Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
TWIK-1 and TREK-1 are potassium channels contributing significantly to astrocyte passive conductance in rat hippocampal slices.
Zhou M, Xu G, Xie M, Zhang X, Schools GP, Ma L, Kimelberg HK, Chen H.
???displayArticle.abstract???
Expression of a linear current-voltage (I-V) relationship (passive) K(+) membrane conductance is a hallmark of mature hippocampal astrocytes. However, the molecular identifications of the K(+) channels underlying this passive conductance remain unknown. We provide the following evidence supporting significant contribution of the two-pore domain K(+) channel (K(2P)) isoforms, TWIK-1 and TREK-1, to this conductance. First, both passive astrocytes and the cloned rat TWIK-1 and TREK-1 channels expressed in CHO cells conduct significant amounts of Cs(+) currents, but vary in their relative P(Cs)/P(K) permeability, 0.43, 0.10, and 0.05, respectively. Second, quinine, which potently inhibited TWIK-1 (IC(50) = 85 microm) and TREK-1 (IC(50) = 41 microm) currents, also inhibited astrocytic passive conductance by 58% at a concentration of 200 microm. Third, a moderate sensitivity of passive conductance to low extracellular pH (6.0) supports a combined expression of acid-insensitive TREK-1, and to a lesser extent, acid-sensitive TWIK-1. Fourth, the astrocyte passive conductance showed low sensitivity to extracellular Ba(2+), and extracellular Ba(2+) blocked TWIK-1 channels at an IC(50) of 960 microm and had no effect on TREK-1 channels. Finally, an immunocytochemical study showed colocalization of TWIK-1 and TREK-1 proteins with the astrocytic markers GLAST and GFAP in rat hippocampal stratum radiatum. In contrast, another K(2P) isoform TASK-1 was mainly colocalized with the neuronal marker NeuN in hippocampal pyramidal neurons and was expressed at a much lower level in astrocytes. These results support TWIK-1 and TREK-1 as being the major components of the long-sought K(+) channels underlying the passive conductance of mature hippocampal astrocytes.
Amzica,
Glial and neuronal interactions during slow wave and paroxysmal activities in the neocortex.
2002, Pubmed
Amzica,
Glial and neuronal interactions during slow wave and paroxysmal activities in the neocortex.
2002,
Pubmed Bergles,
Synaptic activation of glutamate transporters in hippocampal astrocytes.
1997,
Pubmed Butt,
Inwardly rectifying potassium channels (Kir) in central nervous system glia: a special role for Kir4.1 in glial functions.
2006,
Pubmed Cahoy,
A transcriptome database for astrocytes, neurons, and oligodendrocytes: a new resource for understanding brain development and function.
2008,
Pubmed D'Ambrosio,
Functional specialization and topographic segregation of hippocampal astrocytes.
1998,
Pubmed Djukic,
Conditional knock-out of Kir4.1 leads to glial membrane depolarization, inhibition of potassium and glutamate uptake, and enhanced short-term synaptic potentiation.
2007,
Pubmed Feliciangeli,
Does sumoylation control K2P1/TWIK1 background K+ channels?
2007,
Pubmed
,
Xenbase Fink,
Cloning, functional expression and brain localization of a novel unconventional outward rectifier K+ channel.
1996,
Pubmed
,
Xenbase Goldstein,
Sequence and function of the two P domain potassium channels: implications of an emerging superfamily.
1998,
Pubmed Goldstein,
Potassium leak channels and the KCNK family of two-P-domain subunits.
2001,
Pubmed Haydon,
Astrocyte control of synaptic transmission and neurovascular coupling.
2006,
Pubmed Jabs,
Qualitative analysis of membrane currents in glial cells from normal and gliotic tissue in situ: down-regulation of Na+ current and lack of P2 purinergic responses.
1997,
Pubmed Kang,
Astrocyte-mediated potentiation of inhibitory synaptic transmission.
1998,
Pubmed Kim,
Physiology and pharmacology of two-pore domain potassium channels.
2005,
Pubmed Kimelberg,
Supportive or information-processing functions of the mature protoplasmic astrocyte in the mammalian CNS? A critical appraisal.
