In vitro uptake of labeled amino acids by red blood cells of children with protein-calorie malnutrition.

The in vitro uptake of 14C-glycine, 14C-leucine and 35S-methionine by red blood cells as well as the red blood cells and plasma amino acid patterns were studied in 20 children with protein-calorie malnutrition. Blood samples were obtained from each patient on admission, following clinical recovery and, when possible, several months later. Amino acid uptake as well as levels of red blood cells and plasma amino acids are quantitatively changed in protein-calorie malnutrition. Significantly increased uptake of 14C-glycine but decreased uptake of 14C-leucine and 35S-methionine were observed in patients on admission. Following clinical recovery the uptake values of all three amino acids were markedly reduced to levels significantly below normal. Several months later values for glycine and leucine uptake were found to be normal. No significant correlation, however, was found between glycine, leucine, or methionine uptake values and concentrations of these amino groups in RBCs or plasma of patients. It is concluded that the elevations observed in red blood cell amino acids of protein-calorie malnutrition patients are not purely a result of increased amino acid uptake of RBCs and that normalization of both amino acid uptake values and their concentrations in RBCs require longer than the treatment period.