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Cerebral ishemia-hypoxia: biophysics of neurodegeneration and neuroprotection
I. S. Magura
A. A. Bogomoletz Institute of Physiology, National Academy ofSciences of Ukraine, Kiev
Abstract
Neuronal responses to hypoxia-ischemia can be acute or chronic. In the early stages neuronal responses to ischemia-hypoxia
are dependent on the modulation of ion channels. Acute
responses relay mainly on O 2-regulated ion channels which
mediate adaptive changes in neuron excitability. Energy failure, an early consequence of hypoxia-ischemia, causes disruption of ionic homeostasis and accumulation of extracellular
neurotransmitters. NMDA and AMPA/kainate receptors
and Ca 2+ channels contribute to excitotoxic neuronal degeneration.
Excitotoxicity leads to increased Ca 2+ influx, which
can activate cytotoxic intracellular pathways. Reactive oxygen species
(oxygen free radicals) generated during ischemiareperfusion
contribute to the injury. Oxygen free-radicals serve
as important signalling molecules that trigger inflamation and
apoptosis. Excitatory amino acid-receptor antagonists and
Ca2+ channels blockers can provide neuroprotection in experimental
models of hypoxia-ischemia but disrupt normal brain
function. Because of their relative lack of behavioral side
effects, voltage-dependent Na+ channels blockers may have
advantage over other neuroprotective mechanisms. The blockade
of voltage-gated Na+ channels reduces the excitability
of neurons, Na+ influx and the accumulation of intracellular
Na+. These improve the ionic homeostasis and cellular energy
levels and prevent ishemia-hypoxia induced neuron
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© National Academy of Sciences of Ukraine, Bogomoletz Institute of Physiology, 2014-2024.
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