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PMID:18076085

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Citation

Howe, MW, Feig, SL, Osting, SM and Haberly, LB (2008) Cellular and subcellular localization of Kir2.1 subunits in neurons and glia in piriform cortex with implications for K+ spatial buffering. J. Comp. Neurol. 506:877-93

Abstract

Potassium channels of the Kir2 family are widely expressed in neurons and glia, where they form strong inwardly rectifying channels. Existing functional hypotheses for these channels in neurons are based on the weak outward conductance, whereas the leading hypothesis for glia, that they promote potassium spatial buffering, is based on inward conductance. Although the spatial buffering hypothesis has been confirmed for Müller glia in retina, many aspects of Kir2 channels that will be required for understanding their functional roles in neurons and other forms of glia have received little or no study. Particularly striking is the paucity of data regarding their cellular and subcellular localization. We address this gap for Kir2.1-containing channels by using light and electron microscopic immunocytochemistry. The analysis was of piriform cortex, a highly epileptogenic area of cerebral cortex, where pyramidal cells have K(+)-selective strong inward rectification like that observed in Müller cells, where Kir2.1 is the dominant Kir2 subunit. Pyramidal cells in adult piriform cortex also lack I(h), the mixed Na(+)-K(+) current that mediates a slower form of strong inward rectification in large pyramidal cells in neocortex and hippocampus. The experiments demonstrated surface expression of Kir2.1-containing channels in astrocytes and in multiple populations of pyramidal and nonpyramidal cells. Findings for astrocytes were not consistent with predictions for K(+) spatial buffering over substantial distance. However, findings for pyramidal cells suggest that they could be a conduit for spatially buffering K(+) when it is highly elevated during seizure.

Links

PubMed Online version:10.1002/cne.21534

Keywords

Animals; Astrocytes/metabolism; Astrocytes/ultrastructure; Buffers; Immunohistochemistry; Male; Membrane Potentials/physiology; Neural Conduction/physiology; Parahippocampal Gyrus/cytology; Parahippocampal Gyrus/metabolism; Parahippocampal Gyrus/ultrastructure; Potassium/metabolism; Potassium Channels, Inwardly Rectifying/metabolism; Potassium Channels, Inwardly Rectifying/ultrastructure; Pyramidal Cells/cytology; Pyramidal Cells/metabolism; Pyramidal Cells/ultrastructure; Rats; Rats, Sprague-Dawley; Tissue Distribution

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

RAT:KCNJ2

located_in

GO:0043197: dendritic spine

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

RAT:KCNJ2

located_in

GO:0005790: smooth endoplasmic reticulum

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

RAT:KCNJ2

located_in

GO:0005886: plasma membrane

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

RAT:KCNJ2

located_in

GO:0005791: rough endoplasmic reticulum

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

RAT:KCNJ2

located_in

GO:0005794: Golgi apparatus

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

RAT:IRK2

part_of

GO:0043197: dendritic spine

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

RAT:IRK2

part_of

GO:0005886: plasma membrane

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

RAT:IRK2

part_of

GO:0005794: Golgi apparatus

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

RAT:IRK2

part_of

GO:0005791: rough endoplasmic reticulum

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

RAT:IRK2

part_of

GO:0005790: smooth endoplasmic reticulum

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

Notes

See also

References

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