MEDIATORS OF IgE-INDUCED ANAPHYLAXIS: AN IN VITRO STUDY OF MEDIATORS CAUSING CONTRACTION OF RABBIT PULMONARY ARTERY

Abstract

Rabbits were immunized such that antibodies of the IgE class were preferentially produced. Normal rabbit pulmonary artery sections were challenged with supernatant from antigen-treated sensitized blood cells in the presence of antagonists. The hypothesis is that mediators capable of contracting pulmonary arteries are released from blood cells when blood cells are challenged with antigen. Possible mediators are histamine, serotonin, indomethacin and LTD4. Chlorpheniramine (2.6 x 10⁻⁵M) with methysergide (1 x 10⁻⁵ produced a one-hundred-twenty-fold inhibition of contraction. Chlorpheniramine with FPL-55712 (1 x 10⁻⁵M) did not significantly alter the response seen with chlorpheniramine alone. When supernatant obtained from sensitized blood cells pretreated with 1 x 10⁻⁵ indomethacin was used to challenge muscle rings in the presence of chlorpheniramine the response was also not significantly different from response seen with chlorpheniramine alone. Histamine contracted pulmonary artery. Chlorpheniramine (2.6 x 10⁻⁵ inhibited the response six-hundred-fold. Serotonin also contracted pulmonary artery. Methysergide (10⁻⁵M) blocked the response seven-hundred-fold.