| 1. |
- Lauritzen, M., et al.
(author)
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Cortical spreading depression is associated with arachidonic acid accumulation and preservation of energy charge
- 1990
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In: Journal of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 0271-678X .- 1559-7016. ; 10:1, s. 115-122
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Journal article (peer-reviewed)abstract
- The present study aimed to study the relation between the release of arachidonic acid (AA) and the energy state in cerebral cortices of rats during single episodes of cortical spreading depression (CSD). The changes in concentrations of AA, labile phosphate compounds [ATP, ADP, AMP, and phosphocreatine (PCr)], and glycolytic metabolites (lactate, pyruvate, glucose, and glycogen) were studied during and following the large change of the local direct current (DC) potential. Free AA increased markedly during the DC shift, continued to increase during the subsequent 3 min, and returned to control levels at 4-5 min after CSD. PCr decreased by 38% in the first minutes following the DC shift, while ADP increased by 38%. Both returned to normal within a few minutes. ATP, AMP, and energy charge remained constant throughout the experimental period. Glucose decreased by 47% and glycogen by 34% for a few minutes following CSD, while lactate increased by 105% at 2-3 min and by 77% at 4-5 min after CSD. The metabolites returned to control levels at 10 min after CSD. Considering the constant energy charge at all time points during CSD, it is suggested that the AA rise reflects augmented phospholipase activity due to either increased intracellular [Ca2+] or receptor stimulation or both. The possibility that N-methyl-D-aspartate receptors play a role in the release of AA, and that free AA in turn could be part of the mechanism of CSD, is discussed.
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| 2. |
- Zhang, E., et al.
(author)
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Influence of MK-801 on brain extracellular calcium and potassium activities in severe hypoglycemia
- 1990
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In: Journal of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 0271-678X .- 1559-7016. ; 10:1, s. 136-139
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Journal article (peer-reviewed)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. 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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