A kinetic analysis and replication of decreased platelet serotonin uptake in depressed patients

Platelet serotonin uptake was kinetically measured in 32 psychiatric inpatients and 32 age- and sex-matched controls. Patients were categorized into four groups: depressed patients, manic bipolars, other affective disorders, and nonaffective psychiatric disorders. A randomized block factorial analysis of variance indicated that the depressed patients had a significantly lower maximal velocity ( V max ) of serotonin uptake in comparison to matched controls, without a statistically significant difference in K m . No statistically significant difference was found for any of the other diagnostic groups in comparison to controls for V max or K m . These results are compared with previous studies of platelet serotonin transport in clinically depressed patients and in physostigmine-induced depression.