Effect of antagonists for NK(2)and B(2) receptors on antigen-induced airway responses in allergic rabbits.

The effects of the tachykinin NK(2)receptor antagonist, MEN 11420 (300 nmol/kg) and the bradykinin B(2)receptor antagonist, CP 0597 (17.2 and 172 nmol/kg) were studied in a rabbit model of antigen-induced airway responses. Antigen inhalation induced acute bronchoconstriction, airway hyperresponsiveness to histamine, and pulmonary eosinophil infiltration in 3-month-old rabbits immunized with Alternaria tenuis antigen within 24 h of birth. Treatment with MEN 11420 significantly reduced the acute bronchoconstriction induced by antigen, in terms of lung resistance. Antigen-induced changes in dynamic compliance were unaffected. CP 0597 had no effect on antigen-induced changes in lung function. Neither MEN 11420 nor CP 0597 had a significant effect on the antigen-induced increase in airway responsiveness to inhaled histamine or the pulmonary eosinophil infiltration 24 h after antigen challenge. We conclude that blockade of the NK(2)receptor can alter acute airway responses to antigen, but not antigen-induced eosinophilia or hyperresponsiveness to histamine. We also conclude that bradykinin B(2)receptor-mediated responses do not play a role in airway responses to antigen.