AMINO-ACID DISTRIBUTION IN HUMAN BLOOD - A SIGNIFICANT POOL OF AMINO-ACIDS IS ADSORBED ONTO BLOOD-CELL MEMBRANES

The recently published existence of a pool of amino acids adsorbed ont o the blood cell membranes in the rat has provided a new insight into the role of the blood cell amino acid pools, in the context of tissue- blood amino acid transport and their metabolic relationships. In the p resent study, this pool has been measured in a large (n=40) representa tive healthy human population. This pool represents 9% of, the blood c ell amino acids, which is somewhat lower but in the same order as that previously measured in the rat. The inside-erythrocyte and plasma poo ls have also been quantified, giving an inside to outside ratio of 1.3 2 for the combined total amino acids. Statistically significant age re lated changes in the different blood compartments were detected for so me amino acids (aspartate, asparagine, glutamine, tyrosine, methionine , phenylalanine, tryptophan and lysine) as well as for the ratio of tr yptophan to the large neutral amino acids. The results obtained emphas ize the importance of the amino acid red blood cell pool and assign to it the same order as the plasma pool. The results also feature the me mbrane-attached I of some specific amino acids, ie taurine, glutamine, glutamate, aspartate and valine.