title: Influence of saliva flow rate stimulated by gum-chewing on salivary concentrations of catecholamine metabolites.
abstract: BACKGROUND
  The measurement of homovanillic acid (HVA) and 3-methoxy-4-hydroxyphenylglycol (MHPG) in saliva is useful for diagnosis of some psychiatric disorders. Gum-chewing increases salivation and is sometimes used to collect an adequate sample volume of saliva within a shorter time. However, the rate of saliva production may affect the salivary concentrations of these catecholamine metabolites. We clarified whether the salivary concentrations of HVA and MHPG are dependent on the rate of salivation.
  
  
  METHODS
  Stimulated saliva was collected from healthy volunteers chewing a tasteless and flavorless chewing gum after unstimulated saliva was collected without gum-chewing. The salivary HVA and MHPG concentrations were measured using newly developed LC/ESI-MS/MS methods.
  
  
  RESULTS
  The salivary HVA and MHPG concentrations were reproducibly measured when saliva was collected without gum-chewing (unstimulated saliva). In contrast, their salivary concentrations significantly decreased when salivation was stimulated by gum-chewing (p<0.05, Wilcoxon signed-rank test).
  
  
  CONCLUSIONS
  Stimulated saliva by gum-chewing should be used with caution in the measurement of the catecholamine metabolites. LogD is a useful indicator, when predicting whether the salivary concentration of a compound is dependent on the rate of salivation.
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda 278-8510, Japan. higashi@rs.tus.ac.jp
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Higashi
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Hijikuro
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Yamagata
authors.forename: Shoujiro
authors.initials: S
authors.lastname: Ogawa
mesh_terms: D000328:Adult; D002395:Catecholamines / Q000378:metabolism*; D002638:Chewing Gum; D006801:Humans; D012016:Reference Values; D012463:Saliva / Q000378:metabolism*; D012636:Secretory Rate; D055815:Young Adult
chemical_list: D002395:Catecholamines; D002638:Chewing Gum