| dc.description.abstract | To study the effect of ozone in a chronically damaged lung, we used a bleomycin (BLM) induced pulmonary
fibrosis model. Both endotracheal instillation of BLM and O3 exposure both produce lung inflammation and
fibrosis. Oxidative stress would be a common mechanism of damage for both BLM and O3. Our aim was to
assess lung injury induced by 5 and 60 days of intermittent exposure to 0.25 ppm O3 in rats with bleomycininduced
pulmonary fibrosis. Thirty-day-old Sprague Dawley rats were endotracheally instilled with BLM (1
U/100 g body weight) and, 30 days later, exposed to 0.25 ppm O3 (0.25 ppm 4 h per day, 5 days a week).
Histopatology controls were instilled with saline and breathing room air. Histopathological evaluation of
lungs was done 5 and 60 days after O3 exposure. BLM-induced lung damage did not change after 60 days of
intermittent O3 exposure. Five days of O3 exposure increased the mean score of BLM-induced pulmonary
inflammation and fibrosis (p=0.06). Frequency of bronchopneumonia increased from 1/7 to 6/6 (p <0.001),
suggesting that a short-term exposure to O3 in a previously damaged lung might be a risk factor for
developing further lung injury. | |
