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Type II pneumocytes secrete vitamin E together with surfactant lipids
B Rüstow1, R Haupt, P A Stevens
1Institute of Pathological and Clinical Biochemistry, Charité Hospital, Humboldt University, Berlin, Germany.
The American Journal of Physiology
|August 1, 1993
Summary
Lung surfactant contains lipophilic antioxidants like vitamin E, secreted with surfactant to prevent oxidative damage. This study confirms their integral role in lung protection.
Area of Science:
- Pulmonary Medicine
- Biochemistry
Background:
- Lung surfactant is vulnerable to oxidative stress.
- Lipophilic antioxidants may protect surfactant constituents from peroxidation.
Purpose of the Study:
- To investigate if lipophilic antioxidants are secreted with lung surfactant.
- To determine the role of these antioxidants in lung protection.
Main Methods:
- Analysis of lung lavage and surfactant subfractions for antioxidants (vitamins E, A, plasmalogens).
- Tracking radiolabeled vitamin E ([3H]tocopherol) and phospholipids in vivo and in cultured Type II cells.
- Assessing the effect of isoproterenol stimulation and surfactant protein A on secretion.
Main Results:
- Lung surfactant and its subfractions contain vitamin E, vitamin A, and plasmalogens.
- Radioactive vitamin E was secreted with labeled phospholipids in response to isoproterenol.
- Type II cells secreted vitamin E with phospholipids, but not vitamin D, upon stimulation.
- Surfactant protein A inhibited this secretion.
Conclusions:
- Alveolar surfactant incorporates lipophilic antioxidants as essential components.
- Vitamin E appears to be co-secreted with surfactant, contributing to lung antioxidant defense.