Free amino acid concentrations in plasma, erythrocytes, granulocytes, and lymphocytes in umbilical cord blood, children, and adults

Concentrations of free amino acids were measured concurrently in plasma, erythrocytes, granulocytes, and lymphocytes in umbilical cord blood, neonates, children, and adults. In each age group, the patterns of free amino acids were fairly similar in plasma and erythrocytes except for aspartic acid which was more abundant in erythrocytes. Of the amino acids in granulocytes, 71-77% was taurine; in lymphocytes taurine, aspartic acid, and glutamic acid comprised 35-44%, 18-24%, and 20-28%, respectively, of the total in all age groups. Leukocytes may contribute to the interorgan transport of amino acids to about 10% of the erythrocytes' contribution. Postnatally, the levels of glutamic acid and tyrosine in plasma; threonine plus glutamine, serine plus asparagine, and tyrosine in erythrocytes; histidine in granulocytes; and glutamic acid in lymphocytes were significantly increased (p less than 0.001); while the levels of phenylalanine and lysine in plasma; taurine in erythrocytes; valine and phenylalanine in granulocytes; and threonine plus glutamine, tyrosine, and phenylalanine in lymphocytes were significantly decreased (p less than 0.001). After the neonatal period concentrations of taurine and aspartic acid in erythrocytes, taurine and valine in granulocytes, and tyrosine and phenylalanine in lymphocytes increased gradually with age; while concentrations aspartic acid in plasma, histidine in granulocytes, and glycine in lymphocytes decreased gradually with age. The levels of glycine and valine in plasma, alanine and valine in erythrocytes, serine plus asparagine, glycine, alanine, and tyrosine in granulocytes, and aspartic acid, serine plus asparagine, and alanine in lymphocytes remained constant in all age groups.(ABSTRACT TRUNCATED AT 250 WORDS)