title: Diffuse alveolar damage in the rat lung after short and long term exposure to nitrogen dioxide.
abstract: In order to quantify parenchymal, vascular and epithelial changes occurring in the exudative and organizing phase of diffuse alveolar damage (DAD) induced by inhaled NO2 groups of 7 rats were continuously exposed to 5, 10 or 20 ppm NO2 for 3 and 25 days alternatively. AgNOR analysis revealed the highest proliferative activity in the epithelium of the respiratory bronchioles. In this region already after 3d exposure to 5 ppm the maximum AgNOR number was reached. In contrast to long-term exposure after 3d exposure to 5 and 10 ppm NO2 the AgNOR number in the respiratory bronchioles was significantly higher than in central airway epithelia. After long-term exposure to 5 and 10 ppm AgNOR number decreased to normal values or showed no further significant increase, long-term exposure to 20 ppm resulted in a further increase of the AgNOR number. A significant increase of the alveolar circumference and decrease of alveolar surface density was found after an exposure to 20 ppm for 3d and long-term exposure to 10 and 20 ppm NO2, whereas the 5 ppm exposure groups disclosed no significant change of these values. Medial hypertrophy was detected after exposure to 10 and 20 ppm NO2 for 25 days, after the exposure to 5 ppm for 3d and 25d medial thickness was significantly decreased due to vasodilation induced by NO, one of the major reaction products of NO2.
authors.affiliation: Department of Pathology, Philipps-Universität Marburg/Lahn, Germany.
authors.forename: P J
authors.initials: PJ
authors.lastname: Barth
authors.forename: S
authors.initials: S
authors.lastname: Uhlarik
authors.forename: A
authors.initials: A
authors.lastname: Bittinger
authors.forename: U
authors.initials: U
authors.lastname: Wagner
authors.forename: J
authors.initials: J
authors.lastname: Rüschoff
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004646:Emphysema / Q000139:chemically induced; D008297:Male; D009585:Nitrogen Dioxide / Q000494:pharmacology*; D009697:Nucleolus Organizer Region / Q000648:ultrastructure; D011650:Pulmonary Alveoli / Q000187:drug effects* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D012834:Silver; D013194:Staining and Labeling; D013997:Time Factors
chemical_list: D012834:Silver; D009585:Nitrogen Dioxide