title: Utilization of N-acetyl-L-tyrosine and glycyl-L-tyrosine during long-term parenteral nutrition in the growing rat.
abstract: Utilization of N-acetyl-L-tyrosine and glycyl-L-tyrosine as a source of tyrosine in infusion solutions was tested in rats receiving total parenteral nutrition for 4 wk. The four solutions tested were isonitrogenous and isocaloric. One of the solutions contained an adequate amount of L-phenylalanine; in the other three, two-thirds of the phenylalanine was replaced by a corresponding amount of either glycine, glycyl-L-tyrosine or N-acetyl-L-tyrosine. No differences in weight gain or N-balance could be detected as a result of administering either the solution with glycyl-L-tyrosine or with N-acetyl-L-tyrosine in place of the solution containing an adequate phenylalanine content. The solution in which two-thirds of the L-phenylalanine was replaced by glycine yielded only half of the weight gain and correspondingly reduced values for N-balance. Daily urinary excretion rates for N-acetyl-L-tyrosine and glycyl-L-tyrosine were 11% and 0.5%, respectively, of the infused amount. Plasma amino acid pattern was affected differently by the four solutions. The results indicate that both N-acetyl-L-tyrosine and glycyl-L-tyrosine are efficiently utilized by the rat during total parenteral nutrition.
mesh_terms: D000596:Amino Acids / Q000097:blood; D000818:Animals; D001835:Body Weight; D004151:Dipeptides / Q000008:administration & dosage / Q000378:metabolism* / Q000652:urine; D008297:Male; D009584:Nitrogen / Q000378:metabolism; D010289:Parenteral Nutrition, Total; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors; D014443:Tyrosine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism / Q000652:urine
chemical_list: D000596:Amino Acids; D004151:Dipeptides; D014443:Tyrosine; C022013:glycyltyrosine; C025787:N-acetyltyrosine; D009584:Nitrogen