title: Na(+)-K (+)-2Cl (-) cotransport inhibitor attenuates cerebral edema following experimental stroke via the perivascular pool of aquaporin-4.
abstract: BACKGROUND
  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.
authors.affiliation: Department of Neurology, Oregon Health & Science University, Portland, OR, USA.
authors.forename: Elton R
authors.initials: ER
authors.lastname: Migliati
authors.forename: Mahmood
authors.initials: M
authors.lastname: Amiry-Moghaddam
authors.forename: Stanley C
authors.initials: SC
authors.lastname: Froehner
authors.forename: Marvin E
authors.initials: ME
authors.lastname: Adams
authors.forename: Ole Petter
authors.initials: OP
authors.lastname: Ottersen
authors.forename: Anish
authors.initials: A
authors.lastname: Bhardwaj
mesh_terms: D000818:Animals; D051401:Aquaporin 4 / Q000037:antagonists & inhibitors*; D001929:Brain Edema / Q000209:etiology* / Q000503:physiopathology*; D002034:Bumetanide / Q000494:pharmacology*; D002544:Cerebral Infarction / Q000150:complications / Q000209:etiology / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018696:Neuroprotective Agents / Q000494:pharmacology*; D049994:Sodium Potassium Chloride Symporter Inhibitors / Q000494:pharmacology*; D020521:Stroke / Q000150:complications* / Q000209:etiology; D051844:alpha-Synuclein / Q000172:deficiency
chemical_list: D051401:Aquaporin 4; D018696:Neuroprotective Agents; D049994:Sodium Potassium Chloride Symporter Inhibitors; D051844:alpha-Synuclein; D002034:Bumetanide
references.citation: J Neurosurg. 1993 Feb;78(2):257-66
references.pmid: 8421208
references.citation: Proc Natl Acad Sci U S A. 2001 Nov 20;98(24):14108-13
references.pmid: 11717465
references.citation: J Cereb Blood Flow Metab. 1991 May;11(3):466-71
references.pmid: 1849910
references.citation: J Cell Sci. 1995 Sep;108 ( Pt 9):2993-3002
references.pmid: 8537439
references.citation: J Cereb Blood Flow Metab. 2006 Oct;26(10):1234-49
references.pmid: 16421506
references.citation: Mol Pharmacol. 2009 Jul;76(1):105-12
references.pmid: 19403703
references.citation: Nat Med. 2000 Feb;6(2):159-63
references.pmid: 10655103
references.citation: J Cereb Blood Flow Metab. 2006 Jul;26(7):951-8
references.pmid: 16306935
references.citation: Annu Rev Physiol. 1996;58:619-48
references.pmid: 8815812
references.citation: Am J Physiol. 1983 Sep;245(3):C235-40
references.pmid: 6614157
references.citation: Brain Res Brain Res Protoc. 1998 Jun;2(4):243-9
references.pmid: 9630654
references.citation: J Neurosurg. 1995 Dec;83(6):1051-9
references.pmid: 7490620
references.citation: J Neuropathol Exp Neurol. 1967 Jan;26(1):1-14
references.pmid: 5336776
references.citation: J Clin Pharmacol. 1981 Nov-Dec;21(11):543-54
references.pmid: 7338564
references.citation: Proc Natl Acad Sci U S A. 2002 Oct 1;99(20):13131-6
references.pmid: 12232046
references.citation: J Cell Biol. 2000 Sep 18;150(6):1385-98
references.pmid: 10995443
references.citation: Am J Physiol. 1994 Jan;266(1 Pt 1):C284-92
references.pmid: 8304423
references.citation: Stroke. 1994 Jan;25(1):165-70
references.pmid: 8266365
references.citation: J Neurosci. 1999 Sep 15;19(18):7823-33
references.pmid: 10479685
references.citation: J Physiol. 2005 Oct 1;568(Pt 1):123-35
references.pmid: 16020454
references.citation: Stroke. 1993 Jan;24(1):117-21
references.pmid: 8418534
references.citation: Crit Care Med. 2008 Sep;36(9):2634-40
references.pmid: 18679106
references.citation: Am J Physiol Cell Physiol. 2005 Aug;289(2):C283-92
references.pmid: 15800057
references.citation: J Cereb Blood Flow Metab. 2002 Apr;22(4):367-78
references.pmid: 11919508
references.citation: Intensive Care Med. 1998 Jun;24(6):620-3
references.pmid: 9681786
references.citation: Proc Natl Acad Sci U S A. 2006 Sep 5;103(36):13532-6
references.pmid: 16938871
references.citation: J Clin Neurosci. 2002 Mar;9(2):113-24
references.pmid: 11922696
references.citation: Brain Res. 2006 Nov 29;1122(1):222-9
references.pmid: 17014830
references.citation: Diabetes. 2008 Oct;57(10):2588-94
references.pmid: 18633109
references.citation: J Cereb Blood Flow Metab. 2000 Jan;20(1):112-8
references.pmid: 10616799
references.citation: Proc Natl Acad Sci U S A. 2003 Feb 18;100(4):2106-11
references.pmid: 12578959
references.citation: FASEB J. 2004 Mar;18(3):542-4
references.pmid: 14734638
references.citation: J Cereb Blood Flow Metab. 1996 Jul;16(4):605-11
references.pmid: 8964799
references.citation: J Cereb Blood Flow Metab. 2004 Sep;24(9):1046-56
references.pmid: 15356425
references.citation: Am J Physiol Cell Physiol. 2005 Dec;289(6):C1492-501
references.pmid: 16079189
references.citation: Curr Neurol Neurosci Rep. 2007 Nov;7(6):513-21
references.pmid: 17999898
references.citation: Am J Physiol. 1994 Oct;267(4 Pt 1):C869-85
references.pmid: 7943281
references.citation: Crit Care Med. 2007 Feb;35(2):526-31
references.pmid: 17205030
references.citation: Brain Res. 2003 Jan 24;961(1):22-31
references.pmid: 12535773
references.citation: Neuroscience. 2004;129(4):1031-44
references.pmid: 15561418
references.citation: J Neurosci. 1997 Jan 1;17(1):171-80
references.pmid: 8987746
references.citation: J Cereb Blood Flow Metab. 2001 Jun;21(6):711-21
references.pmid: 11488540
references.citation: FASEB J. 2004 Aug;18(11):1291-3
references.pmid: 15208268
references.citation: J Cereb Blood Flow Metab. 2008 Dec;28(12):1898-906
references.pmid: 18648381
references.citation: Am J Physiol. 1997 Jan;272(1 Pt 1):C173-83
references.pmid: 9038823