Contractile properties of smooth muscles of bronchial tubes of porpoises in formation of hyperreactance airways, were studied. Sensitization by ovalbumin results in formation of hyperresponsiveness of the airways as shown in increase in amplitude of contractile responses to histaminergic influences and oppression of adrenergic relaxations of segments. Respiratory epithelium oppresses contractile responses of airways in intact animals to histaminergic influences. Influence of epithelium on adrenergic responses depends on precontractile factor: they increase in prereduction by histamine. In formation of hyperresponse, the epithelium loses ability to modulate responses of smooth muscles of the airways. Incubation segments of smooth muscles of the airways in interleukin 5 increases contractile responses to histaminergic influences. Receptor of interleukin 5 (the soluble fraction) neutralizes the effect of exogenous interleukin 5, and incubation of receptor of sensitized animals oppresses histaminergic contractile responses.