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Synaptic Transmission in the Brain

  • K. Krnjević
Conference paper
Part of the Verhandlungen der Gesellschaft Deutscher Naturforscher und Ärzte book series (NATURFORSCHER, volume 106)

Summary

  1. 1.

    Synaptic transmission in the mammalian brain is probably mediated by excitatory or inhibitory substances released from nerve endings.

     
  2. 2.

    Excitatory transmitters may act by increasing the movement of Na+ into cells, or by reducing the membrane permeability to K+.

     
  3. 3.

    Glutamic acid is likely to be one of the main fast-acting excitatory transmitters in the central nervous system.

     
  4. 4.

    Acetylcholine has a slower excitatory action tending to promote repetitive discharges. This action is limited to certain types of cells; it appears to be mediated by a reduction in K+ permeabity.

     
  5. 5.

    The strongest inhibitory effects are probably mediated by γ-aminobutyric acid (GABA) and possibly some related amino-acids. They are caused by a large increase in Cl- permeability.

     
  6. 6.

    Both excitatory and depressant effects have been observed at various sites with monoamines (noradrenaline, dopamine and 5-HT).

     

Zusammenfassung

  1. 1.

    Die synaptische Erregungsleitung im Gehirn des Säugetieres wird wahrscheinlich durch exzita-torische und inhibitorische Substanzen vermittelt, die von den Nervenendigungen freigesetzt werden.

     
  2. 2.

    Exzitatorische Überträgersubstanzen können ihre Wirkung dadurch ausüben, daß sie die Bewegung von Natriumionen in die Zelle steigern, oder daß sie die Membranpermeabilität gegenüber Kaliumionen herabsetzen.

     
  3. 3.

    Glutaminsäure ist wahrscheinlich eine der hauptsächlichen raschwirkenden exzitatorischen Überträgersubstanzen des zentralen Nervensystems.

     
  4. 4.

    Acetylcholin hat eine langsamere exzitatorische Wirkung und tendiert dazu, wiederholte Entladungen zu begünstigen. Diese Wirkung ist auf gewisse Zelltypen beschränkt; der Mechanismus scheint in einer Reduzierung der Kaliumpermeabilität zu bestehen.

     
  5. 5.

    Die stärksten inhibitorischen Wirkungen werden wahrscheinlich durch γ-Aminobuttersäure (GABA) und möglicherweise einige verwandte Aminosäuren vermittelt. Sie sind durch eine starke Zunahme der Chlorpermeabilität bedingt.

     
  6. 6.

    Sowohl exzitatorische wie depressorische Wirkungen wurden an verschiedenen Substraten mit Monoaminen (Noradrenalin, Dopamin und 5-Hydroxytryptamin) beobachtet.

     

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Copyright information

© Springer-Verlag Berlin Heidelberg 1970

Authors and Affiliations

  • K. Krnjević
    • 1
  1. 1.Department of Research in AnaesthesiaMcGill UniversityMontreal (109)Canada

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