The role of upper airways in antigen-induced bronchoconstriction.

The bronchoconstrictor effect of antigen was tested in 15 dogs. The upper and the lower airways were sequently exposed through a specially confected endotracheal tube. The antigen was also generally administered through a mouth mask. Bronchoconstriction was induced after each kind of exposure. The results argue for reflex bronchoconstriction. The sensory receptors localized in the upper part of the airways are responsible for about 50% of antigen-induced bronchoconstriction. The decrease of PO2a was less marked following Ascaris suum extract aerosol administration to the upper part of the airways. Control measurements demonstrated the reproducibility of antigen-induced bronchoconstriction.