<i>L</i>-Tyrosine and <i>L</i>-Tryptophan Transport in Red Blood Cells in Normal Subjects

Abstract

Blood cells may be used as a model in the central transport mechanisms of amino acids, precursors of amines, implicated in some hypotheses of psychiatric diseases. In a previous paper, we showed a deficit of tyrosine transport by red cells incubated in the plasma of depressed patients. In the present study, we have investigated the interaction of these peripheral transport mechanisms for tyrosine and tryptophan with other amino acid transports, such as the L and ASC systems, and the role of sodium ions in the extracellular medium. We also describe the inhibition induced by incubation at a low temperature, and a probable role of the membrane viscosity. The interest of incubating the cells in their own plasma, in order to have physiological conditions, is also discussed.

In vivo metabolism and partitioning of 6-[18F]fluoro-L-meta-tyrosine in whole blood: a unified compartment model

“…The differences in kinetics observed for these two compounds can be attributed in large part to the different transport systems that carry them from plasma to erythrocytes. FmT is likely to enter the erythrocytes by facilitated diffusion via the L and T transport systems for amino acids (Tunnicliff 1994, Widmer et al 1986. FHPAA is thought to cross the erythrocytes membrane via the specific H + /HCO − 3 co-transporter, which is the dominant transport system for monocarboxylates (Poole and Halestrap 1993).…”

Evolution of Red Blood Cell Membrane Transport and Plasma Level of <i>L</i>-Tyrosine and <i>L</i>-Tryptophan in Depressed Treated Patients According to Clinical Improvement

“…The transport of TYR and TRP across the red cell membrane was measured as previously described [Widmer et al, 1986], Briefly 10 ml of venous blood was collected on heparinate and samples of 1 ml whole blood were incubated for 10 min in the presence of a mixture of unlabelled TYR and TRP and l4C-TYR or 3H-TRP to obtain a final concentration of 10-4 Af. After centrifugation for 10 min at 20,000 g, plasma was taken up in triplicate (100 pi) and digested with a Ready-Solv solution before measurement in the liq uid scintillation counter.…”