Influence of Acetylcholine on Human Pulmonary Circulation under Normal and Hypoxic Conditions. ∗

Abstract

Summary

Acetylcholine infused into the main pulmonary artery caused a slight fall in pulmonary arterial pressure when the subject breathed ambient air, but a greater fall in pressure after pulmonary hypertension had been produced by hypoxia. The fall in pressure was associated with either a constant or an increased cardiac output. The evidence suggests that acetylcholine causes vasodilata-tion in the lungs and that this action is largely dependent on the pre-existing tone of the pulmonary vessels.