Human platelet serotonin content: methodological aspects and physiological variations.

Platelet serotonin (5-HT) content was determined from platelet rich plasma (PRP) of volunteers using high pressure liquid chromatography (HPLC) coupled with electrochemical detection following platelet lysis by perchloric acid. Several methodological and physiological aspects were studied. Blood collection with either EDTA or ACD-C anticoagulation gave identical results and blood storage at room temperature for at least two hours did not affect platelet 5-HT content, which allowed blood transfer to the laboratory. Deproteinized samples could be stored at either +4 degrees C for 48 hours or -80 degrees C for several weeks before HPLC determination. The partial degradation of 5-HT during storage was proportional to that of an internal standard at +4 degrees C or at -80 degrees C, but not at -20 degrees C. Comparison of platelet 5-HT content and serum 5-HT levels using the same HPLC method showed a good correlation although the absolute values differed. The mean platelet 5-HT content in healthy subjects aged 20-60 years was 0.364 + 0.093 nmol/10(+8) platelets (x + SD, n = 88). Men had slightly less platelet 5-HT than women and platelet 5-HT content was found to be lower in women over 60 years of age. This may come partly from hormonal suppression since platelet 5-HT contents were found to be positively correlated to plasma estrogen concentrations in a group of peri- and postmenopausal women.