Changes in rat lung structure and composition as a result of subchronic exposure to acrolein.

Groups of Fischer-344 rats were exposed to either filtered air, 0.4, 1.4, or 4.0 ppm acrolein for 62 days (6 h/day, 5 days/week). Mortality was observed only in the 4.0 ppm chamber, where 32 of 57 male rats died, but none of the 8 exposed females died. The lungs of the 4.0 ppm group were heavier than those of the larger control animals. Relative to controls, there was a 20% increase in total dry lung weight while the percent dry weight decreased 1.5% in the high dose group. This increased dry weight and the absence of significant changes in the DNA and protein content per unit dry weight indicated that the greater lung weight observed in this group was in part due to increased cellularity. Lung connective tissue content was increased as a result of subchronic acrolein exposure. The amount of elastin per unit dry weight was 173% of control values in the animals exposed to 4.0 ppm acrolein. Collagen levels were elevated in both the 1.4 and 4.0 ppm groups, 113 and 137%, respectively, of control values. Histologically, the 4.0 ppm animals demonstrated bronchiolar epithelial necrosis and sloughing, bronchiolar edema with macrophages, and focal pulmonary edema. Exposure related lesions were observed in only 3 of the 31 rats examined from the 1.4 ppm chamber and in none of the animals exposed to 0.4 ppm acrolein.