Na(+)-K (+)-2Cl (-) cotransport inhibitor attenuates cerebral edema following experimental stroke via the perivascular pool of aquaporin-4

Neurocrit Care. 2010 Aug;13(1):123-31. doi: 10.1007/s12028-010-9376-8.

Abstract

Introduction: The Na(+)-K(+)-2Cl(-) cotransporter localized in the brain vascular endothelium has been shown to be important in the evolution of cerebral edema following experimental stroke. Previous in vivo studies have demonstrated that bumetanide, a selective Na(+)-K(+)-2Cl(-) cotransport inhibitor, attenuates ischemia-evoked cerebral edema. Recently, bumetanide has been shown to also inhibit water permeability via aquaporin-4 (AQP4) expressed in Xenopus laevis oocytes. We tested the hypothesis that the perivascular pool of AQP4 plays a significant role in the anti-edema effect of bumetanide by utilizing wild-type (WT) mice as well as mice with targeted disruption of alpha-syntrophin (alpha-Syn(-/-)) that lack the perivascular pool of AQP4.

Methods: Isoflurane-anesthetized adult male WT C57Bl6 and alpha-Syn(-/-) mice were subjected to 90 min middle cerebral artery occlusion (MCAO) followed by 24 or 48 h of reperfusion. Adequacy of MCAO and reperfusion was monitored with laser-Doppler flowmetry over the ipsilateral parietal cortex. Infarct volume (tetrazolium staining), cerebral edema (wet-to-dry ratios), and AQP4 protein expression (immunoblotting) were determined in different treatment groups in separate sets of experiments.

Results: Bumetanide significantly attenuated infarct volume and decreased ipsilateral hemispheric water content in WT mice compared to vehicle treatment. In alpha-Syn(-/-) mice, bumetanide treatment had no effect on infarct volume or ischemia-evoked cerebral edema. Bumetanide-treated WT mice had a significant attenuation of AQP4 protein expression at 48 h post-MCAO compared to vehicle-treated WT mice.

Conclusions: These data suggest that bumetanide exerts its neuroprotective and anti-edema effects partly via blockade of the perivascular pool of AQP4 and may have therapeutic potential for ischemic stroke in the clinical setting.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Aquaporin 4 / antagonists & inhibitors*
  • Brain Edema / etiology*
  • Brain Edema / physiopathology*
  • Bumetanide / pharmacology*
  • Cerebral Infarction / complications
  • Cerebral Infarction / etiology
  • Cerebral Infarction / pathology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Neuroprotective Agents / pharmacology*
  • Sodium Potassium Chloride Symporter Inhibitors / pharmacology*
  • Stroke / complications*
  • Stroke / etiology
  • alpha-Synuclein / deficiency

Substances

  • Aquaporin 4
  • Neuroprotective Agents
  • Sodium Potassium Chloride Symporter Inhibitors
  • alpha-Synuclein
  • Bumetanide