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2015 ; 7
(5
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Astrocyte regulation of blood flow in the brain
#MMPMID25818565
MacVicar BA
; Newman EA
Cold Spring Harb Perspect Biol
2015[Mar]; 7
(5
): ä PMID25818565
show ga
Neuronal activity results in increased blood flow in the brain, a response named
functional hyperemia. Astrocytes play an important role in mediating this
response. Neurotransmitters released from active neurons evoke Ca(2+) increases
in astrocytes, leading to the release of vasoactive metabolites of arachidonic
acid from astrocyte endfeet onto blood vessels. Synthesis of prostaglandin E2
(PGE2) and epoxyeicosatrienoic acids (EETs) dilate blood vessels, whereas
20-hydroxyeicosatetraenoic acid (20-HETE) constricts vessels. The release of K(+)
from astrocyte endfeet may also contribute to vasodilation. Oxygen modulates
astrocyte regulation of blood flow. Under normoxic conditions, astrocytic Ca(2+)
signaling results in vasodilation, whereas under hyperoxic conditions,
vasoconstriction is favored. Astrocytes also contribute to the generation of
vascular tone. Tonic release of both 20-HETE and ATP from astrocytes constricts
vascular smooth muscle cells, generating vessel tone. Under pathological
conditions, including Alzheimer's disease and diabetic retinopathy, disruption of
normal astrocyte physiology can compromise the regulation of blood flow.
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