the test on rats has revealed varying concentrations of amino acids when they are passing through the liver : a half of certain amino acids ( lysine , glycine , proline etc . ) is retained in the liver , other ( cystine ) increase their concentration in the hepatic vein as compared to that in the portal vein , whereas amino acids with ramified carbon chain are insignificantly retained by the liver .
C0017890
glycine
C0002520
amino acids