Astrocytes in primary cultures: Membrane potential characteristics reveal exclusive potassium conductance and potassium accumulator properties

Walz, Wolfgang; Wuttke, W; Hertz, Leif

doi:10.1016/0006-8993(84)90772-8

Cited by 126 publications

(43 citation statements)

References 21 publications

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“…One of the characteristic features of glial cells in several tissues is their membrane selectivity for K ϩ , and a low (in some cases, negligible) permeability to Na ϩ and Cl Ϫ (Bigiani 2001;Kettenmann et al 1983;Newman 1985Newman , 1989Ransom and Sontheimer 1995;Sugihara and Furukawa 1996;Walz and Schule 1982;Walz et al 1984). Results from the ion substitution experiments described here demonstrate that vomeronasal supporting cells have membranes that are permeable not only to K ϩ , but also to Na ϩ and Cl Ϫ .…”

Section: Resting Membrane Permeabilities In Vomeronasal Supporting Cellsmentioning

confidence: 72%

Ion Conductances in Supporting Cells Isolated From the Mouse Vomeronasal Organ

Ghiaroni

Fieni

Tirindelli

et al. 2003

Journal of Neurophysiology

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. Ion conductances in supporting cells isolated from the mouse vomeronasal organ. J Neurophysiol 89: 118 -127, 2003. 10.1152/jn.00545.2002. The vomeronasal organ (VNO) is a chemosensory structure involved in the detection of pheromones in most mammals. The VNO sensory epithelium contains both neurons and supporting cells. Data suggest that vomeronasal neurons represent the pheromonal transduction sites, whereas scarce information is available on the functional properties of supporting cells. To begin to understand their role in VNO physiology, we have characterized with patch-clamp recording techniques the electrophysiological properties of supporting cells isolated from the neuroepithelium of the mouse VNO. Supporting cells were distinguished from neurons by their typical morphology and by the lack of immunoreactivity for G␥8 and OMP, two specific markers for vomeronasal neurons. Unlike glial cells in other tissues, VNO supporting cells exhibited a depolarized resting potential (about Ϫ29 mV). A Goldman-Hodgkin-Katz analysis for resting ion permeabilities revealed indeed an unique ratio of P K :P Na :P Cl ϭ 1:0.23:1.4. Supporting cells also possessed voltage-dependent K ϩ and Na ϩ conductances that differed significantly in their biophysical and pharmacological properties from those expressed by VNO neurons. Thus glial membranes in the VNO can sustain significant fluxes of K ϩ and Na ϩ , as well as Cl Ϫ . This functional property might allow supporting cells to mop-up and redistribute the excess of KCl and NaCl that often occurs in certain pheromone-delivering fluids, like urine, and that could blunt the sensitivity of VNO neurons to pheromones. Therefore vomeronasal supporting cells could affect chemosensory transduction in the VNO by regulating the ionic strength of the pheromone-containing medium.

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Section: Resting Membrane Permeabilities In Vomeronasal Supporting Cellsmentioning

confidence: 72%

Ion Conductances in Supporting Cells Isolated From the Mouse Vomeronasal Organ

Ghiaroni

Fieni

Tirindelli

et al. 2003

Journal of Neurophysiology

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“…Ion transport and electrical parameters in these cultures resemble those of astrocytes in situ (Walz and Hertz. 1983h;Walz et al. 1984).…”

Section: Methodsmentioning

confidence: 99%

Intense Furosemide-Sensitive Potassium Accumulation in Astrocytes in the Presence of Pathologically High Extracellular Potassium Levels

Walz

Hertz

1984

J Cereb Blood Flow Metab

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An intense K+ accumulation in primary cultures of astrocytes, occurring when external K+ was increased from 5.4 to 54 m M, was investigated. This increase resulted in a doubling of the K+ content within 10 s. Thirty percent of the accumulation was inhibited by furosemide (2 m M). This drug had no effect on the unidirectional influx of K+ at 5.4 m M K+, but when the extracellular K+ concentration was increased, there appeared to be a furosemide-sensitive component of the influx. This component increased with increasing external K+ levels, reaching 44% of the total influx at 72 m M. These results show that astrocytes exhibit an intense furosemide-sensitive K+ accumulation which is activated by K+ levels resembling those occurring in the extracellular compartment during pathological events. Previous studies on a furosemide-sensitive Cl− pump in cultured astrocytes suggest that this accumulation might be via KCl cotransport, which in other systems is involved in volume control.

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“…In mammalian glial cells, the deviation from the Nernst equation has been attributed to a rise in intracellular K+ concentration at high [K+]. values (Kettenmann et al 1983;Walz et al 1984), to the involvement of ionic permeabilities other than K+ (Ransom & Goldring, 1973a) or to the ionic leakage caused by electrode penetration (Dennis & Gerschenfeld, 1969 Spontaneous potentials in glial cells were much slower than those observed in central neurones (Hubbard et al 1967;Takahashi, 1984) [K+]o changes evoked by a single afferent volley in the present study was much slower than that reported for the cat dorsal horn in vivo (duration, 0-2-3 s; Kri"z et al 1975). This difference can be attributed in part to lower temperatures (approximately 25°C) in the present study.…”

Section: Morphology Of Inexcitable Cellsmentioning

confidence: 99%

Slow depolarizing potentials recorded from glial cells in the rat superficial dorsal horn.

Takahashi

Tsuruhara

1987

The Journal of Physiology

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SUMMARY1. Intracellular potentials were recorded from inexcitable cells in the superficial dorsal horn of the rat lumbar spinal cord in vitro.2. These cells had a large resting membrane potential (up to -90 mV) but when depolarized were unable to produce action potentials. The resting potential was highly dependent upon extracellular K+ concentrations ([K+]0), with a slope of about 45 mV for a 10-fold change in [K+].3. Electrical stimulation of dorsal roots evoked a slow depolarizing potential lasting for many seconds in the inexcitable cells. The slow potentials were not accompanied by any appreciable change in input conductance, nor were their amplitudes dependent upon the membrane potential.4. The morphology of the inexcitable cells marked by intracellular injection of a fluorescent dye, Lucifer Yellow, was consistent with their being glial cells.5. [K+]. values were measured by K+-sensitive electrodes simultaneously with intracellular glial potentials. Changes in the K+-electrode potential occurred in parallel with slow depolarizing potentials following stimulation of dorsal roots. When the stimulus intensity was altered, changes in the magnitude of the K+-electrode response were correlated with those of the slow potentials.6. Replacement of extracellular Ca2+ by Mg2+ abolished both the slow potentials and K+-electrode responses evoked by afferent stimulation, suggesting that impulses in primary afferent fibres do not directly contribute to the glial slow potentials.7. It is concluded that the slow potentials in glial cells result from a transient increase in [K+]. at the superficial dorsal horn, which is induced by activation of neighbouring internuncial neurones.

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Astrocytes in primary cultures: Membrane potential characteristics reveal exclusive potassium conductance and potassium accumulator properties

Cited by 126 publications

References 21 publications

Ion Conductances in Supporting Cells Isolated From the Mouse Vomeronasal Organ

Ion Conductances in Supporting Cells Isolated From the Mouse Vomeronasal Organ

Intense Furosemide-Sensitive Potassium Accumulation in Astrocytes in the Presence of Pathologically High Extracellular Potassium Levels

Slow depolarizing potentials recorded from glial cells in the rat superficial dorsal horn.

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