Changes in amino acid metabolism during activation of mouse macrophage-like cell lines.

BACKGROUND recent reports have suggested the applicability of salivary amino acids as markers for various diseases. In order to understand the role of macrophages in the age-related changes of salivary amino acid composition, we compared the amino acid production and consumption between control and activated macrophages. MATERIALS AND METHODS mouse macrophage-like cells (RAW264.7, J774.1) were activated by Escherichia coli lipopolysaccharide (LPS). Concentrations of nitric oxide (NO) and amino acids in the culture medium during culture were determined by Griess method and amino acid analyzer, respectively, to delineate their metabolic rates. RESULTS LPS activated these macrophages, as judged by the enhanced production of NO and citrulline. The activated macrophages produced greater amounts of glycine, glutamic acid, alanine and histidine as compared with control cells, and consumed serine and glutamine at the highest rates. CONCLUSION The present study suggests the possible role of activated macrophages in age-related changes in salivary amino acid composition.