This book presents the papers that were delivered at the Satellite Symposium of the International Society for Neurochemistry in Padua, September, 1975. Having such Satellite Symposia was a new experiment for the Society, and all signs, including those from Padua, indicate that it was a very successful experiment, which will be an old tradition for the Society. The large international meeting affords the opportunity for presentations from all areas, for meeting of colleagues from various backgrounds and disciplines. The Satellite Symposia allow people from the same area of interest to discuss their subject in depth, and as such represent meetings of possibly the greatest practical significance for the partici­ pants. The Padua Symposium was no exception: all who particiDated in it could testify to its success in exchanging of information, learning of new approaches, and acqu~r~ng of new ideas, also the strengthening of old friendships, forming of new friendships and new collaborations, and exposing ideas to criticisms, suggestions, discussions. As a sign of the interest and success of the partici­ pants I can mention that all participants have sent in their contributions. Perhaps editors of volumes would anpreciate that the very last came in no later than two months past the deadline.

Inhalt

Section I Metabolite Transport.- Metabolite Transport at Cell Membranes.- Mediation of apparently spontaneous metabolite migrations.- Each active transport has a reverse phase.- Meaning of duality or multiplicity of transport systems.- Evidence that exodus occurs by reversal of a weaker pump.- Increased importance of discriminating distinct transport systems.- Roles of receptor sites for amino acid transport in neurotransmission?.- The place of the hydrogen ion.- The future: Generation versus interconversion of energetic gradients.- Possible Role of Glutathione in Transport Processes.- Enzymatic synthesis and degradation of glutathione.- The ?-glutamyl cycle.- Evidence for the function of the ?-glutamyl cycle in amino acid transport.- Heritable disorders of metabolism due to deficiencies in enzymes of the ?-glutamyl cycle.- Section II Barriers in the Living Brain.- Transport Mechanisms in the Cerebrospinal Fluid System for Removal of Acid Metabolites from Developing Brain.- Maturation of bulk flow.- Development of intracranial mechanisms for efflux of:.- (a) para-aminohippuric acid (PAH).- (b) 5-hydroxyindoleacetic acid (5-HIAA).- Sink action of the cerebrospinal fluid (CSF) system.- The Morphological Approach to the Study of Normal and Abnormal Brain Permeability.- Induced opening of the blood-brain barrier.- tumors.- hyperosmotic opening.- hypertensive opening.- Loci where there is no barrier.- permeable vessels.- The Transport of Metabolizable Substances into the Living Brain.- Glucose and other energy yielding substances.- Glucose.- ketone bodies.- pyruvate and lactate.- Amino acids.- differences in influx of amino acids into the brain.- exclusion of amino acids from the brain by inhibition of transport mechanisms.- two sites of cerebral transport.- The relation of cerebral transport to various brain disorders.- aminoacidurias.- changes in transport which affect neurotransmitters.- hormonal abnormalities affecting transport into the brain.- The Specificity of Amino Acid and Sugar Carriers in the Capillaries of the Dog Brain Studied in Vivo by Rapid Indicator Dilution.- Methods and interpretation.- Carrier for amino acids.- Sugar carrier.- Possible Role of Insulin in the Transport of Tyrosine and Tryptophan from Blood to Brain.- Insulin effect on amino acid concentrations.- Mechanism of the effect.- Conclusion.- The Influence of Liver-Bypass on Transport and Compartmentation in vivo.- Consideration of the transformation of metabolizeable.- molecules after they have entered the brain from the blood.- Metabolic labelling patterns from various precursor substrates the evidence for the compartmentation of metabolism within the brain.- Evidence for rapid transformation of transported substrates.- Substrate uptake and metabolism in a pathological condition affecting astrocytes.- comparative studies between normal rats and animals with a portocaval anastomosis.- Certain Aspects of Drug Distribution to Brain.- Transcapillary exchange.- Blood-brain barrier permeability.- Drug distribution to brain.- Penetration of Proteins in the Central Nervous System.- Penetration of proteins into the CSF.- Penetration of proteins into the tissue.- Routes of penetration.- Increased penetration.- Pathological conditions.- Pharmacological studies.- Section III Transport Studies in Various Nervous Tissue Preparations.- The Characteristics of Glucose Transport Across the Blood Brain Barrier and its Relation to Cerebral Glucose Metabolism.- Glucose transport kinetics under physiological conditions.- Glucose transport kinetics during hypoglycemia.- Glucose transport kinetics during anoxia.- Mechanism of glucose transport.- Comparison with glucose transport in the erythrocyte.- Proposed model for glucose transport at the blood brain interface.- Mechanisms for the Passive Regulation of Extracellular K+ in the Central Nervous System: The Implications of Invertebrate Studies.- K+ homeostasis.- The function of astrocytes.- Invertebrate studies.- Vertebrate studies.- glia as spatial buffers for K+.- Crustacean studies.- Amino Acid Transport in Spinal and Sympathetic Ganglia.- Structure and functions of dorsal root and superior cervical ganglia.- The neurone - glia functional unit.- Uptake of putative amino acid transmitters.- effect of dorsal root section.- metabolic requirements.- kinetic characteristics and sodium dependence.- Localization of amino acids.- Drug inhibition of GABA and glutamate uptake.- Amino acid release.- Exchange processes.- Conclusions.- Uptake of Neurotransmitters and Precursors by Clonal Cell Lines of Neural Origin.- Transport in clonal cell lines.- Uptake of ?-aminobutyric acid (GABA).- Uptake of aspartate, glutamate, glycine and taurine.- Transport of choline.- Transport of precursors and biogenic amines.- On the Uptake Mechanism of Choline in Nerve Cell Cultures.- Cell cultures.- Choline uptake experiments.- Results.- Discussion.- The Uptake and Release of ?-Aminobutyric Acid (Gaba) by the Retina.- Role of GABA in the retina.- GABA uptake in the retina.- Effect of GABA-T inhibitors on GABA uptake.- Sites of GABA uptake.- subcellular distribution of (3H)GABA.- autoradiographic localization of GABA uptake sites.- Efflux of GABA from the retina.- Amino Acid Transport in Isolated Neurons and Glia.- Bulk-prepared neuronal and glial cell fractions as models for amino acid transport studies.- General features of amino acid transport in neuronal and glial cells.- High-affinity uptake in relation to transmitter inactivation.- Metabolic and ionic requirements for amino acid uptake.- Amino acid release from isolated fractions as studied by perfusion.- Inhibitors as tools to study cell specificity of amino acid uptake.- Glutamate-glutamine compartmentation.- Summary.- Transport of Taurine in the Central Nervous System.- Taurine transport in vitro.- Taurine influx in vitro.- Taurine efflux in vitro.- Taurine binding to synaptosomal membranes.- Transport of Adenine Derivatives in Tissues of the Brain.- Translocation and central effects of adenosine.- Entry of adenine derivatives to tissues of the brain.- Adenine.- Adenosine.- Hypoxanthine.- adenine mononucleotides.- Output of adenine derivatives from cerebral tissues.- released compounds and cyclic AMP.- Intracellular movements of adenine derivatives.- Kinetical Analysis of the uptake of Glucose Analogs by rat Brain Cortex Slices from Normal and Ischemic Brain.- Uptake of glucose analogues by slices from normal brain.- A model of the brain slice.- determination of model parameters.- uptake of glucose analogues and mannitol.- determination of the cellular transport by model fitting.- extracellular diffusion versus me…