Comparisons of Breathing Rate, Cellular Response, Airway Obstruction (Determined by Postmortem Pulmonary Hyperinflation) and the Wet/Dry Weight Ratios of Guinea Pigs Exposed to Cotton Dust Aerosol

D.G. Frazer, V.A. Robinson, D.S. DeLong, V. Castranova, T.A. Jones, and E.L. Petsonk


 
ABSTRACT

In this study 24 guinea pigs were subjected to 20 mg/m3 of respirable cotton dust for 6 hrs. The animals were exposed in 3 groups of eight animals. Each group was exposed to cotton dust produced with a modified Pitt-3 generator using 30 gms of bulk cotton dust material. In addition, there were 12 control guinea pigs which were exposed to filtered air for 6 hrs. Four different pulmonary responses of the control and cotton dust exposed animals were measured prior to exposure, at 0-hr post exposure, and at 18-hr post exposure. First, breathing rate was measured in air and in 10% CO2 in air for all animals in each group. Second, leukocyte and macrophage recovery was determined following bronchopulmonary lavage in one-half of each exposed and control group. Third, airway obstruction was estimated in the remaining exposed and control animals by determining the degree of postmortem pulmonary hyperinflation. Fourth, lung fluid balance was assessed by determining changes in the wet/dry weight of excised lungs used in the hyperinflation measurements. The results showed that in guinea pigs exposed to cotton dust 1) airway obstruction occurred prior to the maximum influx of leukocytes into the lung, indicating that leukocyte infiltration may not be responsible for airway obstruction and 2) the breathing rate response measured in air and 10% CO2 appeared to be a good indicator of fluid and leukocyte infiltration into the lung, but did not appear to accurately reflect changes in airway obstruction.



Reprinted from Proceedings: 1989 Beltwide Cotton Dust Conference pp. 129 - 133
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998