title: Interaction between airway edema and lung inflation on responsiveness of individual airways in vivo.
abstract: Interaction between airway edema and lung inflation on responsiveness of individual airways in vivo. J. Appl. Physiol. 83(2): 366-370, 1997.-Inflammatory changes and airway wall thickening are suggested to cause increased airway responsiveness in patients with asthma. In five sheep, the dose-response relationships of individual airways were measured at different lung volumes to methacholine (MCh) before and after wall thickening caused by the inflammatory mediator bradykinin via the bronchial artery. At 4 cmH2O transpulmonary pressure (Ptp), 5 microg/ml MCh constricted the airways to a maximum of 18 +/- 3%. At 30 cmH2O Ptp, MCh resulted in less constriction (to 31 +/- 5%). Bradykinin increased airway wall area at 4 and 30 cmH2O Ptp (159 +/- 6 and 152 +/- 4%, respectively; P < 0.0001). At 4 cmH2O Ptp, bradykinin decreased airway luminal area (13 +/- 2%; P < 0.01), and the dose-response curve was significantly lower (P = 0.02). At 30 cmH2O, postbradykinin, the maximal airway narrowing was not significantly different (26 +/- 5%; P = 0.76). Bradykinin produced substantial airway wall thickening and slight potentiation of the MCh-induced airway constriction at low lung volume. At high lung volume, bradykinin increased wall thickness but had no effect on the MCh-induced airway constriction. We conclude that inflammatory fluid leakage in the airways cannot be a primary cause of airway hyperresponsiveness.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins School of Hygiene and Public Health, Baltimore, Maryland 21205, USA. rbrown@welchlink.welch.jhu.edu
authors.forename: R H
authors.initials: RH
authors.lastname: Brown
authors.forename: W
authors.initials: W
authors.lastname: Mitzner
authors.forename: E M
authors.initials: EM
authors.lastname: Wagner
mesh_terms: D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D008168:Lung / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology*; D008176:Lung Volume Measurements; D016210:Methacholine Chloride / Q000494:pharmacology; D011654:Pulmonary Edema / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012121:Respiration, Artificial; D012756:Sheep; D014057:Tomography, X-Ray Computed
chemical_list: D016210:Methacholine Chloride; D001920:Bradykinin