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Na,K-ATPase gene transfer mitigates an oxidant-induced decrease of active sodium transport in rat fetal ATII cells
1Departments of Pediatrics and Anesthesiology, University of Alabama at Birmingham, Birmingham, Alabama; and Departments of Medicine, Evanston Northwestern Healthcare and Northwestern University, Chicago, Illinois.
American Journal of Respiratory Cell and Molecular Biology
|March 14, 2001
Summary
Adenovirus-mediated transfer of the beta(1) subunit of sodium-potassium ATPase (Na,K-ATPase) enhanced sodium transport in lung cells. This genetic modification also improved resistance to hydrogen peroxide injury, suggesting a protective role.
Area of Science:
- Cell Biology
- Molecular Biology
- Respiratory Physiology
Background:
- The Na,K-ATPase is crucial for maintaining ion gradients and vectorial transport in epithelial cells.
- Lung epithelial cells are susceptible to oxidative stress, which can impair ion transport.
- Understanding mechanisms to enhance Na,K-ATPase function is vital for lung health.
Purpose of the Study:
- To determine if adenovirus-mediated gene transfer of Na,K-ATPase subunits (alpha(1) or beta(1)) increases transepithelial Na(+) transport in rat fetal distal lung epithelial (FDLE) monolayers.
- To assess if this gene transfer enhances FDLE cell resistance to hydrogen peroxide (H(2)O(2)) injury.
- To investigate the role of Na,K-ATPase subunits in maintaining lung epithelial barrier function under stress.
Main Methods:
- FDLE cells were isolated from rat fetuses and cultured to form confluent monolayers.
- Cells were infected with adenoviruses encoding for rat Na,K-ATPase alpha(1) or beta(1) subunits.
- Transepithelial sodium transport was measured using short-circuit current (I(SC)) in Ussing chambers.
- Protein levels were confirmed by Western blot analysis.
- Monolayers were subjected to oxidative injury using hydrogen peroxide.
Main Results:
- Transfection with ad beta(1) significantly increased baseline I(SC) in a dose-dependent manner.
- The ouabain-sensitive component of I(SC) (ouab(max)), reflecting Na,K-ATPase activity, was significantly elevated after ad beta(1) infection.
- Transfection with ad alpha(1) did not affect measured variables.
- Monolayers infected with ad beta(1) exhibited enhanced resistance to H(2)O(2)-induced injury, maintaining higher I(SC) levels.
Conclusions:
- Overexpression of the Na,K-ATPase beta(1) subunit enhances vectorial Na(+) transport in FDLE cells.
- Increased beta(1) subunit levels may protect lung epithelial monolayers from oxidative stress-induced dysfunction.
- Targeting Na,K-ATPase beta(1) subunit expression could be a therapeutic strategy for lung diseases involving impaired ion transport and oxidative injury.