The chloride transporter Na(+)-K(+)-Cl- cotransporter isoform-1 contributes to intracellular chloride increases after in vitro ischemia.

Published

Journal Article

Ischemic episodes in the CNS cause significant disturbances in neuronal ionic homeostasis. To directly measure changes in intracellular Cl- concentration ([Cl-]i) during and after ischemia, we used Clomeleon, a novel ratiometric optical indicator for Cl-. Hippocampal slices from adult transgenic mice expressing Clomeleon in hippocampal neurons were subjected to 8 min of oxygen-glucose deprivation (OGD) (an in vitro model for ischemia) and reoxygenated in the presence of glucose. This produced mild neuronal damage 3 h later that was prevented when the extracellular [Cl-] was maintained at 10 mm during reoxygenation. OGD induced a transient decrease in fluorescence resonance energy transfer within Clomeleon, indicating an increase in [Cl-]i. During reoxygenation, there was a partial recovery in [Cl-]i, but [Cl-]i rose again 45 min later. To investigate sources of Cl- accumulation, we examined the effects of Cl- transport inhibitors on the rises in [Cl-]i during and after OGD. Bumetanide and furosemide, which inhibit Cl- influx through the Na(+)-K(+)-Cl- cotransporter isoform-1 (NKCC-1) and efflux through the K(+)-Cl- cotransporter isoform-2, were unable to inhibit the first rise in [Cl-]i, yet entirely prevented the secondary rise in [Cl-]i during reoxygenation. In contrast, picrotoxin, which blocks the GABA-gated Cl- channel, did not inhibit the secondary rise in [Cl-]i after OGD. [Cl-]i increases during reoxygenation were accompanied by an increase in phosphorylation of NKCC-1, an indication of increased NKCC-1 activity after OGD. We conclude that NKCC-1 plays an important role in OGD-induced Cl- accumulation and subsequent neuronal damage.

Full Text

Duke Authors

Cited Authors

  • Pond, BB; Berglund, K; Kuner, T; Feng, G; Augustine, GJ; Schwartz-Bloom, RD

Published Date

  • February 1, 2006

Published In

Volume / Issue

  • 26 / 5

Start / End Page

  • 1396 - 1406

PubMed ID

  • 16452663

Pubmed Central ID

  • 16452663

Electronic International Standard Serial Number (EISSN)

  • 1529-2401

Digital Object Identifier (DOI)

  • 10.1523/JNEUROSCI.1421-05.2006

Language

  • eng

Conference Location

  • United States