Increased uptake of serotonin by blood platelets from patients with bipolar primary affective disorder-bipolar type.

Active uptake of serotonin (5-HT) by blood platelets with bipolar primary affective disorder-bipolar type has been compared to that of their family members and healthy controls, and Km and Vmax values were calculated for each subject. The uptake of patients' platelets, as reflected by Vmax, was found to be significantly higher than that of healthy controls (P less than 0.05) and non significantly higher than that of family members (P less than 0.05). The average value obtained (in pmol/10(8) platelets/5 min) were 253.4 (patients), 199.7 (families), and 171.5 (controls). The increased uptake by patients' platelets was not dependent on the state of disease. In two families, daughters of the patients exhibited the same uptake pattern as their ill mothers. The Km values for patients, family members, and controls were all about 1.06 x 10(-6) M. This study raises the possibility that the differences between patients and healthy individuals might be attributed to genetic factors. The meaning and interpretation of the findings are discussed.