BLOOD-CELL TO PLASMA GRADIENTS OF AMINO-ACIDS IN ARTERIAL AND VENOUS-BLOOD IN FED AND FASTED RATS

Measurement of amino acid concentrations in blood cells and plasma, an d the calculated blood cell to plasma gradients (C/P) from both affere nt and efferent vessels to tissues, allowed evaluation of the effect o f several tissues (splanchnic bed, skeletal muscle and kidney) on bloo d amino acid distribution in fed and starved rats. Combined effects of tissues and erythrocyte transport capabilities determined specific C/ P values for each amino acid. For amino acids related to the L-system, the high capacity of this erythrocyte transport many buffer some C/P changes as an effect of tissue metabolism. For less permeable amino ac ids (like Asp and Glu) plasma changes were mainly responsible for chan ges in C/P values, whereas for other amino acids (such as basic amino acids) blood cells became the main determinants of C/P changes, mainly in starvation. In general, the role of erythrocytes in amino acid tra nsport was enhanced in starvation.