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Influence of MK-801 on brain extracellular calcium and potassium activities in severe hypoglycemia

Zhang, E. ; Hansen, A. J. ; Wieloch, T. LU and Lauritzen, M. (1990) In Journal of Cerebral Blood Flow and Metabolism 10(1). p.136-139
Abstract

The purpose of the present study was to examine the effect of blockade of N-methyl-D-aspartate (NMDA) receptors on the depolarization associated with severe hypoglycemia, which is commonly preceded by one or a few transient depolarizations reminiscent of cortical spreading depression (CSD). In the cerebral cortices of rats [K+](e) and [Ca2+](e) were measured with ion-selective microelectrodes. NMDA blockade was achieved by injection of MK801 in doses that block CSD. In control rats, the latency from the time point when blood glucose reached minimal levels to onset of ionic shifts was 33.2 ± 3.5 min, and [K+](e) rose from 3.2 ± 0.2 to 55 ± 5 mM. All variables remained unchanged in rats treated with MK801.... (More)

The purpose of the present study was to examine the effect of blockade of N-methyl-D-aspartate (NMDA) receptors on the depolarization associated with severe hypoglycemia, which is commonly preceded by one or a few transient depolarizations reminiscent of cortical spreading depression (CSD). In the cerebral cortices of rats [K+](e) and [Ca2+](e) were measured with ion-selective microelectrodes. NMDA blockade was achieved by injection of MK801 in doses that block CSD. In control rats, the latency from the time point when blood glucose reached minimal levels to onset of ionic shifts was 33.2 ± 3.5 min, and [K+](e) rose from 3.2 ± 0.2 to 55 ± 5 mM. All variables remained unchanged in rats treated with MK801. In another four rats treated with MK801, [Ca2+](e) declined from 1.06 ± 0.22 to 0.12 ± 0.02 mM. Plasma glucose measurements indicated that the cortex depolarized at a plasma glucose concentration between 0.7 and 0.8 mM, i.e., within a narrow range, suggesting a threshold phenomenon. In conclusion, activation of NMDA receptors seems of minor importance for hypoglycemic depolarization. The ionic transients that precede the persistent hypoglycemic depolarization are probably mediated by mechanisms distinct from those of electrically induced CSD.

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
cortical spreading depression, extracellular ions, glutamate, hypoglycemia
in
Journal of Cerebral Blood Flow and Metabolism
volume
10
issue
1
pages
136 - 139
publisher
Nature Publishing Group
external identifiers
  • pmid:2404997
  • scopus:0025090065
ISSN
0271-678X
DOI
10.1038/jcbfm.1990.18
language
English
LU publication?
yes
id
bc7cf751-a09f-4571-9980-309b81d2cff2
date added to LUP
2019-06-13 16:59:44
date last changed
2024-01-01 10:25:03
@article{bc7cf751-a09f-4571-9980-309b81d2cff2,
  abstract     = {{<p>The purpose of the present study was to examine the effect of blockade of N-methyl-D-aspartate (NMDA) receptors on the depolarization associated with severe hypoglycemia, which is commonly preceded by one or a few transient depolarizations reminiscent of cortical spreading depression (CSD). In the cerebral cortices of rats [K<sup>+</sup>](e) and [Ca<sup>2+</sup>](e) were measured with ion-selective microelectrodes. NMDA blockade was achieved by injection of MK801 in doses that block CSD. In control rats, the latency from the time point when blood glucose reached minimal levels to onset of ionic shifts was 33.2 ± 3.5 min, and [K<sup>+</sup>](e) rose from 3.2 ± 0.2 to 55 ± 5 mM. All variables remained unchanged in rats treated with MK801. In another four rats treated with MK801, [Ca<sup>2+</sup>](e) declined from 1.06 ± 0.22 to 0.12 ± 0.02 mM. Plasma glucose measurements indicated that the cortex depolarized at a plasma glucose concentration between 0.7 and 0.8 mM, i.e., within a narrow range, suggesting a threshold phenomenon. In conclusion, activation of NMDA receptors seems of minor importance for hypoglycemic depolarization. The ionic transients that precede the persistent hypoglycemic depolarization are probably mediated by mechanisms distinct from those of electrically induced CSD.</p>}},
  author       = {{Zhang, E. and Hansen, A. J. and Wieloch, T. and Lauritzen, M.}},
  issn         = {{0271-678X}},
  keywords     = {{cortical spreading depression; extracellular ions; glutamate; hypoglycemia}},
  language     = {{eng}},
  month        = {{01}},
  number       = {{1}},
  pages        = {{136--139}},
  publisher    = {{Nature Publishing Group}},
  series       = {{Journal of Cerebral Blood Flow and Metabolism}},
  title        = {{Influence of MK-801 on brain extracellular calcium and potassium activities in severe hypoglycemia}},
  url          = {{http://dx.doi.org/10.1038/jcbfm.1990.18}},
  doi          = {{10.1038/jcbfm.1990.18}},
  volume       = {{10}},
  year         = {{1990}},
}