In the present investigation a possible involvement of tachykinins during sulfur dioxide-(SO2) and metabisulfite-(MBS) induced bronchoconstriction, and paraquat (PQ)-induced mortality was studied. SO2 (250ppm) inhalation and MBS (3mM) perfusion induced a marked decrease of compliance and conductance in the isolated and perfused lung. SO2-induced bronchoconstriction was associated with release of Calcitonin Gene Related Peptide, suggesting activation of capsaicin sensitive sensory nerves. Pretreatment of animals with capsaicin, in order to deplete the tachykinin content of sensory nerves, significantly reduced SO2- and MBS-induced bronchoconstriction. PQ (25mg/Kg) treatment induced high mortality (75%) after 3 weeks. Pretreatment with capsaicin significantly protected versus PQ induced mortality (25%). The results suggest that tachykinin content in the respiratory airways participate to SO2- and MBS-induced bronchoconstriction and PQ mortality.