Alveolar microenvironment and its relationship to the retention and transport into blood of aerosols deposited in the alveoli

The literature was critically reviewed to obtain a comprehensive view of the nature of the alveolar microenvironment, with emphasis on properties which may affect the retention kinetics of inhaled materials in the alveoli. The ultra-structure of the air-blood barrier, its permeability characteristics and the nature of the alveolar fluid were examined. Indirect evaluations of the general solute concentrations, pH, and precipitate and chelate forming agents of the alveolar fluid were made. Based on this information, possible mechanisms for the retention kinetics in the lung of inhaled, water-soluble trivalent materials are discussed. Suggestions for future experiments are included. (author)