title: Deletion of aquaporin-4 increases extracellular K(+) concentration during synaptic stimulation in mouse hippocampus.
abstract: The coupling between the water channel aquaporin-4 (AQP4) and K(+) transport has attracted much interest. In this study, we assessed the effect of Aqp4 deletion on activity-induced [K(+)]o changes in acute slices from hippocampus and corpus callosum of adult mice. We show that Aqp4 deletion has a layer-specific effect on [K(+)]o that precisely mirrors the known effect on extracellular volume dynamics. In CA1, the peak [K(+)]o in stratum radiatum during 20 Hz stimulation of Schaffer collateral/commissural fibers was significantly higher in Aqp4 (-/-) mice than in wild types, whereas no differences were observed throughout the [K(+)]o recovery phase. In stratum pyramidale and corpus callosum, neither peak [K(+)]o nor post-stimulus [K(+)]o recovery was affected by Aqp4 deletion. Our data suggest that AQP4 modulates [K(+)]o during synaptic stimulation through its effect on extracellular space volume.
authors.affiliation: Letten Centre, Institute of Basic Medical Sciences, University of Oslo, 0317, Oslo, Norway.
authors.forename: Nadia Nabil
authors.initials: NN
authors.lastname: Haj-Yasein
authors.forename: Cecilie Elisabeth
authors.initials: CE
authors.lastname: Bugge
authors.forename: Vidar
authors.initials: V
authors.lastname: Jensen
authors.forename: Ivar
authors.initials: I
authors.lastname: Østby
authors.forename: Ole Petter
authors.initials: OP
authors.lastname: Ottersen
authors.forename: Øivind
authors.initials: Ø
authors.lastname: Hvalby
authors.forename: Erlend Arnulf
authors.initials: EA
authors.lastname: Nagelhus
mesh_terms: D000818:Animals; D051401:Aquaporin 4 / Q000172:deficiency* / Q000235:genetics; D004558:Electric Stimulation; D005110:Extracellular Space / Q000378:metabolism*; D006624:Hippocampus / Q000378:metabolism*; D066298:In Vitro Techniques; D017736:Ion-Selective Electrodes; D051379:Mice; D008822:Mice, Transgenic; D011188:Potassium / Q000378:metabolism*; D013569:Synapses / Q000502:physiology*
chemical_list: C496031:Aqp4 protein, mouse; D051401:Aquaporin 4; D011188:Potassium
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