Effect of elastase instilled into the trachea on airways mechanics in guinea pigs.
Instilled elastase caused an inflammatory response in the lungs of guinea pigs which was observed at 6 h, 24 h, and 48 h post-treatment. The inflammation was most marked at 24 h and was characterised by a loss of epithelial cilia and detachment of epithelial cells from the basement membrane, a marked increase in polymorphonuclear leukocytes (PMNs) in blood vessels of the tracheal submucosa and an infiltration of macrophages into the parenchyma. Compared with controls, isolated tracheal preparations from 24 h and 48 h elastase pretreated animals were hyperreactive (Emax) to histamine and carbachol. This hyperreactivity persisted in tracheas from 48 h elastase pretreated animals after removal of the epithelial layer. Parenchymal strips were hyperreactive to histamine only. Tissue sensitivity (EC50) was little affected by elastase. Tracheal preparations incubated in 0.01% elastase for 3 h responded normally. In vivo responses of Raw and Cdyn to histamine were unaffected by elastase at 24 h and 48 h. However, the slope of the dose-response curve to acetylcholine was steepened 24 h after elastase instillation, but not at 48 h. In contrast to other models of inflammation elastase evokes in vitro but not in vivo hyperresponsiveness.
Willet
K E
KE
Department of Physiology, University of Western Australia, Nedlands.
Mitchell
H W
HW
D000818:Animals; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007267:Injections; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D010196:Pancreatic Elastase / Q000008:administration & dosage / Q000494:pharmacology*; D012137:Respiratory System / Q000033:anatomy & histology / Q000187:drug effects*; D014132:Trachea
D010196:Pancreatic Elastase