Vagal reflexes in the bronchoconstriction occurring after induced intravascular platelet aggregation.

Intravascular platelet aggregation induced in cats by i.v. infusions of collagen caused a transient increase in pulmonary vascular resistance (PVR) and in non-elastic pulmonary resistance (RL), and a transient decrease in dynamic lung compliance (dyn CL). PVR,dyn CL and platelet aggregation after collagen infusions were unaffected by bilateral cervical vagotomy and atropinization, wheras these procedures reduced the post-infusion rise in RL by about 50 per cent. The administration of indomethacin inhibited platelet aggregation as well as bronchoconstriction after collagen infusion. The present investigation indicates that intravascular platelet aggregation will cause reflex bronchoconstriction mediated by vagal efferent fibres.