Effect of 0.25 ppm ozone exposure on pulmonary damage induced by bleomycin.
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 bleomycin-induced 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 03 (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.
Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile. moyarzun@med.uchile.cl
Manuel
M
Oyarzún
Nelson
N
Dussaubat
Sergio
S
González
D000818:Animals; D001761:Bleomycin; D001996:Bronchopneumonia / Q000139:chemically induced* / Q000473:pathology; D004195:Disease Models, Animal; D004357:Drug Synergism; D008168:Lung / Q000187:drug effects* / Q000473:pathology; D010126:Ozone / Q000633:toxicity*; D011658:Pulmonary Fibrosis / Q000139:chemically induced* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D001761:Bleomycin; D010126:Ozone