COMPARTMENTATION OF GLUTAMIC ACID METABOLISM IN BRAIN SLICES*

Authors

  • S. Berl,

    1. Department of Neurology, College of Physicians and Surgeons, Columbia University, Department of Chemistry, Fordham University, New York
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    • Supported by Public Health Service Research Career Program Award 5-K3-NB-5117-05, National Institute for Neurological Diseases and Blindness.

  • W. J. Nicklasi,

    1. Department of Neurology, College of Physicians and Surgeons, Columbia University, Department of Chemistry, Fordham University, New York
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    • NASA Predoctoral Trainee grant No. Ns-G[T]-121.

  • D. D. Clarke

    1. Department of Neurology, College of Physicians and Surgeons, Columbia University, Department of Chemistry, Fordham University, New York
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  • *

    This work was supported in part by Public Health Service Grants No. NB-04064-05 from the National Institute for Neurological Diseases and Blindness and GM-12882 from the National Institute for General Medical Sciences, National Institute of Health and by a grant from the United Cerebral Palsy Research and Educational Foundation.

  • Acknowledgement—We would like to thank Miss Iren Tar for her excellent technical assistance.

Abstract

(1) Compartmentation of glutamate metabolism in brain cortex previously observed only in vivo, has now been demonstrated in vitro.This was shown by using [U-14C]aspartate and [U-14C]glutamate as tracer substrates.

(2) Preparation and maintenance of the slices at 0° resulted in reversible inhibition of glutamine synthesis. Preincubation at 37° for 10 min or preparation of the slices at room temperature partially overcame this inhibition.

(3) Transfer to fresh medium after preincubation had an added stimulatory effect on glutamine synthesis.

(4) Incubation in high K+ medium (27 mm) altered the relative specific activity of glutamine.

(5) The data are in keeping with the postulate of the existence of at least two different pools of citric acid cycle intermediates in the cerebral cortex.

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