Linked Life Data

17091490

Source:http://linkedlifedata.com/resource/pubmed/id/17091490

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2006-12-14
pubmed:abstractText
Glial cell-mediated potassium and glutamate homeostases play important roles in the regulation of neuronal excitability. Diminished potassium and glutamate buffering capabilities of astrocytes result in hyperexcitability of neurons and abnormal synaptic transmission. The role of the different K+ channels in maintaining the membrane potential and buffering capabilities of cortical astrocytes has not yet been definitively determined due to the lack of specific K+ channel blockers. The purpose of the present study was to assess the role of the inward-rectifying K+ channel subunit Kir4.1 on potassium fluxes, glutamate uptake and membrane potential in cultured rat cortical astrocytes using RNAi, whole-cell patch clamp and a colorimetric assay. The membrane potentials of control cortical astrocytes had a bimodal distribution with peaks at -68 and -41 mV. This distribution became unimodal after knockdown of Kir4.1, with the mean membrane potential being shifted in the depolarizing direction (peak at -45 mV). The ability of Kir4.1-suppressed cells to mediate transmembrane potassium flow, as measured by the current response to voltage ramps or sequential application of different extracellular [K+], was dramatically impaired. In addition, glutamate uptake was inhibited by knock-down of Kir4.1-containing channels by RNA interference as well as by blockade of Kir channels with barium (100 microM). Together, these data indicate that Kir4.1 channels are primarily responsible for significant hyperpolarization of cortical astrocytes and are likely to play a major role in potassium buffering. Significant inhibition of glutamate clearance in astrocytes with knock-down of Kir4.1 highlights the role of membrane hyperpolarization in this process.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0894-1491
pubmed:author
pubmed:copyrightInfo
Copyright 2006 Wiley-Liss, Inc.
pubmed:issnType
Print
pubmed:volume
55
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
274-81
pubmed:dateRevised
2007-12-3
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Downregulation of Kir4.1 inward rectifying potassium channel subunits by RNAi impairs potassium transfer and glutamate uptake by cultured cortical astrocytes.
pubmed:affiliation
Department of Biochemistry, Universidad Central del Caribe, Bayamón, Puerto Rico.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural