Abstract:
The aim of the present study is to clarify the participation of the erythrocytes to inter-organ exchange of amino acids. Three experiments were carried out. The first, in vitro on the blood of rat, was concerned with the analysis of amino acids movements between plasma and erythrocytes when plasma concentrations were suddenly modified. In the second, in vivo in the rat, amino acids arterio-venous differences in the two blood compartments, plasma and erythrocytes, were assessed in the intestine. The third experiment carried in vivo in the man, dealt with the study of plasma and erythrocytes kinetics of amino acids after an orally uptake of a load of amino acids. We have used liquid ion exchange chromatography for amino acids analysis. Erythrocytes contents have been estimated from plasma and hemolysed blood concentrations and the corrected hematocrit. The confrontation of results obtained in man to those observed in rat, proves for amino acids whose erythrocytes movements were manifestly significant the following : ocAB, VAL, MET, ILE, LEU and PHE are carried both by erythrocytes of man and rat ; TAU, ALA and ORN are transported by the erythrocytes of man and not by those of rat ; TYR and TRP are rather transported by rat erythrocytes only. These results are compatible with the existence in man and rat erythrocytes membrane of the L system for neutral and branched chain amino acids and the T
system for aromatic amino acids. The ASC system for alanine and the system y+ for
cationic amino acids, would be active in the present study only in human erythrocytes. The plasma remains the main vehicle. We can not however ignore the intervention of the erythrocytes in inter-organ transfer of amino acids. A regulating role of plasma homeostasis by the pool erythrocytes amino acid is to be considered.
