Endogenous platelet serotonin release monitored during aggregation by means of a new electrochemical technique

Differential pulse voltammetry combined with electrochemically treated carbon fibre microelectrodes was used to monitor endogenous serotonin release occurring during platelet aggregation. After platelet stimulation by thrombin, an oxidation peak was recorded at +280 mV. HPLC analyses performed with fluorimetric detection have shown that this released electroactive compound was essentially serotonin. Moreover, serotonin measurements in the same samples by the technique reported here and by fluorimetry were found to be very similar (1.15 +/- 0.30 microM and 1.17 +/- 0.15 (mean +/- S.D., n = 6), respectively). Extracellular serotonin concentrations could be estimated either directly during aggregation or in supernatants obtained from stimulated or lysed platelets. Maximal serotonin concentrations have been found to be 6.93 +/- 0.37 and 3.28 +/- 0.39 nmol/10(9) platelets from rat and human, respectively. Using the reported procedure, we have observed that no serotonin was released from thrombin-stimulated platelets prepared from rats treated with reserpine. Our new technique represents a selective and performant tool for rapid determination of endogenous serotonin platelet secretion.