Effect of ozone oxidative stress on potassium current in human lung cells: chemical mediators

Introduction: Given that the ionic balance of the pulmonary epithelial lining fluid (ELF) is essential for correct gas exchange, our previous studies analyzed the effects of ozone, one of the most harmful pollutants for the respiratory system, on K+ currents in human cultured lung epithelial cells. O3 exposure (0.1 ppm, 30’) significantly alters the flow of K+ ions, reducing the outward rectifier current component. O3 does not act directly, but through its bio-products, among which the main ones are 4HNE and H2O2.In this study we analyzed the action of 4HNE and H2O2 on K+ currents in second type pneumocytes and verified the protective effect of catalase. Material and Methods: A549 cellular line: lung epithelial cell model. 4HNE: 5, 10 and 20 uM concentration, 30’. H2O2: 20 uM concentration, 30’. Catalase: 1000U/ml concentration, 1.30h. Western blot and patch clamp technique: to study the action of the bio-products on K+ currents in A549 cells. Results: 4HNE was able to significantly decrease the K+ current, but its action was less effective than O3. H2O2 also decreased the K+ current, but the effect did not reach the significance. Catalase shows the ability in preserving the outward rectifier component depressed by 4HNE, bringing back the current to the control level. Conclusion: We can conclude that 4HNE is the main mediator of ozone, but its action also involves other compounds to a lesser extent. Further studies are needed to understand the pathway activated by 4HNE inside the cell and which pharmacological compounds can protect it.