Effects of culture conditions on susceptibility of alveolar epithelial cell monolayers to NO2.

The effects of nitrogen dioxide (NO2) exposure on primary cultured monolayers of rat type II pneumocytes were investigated as a function of the isolation and culture conditions. Monolayers were cultured in Eagle's minimum essential medium (MEM) and in MEM supplemented with Ham's F-12; in some experiments, the initial cell suspension was also replated after 3 h. Both supplementation of the basal medium and replating increased the sensitivity of the monolayers to NO2, as measured by reduction in dome formation of plastic dishes 24 h post-exposure. These findings suggest that comparisons of in vitro toxicologic observations may be complicated by the effects of specific experimental conditions.