Concentrations of Nineteen Amino Acids in Plasma and Urine of Fasting Normal Males.

Abstract

The plasma and urine concns. of 19 amino acids was simultaneously detd. microbiologically in 13-18 healthy young male subjects after a 12-hr. fast. The mean amino acid plasma levels (mg./100 ml.) glutamine, 7.51 [plus or minus] 1.63; alanine, 3.96 [plus or minus] 1.47; lysine, 3.68 [plus or minus] 1.15; valine, 3.23 [plus or minus] 53; cysteine-cystine, 3.02 [plus or minus] 1.16; glycine, 2.91 [plus or minus] 1.36; proline, 2.61 [plus or minus] 1.26; leucine, 2.48 [plus or minus] .90; arginine, 2.26 [plus or minus] .47; histidine, 2.11 [plus or minus] .61; threonine, 2.06 [plus or minus] .69; isoleucine, 2.0 [plus or minus] .79; phenylalanine, 1.99 [plus or minus] 82; tryptophan, 1.74 [plus or minus] .51; serine, 1.39 [plus or minus] .44; tyrosine, 1.32 + .37; glutamic acid, .89 [plus or minus] 39; methionine, .57 [plus or minus] .27; aspartic acid, 33 [plus or minus] .37. The amt. of each amino acid excreted during the 2-hr. test period varied widely. Glycine (3-36 mg.Ar.) and histidine (2.7-23.0 mg./hr.) were excreted in the largest quantity; glutamine (1.6-4.6 mg./hr.) and cystine-cysteine (0.4-4.3 mg./hr.) in intermediate amts.; leucine, isoleucine, valine, methionine, and the dicarboxylic acids in small amts. (less than 1 mg./hr.). The remaining 9 amino acids were excreted in amts. of 1.0-3.4 mg./hr.