ALTERED LUNG-FUNCTION AND STRUCTURE IN THE RAT AFTER SUBCHRONIC EXPOSURE TO ACROLEIN

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Abstract
Lung mechanics and diffusion and associated structural correlates were evaluated in groups of 24 male Fischer-344 rats exposed 62 days (6 h/day, 5 days/wk) to 0, 0.4, 1.4, or 4.0 ppm acrolein. Exposure to 4.0 ppm resulted in depressed flow-volume curves, leftward shifts of the compliance curve, and enlarged lung volumes, suggesting airway obstruction. Air-flow dysfunction correlated with the presence of focal peribronchial lesions and lung elastin concentrations. In contrast, the flow-volume dynamics of the 0.4 ppm rats were significantly enhanced without corresponding lung histologic and compositional changes. Rats exposed to 1.4 ppm were not functionally different from control animals, but did have infrequent bronchiolar lesions and marginally increased collagen. All exposure groups exhibited increase in DLCO that correlated with lung tissue surface area, apparently related to alveolar hyperinflation and possibly lung tissue growth. Acrolein produces distinct functional lesions at 0.4 and 4.0 ppm, which, when present at an intermediate exposure challenge, appear to sum algebraically and obsure the presence of disease.