MORPHOLOGICAL CHANGES IN THE LUNGS OF RATS LIVING UNDER COMPRESSED AIR CONDITIONS.

Area of Science:

• Pulmonary physiology
• Toxicology
• Cellular biology

Background:

• Age-related differences exist in rat lung alveolar structure.
• High oxygen tension can induce acute and chronic lung injury.

Purpose of the Study:

• To investigate the effects of prolonged high oxygen exposure on rat lungs.
• To compare the responses of young and old rats to hyperoxia.
• To examine the development of adaptation and tolerance to oxygen toxicity.

Main Methods:

• Rats of different ages were exposed to 83.6% oxygen.
• Morphological changes in lung tissue were assessed.
• Responses to acute oxygen poisoning and reexposure were evaluated.

Main Results:

• High oxygen exposure increased alveolar cell number and size (hyperplasia and hypertrophy) in both young and old rats, with changes persisting after return to normal air.
• Young rats showed greater resistance to acute oxygen poisoning, experiencing less severe pulmonary edema compared to old rats.
• Chronic exposure led to arteriolar lesions (thickening, hyalinization, thrombosis) and pulmonary artery lesions (medial changes, cartilage formation).
• Rats exposed to high oxygen developed an adaptation, preventing acute oxygen poisoning upon reexposure, with persistent increased alveolar cellularity.

Conclusions:

• Age significantly influences susceptibility to oxygen toxicity, with younger rats exhibiting greater resilience.
• Prolonged hyperoxia induces adaptive cellular and vascular changes in the lungs.
• Adaptation to high oxygen tension involves persistent morphological alterations and prevents subsequent acute toxicity.