Late response of the upper airway of the rat to inhaled antigen.
We studied the magnitude and time course of changes in upper airway resistance (Ruaw) of actively sensitized Brown-Norway rats after aerosol challenge with ovalbumin (OA). Two weeks after sensitization, eight rats were challenged by inhalation of aerosolized OA through the nose. The airway responses of these rats 5-10 h after OA challenge were compared with those of seven animals challenged with saline. Seven of eight test rats had increased Ruaw, and six displayed discrete late responses (LR). Ruaw during expiration was highly alinear so analysis was confined to Ruaw during inspiration (Ruaw,I). The Ruaw,I averaged over 5 h was 1.262 +/- 0.09 (SE) cmH2O.ml-1.s, 2.6 times the value for saline-challenged animals (0.476 +/- 0.143 cmH2O.ml-1.s), and it reached a peak value of 3.454 +/- 0.45 cmH2O.ml-1.s. The time to the peak of the LR was 446 +/- 37.3 min. The duration of the LR in the upper airway was 146 +/- 34.9 min. At the time corresponding to the peak value of Ruaw,I, the lung elastance in the test rats was double the value preceding the peak. Lung elastance was unchanged in the control group. We conclude that inhalation of antigen through the upper airway of the sensitized rat results in a substantial increase in upper airway resistance and a distinct LR. The predominant site of the change in respiratory system resistance is in the upper airway.
Xu
L J
LJ
Meakins-Christie Laboratories, University Clinic, Royal Victoria Hospital, Montreal, Quebec, Canada.
Eidelman
D H
DH
Bates
J H
JH
Martin
J G
JG
D000280:Administration, Inhalation; D000403:Airway Resistance / Q000502:physiology; D000818:Animals; D000941:Antigens / Q000008:administration & dosage / Q000276:immunology*; D004947:Esophagus / Q000502:physiology; D005260:Female; D007442:Intubation, Intratracheal; D008170:Lung Compliance / Q000502:physiology; D008297:Male; D010047:Ovalbumin / Q000276:immunology; D051381:Rats; D012143:Respiratory Physiological Phenomena; D012137:Respiratory System / Q000276:immunology
D000941:Antigens; D010047:Ovalbumin