Site of respiratory reaction in allergic rats challenged via the airways

Rats systemically sensitized to DNP-ovalbumin show a characteristic respiratory response to antigen challenge delivered via the airway. The slowing of expiratory air flow which occurs on aerosol challenge still occurs when the antigen is injected via a tracheostomy but not when it is delivered solely to the upper airways. Disodium cromoglycate administered via the tracheostomy 1 min before intratracheal antigen challenge reduces the respiratory response.