K+ inward rectifier currents in reactive astrocytes from adult rat brain

Perillan, P. R.; Li, Xing; Simard, J. Marc

doi:10.1002/(sici)1098-1136(199909)27:3<213::aid-glia3>3.0.co;2-1

Cited by 16 publications

(20 citation statements)

References 61 publications

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“…Phase contrast microscopy of primary cultures derived from gelatin sponge implants in adult rat brains showed that Ͼ90% of cells exhibited a polygonal morphology, appearing as broad flat cells or as cells with a few thick processes (Perillá n et al, 1999). Cells with a stellate morphology, defined as cells with spheroidal perikarya and multiple thin processes, tended to occur in sparse clusters in some cultures of adult reactive astrocytes.…”

Section: Resultsmentioning

confidence: 99%

“…They almost invariably exhibit weak rectification, i.e., they show substantial outward current immediately positive to the reversal potential, as may be found with Kir4.1 channels. We recently characterized inward rectifier currents in polygonal reactive astrocytes from adult rat brain, however, and found that in these cells, inward rectifier currents exhibited the striking feature of strong rectification (Perillá n et al, 1999), a property not typical of Kir4.1, and not previously reported in mammalian astrocytes.…”

Section: Introductionmentioning

confidence: 84%

“…Primary cultures of adult reactive astrocytes were derived from gelatin sponge pellets that had been implanted into a stab wound in the parietal lobe of adult Wistar rats as previously described (Perillá n et al, 1999). Gelatin sponge pellets were harvested at 8 days and washed 3 times in phosphate-buffered saline (PBS) to remove adherent tissue.…”

Section: Materials and Methods Cell Culturementioning

confidence: 99%

“…For these experiments, the bath solution contained 3 mM K ϩ to maintain normal resting potential of the cell, and pipettes were filled with a solution containing 145 mM K ϩ , to maximize conductance of the inward rectifier channels (Perillá n et al, 1999) and to allow conversion to a conventional whole-cell configuration for measurement of the cell membrane potential (E m ). Original records of single-channel currents obtained during hyperpolarizing test pulses to Ϫ70 mV, Ϫ110 mV, and Ϫ130 mV (holding potential, E m ϭ 0 mV) are shown in Figure 1A.…”

Section: Single-channel Currentsmentioning

confidence: 99%

“…would be due exclusively to the small conductance channel, since only that channel was apparent in the single-channel experiments, whereas the macroscopic inward rectifier current in the stellate cells would be due to a combination of the small conductance channel and the 24 -27 pS channel. We knew from preliminary experiments that the strong rectifier in polygonal cells was highly sensitive to dialysis during conventional whole-cell recording, which was the reason why we had used a nystatin-perforated patch technique in our previous report (Perillá n et al, 1999). Here, we exploited this feature of rundown to help identify macroscopic current due to the small conductance channel in the three subtypes of cells.…”

Section: D-fmentioning

confidence: 99%

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Inward rectifier K+ channel Kir2.3 (IRK3) in reactive astrocytes from adult rat brain

Perillan

Potts

et al. 2000

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 84%

Section: Materials and Methods Cell Culturementioning

confidence: 99%

Section: Single-channel Currentsmentioning

confidence: 99%

Section: D-fmentioning

confidence: 99%

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Inward rectifier K+ channel Kir2.3 (IRK3) in reactive astrocytes from adult rat brain

Perillan

Potts

et al. 2000

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Chlorotoxin‐sensitive Ca²⁺‐activated Cl⁻ channel in type R2 reactive astrocytes from adult rat brain

