Circulating factors that modify lung cell DNA synthesis following exposure to inhaled oxidants. I. Effect of serum and lavage on lung fibroblasts following exposure of adult rats to 1 ppm ozone

Abstract

Adult rats were exposed to 1 ppm (1.96 mg/m3) ozone or air for 2 wk. Animals were sacrificed at 3, 5, 7, or 14 d after the onset of exposure, and samples of plasma and lung lavage were obtained. Heat‐inactivated plasma, from animals exposed to ozone for 7 or 14 d, significantly increased DNA synthesis by lung fibroblasts compared with plasma from air‐exposed animals. Fractionation of plasma and lavage samples indicated that the factor responsible had an isoelectric point of 6.45–6.75 and a molecular weight of 32 ± 2 kDa. This factor has a dose‐dependent effect on lung fibroblast DNA synthesis in culture, but no significant effect on cultured pneumocyte DNA synthesis. The factor is detectable within 72 h of exposure, and may hold some promise as a marker of early oxidant lung injury.