Chasing the elusive animal model of late-phase bronchoconstriction: studies in dogs, guinea pigs and rats.

Antigen inhalation in sensitized dogs, guinea pigs and rats resulted in a marked, late-phase, eosinophil-rich, influx of inflammatory cells into the bronchial lumen. Attempts to demonstrate an associated late-phase bronchoconstriction were disappointing. We were unable to demonstrate a late-phase bronchoconstriction in either rats or dogs, even when dogs were pretreated with metyrapone to reduce blood cortisol levels. In ovalbumin-sensitized guinea pigs, challenged with low doses of ovalbumin, we observed an immediate bronchoconstriction, a late-phase bronchopulmonary eosinophilia but no late-phase bronchoconstriction. However, inhalation of very high doses of antigen in mepyramine-treated sensitized guinea pigs did induce a moderate late-phase bronchoconstriction.