Zusammenfassung
Bei 15 gesunden freiwilligen Versuchspersonen haben wir die Hirndurchblutung, die cerebrale Aufnahme von Sauerstoff und Glucose sowie die Abgabe von Kohlensäure und Lactat aus dem Gehirn gemessen. Ferner wurden die cerebralen arteriovenösen Differenzen von Taurin, Harnstoff, Asparaginsäure, Threonin-Asparagin, Serin, Glutaminsäure, Prolin, Citrullin, Glycin, Alanin, Valin, Cystin, Methionin, Isoleucin, Leucin, Tyrosin, Phenylalanin, Ammoniak, Ornithin, Lysin und Histidin bestimmt. Die für den Normalfall ermittelten Werte von Hirndurchblutung, Sauerstoff- und Glucoseverbrauch des Gehirns sowie Abgabe von Kohlensäure und Milchsäure aus dem Gehirn stimmen mit denen anderer Untersucher überein. Die Differenzen der Aminosäurenkonzentrationen zwischen arteriellem und hirnvenösem Mischblut zeigten im Durchschnitt entweder eine positive (Aufnahme), negative (Abgabe) oder keine Differenz. Lediglich die sog. glucoplastischen Aminosäuren zeigten eine größere cerebrale arteriovenöse Differenz. Unter normalen Bedingungen findet zwar ein Austausch von Aminosäuren zwischen Blut und Hirngewebe statt, die entscheidende Bildung von Aminosäuren erfolgt jedoch erst im Gehirn in dem um einen γ-Aminobuttersäure-shunt erweiterten Krebscyclus. Normalerweise werden in die beiden im Gehirn befindlichen Aminosäurepools mehr Aminosäuren eingeschleust als für funktionelle oder strukturelle Aufgaben notwendig ist, so daß der „Überschuß“ aus dem Gehirn abgegeben wird.
Summary
In 15 healthy volunteers we measured cerebral blood flow, the uptake of oxygen and glucose, and the output of CO2 and lactate of the brain. Furtheron we determined the cerebral arterio-venous differences of taurine, urea, aspartate, threonineasparagine, serine glutamic, acid, proline, citrulline glycine, alanine, valine, cystine, methionine, isoleucine, leucine, tyrosine, phenylalanine, ammonia, ornithine, lysine, and histidine. The normal values of cerebral blood flow, uptake of oxygen and glucose, and the output of CO2 and lactate agreed with those reported by other investigators. Differences of the mean concentrations of the amino-acids between arterial and venous blood of the internal jugular bulb were positive (uptake) as well as negative (output) or there was no difference at all. Under normal conditions we found a small exchange of amino acids between blood and brain. The main formation of amino acids in the brain, however, is accounted for by the combined activity of the Krebs cycle and the GABA-shunt. Normally, more amino acids are synthetized than required by the two cerebral amino acid pools for maintaining the structural and functional tasks of the brain, the excess amino acids being released into the venous blood.
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Literatur
Barkulis, S. S., Geiger, A., Kawakita, Y., Aguilar, V.: A study on the incorporation of14C derived from glucose into the free amino acids of the brain cortex. J. Neurochem.5, 339 (1960).
Berl, S., Takagaki, G., Clarke, D. D., Waelsch, H.: Metabolic compartments in vivo. Ammonia and glutamic acid metabolism in brain and liver. J. biol. Chem.237, 2562 (1962).
Bernsmeier, A., Siemons, K.: Die Messung der Hirndurchblutung mit der Stickoxydulmethode. Pflügers Arch. ges. Physiol.258, 149 (1953).
Bessman, S. P.: Ammoniagenic coma: the chemistry of an endogenous intoxication. In: Proceed. IV. Intern. Congr. Biochem. Vienna 1958. New York-London-Paris-Los Angeles: Pergamon Press 1959.
Elliot, K. A. C.:γ-aminobutyric acid and factor I. Rev. canad. Biol.17, 367 (1958).
Florey, E., Florey, E.: Studies on the distribution of factor I in mammalian brain. J. Physiol. (Lond.)144, 220 (1958).
Gaitonde, M. K., Marchi, S., Richter, D.: The utilization of glucose in the brain and other organs of the cat. J. Physiol. (Lond.)168, 48 (1963).
—— Dahl, D. R., Elliot, K. A. C.: Entry of glucose carbon into amino acids of rat brain and liver in vivo after injection of uniformly14C-labelled glucose. Biochem. J.94, 345 (1965).
