Epithelial modulation of antigen-induced tracheal smooth muscle contractions in actively sensitized guinea-pigs.
Coaxial bioassay system (guinea-pig trachea and rat anococcygeus muscle as donor and bioassay organs, respectively) and tracheal open ring preparations from ovalbumin-sensitized guinea-pigs were used to investigate the role of the epithelium in response to the antigen challenge. Ovalbumin induced concentration-dependent relaxations in the phenylephrine precontracted rat anococcygeus muscle suspended in the lumen of sensitized guinea-pig tracheal tube preparations in the presence of either indomethacin or mepacrine. Removal of the epithelium abolished ovalbumin-induced relaxation responses. In tracheal open ring preparations, epithelium removal shifted the ovalbumin concentration-response curve to the left in both the control and mepacrine-treated experiments. Indomethacin significantly potentiated the ovalbumin-induced contractions in epithelium-intact preparations, while in epithelium-denuded ones no significant change was observed. In the presence of indomethacin, the maximum contractile responses were significantly higher in epithelium-intact preparations than in epithelium-denuded ones. These results provide direct evidence for the release of epithelium-derived relaxant factor(s), which is (are) neither a cyclooxygenase nor a lipoxygenase product, in response to the antigen challenge. In addition, the observation of the increased maximum contraction to antigen in epithelium-intact preparations in the presence of indomethacin, suggests the involvement of contractile influences derived from the epithelium in antigen-induced responses of airways.
Egilmez
Y
Y
Department of Pharmacology, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
Ilhan
M
M
D000818:Animals; D000941:Antigens / Q000494:pharmacology*; D001986:Bronchial Spasm / Q000276:immunology / Q000503:physiopathology; D004848:Epithelium / Q000276:immunology / Q000502:physiology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000276:immunology*; D009130:Muscle, Smooth / Q000276:immunology / Q000502:physiology*; D010047:Ovalbumin / Q000494:pharmacology; D014132:Trachea / Q000276:immunology* / Q000502:physiology*
D000941:Antigens; D010047:Ovalbumin