title: Distinct expression/function of potassium and chloride channels contributes to the diverse volume regulation in cortical astrocytes of GFAP/EGFP mice.
abstract: Recently, we have identified two astrocytic subpopulations in the cortex of GFAP-EGFP mice, in which the astrocytes are visualized by the enhanced green-fluorescent protein (EGFP) under the control of the human glial fibrillary acidic protein (GFAP) promotor. These astrocytic subpopulations, termed high response- (HR-) and low response- (LR-) astrocytes, differed in the extent of their swelling during oxygen-glucose deprivation (OGD). In the present study we focused on identifying the ion channels or transporters that might underlie the different capabilities of these two astrocytic subpopulations to regulate their volume during OGD. Using three-dimensional confocal morphometry, which enables quantification of the total astrocytic volume, the effects of selected inhibitors of K⁺ and Cl⁻ channels/transporters or glutamate transporters on astrocyte volume changes were determined during 20 minute-OGD in situ. The inhibition of volume regulated anion channels (VRACs) and two-pore domain potassium channels (K(2P)) highlighted their distinct contributions to volume regulation in HR-/LR-astrocytes. While the inhibition of VRACs or K(2P) channels revealed their contribution to the swelling of HR-astrocytes, in LR-astrocytes they were both involved in anion/K⁺ effluxes. Additionally, the inhibition of Na⁺-K⁺-Cl⁻ co-transporters in HR-astrocytes led to a reduction of cell swelling, but it had no effect on LR-astrocyte volume. Moreover, employing real-time single-cell quantitative polymerase chain reaction (PCR), we characterized the expression profiles of EGFP-positive astrocytes with a focus on those ion channels and transporters participating in astrocyte swelling and volume regulation. The PCR data revealed the existence of two astrocytic subpopulations markedly differing in their gene expression levels for inwardly rectifying K⁺ channels (Kir4.1), K(2P) channels (TREK-1 and TWIK-1) and Cl⁻ channels (ClC2). Thus, we propose that the diverse volume changes displayed by cortical astrocytes during OGD mainly result from their distinct expression patterns of ClC2 and K(2P) channels.
authors.affiliation: Department of Cellular Neurophysiology, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors.forename: Jana
authors.initials: J
authors.lastname: Benesova
authors.forename: Vendula
authors.initials: V
authors.lastname: Rusnakova
authors.forename: Pavel
authors.initials: P
authors.lastname: Honsa
authors.forename: Helena
authors.initials: H
authors.lastname: Pivonkova
authors.forename: David
authors.initials: D
authors.lastname: Dzamba
authors.forename: Mikael
authors.initials: M
authors.lastname: Kubista
authors.forename: Miroslava
authors.initials: M
authors.lastname: Anderova
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D048429:Cell Size / Q000187:drug effects; D002540:Cerebral Cortex / Q000166:cytology*; D018118:Chloride Channels / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism*; D005947:Glucose / Q000172:deficiency; D049452:Green Fluorescent Proteins / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D049990:Membrane Transport Modulators / Q000494:pharmacology; D051379:Mice; D008822:Mice, Transgenic; D008954:Models, Biological; D010100:Oxygen; D015221:Potassium Channels / Q000378:metabolism*; D012727:Sex Characteristics; D028021:Sodium-Potassium-Chloride Symporters / Q000378:metabolism; D027981:Symporters / Q000378:metabolism; D050496:Vesicular Glutamate Transport Proteins / Q000378:metabolism; D000096922:K Cl- Cotransporters
chemical_list: D018118:Chloride Channels; D005904:Glial Fibrillary Acidic Protein; D005947:Glucose; D049452:Green Fluorescent Proteins; D049990:Membrane Transport Modulators; D010100:Oxygen; D015221:Potassium Channels; D028021:Sodium-Potassium-Chloride Symporters; D027981:Symporters; D050496:Vesicular Glutamate Transport Proteins; D000096922:K Cl- Cotransporters; C485184:enhanced green fluorescent protein