Aquaporin-4 regulates the velocity and frequency of cortical spreading depression in mice.
Glia
; 63(10): 1860-9, 2015 Oct.
Article
em En
| MEDLINE
| ID: mdl-25944186
ABSTRACT
The astrocyte water channel aquaporin-4 (AQP4) regulates extracellular space (ECS) K(+) concentration ([K(+)]e) and volume dynamics following neuronal activation. Here, we investigated how AQP4-mediated changes in [K(+)]e and ECS volume affect the velocity, frequency, and amplitude of cortical spreading depression (CSD) depolarizations produced by surface KCl application in wild-type (AQP4(+/+)) and AQP4-deficient (AQP4(-/-)) mice. In contrast to initial expectations, both the velocity and the frequency of CSD were significantly reduced in AQP4(-/-) mice when compared with AQP4(+/+) mice, by 22% and 32%, respectively. Measurement of [K(+)]e with K(+)-selective microelectrodes demonstrated an increase to â¼35 mM during spreading depolarizations in both AQP4(+/+) and AQP4(-/-) mice, but the rates of [K(+)]e increase (3.5 vs. 1.5 mM/s) and reuptake (t1/2 33 vs. 61 s) were significantly reduced in AQP4(-/-) mice. ECS volume fraction measured by tetramethylammonium iontophoresis was greatly reduced during depolarizations from 0.18 to 0.053 in AQP4(+/+) mice, and 0.23 to 0.063 in AQP4(-/-) mice. Analysis of the experimental data using a mathematical model of CSD propagation suggested that the reduced velocity of CSD depolarizations in AQP4(-/-) mice was primarily a consequence of the slowed increase in [K(+)]e during neuronal depolarization. These results demonstrate that AQP4 effects on [K(+)]e and ECS volume dynamics accelerate CSD propagation.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Depressão Alastrante da Atividade Elétrica Cortical
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Encéfalo
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Camundongos Transgênicos
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Aquaporina 4
Limite:
Animals
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article