INHALATION OF COTTON DUST IS ASSOCIATED WITH INCREASES IN NITRIC OXIDE PRODUCTION BY RAT BRONCHOALVEOLAR LAVAGE CELLS

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Abstract
The inhalation of cotton or other organic dusts can cause alterations in pulmonary function, and these pulmonary effects appear, in part, due to endotoxin contamination of the dusts. Since endotoxin is a potent stimulus for the induction of nitric oxide (NO) synthesis, we examined whether the inhalation of cotton dust might also be associated with increases in NO production. Rats were exposed to normal air, cotton dust aerosol (40.6 3.7 mg/m3), or a nebulized aerosol of endotoxin (2.2 x 104 EU/m3) for 3 h, and responses were studied 18 h postexposure. Increases in inducible NO synthase (iNOS) production by bronchoalveolar lavage cells (BALC) from rats occurred following exposure to cotton dust or endotoxin as evidenced by increases in iNOS mRNA levels and in vitro nitrate and nitrite production. However, a contribution of NO to oxidant species generation by BALC, as indexed by luminol-dependent chemiluminescence, was observed only in endotoxin-exposed rats. These results indicated that while the inhalation of either cotton dust or endotoxin may be associated with a number of similar responses, the pulmonary consequences can be somewhat different.