Aeroallergen-induced dyspnea in freely moving guinea pigs: quantitative measurement by bias flow ventilated whole body plethysmography

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Abstract
Guinea pigs were sensitized and boostered with i.p. injections of ovalbumin (OA) 10 micrograms + Al(OH)3 100 mg. Thirteen days after the last injection animals (800-1100 g) were placed in bias flow ventilated whole body plethysmographs and allowed to stabilize for 2 h. Lung function was recorded for up to 2 h before and 5 h after aeroallergen challenge (OA 20 mg/ml, 60 s, 20 psi) by a noninvasive pulmonary analyzer for unrestrained rodents. Aeroallergen challenge produced immediate dyspnea and gasping (peaking between 8 and 17 min). Gasping was associated with an increase in amplitude in the box pressure fluctuations (93%), and in the slope of the fluctuations (391%). Respiratory rate increased (103 to 175 breaths/min, 78%), the product of breathing rate times box pressure amplitude increased (161 to 432, 180%). Relaxation time (the time it takes the box pressure signal to drop from its peak to 1/3 of its peak value) declined (0.16 to 0.05 s, 72%). All of these lung dysfunction changes were highly significant (p < 0.001). Lung dysfunction persisted for 60 to 120 min after challenge. One of 8 animals tested died within 10 min. None of the animals exhibited late asthmatic responses during the 5 h post-challenge period. Based on these data we conclude that this technique allows quantitative analysis of dyspnea, gasping, and an abnormal pattern (waveform) of breathing.(ABSTRACT TRUNCATED AT 250 WORDS)