On the accurate measurement of serotonin in whole blood.
Levels of serotonin (5-hydroxytryptamine; 5-HT) in whole blood reflect the levels in the platelets, but there are problems with instability of 5-HT in measurement of whole blood extracts. We therefore developed and validated an assay for whole blood 5-HT using HPLC with fluorometric detection. The procedure involved collecting blood in EDTA vacutainer tubes and aliquoting it with internal standard, alpha-methyl-5-HT, before freezing. The aliquots were thawed on ice and proteins precipitated with perchloric acid containing EDTA and ascorbic acid. The 5-HT was stable in fresh whole blood for 24 h after sampling when stored at room temperature, refrigerated, or ice-cooled. Measurements of the levels of 5-HT in blood collected in heparin, citrate or EDTA were similar, but in blood collected in ACD-buffer the levels were approximately 25% lower. Cell lysis by sonication decreased the 5-HT levels, but this was compensated for by the internal standard. Determinations of 5-HT by HPLC were in good agreement with those by gas chromatography - mass spectrometry. The intra-individual variability between days was 3.6% (n=6). However, single and repeated ingestion of bananas, which are rich in 5-HT, elevated 5-HT in whole blood, indicating dietary influences on platelet 5-HT.
Xiao
R
R
Department of Laboratory Medicine, Karolinska Institute and Hospital, Stockholm, Sweden.
Beck
O
O
Hjemdahl
P
P
D000328:Adult; D000925:Anticoagulants; D001792:Blood Platelets / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D015925:Cryopreservation; D004355:Drug Stability; D004492:Edetic Acid; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D012701:Serotonin / Q000097:blood*; D019862:Zingiberales
D000925:Anticoagulants; D012701:Serotonin; D004492:Edetic Acid