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

The inhalation of cotton or other organic dusts can cause alterations in pulmonary function, and these pulmonary effects appear, in pan due to endotoxin contamination of the dusts. Since endotoxin is a potent s timulus for the induction of nitric oxide (NO) synthesis, we examined whether the inhalation of cotton dust might also be associated with in creases in NO production. Rats were exposed to normal air, cotton dust aerosol (40.6 +/- 3.7 mg/m(3)), or a nebulized aerosol of endotoxin ( 2.2 x 10(4) EU/m(3)) for 3 h, and responses were studied 18 h postexpo sure. Increases in inducible NO synthase (iNOS) production by bronchoa lveolar lavage cells (BALC) from rats occurred following exposure to c otton dust or endotoxin as evidenced by increases in iNOS mRNA levels and in vitro nitrate and nitrite production. However, a contribution o f NO to oxidant species generation by BALC, as indexed by luminol-depe ndent chemiluminescence, was observed only in endotoxin-exposed rats. These results indicated that while the inhalation of either cotton dus t or endotoxin may be associated with a number of similar responses, t he pulmonary consequences can be somewhat different.