SIGNIFICANT CORRELATION BETWEEN C-14 5-HT UPTAKE BY AND H-3 PAROXETINE BINDING TO PLATELETS FROM HEALTHY-VOLUNTEERS

The lack of correlation between 5-HT uptake by platelets and the ability of platelet membrane to bind antidepressant drugs, particularly imipramine, has been reported. However, more recently it has been suggested that H-3-paroxetine could be a better drug with which to study the platelet 5-HT uptake mechanism in disease states. We have therefore compared the ability of platelet-rich plasma (PRP) from normal individuals to take up 5-HT with the ability of platelet membranes to bind paroxetine. A significant correlation was apparent between the V(max) of C-14-5-HT uptake by PRP and the B(max) of H-3-paroxetine binding to platelet membrane from 30 individuals (r = 0.6468, p = 0. 0001). Furthermore, this correlation was highly significant in the 20 female (r = 0.7768, p = 0.00006) but not in the 10 male volunteers. There was also a significant association between V(max) and B(max) and the month of blood sampling but this did not totally account for the correlation between V(max) and B(max). The simultaneous measurement of 5-HT uptake by PRP and paroxetine binding to platelet membranes from both depressed patients and matched controls should be carried out to confirm and extend these findings.