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Lung MK 351A uptake after hypoxia adaptation and subsequent hyperoxia exposure
R M Jackson1, H S Ann, S Oparil
1Birmingham Veterans Administration Medical Center, Division of Pulmonary and Critical Care Medicine, AL 35294.
Lung
|January 1, 1988
Summary
Hypoxia adaptation protects rat lungs from hyperoxia-induced damage. Pre-exposure to low oxygen (hypoxia) minimized decreases in lung angiotensin-converting enzyme (ACE) and surface area caused by high oxygen (hyperoxia).
Area of Science:
- Physiology
- Pulmonary Medicine
- Biochemistry
Background:
- Hyperoxia exposure decreases lung angiotensin-converting enzyme (ACE).
- Hypoxia adaptation enhances survival during oxygen toxicity in rats.
- Lung ACE content is crucial for regulating vasoactive peptides.
Purpose of the Study:
- To investigate the protective effects of hypoxia adaptation on lung ACE content and microvascular surface area following hyperoxia exposure.
- To determine if hypoxia preconditioning can mitigate hyperoxia-induced lung injury.
Main Methods:
- Rats were exposed to normoxia, hypoxia (10% O2), hyperoxia (>95% O2), or hypoxia followed by hyperoxia.
- Lung ACE content was quantified using 125I-MK 351A binding assays in isolated perfused lungs.
- Lung internal surface area was estimated via mean alveolar diameter measurements from histological sections.
Main Results:
- Hyperoxia exposure significantly decreased lung ACE content and alveolar surface area.
- Hypoxia adaptation partially prevented these hyperoxia-induced decreases, demonstrating a protective effect.
- ACE binding correlated directly with the estimated lung surface area.
Conclusions:
- Hypoxia preadaptation minimizes the reduction in lung microvascular ACE content caused by hyperoxia.
- Hypoxia adaptation offers protection against hyperoxia-induced lung injury, preserving both ACE levels and structural integrity.