title: Cough reflex and oral chemesthesis induced by capsaicin and capsiate in healthy never-smokers.
abstract: BACKGROUND
  Many tussive agents are components of foods, but little is known about the relationship between cough reflex and oral chemesthesis sensitivities. We investigated the relationships between cough reflex and oral chemesthesis in individuals using two transient receptor potential vanilloid 1 (TRPV1) agonists with different potencies: capsaicin and capsiate.
  
  
  METHODS
  Twenty-eight healthy never-smokers were allocated to evaluate cough and oral chemesthesis of capsinoids. Cough reflex sensitivities are estimated by the lowest concentrations generating five coughs by each TRPV1 agonist inhalation. Oral chemesthesis sensitivities are estimated by the lowest concentrations which generate a hot sensation when filter paper loaded with each TRPV1 agonist is placed on the tongue.
  
  
  RESULTS
  There were strong correlations between capsaicin- and capsiate-induced cough reflex sensitivities, and between capsaicin- and capsiate-induced oral chemesthesis sensitivities. However, there were no significant correlations between cough reflex and oral chemesthesis sensitivities induced by both capsaicin and capsiate. The cough reflex sensitivities are significantly greater in females than in males whereas there were no gender differences in oral chemesthesis.
  
  
  CONCLUSIONS
  The results showed that the sensitivities of sensory afferents were different between cough reflex and oral chemesthesis, suggesting that TRPV1 sensitivities differ between organs within healthy individuals. Capsiate could be a tussigen for the cough challenge test.
authors.affiliation: Department of Geriatrics and Gerontology, Tohoku University School of Medicine, Seiryo-cho 1-1, Aoba-ku, Sendai, 980-8574, Japan.
authors.forename: Miyako
authors.initials: M
authors.lastname: Yamasaki
authors.forename: Satoru
authors.initials: S
authors.lastname: Ebihara
authors.forename: Takae
authors.initials: T
authors.lastname: Ebihara
authors.forename: Shannon
authors.initials: S
authors.lastname: Freeman
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Yamanda
authors.forename: Masanori
authors.initials: M
authors.lastname: Asada
authors.forename: Motoki
authors.initials: M
authors.lastname: Yoshida
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Arai