The alveolar epithelial barrier permits only restricted passage of solutes, exemplified by a high resistance and equivalent pore properties similar to those of other tight biological barriers. These passive barrier properties may be markedly altered a...
The alveolar epithelial barrier permits only restricted passage of solutes, exemplified by a high resistance and equivalent pore properties similar to those of other tight biological barriers. These passive barrier properties may be markedly altered after insults to the lung, perhaps providing insights into the mechanisms of alveolar epithelial injury. The normally tight alveolar epithelium serves as an effective barrier against the leak of solutes from interstitial and vascular spaces into alveolar spaces, thereby helping to maintain the normal "dry" environment required for efficient gas exchange.
Until recently, the majority of investigations of alveolar fluid balance relied on intact lung models. The information obtained from these intact mammalian lung studies in vivo and in vitro, if useful, can be difficult to interpret mechanistically, largely because of the anatomical complexity of the lung. For more precise information about alveolar epithelial properties, studies of isolated preparations have been done, providing useful additional approaches to underlying transport machanisms and pathways in the alveolar-capillary wall.
In this review article, I introduced the methods being used for study of barrier function in addition to intact lung investigation. And I discussed the barrier properties of the alveolar epithelium relevant to alveolar fluid balance in chemically injured lung, citing the pertinent supporting experimental data where appropriate.