An improved method for the extraction of endogenous platelet serotonin.

Investigations of blood platelet serotonin content, turnover, metabolism, and secretion require sensitive methods for accurate measurement of the amine. The present study has sought a simple, efficient procedure for extracting total platelet serotonin which could also be used for analysis of other platelet chemical constituents. ZnSO4 precipitation, the standard technique for extracting 5-HT, failed to recover total platelet serotonin despite physical and chemical manipulations to improve its availability. Perchloric acid extraction was found to be more efficient, resulting in significantly increased values for endogenous platelet serotonin and recovery of 97 per cent of standard amounts of 5-HT added to platelet pellets. In addition, the perchloric acid extracts could be used for analysis of other platelet constituents such as adenine nucleotides. The improved procedure eliminates the need for large numbers of replicate samples for several assays and, at the same time, provides a more sensitive method for recovery of total platelet serotonin. It may also prove valuable for prolonged in vitro experiments in which extraction must be followed by additional isolation procedures in order to separate indole metabolites of serotonin from the amine for specific quantitation.