Role of the vagus nerves in anaphylaxis and histamine-induced bronchoconstrictions in guinea-pigs.

1. The effects of vagotomy on the respiratory responses of guinea-pigs to anaphylactic reactions and to intravenous injections of histamine acid phosphate are described.2. In spontaneously breathing guinea-pigs, vagotomy reduced by 50% or more the decreases in total lung conductance (bronchoconstriction) and the decreases in lung compliance, and almost abolished the rapid shallow breathing due to histamine.3. In paralysed, artificially ventilated guinea-pigs, vagotomy reduced by more than 33% the decreases in total lung conductance, but had little effect on the changes in lung compliance due to histamine.4. In paralysed, artificially ventilated guinea-pigs, vagotomy reduced by 75% the decrease in total lung conductance and halved the decrease in lung compliance due to anaphylaxis.5. We conclude that a vagal reflex is mainly responsible for the rapid shallow breathing due to histamine, and partly responsible for the bronchoconstrictions due to histamine and to anaphylaxis in guinea-pigs. We suggest that "lung irritant receptors" in the bronchial epithelium are the afferent end-organs involved.