Dalton

Gerzanich

Chen

et al. 2003

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Astrocytes express four types of Cl(-) or anion channels, but Ca(2+)-activated Cl(-) (Cl(Ca)) channels have not been described. We studied Cl(-) channels in a morphologically distinct subpopulation ( approximately 5% of cells) of small (10-12 micro m, 11.8 +/- 0.6 pF), phase-dark, GFAP-positive native reactive astrocytes (NRAs) freshly isolated from injured adult rat brains. Their resting potential, -57.1 +/- 4.0 mV, polarized to -72.7 +/- 4.5 mV with BAPTA-AM, an intracellular Ca(2+) chelator, and depolarized to -30.7 +/- 6.1 mV with thapsigargin, which mobilizes Ca(2+) from intracellular stores. With nystatin-perforated patch clamp, thapsigargin activated a current that reversed near the Cl(-) reversal potential, which was blocked by Cl(-) channel blockers, 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) and Zn(2+), by I(-) (10 mM), and by chlorotoxin (EC(50) = 47 nM). With conventional whole-cell clamp, NPPB- and Zn(2+)-sensitive currents became larger with increasing [Ca(2+)](i) (10, 150, 300 nM). Single-channel recordings of inside-out patches confirmed Ca(2+) sensitivity of the channel and showed open-state conductances of 40, 80, 130, and 180 pS, and outside-out patches confirmed sensitivity to chlorotoxin. In primary culture, small phase-dark NRAs developed into small GFAP-positive bipolar cells with chlorotoxin-sensitive Cl(Ca) channels. Imaging with biotinylated chlorotoxin confirmed the presence of label in GFAP-positive cells from regions of brain injury, but not from uninjured brain. Chlorotoxin-tagged cells isolated by flow cytometry and cultured up to two passages exhibit positive labeling for GFAP and vimentin, but not for prolyl 4-hydroxylase (fibroblast), A2B5 (O2A progenitor), or OX-42 (microglia). Expression of a novel chlorotoxin-sensitive Cl(Ca) channel in a morphologically distinct subpopulation of NRAs distinguishes these cells as a new subtype of reactive astrocyte.

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Voltage‐dependent potassium currents in hypertrophied rat astrocytes after a cortical stab wound

Andĕrová

Antonova

Petrik

et al. 2004

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Changes in the membrane properties of reactive astrocytes in gliotic cortex induced by a stab wound were studied in brain slices of 21-28-day-old rats, using the patch-clamp technique and were correlated with changes in resting extracellular K+ concentration ([K+]e) measured in vivo using K+-selective microelectrodes. Based on K+ current expression, three types of astrocytes were identified in gliotic cortex: A1 astrocytes expressing a time- and voltage-independent K+ current component and additional inwardly rectifying K+ currents (K(IR)); A2 astrocytes expressing a time- and voltage-independent K+ current component and additional delayed outwardly rectifying K+ currents (K(DR)); and complex astrocytes expressing K(DR), K(IR), and A-type K+ (K(A)) currents and Na+ currents (I(Na)). Nestin/bromodeoxyuridine (BrdU)-negative A1 astrocytes were found further than approximately 100 microm from the stab wound and showed an upregulation of K(IR) currents within the first day post-injury (PI), correlating with an increased resting [K+]e. Their number declined from 62% of total astrocytes in control rats to 41% in rats at 7 days PI. Nestin/BrdU-positive A2 astrocytes were found only within a distance of approximately 100 microm from the stab wound and, in comparison to those in control rats, showed an upregulation of K(DR) currents. Their number increased from 8% of the total number of astrocytes in control rats to 39% 7 days PI. Both A1 and A2 astrocytes showed hypertrophied processes and increased GFAP staining, but an examination of cell morphology revealed greater changes in the surface/volume ratio in A2 astrocytes than in A1 astrocytes. Complex astrocytes did not display a hypertophied morphology; K(IR) currents in these cells were upregulated within 1 day PI, while the K(DR), K(A), and I(Na) currents were increased only 6 h PI. We conclude that two electrophysiologically, immunohistochemically, and morphologically distinct types of hypertrophied astrocytes are present at the site of a stab wound, depending on the distance from the lesion, and may have different functions in ionic homeostasis and/or regeneration.

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K+ inward rectifier currents in reactive astrocytes from adult rat brain

Cited by 16 publications

References 61 publications

Inward rectifier K+ channel Kir2.3 (IRK3) in reactive astrocytes from adult rat brain

Inward rectifier K+ channel Kir2.3 (IRK3) in reactive astrocytes from adult rat brain

Chlorotoxin‐sensitive Ca²⁺‐activated Cl⁻ channel in type R2 reactive astrocytes from adult rat brain

Voltage‐dependent potassium currents in hypertrophied rat astrocytes after a cortical stab wound

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K+ inward rectifier currents in reactive astrocytes from adult rat brain

Cited by 16 publications

References 61 publications

Inward rectifier K+ channel Kir2.3 (IRK3) in reactive astrocytes from adult rat brain

Inward rectifier K+ channel Kir2.3 (IRK3) in reactive astrocytes from adult rat brain

Chlorotoxin‐sensitive Ca2+‐activated Cl− channel in type R2 reactive astrocytes from adult rat brain

Voltage‐dependent potassium currents in hypertrophied rat astrocytes after a cortical stab wound

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Chlorotoxin‐sensitive Ca²⁺‐activated Cl⁻ channel in type R2 reactive astrocytes from adult rat brain