Neuronally mediated non-cholinergic contraction of guineapig bronchial smooth muscle is inhibited by a substance P antagonist

Abstract
The isolated main bronchi of the guinea-pig respond to electrical field stimulation with a twitch followed by a slow contraction. Atropine blocked the slow contraction. The substance P antagonist, (d-Pro2,d-Trp7.9)-SP, greatly reduced the atropine-resistant contraction. The results suggest the involvement of substance P in non-cholinergic neurotransmission in the guinea-pig airways.