Free amino acid contents in guinea pig tissues

Free amino acid contents in various guinea pig tissues were determined with an amino acid analyzer. The most abundant amino acids in these tissues were: Gly and Glu in the liver and kidney, Gln, Glu and Ala in the heart, Glu and Gln in the brain, Gly in the blood plasma and Lys in erythrocytes. Glutathione was present as the reduced form in these tissues. Cystine was not detected except in the blood plasma, but cysteine was present in these tissues. These results indicate that most thiols are present in the reduced form in these guinea pig tissues. Taurine contents were low compared with those in rat tissues. The results were discussed in relation to the metabolism of sulfur-containing amino acids, and it was suggested that the oxidative metabolism of L-cysteine was lower in guinea pig tissues than in rat tissues.