Abstract
ABSTRACT.: We carried out morphometric studies to assess the effects of increasing durations of hyperoxic exposure on the developing rat lung and to evaluate the potential for new growth and for regression of structural abnormalities on return to room air. From day 10 of life Sprague-Dawley rats were either exposed to hyperoxia (O.8FIO2) for 2-8 wk or were removed after 2 wk and allowed to “recover” in room air for 2-6 wk. Litter mates maintained in room air served as age matched controls. Every 2 wk experimental and control rats from each group were weighed and killed. The heart and lungs were removed, the pulmonary artery was injected with bariumgelatin, and the lung was fixed in formalin in the inflated state. Morphometric assessments were made of right and left ventricular weights, lung volume, axial artery lumen diameter, alveolar number and concentration, and arterial number, concentration and muscularity. Rats continuously exposed to hyperoxia and rats exposed for only 2 wk showed the same degree of impaired parenchymal lung growth, as judged by a decrease in the concentration and number of alveoli. A significant decrease in arterial concentration, increase in muscularization of peripheral arteries, and medial hypertrophy of muscular arteries occurred after 2 wk of hyperoxia. Despite an initial trend toward regression, these features became progressively severe with continued hyperoxic exposure and by 8 wk were associated with a decreased arterial lumen diameter, with right ventricular hypertrophy and with failure to thrive. In rats exposed to hyperoxia for 2 wk and then returned to room air there was a persistent decrease in arterial number and an increase in muscularization but both features were less severe than in rats continuously exposed. Thus, an 8-wk exposure to hyperoxia in rats from day 10 of life results in decreased lung and vascular growth and in increased muscularity. Even a relatively short 2-wk exposure is associated with impaired alveolar growth and vascular abnormalities which persist into “adult” life.
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Wilson, W., Mullen, M., Olley, P. et al. Hyperoxia-Induced Pulmonary Vascular and Lung Abnormalities in Young Rats and Potential for Recovery. Pediatr Res 19, 1059–1067 (1985). https://doi.org/10.1203/00006450-198510000-00023
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DOI: https://doi.org/10.1203/00006450-198510000-00023
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