Bioreactivity of intratracheally administered slate dust in rats: incorporation of 14C-acetate into lung lipids.

The effect of intratracheally instilled slate dust on the phospholipid profile, and 14C-acetate incorporation into the lipids of lung lavage, whole lung tissue and its subcellular fractions, has been studied in rats. The acellular fraction of lung lavage showed a decrease in the phospholipid content at 4 days and then an increase at 40 days of dust exposure, whereas the cellular fraction showed the reverse. The order of 14C-acetate incorporation into total lipids and individual phospholipids showed a parallel trend. The rate of incorporation with total lipids of lung tissue was higher at the two stages of dust exposure and a similar pattern prevailed in the subcellular fractions, i.e. mitochondrial, microsomal and cytosolic fraction. Acetate incorporation was highest in mitochondria, followed by the microsomes. An increase in the microsomal and mitochondrial cholesterol levels was also observed. There was no significant change in the solvent-extracted 14C-counts of whole plasma, trichloroacetic acid (TCA) precipitate and TCA supernatant of plasma. The results indicate that slate dust causes an enhanced synthesis of pulmonary surfactant and other lung lipids and, therefore, has an effect on the metabolism of type II alveolar epithelial cells.