2007,
Pubmed Kindler,
Localization of the tandem pore domain K+ channel TASK-1 in the rat central nervous system.
2000,
Pubmed Kindler,
Local anesthetic inhibition of baseline potassium channels with two pore domains in tandem.
1999,
Pubmed
,
Xenbase Lesage,
The structure, function and distribution of the mouse TWIK-1 K+ channel.
1997,
Pubmed
,
Xenbase Lesage,
Molecular and functional properties of two-pore-domain potassium channels.
2000,
Pubmed Lesage,
TWIK-1, a ubiquitous human weakly inward rectifying K+ channel with a novel structure.
1996,
Pubmed
,
Xenbase Lopes,
Proton block and voltage gating are potassium-dependent in the cardiac leak channel Kcnk3.
2000,
Pubmed
,
Xenbase Lotshaw,
Biophysical, pharmacological, and functional characteristics of cloned and native mammalian two-pore domain K+ channels.
2007,
Pubmed Meadows,
Cloning, localisation and functional expression of the human orthologue of the TREK-1 potassium channel.
2000,
Pubmed
,
Xenbase Niemeyer,
Modulation of the two-pore domain acid-sensitive K+ channel TASK-2 (KCNK5) by changes in cell volume.
2001,
Pubmed Orkand,
Effect of nerve impulses on the membrane potential of glial cells in the central nervous system of amphibia.
1966,
Pubmed Patel,
Properties and modulation of mammalian 2P domain K+ channels.
2001,
Pubmed Patel,
Inhalational anesthetics activate two-pore-domain background K+ channels.
1999,
Pubmed Patel,
A mammalian two pore domain mechano-gated S-like K+ channel.
1998,
Pubmed Pountney,
Identification and cloning of TWIK-originated similarity sequence (TOSS): a novel human 2-pore K+ channel principal subunit.
1999,
Pubmed
,
Xenbase Rajan,
Sumoylation silences the plasma membrane leak K+ channel K2P1.
2005,
Pubmed
,
Xenbase Ransom,
Biophysical and pharmacological characterization of inwardly rectifying K+ currents in rat spinal cord astrocytes.
1995,
Pubmed Rusznák,
Differential distribution of TASK-1, TASK-2 and TASK-3 immunoreactivities in the rat and human cerebellum.
2004,
Pubmed Schools,
Electrophysiologically "complex" glial cells freshly isolated from the hippocampus are immunopositive for the chondroitin sulfate proteoglycan NG2.
2003,
Pubmed Schools,
Development of gap junctions in hippocampal astrocytes: evidence that whole cell electrophysiological phenotype is an intrinsic property of the individual cell.
2006,
Pubmed Steinhäuser,
Heterogeneity in the Membrane Current Pattern of Identified Glial Cells in the Hippocampal Slice.
1992,
Pubmed Talley,
Two-pore-Domain (KCNK) potassium channels: dynamic roles in neuronal function.
2003,
Pubmed Taverna,
Differential expression of TASK channels between horizontal interneurons and pyramidal cells of rat hippocampus.
2005,
Pubmed Torborg,
TASK-like conductances are present within hippocampal CA1 stratum oriens interneuron subpopulations.
2006,
Pubmed Verkhratsky,
Ion channels in glial cells.
2000,
Pubmed Wallraff,
The impact of astrocytic gap junctional coupling on potassium buffering in the hippocampus.
2006,
Pubmed Xie,
Sodium channel currents in rat hippocampal NG2 glia: characterization and contribution to resting membrane potential.
2007,
Pubmed Xie,
Oxygen and glucose deprivation-induced changes in astrocyte membrane potential and their underlying mechanisms in acute rat hippocampal slices.
2008,
Pubmed Zhou,
Development of GLAST(+) astrocytes and NG2(+) glia in rat hippocampus CA1: mature astrocytes are electrophysiologically passive.
2006,
Pubmed Zhou,
Freshly isolated astrocytes from rat hippocampus show two distinct current patterns and different [K(+)](o) uptake capabilities.
2000,
Pubmed