Gibbs, E. L., Lennox, W. G., Nims, L. F., Gibbs, F. A.: Arterial and cerebral venous blood (arterial-venous differences in man). J. biol. Chem.144, 325 (1942).
Gottstein, U., Bernsmeier, A., Sedlmeyer, I.: Der Kohlenhydratstoffwechsel des menschlichen Gehirns. I. Untersuchungen mit substratspezifischen enzymatischen Methoden bei normaler Hirndurchblutung. Klin. Wschr.41, 943 (1963).
Hoyer, S., Becker, K.: Hirndurchblutung und Hirnstoffwechselbefunde bei neuropsychiatrisch Kranken. Nervenarzt37, 322 (1966).
Kety, S. S., Schmidt, C. F.: The nitrous oxide method for the quantitative determination of cerebral blood flow in man: theory, procedure and normal values. J. clin. Invest.27, 476 (1948).
—— The general metabolism of the brain in vivo. In: D. Richter, Metabolism of the nervous system. London: Pergamon Press 1957.
Lajtha, A., Furst, S., Gerstein, A., Waelsch, H.: Amino acid and protein metabolism of the brain. — I. Turnover of free and protein bound lysine in brain and other organs. J. Neurochem.1, 289 (1957).
—— Amino acid and protein metabolism of the brain. — II. The uptake of L-lysine by brain and other organs of the mouse at different ages. J. Neurochem.2, 209 (1958).
—— Berl, S., Waelsch, H.: Amino acid and protein metabolism of the brain. — IV. The metabolism of glutamic acid. J. Neurochem.3, 322 (1959).
—— Amino acid and protein metabolism of the brain. — V. Turnover of leucine in mouse tissues. J. Neurochem.3, 358 (1959).
Levi, G., Kandera, J., Lajtha, A.: Control of cerebral metabolite levels. I. Amino acid uptake and levels in various species. Arch. Biochem.119, 303 (1967).
Lindsay, J. R., Bachelard, H. S.: Incorporation of14C from glucose into α-keto acids and amino acids in rat brain and liver in vivo. Effects of neurotropic drugs on glucose metabolism in rat brain in vivo. Biochem. Pharmacol.15, 1045 (1966).
McIlwain, H.: Biochemistry and the central nervous system. London: Churchill 1955.
Moore, S., Stein, W. H.: Procedures for the chromatographic determination of amino acids on four per cent cross-linked sulfonated polystyrene resins. J. biol. Chem.211, 893 (1954).
—— —— A modified ninhydrin reagent for the photometric determination of amino acids and related compounds. J. biol. Chem.211, 907 (1954).
Neame, K. D.: Uptake of 1-histidine, 1-proline, 1-tyrosine and 1-ornithine by brain, intestinal mucosa, testis, kidney, spleen, liver, heart muscle, skeletal muscle and erythrocytes of the rat in vitro. J. Physiol. (Lond.)162, 1 (1962).
O'Neal, R. M., Koeppe, R. E.: Precursors of the acidic amino acids of rat brain. Fed. Proc.23, 333 (1963).
Otsuki, S., Watanabe, S., Ninomiya, K., Hoaki, T., Okumura, N.: Correlation between [U-14C] glucose metabolism and function in perfused cat brain. J. Neurochem.15, 859 (1968).
Rodnight, R., McIlwain, H., Tresize, M. A.: Analysis of arterial and cerebral venous blood from the rabbit. J. Neurochem.3, 209 (1959).
Sacks, W.: Cerebral metabolism of doubly labelled glucose in humans in vivo. J. appl. Physiol.20, 117 (1965).
Berg, C. J. van den, Krzalic, L. J., Mela, P., Waelsch, H.: Compartmentation of glutamate metabolism in brain. Evidence for the existence of two different tricarboxylic acid cycles in brain. Biochem. J.113, 281 (1969).
Sande, M. van, Mardens, Y., Andriaessens, K., Lowenthal, A.: The free amino acids in human cerebrospinal fluid. J. Neurochem.17, 125 (1970).
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Hoyer, S. Der Aminosäuren-Stoffwechsel des normalen menschlichen Gehirns. Klin Wochenschr 48, 1239–1243 (1970). https://doi.org/10.1007/BF01487133
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DOI: https://doi.org/10.1007/BF01487133