Long-term consequences of exposure to ozone. I. Lung collagen content

Lung collagen content of rats and monkeys (Macaca fascicularis) exposed to ozone for 1 to 13 weeks and for 1 year, respectively, was quantified by measurement of 4-hydroxyproline in hydrolysates of whole lungs. In addition, ratios of type I to type III collagen in the lungs of the same monkeys were also evaluated by cyanogen bromide peptide mapping techniques. We observed elevated levels of collagen in lungs of both species of animals exposed to ozone. We conclude that elevations in collagen synthesis rates in lungs of rats and monkeys acutely exposed to high levels of ozone are reflected by corresponding increases in lung collagen content over subchronic and chronic time frames. Preliminary results on young rats also suggest that removal of rats from atmospheres containing ozone does not cause reversal of such increases in lung collagen content. To the contrary, recovery periods of up to 6 weeks seem to exacerbate the observed increases in lung collagen content.