Effect of urethan anesthesia on cigarette smoke-induced airway injury in guinea pigs

Abstract

The effect of urethan anesthesia on cigarette smoke-induced airway responsiveness and permeability was studied in the guinea pig. Airway responsiveness was determined by measuring changes to airway resistance to graded doses of aerosolized histamine, and mucosal permeability was determined by measuring the appearance of fluorescein isothiocyanate-dextran (FITC-D) in the blood and examining its distribution in lung tissue after it had been delivered to the lung in an aerosol. The results confirm previous studies that smoke exposure increased airway responsiveness and mucosal permeability. They also show that urethan anesthesia administered before smoke exposure prevented the smoke-related changes in airway reactivity and mucosal permeability. In animals that remained conscious during the smoke exposure, there was increased deposition of the dextran in the regions of the bronchioloalveolar junctions with a more rapid uptake of FITC-D into the blood. We postulate that, when urethan anesthesia is administered before smoke exposure, the exudative phase of the inflammatory reaction produced by smoke exposure is suppressed.

Sensitivity of upper airway reflexes in cigarette smokers: effect of abstinence

“…Other workers agree that epithelial loss and damage may be extensive with similar changes to those caused by ozone and this probably accounts for increased bronchial reflex sensitivity after infection [15,[18][19][20]. In addition, acute smoke exposure in guineapigs is known to increase tracheal mucosal permeability with increased airway responsiveness to inhaled histamine [21]. We postulate that a similar mechanism may affect the airway lining in the chronic smoker.…”

Study of airway epithelial permeability with dextran

“…Dextrans were first used as paracellular tracers by Palade and co-workers in studies of capillary permeability (Simionescu and Palade, 1971;Simionescu et al, 1972); and since then have been used to assess permeability in many tissues and organs (e.g., Heinzmann, 1980;Hulstrom and Svensjo, 1979); there is only one report using dextrans to assess permeability characteristics in pulmonary tissues (Burns et al, 1987) and that was assessing bronchiolar level penetration and not the trachea. The characteristics of penetration of dextran and HRP, have not, until now, been compared in the same airway tissue (trachea) using the same methods to experimentally increase paracellular permeability.…”