Role of the parasympathetic system in antigen-induced bronchospasm

Abstract

Human subjects, sensitive to ragweed, inhaled aerosols of increasing concentrations of ragweed pollen extract in the presence and absence of pretreatment with inhaled atropine. The cumulative dose of antigen required for a 35% decrease in airways conductance was termed PD35. Atropine, 1.2 or 5 mg, increased airways conductance before antigenic challenge but did not significantly alter the PD35 for ragweed extract, although these doses of atropine inhibited airways response to inhaled methacholine chloride and citric acid. The cholinergic nervous system plays a modulating role in bronchomotor tone and responses to irritants, but parasympathetic reflexes are not invariably a major component of human bronchial response to inhaled allergen.