Objective: To assess role of hydroxyl radials in the ozone-induced upper airway hyper-responsiveness to tachykinins. Methods: A prospective, controlled, animal model (n = 96) was performed. Half of them exposed to air (A-group, placebo) and the other half exposed to 3 ppm ozone (O-group) for 2 h. Two hours post air/ozone exposure, animals were anesthetized and equally randomized to be pretreated with one of the three treatments, including saline vehicle, dimethylthiourea (DMTU; 500 mg/kg m, a hydroxyl radical scavenger), or phosphoramidon (Phos; 2 mg/kg, an inhibitor for neutral endopeptidase). Ten minutes after pretreatment, half of the animals in each group were i.v. injected with capsaicin (2 μg/kg), and the other half were i.v. injected with substance P (10 μg/kg) to produce Evans blue dye extravasation. Results: Nasal exudative response to capsaicin or substance P in O-group was found to be significantly greater than that in A-group. This ozone-induced nasal airway hyperresponsiveness was largely prevented by DMTU. Phosphoramidon produced a similar nasal airway hyperresponsiveness in the A-group, but failed to alter ozone-induced nasal airway hyperresponsiveness in O-group. In sharp contrast, only substance P, but not capsaicin, produced a laryngeal exudative response in the A-group, which was similar to that in the O-group. The laryngeal exudative response to substance P was not significantly affected by DMTU or Phos. Conculsion: In the guinea-pig model, hydroxyl radicals play a vital role in the development of ozone-induced nasal airway hyperresponsiveness to tachykinins. It is possibly mediated through the suppressive action of ozone on the tachykinin degradation.
ASJC Scopus subject areas
Ho, C. Y., Tan, C. T., Tsai, H. H., & Kou, Y. R. (2008). Ozone-induced nasal hyperresponsiveness to tachykinins in guinea pigs. American Journal of Rhinology, 22(5), 463-467. https://doi.org/10.2500/ajr.2008.22.3208