Increased vascular permeability and reduced neutral endopeptidase activity in rat nasal mucosa after ozone exposure

Kim, Yong Min; Jung, Bong Jin; Kim, Byung Kook; Rha, Ki Sang

Abstract

BACKGROUND AND OBJECTIVES
Exposure to ozone has several effects on the respiratory tract, including airway inflammation and hyperresponsiveness. It has been suggested that these were associated with decreased NEP (neutral endopeptidase) activity. The purpose of this study is to investigate whether ozone exposure increases the vascular permeability in nasal mucosa, and if the vascular permeability is increased, whether it is associated with decreased NEP activity.
MATERIALS AND METHODS
Twenty Wistar rats were divided into four experimental groups: control group (group 1), phosphoramidon pretreated group (group 2), ozone exposure (3 ppm for 30 minutes) group (group 3), and phosphoramidon + ozone exposure group (group 4). Sixty minutes after ozone exposure or 10 minutes after phosphoramidon pretreatment, capsaicin (100microgram/kg) was injected via femoral vein. Immediately, nasal lavage fluid was obtained and Evans blue dye was infused via femoral vein. Five minutes later, rats were sacrificed and nasal mucosa was taken. We measured the amount of extravasated Evans blue dye in nasal mucosa, and the concentration of albumin in nasal lavage fluid.
RESULTS
Evans blue extravasation were significantly increased in groups 2, 3, and 4 when compared with group 1 (p<0.05), and in group 4 when compared with group 3 (p<0.05). Albumin concentration in nasal lavage fluid was increased in groups 2, 3, and 4, compared with group 1. But, there were no statistically significant differences.
CONCLUSION
These results suggest that ozone increases the vascular permeability of nasal mucosa, and this is partially associated with decreased NEP activity after ozone exposure.