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KMID : 0351619760170010022
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Kyungpook Medical Journal
1976 Volume.17 No. 1 p.22 ~ p.34
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Effects of Nitrogen Dioxide on Ultrastructure of the Rat Lung
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Abstract
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This study vas undertaken to investigate the ultra:~tructural changes in lungs of the rat, exposed to nitrogen dioxide(NOz).
Twenty healthy albino rats, weighing 200 to 250gm~., were divided into 3 groups.
Group 1. Control group, 2 rats: Untreated.
Group 2. I experimental group, 9 rats: Exposed to 200 ppm of nitrogen dioxide for 5 hours. Group 3. II experimental group, 9 rats: Exposed to 500 ppm of nitrogen dioxide for 5 hours. Experimental rats were sacrificed at 0 hour (3 rags), 4 hours (3 rats) and 12 hours (3 rats) after exposure to nitrogen dioxide from the group 2 and 3. Lungs were extirpated and examined with both light and electron microscopes.
The results were summarized as follow:
1) Light microscopic observation:
The findings of lung tissues were very similar in ´the both experimental groups. Immediately after exposure to NOz, marked congestion, interstitial edema and thickening of the alveolar septae were noted. Occasionally mild hemorrhage was obser~red. Blebs and cilia on the surface of the bronchiolar epithelium were diminished. Four and 12 1!~ours after exposure, congestion and interstitial edema were considerably diminished and the alveolar lining cells were increased in number with mild thickening of the alveolar septae.
2) Electron microscopic observation:
No significant changes were noted in type j alveolar cells in the both experimental groups. Most prominent changes occurred in the type 11 alveolar cells in the experimental groups. Immediately after exposure to NOz, microvilli on free surface of the type II cells were considerably flattened and chanties of the osmiophilic inclusion bodies, such as numerical increase, pleomorphism, decreased density and vacuolization were moderately noted. Some of these inclusion bodies were extruded into the alveolar lumen. Four and 12 hours after exposure, these changes described above were considerably diminished, while huge osmiophilic inciusion bodies accompanied by marked increase of their matrix density were observed.
The endothelial cells of alveolar capillaries showed mild increase of pinocytotic vesicles and dilatation of rough ER.
3) It can be concluded, therefore, that prominent cb.anges are found to be limited to the lungs of the experimental animals in acute nitrogen dioxide poisoning (animals exposed to 200.0 and/or 500.0 ppm for 5 hours) as follows:
a) barked congestion and interstitial edema of the lung
b) A mild hemorrhage of the lung
c) A moderate degenerative and adaptive changes of the type II alveolar cells, with em on their osmiophilic inclusion bodies
d) A mild degenerative changes in the alveolar capillary endothelial cells.
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