Alveolar Oxygen Tension and Angio-architecture of the Distal Adult Lung

Abstract

The present study demonstrates the fine structure of pulmonary capillaries first injured and then undergoing growth in response to a change in the ambient alveolar oxygen tension. Breathing a high fraction of inspired oxygen (FiO₂ 0.75) triggers restriction by endothelial cell injury and effacement leading to segment narrowing and shortening and segment loss as demonstrated by a fall in density. Subsequently, breathing a relatively low fraction (FiO₂ 0.21) triggers capillary assembly (angiogenesis), which reverses the changes. The data underscore the structural reprogramming (reduction and restoration) of pulmonary capillaries in response to significant shifts in oxygen tension.

• High oxygen
• hyperoxia-regression
• hypoxia-regeneration
• pulmonary capillary remodeling
• relative hypoxia