Volumetric evaluation of pulmonary alveolar toxicity: the BHT model
Abstract
Butylated hydroxytoluene (BHT) provides a good model of toxicity to the pulmonary alveolar epithelium of mice. The volume fraction (Vv) of each epithelial cell type is determined by volumetric analysis, using point counting on electron micrographs of mice treated with a combination of BHT and oxygen. BHT is the major influence in inducing the degeneration of type I pneumocytes, early (days 1 to 3) after its administration. These lesions in turn trigger epithelial regeneration (at days 3 to 5), effected by type II pneumocytes. The most sensitive index of epithelial modifications is found in the Vv of the intermediate type cell, which represents the transformation of type II into type I cells. Addition of a high concentration of oxygen (95%) for 24 hours does not much enhance this toxicity, but hastens epithelial regeneration by the type II pneumocyte.