Pulmonary response to antigen infusion in the sensitized guinea pig: modification by atropine.

Alterations in pulmonary conductance, dynamic compliance, respiratory frequency, minute volume, mean arterial pressure, pulse rate, relaxation volume-to-dry weight ratio, and wet-to-dry weight ratio resulting from antigen infusion in sensitized guinea pigs was examined with and without atropine treatment. In untreated animals 3 min after antigen infusion there were significant decreases in dynamic compliance and pulmonary conductance with an increase in relaxation volume-to-dry weight ratio while other parameters were not altered. In atropine-treated animals antigen infusion resulted in a decreased dynamic compliance and an increased relaxation volume-to-dry weight ratio but no significant change in pulmonary conductance. This suggests that the alterations in large and central airway tone resulting from antigen infusion are mediated predominantly by secondary cholinergic mechanisms while peripheral airway effects are mainly noncholinergic.