[Distribution of metanephrines in methanol-treated human whole saliva analyzed by HPLC]

Organic solvent extraction of three metanephrines (MNs) in supernatant and sediment fractions obtained by the addition of methanol to the whole saliva and liquid chromatographic analysis with voltammetric detection are described. Two milliliters of unstimulated whole saliva obtained from 13 healthy males was treated with chilled methanol to separate mucin clots. The mucin clots, supernatant, and whole saliva were then hydrolyzed at 98 degrees C for 40 minutes at pH 0.5-0.8. These hydrolyzed samples were subsequently brought up to pH 10.0 with a 6 N NaOH solution in 0.1 M borate buffer (pH 10.0), and then 5-HT and MNs were extracted into toluene: isoamylalcohol (3:2) from the basic phase. MNs in their organic phase were extracted back into 0.1 M acetic acid and used for the high-performance liquid chromatographic (HPLC) analysis. The supernatant fraction showed a higher distribution for MNs than the sediment and whole saliva fractions. The chromatographic profile obtained from the supernatant and the whole saliva fractions contained some serotonin in a pattern similar to that reported from urinary analysis. The use of methanol for the fractionation of saliva resulted in good differential determination of MNs and revealed their distribution in the three salivary fractions. It is attractive to speculate that patients undergoing restorative treatment possibly manifest their anxiety by salivary excretion containing serotonin and MNs. These compounds in saliva may be useful markers of emotional responses.