased modulatory capacity of imipramine binding sites and that the clinical effectiveness of these drugs is associated with the said modulatory capacity.