In Reply.—
Modai et al are correct in pointing out that their method permits the assessment of active uptake of serotonin. We apologize for our misunderstanding of their means of estimating passive diffusion. However, the use of only a single tube to assess passive diffusion and of duplicate tubes to assess total uptake is questionable, because the data on passive diffusion contribute as much to the measurement of active uptake as do those on total uptake.The important issue of whether schizophrenic patients suffering acute exacerbation have decreased active uptake of serotonin in their platelets requires further study, because we cannot confirm the report by Modai et al of low uptake in schizophrenics. S. Stahl, MD, PhD, and P. Berger, MD, of Stanford (Calif) University also have not found decreased uptake of serotonin in the platelets of schizophrenics not receiving medication (oral communication, Nov 15, 1981). There could be some differences between