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Determining Ciliary Function and Membrane Impermeability of the Pseudostratified Lung Airway Epithelium
Published on: February 21, 2025
Epithelial Na+ channels derived from human lung are activated by shear force
Martin Fronius1, Roman Bogdan, Mike Althaus
1Institute of Animal Physiology, University of Giessen Lung Center, Justus-Liebig-University, Giessen, Germany. martin.fronius@bio.uni-giessen.de
Respiratory Physiology & Neurobiology
|November 21, 2009
Summary
Lung epithelial sodium channels (hENaC) are directly activated by physiological shear forces during breathing. This mechanical activation, enhanced by trypsin, plays a role in regulating lung fluid balance.
Area of Science:
- Pulmonary physiology
- Cellular biophysics
- Ion channel function
Background:
- Pulmonary epithelial cells experience constant physical forces, including shear force (SF), during respiration.
- The lung epithelial sodium channel (hENaC) is crucial for regulating sodium reabsorption and fluid balance in the lungs.
Purpose of the Study:
- To investigate whether the human epithelial sodium channel (hENaC) is directly activated by shear force.
- To characterize the functional response of hENaC to physiologically relevant shear stress.
Main Methods:
- Cloning and expression of hENaC in Xenopus oocytes.
- Electrophysiological characterization, including whole-cell patch-clamp and single-channel recordings.
- Application of shear force using a controlled fluid stream.
Main Results:
- Application of SF induced a reversible increase in inward current, indicating hENaC activation.
- Trypsin treatment augmented the SF-induced response, suggesting a role for proteolytic cleavage.
- Outside-out single-channel recordings confirmed direct SF activation of hENaC, with increased open probability (NP(O)) in 5/9 experiments.
Conclusions:
- Lung-derived hENaCs are directly activated by shear force.
- This mechanical activation mechanism may be important for regulating pulmonary sodium reabsorption and maintaining lung fluid homeostasis.
