Serotonin-induced increases in platelet cytosolic calcium concentration in depressed, schizophrenic, and substance abuse patients

Exaggerated intracellular calcium responses to challenges with serotonin (5-HT) have been reported in depression, In our studies, consistent with previous reports, patients with depression exhibited art exaggerated increase in 5-HT-stimulated intracellular calcium concentration ([Ca++](i)). Basal cytosolic calcium as elevated in both calcium-free and I mM calcium media in depressed patients, The increased responsiveness to 5-HT was seen in both conditions. Patients with schizophrenia and substance abuse did not differ from normal controls. The 5-HT response was correlated with diastolic blood pressure (r = 0.33, p = 0.02): however, this association did not fully account for the exaggerated [Ca++](i) responses in the depressed group, These findings suggest that exaggrated increases in [Ca++](i) in response to serotonin are a characteristic of depressed patients not shared with schizophrenic and substance abuse patients. The relationship of depression to hypertension, two conditions that share abnormalities of calcium homeostasis, warrants further study.