Evidence for electrogenic sodium-bicarbonate cotransport in cultured rat cerebellar astrocytes

Brune, Thomas; Fetzer, S; Backus, Kurt H.; Deitmer, Joachim W.

doi:10.1007/bf02584031

Cited by 60 publications

(53 citation statements)

References 33 publications

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“…Electrogenic NBC activity has been identified and characterized in mammalian astrocytes in situ (Grichtchenko and Chesler, 1994a;Grichtchenko and Chesler, 1994b), as well as cultured from several brain regions (Bevensee et al, 1997a;Bevensee et al, 1997b;O'Connor et al, 1994;Brune et al, 1994). Our data are consistent with NBCe1-C being responsible for such activity in situ, although NBCe1-B activity may play a larger role when astrocytes are cultured.…”

Section: Discussionsupporting

confidence: 82%

Localization of electrogenic Na/bicarbonate cotransporter NBCe1 variants in rat brain

et al. 2008

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The activity of HCO 3 − transporters contributes to the acid-base environment of the nervous system.In the present study, we used in situ hybridization, immunoblotting, immunohistochemistry, and immunogold electron microscopy to localize electrogenic Na/bicarbonate cotransporter NBCe1 splice variants (-A, -B, and -C) in rat brain. The in situ hybridization data are consistent with NBCe1-B and -C, but not -A, being the predominant NBCe1 variants in brain, particularly in the cerebellum, hippocampus, piriform cortex, and olfactory bulb. An antisense probe to the B and C variants strongly labeled granule neurons in the dentate gyrus of the hippocampus, and cells in the granule layer and Purkinje layer (e.g., Bergmann glia) of the cerebellum. Weaker labeling was observed in the pyramidal layer of the hippocampus and in astrocytes throughout the brain. Similar, but weaker labeling was obtained with an antisense probe to the A and B variants. In immunoblot studies, antibodies to the A and B variants (αA/B) and C variant (αC) labeled ~130-kDa proteins in various brain regions. From immunohistochemistry data, both αA/B and αC exhibited diffuse labeling throughout brain, but αA/B labeling was more intracellular and punctate. Based on co-localization Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. studies with antibodies to neuronal or astrocytic markers, αA/B labeled neurons in the pyramidal layer and dentate gyrus of the hippocampus, as well as cortex. αC labeled glia surrounding neurons (and possibly neurons) in the neuropil of the Purkinje cell layer of the cerebellum, the pyramidal cell layer and dentate gyrus of the hippocampus, and the cortex. According to electron microscopy data from the cerebellum, αA/B primarily labeled neurons intracellularly and αC labeled astrocytes at the plasma membrane. In summary, the B and C variants are the predominant NBCe1 variants in rat brain and exhibit different localization profiles. NIH Public Access

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Section: Discussionsupporting

confidence: 82%

Localization of electrogenic Na/bicarbonate cotransporter NBCe1 variants in rat brain

et al. 2008

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“…6B). The effects of DIDS, as expected (Brune et al, 1994;O'Connor et al, 1994), were not fully reversible.…”

Section: Origin Of K A-induced [H ؉ ] I Changes In Co 2 -Buffered Salinementioning

confidence: 60%

Mechanisms of H⁺and Na⁺Changes Induced by Glutamate, Kainate, and d-Aspartate in Rat Hippocampal Astrocytes

1996

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The excitatory transmitter glutamate (Glu), and its analogs kainate (KA), andd-aspartate (d-Asp) produce significant pH changes in glial cells. Transmitter-induced pH changes in glial cells, generating changes in extracellular pH, may represent a special form of neuronal–glial interaction. We investigated the mechanisms underlying these changes in intracellular H+concentration ([H+]i) in cultured rat hippocampal astrocytes and studied their correlation with increases in intracellular Na+concentration ([Na+]i), using fluorescence ratio imaging with 2′,7′-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF) or sodium-binding benzofuran isophthalate (SBFI). Glu, KA, ord-Asp evoked increases in [Na+]i; Glu ord-Asp produced parallel acidifications. KA, in contrast, evoked biphasic changes in [H+]i, alkaline followed by acid shifts, which were unaltered after Ca2+removal and persisted in 0 Cl−-saline, but were greatly reduced in CO2/HCO−3-free or Na+-free saline, or during 4,4′-diisothiocyanato-stilbene-2,2′-disulphonic acid (DIDS) application. The non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) blocked KA-evoked changes in [H+]iand [Na+]i, indicating that they were receptor–ionophore mediated. In contrast, CNQX increased the [H+]ichange and decreased the [Na+]ichange induced by Glu.d-Asp, which is transported but does not act at Glu receptors, induced [H+]iand [Na+]ichanges that were virtually unaltered by CNQX. Our study indicates that [Na+]iincreases are not primarily responsible for Glu- or KA-induced acidifications in astrocytes. Instead, intracellular acidifications evoked by Glu ord-Asp are mainly caused by transmembrane movement of acid equivalents associated with Glu/Asp-uptake into astrocytes. KA-evoked biphasic [H+]ichanges, in contrast, are probably attributable to transmembrane ion movements mediated by inward, followed by outward, electrogenic Na+/HCO−3cotransport, reflecting KA-induced biphasic membrane potential changes.

