Fatigue of airway obstruction during long-term exposure to allergen aerosol.

The response to prolonged antigen exposure and the potentiation of airway resistance increase to ACH challenge, after this exposure, were studied on sixteen boxer dogs. One group of animals presented fatigue to A.E. after 3 hours of exposure. This group developed an increased response to ACH aerosol after fatigue to antigen was present. In a second group of dogs, absence of fatigue during prolonged exposure to allergen was observed. A growing tendency of Edyn (as an index of airway resistance) was observed after 5 hours of exposure. The therapeutical influence of bilateral vagus blockade was tested in these last animals. Blockade of nervus vagus released airway obstruction during prolonged allergen exposure and no bronchoconstriction was observed after ACH challenge during blockade.