Human cerebral free amino acids in hepatic coma.

Free amino acids and some related compounds in autopsy specimens of different human brain areas have been determined by column chromatography. Only in patients with hepatic coma could a significant difference in the contents of tyrosine and lysine between caudate nucleus and N. amygdalae be found. In comparison with control subjects the brains of patients with hepatic coma contained significantly higher concentrations of glutamine, isoleucine, histidine and ammonia. In patients with hepatic coma after complete parenteral nutrition plus L-valine administration, dying from other causes, the brain levels of alanine and valine were decreased, while the content of taurine was significantly increased. However, most of the amino acid levels in brain tended toward lower levels. A very significant reduction after treatment with L-valine could be observed in glutamine and ammonia concentration. It is suggested that L-valine has some beneficial action on ammonia detoxification and has also a competing action on amino acid uptake mechanism (specially with the large neutral amino acids).