Pulmonary inflammation without bronchial hyperresponsiveness in vivo or in vitro after sephadex instillation in pigs

1. In rodent models, Sephadex produces pulmonary inflammation that may be associated with bronchial hyperresponsiveness. In the present study we examined whether Sephadex-induced inflammation altered airway narrowing in pigs. 2. Twenty millilitres of 10 mg/mL Sephadex suspension was instilled twice intratracheally into anaesthetized pigs (days 1 and 7 of a 9 day study). In vivo bronchial responsiveness was assessed from the effect of acetylcholine (ACh) aerosol on airways resistance and dynamic compliance before Sephadex instillation and on days 3, 5 and 9. Lung histology and in vitro bronchial responsiveness was assessed on day 9. In vitro responsiveness was assessed by measuring the reduction in flow through perfused 2 mm i.d. bronchial segments in response to ACh applied luminally and adventitially. 3. Sephadex produced a focal peribronchial granulomatous reaction characterized by the presence of macrophages, eosinophils, neutrophils and giant cells. Changes in airway resistance and lung compliance in response to ACh did not change over the study period. The response of perfused bronchial segments to luminally or adventitially applied ACh was also unaltered. 4. Sephadex-induced pulmonary inflammation does not alter airway narrowing in vitro nor bronchial hyperresponsiveness in vivo in the pig.