title: Effect of subchronic in vivo exposure to nitrogen dioxide on lung tissue inflammation, airway microvascular leakage, and in vitro bronchial muscle responsiveness in rats.
abstract: OBJECTIVE
  In a previous study on bronchoalveolar lavage fluid from rats exposed in vivo for seven days to 10 ppm nitrogen dioxide (NO2), it has been shown that there is an influx of macrophages into the airways. The present study investigated the effect of seven day exposure to 10 ppm NO2, on: (a) lung tissue inflammation and morphology; (b) airway microvascular leakage; (c) in vitro contractile response of main bronchi.
  
  
  METHODS
  Lung tissue was studied by light microscopy, after fixing the lungs by inflation with 4% formalin at a pressure of 20 cm H2O. Microvascular leakage was measured by extravasation of Evans blue dye in the larynx, trachea, main bronchi, and intrapulmonary airways. Smooth muscle responsiveness was evaluated by concentration-responses curves to acetylcholine (10(-9)-10(-3) M), serotonin (10(-9)-10(-4) M), and voltage-response curves (12-28 V) to electrical field stimulation.
  
  
  RESULTS
  Histology showed an increased total inflammation at the level of respiratory bronchioles and alveoli. No influx of inflammatory cells was found in the main bronchi. A loss of cilia in the epithelium of small airways and ectasia of alveolar capillaries was also found. By contrast, no alterations to microvascular permeability or modification of bronchial smooth muscle responsiveness was found.
  
  
  CONCLUSIONS
  Subchronic exposure to 10 ppm NO2 causes airway inflammation and structural damage, but does not cause any persistent alteration to microvascular permeability or bronchial smooth muscle responsiveness in rats.
authors: Institute of Occupational Medicine, University of Padova, Italy.
authors: P
authors: P
authors: Chitano
authors: V
authors: V
authors: Rado
authors: A
authors: A
authors: Di Stefano
authors: A
authors: A
authors: Papi
authors: A
authors: A
authors: Boniotti
authors: G
authors: G
authors: Zancuoghi
authors: P
authors: P
authors: Boschetto
authors: M
authors: M
authors: Romano
authors: M
authors: M
authors: Salmona
authors: A
authors: A
authors: Ciaccia
authors: L M
authors: LM
authors: Fabbri
authors: C E
authors: CE
authors: Mapp
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D016084:Bronchoconstriction / Q000187:drug effects; D002199:Capillary Permeability / Q000187:drug effects*; D004558:Electric Stimulation; D008168:Lung / Q000187:drug effects* / Q000473:pathology; D009130:Muscle, Smooth / Q000187:drug effects*; D009585:Nitrogen Dioxide / Q000009:adverse effects*; D011014:Pneumonia / Q000139:chemically induced*; D011652:Pulmonary Circulation / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000494:pharmacology
chemical_list: D012701:Serotonin; D000109:Acetylcholine; D009585:Nitrogen Dioxide