Sulfur-dioxide-induced bronchitis in dogs. Effects on airway responsiveness to inhaled and intravenously administered methacholine

Am Rev Respir Dis. 1987 Apr;135(4):840-7. doi: 10.1164/arrd.1987.135.4.840.


Chronic bronchitis was induced in 7 dogs of mixed breed by chronic exposure to SO2 gas. Within the first 2 to 4 wk of exposure, the dogs developed cough and mucous hypersecretion, chronic airway obstruction (increased pulmonary resistance), and persistent lung inflammation as demonstrated by an increase in the number of neutrophils recovered in the bronchoalveolar lavage (BAL) fluid. Airway responsiveness to methacholine aerosol decreased 2- to 3-fold within 8 wk of SO2 exposure. In contrast, airway responsiveness to intravenous administration of methacholine did not change. The data suggest that the decreased airway responsiveness observed during persistent pulmonary inflammation in SO2-exposed dogs is not due to an altered state of airway contractile elements but likely reflects expression of an inhibitory influence of the mucoepithelial barrier.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Airway Resistance
  • Animals
  • Bronchial Provocation Tests
  • Bronchitis / chemically induced*
  • Bronchitis / physiopathology
  • Chronic Disease
  • Dogs
  • Female
  • Male
  • Methacholine Chloride
  • Methacholine Compounds*
  • Mucus / metabolism
  • Sulfur Dioxide / toxicity*
  • Time Factors


  • Methacholine Compounds
  • Sulfur Dioxide
  • Methacholine Chloride