Amino acid changes and pulmonary response of rats to silica dust

Abstract

The effect of intratracheal injection of quartz on the free amino acids of lung, serum, and liver and the bound amino acids of lung was studied in rats, at intervals preceding and following the formation of collagen. The studies revealed that amino acid metabolism is significantly altered in silicotic rat lung. Changes in the body pool of amino acids seem to be related to both collagen and noncollagen formation in silicotic lung. It appears that some of the amino acid residues for collagen formation in lung in response to silica exposure are made available by the in situ formation from available precursors, while others are contributed by other organs, especially liver. A central role for glutamic acid metabolism in the genesis of pulmonary fibrosis is discussed.