Effect of indomethacin and atropine in experimental asthma in conscious guinea pigs

Pulmonary mechanics were measured in unanesthetized guinea pigs sensitized to horseradish peroxidase (HRP) before and during two aerosolized challenges of this antigen. During the first challenge the pulmonary resistance increased in all animals. Prior to second challenge the animals received either atropine (0.2 mg/kg) or indomethacin (10 mg/kg) intraperitoneally. We found that during the second challenge the indomethacin group had an increase in pulmonary resistance slightly greater or similar to that during the first exposure to the antigen, while the animals treated with atropine had a significantly diminished response (P less than 0.05). In five guinea pigs sensitized to HRP but challenged with a nonspecific aerosal made up of rabbit albumin, we found that pulmonary resistance increased in some animals and that this increase could be partially blocked by atropine. These results show that indomethacin has no effect on this model of allergic airways disease. They also confirm the importance of the vagus nerves in allergic bronchoconstriction and in addition show that nonspecific hyperirritability can be induced in some animals by immunization.