Transport Mechanisms of Tryptophan in Blood Cells, Nerve Cells, and at the Blood-Brain Barrier : Proceedings of the International Symposium, Prilly/Lausanne, Switzerland, July 6–7, 1978

Most of the neutral amino acids are transported across the plasma membrane by two or moreparallel transport systems. In this study, we have limited transport interactions to System A and L by studying amino acids not transported by System ASC. Results are presented to emphasize that such amino acids as leucine, phenylalanine and tryptophan do enter the Ehrlich cell to substantial degrees by System A. We show how the phenomenon of competitive stimulation presents a strong argument that these systems operate between the same two compartments, extracellular and cellular. To discover what is needed to bring two amino acids into the transport relation shown by tryptophan and methionine, we arbitrarily set up two classes of amino acids: (1) those whose steady-state gradients will be increased when System L is deleted; (2) those whose gradients will instead be decreased. On blockading System L with 2-aminonorbornane-2-carboxylic acid applied in symmetry to the two sides of the plasma membrane, we show as predicted that the gradient maintained for methionine is strongly increased, that for tryptophan decreased. The initial rate of uptake of all the amino acids mentioned is highly sensitive to the nature of the cellular amino acid pool. A high influx by exchange, relative to net influx, appears to characterize the amino acids that respond to competitive stimulation. Albumin-bound tryptophan appears not directly accessible to the tested carners. ,,. Front Matter....Pages I-X Interaction Between Parallel Transport Systems Examined With Tryptophan and Related Amino Acids....Pages 1-13 A Comparison of Amino Acid Transport and Ouabain Binding in Brain Endothelium and Salivary Epithelium Studied in vivo by Rapid Paired-Tracer Dilution....Pages 15-27 Kinetics of Tryptophan Transport Across the Blood-Brain Barrier....Pages 29-42 The Role of Blood-Brain Barrier Transport of Tryptophan and Other Neutral Amino Acids in the Regulation of Substrate-Limited Pathways of Brain Amino Acid Metabolism....Pages 43-54 Diet-Induced Changes in Plasma Amino Acid Pattern: Effects on the Brain Uptake of Large Neutral Amino Acids, and on Brain Serotonin Synthesis....Pages 55-67 When—and Why—Should Nutritional State Control Neurotransmitter Synthesis?....Pages 69-79 Relationships Between Plasma, CSF and Brain Tryptophan....Pages 81-92 Ontogenesis of Tryptophan Transport in the Rat Brain....Pages 93-105 Kinetics of Tryptophan Transport Into the Brain....Pages 107-114 Structural Specificity of the Carrier for L-Tryptophan in Rat Cerebral Cortex Slices....Pages 115-124 Interactions Between Tryptophan, Phenylalanine and Sugar Transport in the Small Intestinal Mucosa....Pages 125-137 Transport of Tryptophan and Other Amino Acids by Mammalian Erythrocytes....Pages 139-151 Zero-Trans Uptake of L-Tryptophan in the Human Erythrocyte....Pages 153-160 Tryptophan Accumulation by Blood Platelets of Depressed Patients....Pages 161-163 Distribution of Tryptophan in Erythrocytes, Leukocytes and Thrombocytes, and Its Binding to Plasma Albumin....Pages 165-176 The Influence of Oral Tryptophan on Cortical Evoked Responses in Normals and Schizophrenics....Pages 177-188 Blood-Brain Movements of Tryptophan and Tyrosine in Manic-Depressive Illness and Schizophrenia....Pages 189-196 Distribution of Tryptophan and Tyrosine in Unipolar Affective Disorders as Defined by Multicompartmental Analysis....Pages 197-207 Serotonergic Mechanisms in Myoclonus....Pages 209-216 Comment on the Methodology for Separating and Determining Free and Albumin-Bound Tryptophan Levels in Blood Samples....Pages 217-219 Methodological Problems in the Determination of Total and Free Plasma Tryptophan....Pages 221-226 Summary: Circulating Tryptophan, Brain Tryptophan, and Psychiatric Disease....Pages 227-236 Back Matter....Pages 237-240