Abstract
Isolated liver cells from adult rats were cultured for 24 hours in enriched medium (Williams medium E, WE) with 10% fetal bovine serum, and with or without various hormones and then the amino acid concentrations in the medium were measured. The concentrations of alanine, glycine, arginine and aspartate decreased very much, the decreases in alanine and glycine being markedly enhanced by the presence of glucagon. The concentrations of lysine, tyrosine, phenylalanine, threonine and methionine decreased moderately and dexamethasone stimulated that of tyrosine, particularly.
On the other hand, the concentrations of isoleucine, leucine, proline, cystine, glutamate and histidine did not change significantly and those of serine, valine and ornithine increased.
These results can mainly be explained by the metabolic activities of liver cells, particularly gluco-neogenesis for alanine and aspartate, ureogenesis for arginine and ornithine, and interconversion of serine and glycine and the inability of hepatocytes to metabolize branched chain amino acids. These explanations were supported more clearly by results using unsupplemented salt solution (Hanks' solution). In this medium the concentrations of amino acids released into the medium were very similar to those found in liver proteins, except for those of alanine, glutamate, aspartate, proline and arginine, which were much lower than in liver proteins.
The present work also suggests that liver cells in primary culture retain various liver functions and thus are useful for studies on liver functions in vitro.
