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Hypertonic saline increases tight junction permeability in airway epithelium
M Högman1, A C Mörk, G M Roomans
1Section of Integrative Physiology, Dept of Medical Cell Biology, Uppsala University, Uppsala, Sweden. marieann.hogman@medcellbiol.uu.se
The European Respiratory Journal
|December 31, 2002
Summary
Hyperosmolar salt solutions open airway tight junctions in asthma, potentially worsening symptoms. This effect is reversible and may enhance drug delivery to lung tissues.
Area of Science:
- Epithelial biology
- Respiratory medicine
- Cellular physiology
Background:
- Asthma patients exhibit sensitivity to inhaled hyperosmolar solutions.
- The integrity of airway epithelium tight junctions is crucial for respiratory health.
Purpose of the Study:
- To investigate the impact of hyperosmolar salt solutions on airway epithelial tight junctions.
- To explore the potential role of tight junction permeability in asthma pathogenesis and drug delivery.
Main Methods:
- Rat tracheas were perfused with varying concentrations of sodium chloride (NaCl) solutions.
- Electron microscopy with lanthanum chloride tracer was used to assess tight junction penetration.
- Osmotic effects were compared between salt solutions and mannitol.
Main Results:
- Hyperosmolar NaCl solutions significantly increased lanthanum penetration through tight junctions.
- Increased osmolarity from 295 mOsm to 589 or 876 mOsm led to 50-57% tight junction opening.
- The effect of hyperosmolarity was reversible, with tight junction permeability returning to baseline levels.
- Mannitol at 589 mOsm did not significantly open tight junctions, unlike NaCl.
Conclusions:
- Hyperosmolar salt solutions reversibly open airway epithelial tight junctions.
- This opening may contribute to exercise-induced asthma and enhance the penetration of inhaled therapeutics.
- Understanding tight junction dynamics offers potential therapeutic strategies for asthma.