Effect of hyperoxia on the cytoarchitecture of cultured endothelial cells

When confluent pulmonary artery endothelial cells in culture were exposed to hyperoxia (95% O2 and 5% CO2), they became enlarged and mean corpuscular volume increased 30-35%. Rhodamine-phalloidin staining of actin filaments demonstrated that hyperoxia was associated with a progressive alteration in the actin distribution. Three days after oxygen exposure, the number and thickness of cytoplasmic stress fibers were increased, while the peripheral bands were disrupted or absent. Sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed that the amount of filamentous actin was increased in oxygen-exposed cells, while the total actin content remained unchanged, suggesting that oxygen exposure shifted the equilibrium from G actin to F actin.