Compliance and stability of the bronchial wall in a model of allergen-induced lung inflammation

Airway wall remodeling in response to inflammation might alter load on airw ay smooth muscle and/or change airway wall stability. We therefore determin ed airway wall compliance and closing pressures in an animal model. Weanlin g pigs were sensitized to ovalbumin (OVA; ip and sc, n = 6) and were subseq uently challenged three times with OVA aerosol. Control pigs received 0.9% NaCl (n = 4) in place of OVA aerosol. Bronchoconstriction in vivo was asses sed from lung resistance and dynamic compliance. Semistatic airway complian ce was recorded ex vivo in isolated segments of bronchus, after the final O VA aerosol or 0.9% NaCl challenge. Internally or externally applied pressur e needed to close bronchial segments was determined in the absence or prese nce of carbachol (1 mu M). Sensitized pig lungs exhibited immediate broncho constriction to OVA aerosol and also peribronchial accumulations of monocyt es and granulocytes. Compliance was reduced in sensitized bronchi in vitro (P < 0.01), and closing pressures were increased (P < 0.05). In the presenc e of carbachol, closing pressures of control and sensitized bronchi were no t different. We conclude that sensitization and/or inflammation increases a irway load and airway stability.