Sulphur dioxide-induced airway hyperreactivity and pulmonary inflammation in dogs.

Anaesthetised Beagle dogs were exposed to sulphur-dioxide (SO2) for 2 h and the pulmonary effects studied up to 24 h using bronchoalveolar lavage (BAL) and lung mechanics measurements. SO2-induced hyperreactivity to histamine was associated with epithelial cell shedding, an increase in airway permeability to plasma proteins and an increase in BAL PGE2 content. Leukotrienes were not recovered in BAL. Ibuprofen reduced hyperreactivity at 24 h post SO2 but not immediately after SO2 and had no effect on BAL cells at anytime. These results suggest that 2 phases of hyperreactivity exist--an immediate effect which may involve epithelial cell loss and a later phase which may be inflammatory.