The role of epithelium in the responsiveness of the bronchi to stimuli

Abstract

Airway narrowing in response to different modes of stimuli was measured using a perfused bronchial segment. Acetylcholine, carbachol, histamine, high [K+] and vanadate perfused through the lumen gave small responses as shown by the reduction in flow, but fully constricted the airway when applied to the outside. ACh was 29 times more sensitive on the outside. When the epithelium was removed airway narrowing by these stimuli was increased to equal that on the outside. It was concluded that the role of the epithelia as a barrier is all important. Evidence for an EpDIF released by the epithelium could not be obtained.