Airway Sensitivity to Slow-Reacting Substance of Anaphylaxis, Histamine, and Antigen in Ascaris Sensitive Monkeys1–4

The effects of Ascaris suum antigen, histamine, and slow-reacting substance of anaphylaxis (SRS-A) on the respiratory system were compared in 3 anesthetized rhesus monkeys. The agents were administered by instillation into the trachea, and the animals were studied in a volume displacement body Plethysmograph. Two of the animals showed skin and bronchial sensitivity to Ascaris suum antigen and responded to it with increased pulmonary resistance and decreased dynamic compliance. A similar response was seen in all 3 animals after instillation of histamine, but SRS-A at 2 concentrations produced a predominant effect of decreased dynamic compliance with lesser alterations in pulmonary resistance. The effects of SRS-A were slow in onset and prolonged, as compared to the abrupt and short-lived effects of Ascaris suum antigen and histamine. The pre-dominant effect of SRS-A on dynamic compliance suggests a more peripheral site of action of this mediator. In 5 monkeys allergic to Ascaris, no SRS-A could be detected...