Epithelium‐dependent potentiation of anaphylactic contractions by β‐endorphin in tracheae isolated from actively sensitized guinea‐pigs

Abstract

1 It has been shown that opioid peptides modulate airway function. In the present study, the effect of fi-endorphin on antigen-induced contractions of isolated tracheal rings from actively sensitized guineapigs has been studied. 2 /5-Endorphin had a concentration-dependent bimodal effect on anaphylactic contractions of the trachea. Low concentrations of fi-endorphin (10-10 and 10-8M) significantly potentiated anaphylactic contractions, whereas higher concentrations (10-v and 1-6M) significantly suppressed anaphylactic contractions of guinea-pig trachea. 6 In epithelium-denuded tracheae, both 10-8 and 10-7 M f-endorphin suppressed the anaphylactic contractions, whereas 10-8 and 10-7M des-Tyr'-fJ-endorphin did not affect anaphylactic contractions. It is concluded that the potentiation of the anaphylactic contraction in intact trachea is epithelium-dependent whereas the suppression of the anaphylactic contraction is epithelium-independent.