Printed in UK- all rights reserved Copyright ERS Journals Ltd 1994 European Respiratory Journal

Video-imaging of lumen narrowing; muscle shortening and flow responsiveness in isolated bronchial segments of the pig H.W. Mitchell, M.P. Sparrow Video-imaging of lumen narrowing; muscle shortening and flow responsiveness in isolated bronchial segments of the pig. H.W. Mitchell, M.P. Sparrow. ERS Journals Ltd 1994. ABSTRACT: The amount of smooth muscle shortening required to cause narrowing of the bronchial lumen and to significantly alter airflow in an airway has not been measured directly. Accordingly, in this study, the lumens of isolated fluid-filled bronchial segments from pigs were directly visualized using a fibreoptic endoscope and video-recording. The extent of lumen narrowing was related to smooth muscle contraction, determined morphometrically, and to bronchial lumen flow. Narrowing was produced by electrical field stimulation (EFS), (70 V, 20 Hz, 2–3 ms) and acetylcholine (ACh), (10-5–10-2 M)