Antigen-induced contraction of guinea-pig trachea: search for mediator release with cascade superfusion bioassay.

Ovalbumin induces contraction of sensitized guinea-pig trachea, both in the presence and absence of indomethacin. Cascade superfusion bioassay was employed to detect mediator release. A prostaglandin E-like material was released in response to antigen in the absence of indomethacin but, no biologically active material could be detected from trachea in the presence of indomethacin. Thus the substance responsible for antigen-induced tracheal contraction, although appearing to be a lipoxygenase product, is as yet undefined.