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“…6B). Since an additional acid-extrusion mechanism, the DIDS-sensitive Na¤-HCO×¦ cotransport, has been found in rat cerebellar astrocytes (Shrode & Putnum, 1994;Brune, Fetzer, Backus & Deitmer, 1994) we tested whether this astrocyte Na¤-HCO×¦ cotransport is inhibited by HµOµ (100 ìÒ), using a similar method to that in Fig. 6B, and found that the level of the second DIDS-induced response was 78·5 ± 8·8 % of the first (n = 3).…”

Section: ------------------------------------------------------------mentioning

confidence: 99%

“…Rat cerebellar astrocytes have, in addition, the electrogenic Na¤-HCO×¦ cotransport (Shrode & Putnum, 1994;Brune et al 1994). Since the Na¤-H¤ exchanger and Na¤-dependent Cl¦-HCO×¦ exchangerÏNa¤-HCO×¦ cotransport are inhibited by amiloride and DIDS, respectively, the fact that the pHé decreased even further (see Fig.…”

Section: Lactate Productionmentioning

confidence: 99%

Mechanism of oxidative stress‐induced intracellular acidosis in rat cerebellar astrocytes and C₆ glioma cells

Tsai

Wang

Chen

et al. 1997

The Journal of Physiology

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Following ischaemic reperfusion, large amounts of superoxide anion (.O2−), hydroxyl radical (.OH) and H2O2 are produced, resulting in brain oedema and changes in cerebral vascular permeability. We have found that H2O2 (100 μm) induces a significant intracellular acidosis in both cultured rat cerebellar astrocytes (0.37 ± 0.04 pH units) and C6 glioma cells (0.33 ± 0.07 pH units). Two membrane‐crossing ferrous iron chelators, phenanthroline and deferoxamine, almost completely inhibited H2O2‐induced intracellular acidosis, while the non‐membrane‐crossing iron chelator apo‐transferrin had no effect. Furthermore, the acidosis was completely inhibited by two potent membrane‐crossing .OH scavengers, N‐(2‐mercaptopropionyl)‐grycine (N‐MPG) and dimethyl thiourea (DMTU). Since .OH can be produced during iron‐catalysed H2O2 breakdown (Fenton reaction), we have shown that a large reduction in pH1 in glial cells can result from the production of intracellular .OH via H2O2 oxidation. We have ruled out the possible involvement of: (i) an increase in intracellular Ca2+ levels; and (ii) inhibition of oxidative phosphorylation. Our results suggest that .OH inhibits glycolysis, leading to ATP hydrolysis and intracellular acidosis. This conclusion is based on the following observations: (i) in glucose‐free medium, or in the presence of iodoacetate or 2‐deoxy‐D‐glucose, H2O2‐induced acidosis is completely suppressed; (ii) H2O2 and iodoacetate both produce an increase in levels of intracellular free Mg2+, an indicator of ATP breakdown; and (iii) direct measurement of intracellular ATP levels and lactate production show 50 and 55% reductions in ATP content and lactate production, respectively, following treatment with 100 μm H2O2. Inhibition of the pH1 regulators (i.e. the Na+–H+ exchange and possibly the Na+–HCO3−–dependent pH1 transporters) resulting from H2O2‐induced intracellular ATP reduction may also be involved in the H2O2‐evoked intracellular acidosis in glial cells.

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Evidence for electrogenic sodium-bicarbonate cotransport in cultured rat cerebellar astrocytes

Cited by 60 publications

References 33 publications

Localization of electrogenic Na/bicarbonate cotransporter NBCe1 variants in rat brain

Localization of electrogenic Na/bicarbonate cotransporter NBCe1 variants in rat brain

Mechanisms of H⁺and Na⁺Changes Induced by Glutamate, Kainate, and d-Aspartate in Rat Hippocampal Astrocytes

Mechanism of oxidative stress‐induced intracellular acidosis in rat cerebellar astrocytes and C₆ glioma cells

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Evidence for electrogenic sodium-bicarbonate cotransport in cultured rat cerebellar astrocytes

Cited by 60 publications

References 33 publications

Localization of electrogenic Na/bicarbonate cotransporter NBCe1 variants in rat brain

Localization of electrogenic Na/bicarbonate cotransporter NBCe1 variants in rat brain

Mechanisms of H+and Na+Changes Induced by Glutamate, Kainate, and d-Aspartate in Rat Hippocampal Astrocytes

Mechanism of oxidative stress‐induced intracellular acidosis in rat cerebellar astrocytes and C6 glioma cells

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Product

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Mechanisms of H⁺and Na⁺Changes Induced by Glutamate, Kainate, and d-Aspartate in Rat Hippocampal Astrocytes

Mechanism of oxidative stress‐induced intracellular acidosis in rat cerebellar astrocytes and C₆ glioma cells