Reactivity of isolated canine bronchus and pulmonary blood vessels to autonomic, autacoid agents and antigen.

Adult dogs were sensitized to horse plasma. Reactivity of isolated bronchus and pulmonary blood vessels to antigen and some selected autonomic and autacoid agents were studied. Pulmonary veins contracted to bradykinin, 5-HT, PGF2alpha, PGE2, histamine, carbachol and antigen (Schultz-Dale reaction). Pulmonary arterial strips contracted to 5-HT and histamine, but only weakly to horse plasma. Bronchial strips contracted to carbachol, 5-HT, histamine and horse plasma, relaxed to isoprenaline, PGE1 and PGE2. Subsequent antigen challenge produced 'desensitization'. Allowing the tissues to 'rest' for 1 and 2 h resulted in partial 'recovery' of the anaphylactic response. This investigation suggests that the contractions of sensitized pulmonary vein and bronchus to specific antigen may contribute to the patho-physiology of pulmonary hypersensitivity in dogs.