Glial H<sup>+</sup> Transport and Control of pH

Schlue, Wolf-R.; Dörner, R.; Rempe, L.; Riehl, B.

doi:10.1111/j.1749-6632.1991.tb15621.x

Cited by 15 publications

(4 citation statements)

References 80 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Activation of leech glutamate receptors evokes an influx of Na' and an efflux of K+ (Dorner et al, 1990;Dorner, 19911, as well as an intra-and extracellular acidosis (Dorner, 1991;Schlue et al, 1991). The experiments presented in this article show that glutamatergic agonists also induce an increase in [Ca2+li in neuropile glial cells (see also Deitmer and Munsch, 19921, and in Retzius neurones.…”

Section: Discussionmentioning

confidence: 81%

“…Electrophysiological studies have shown that neuropile glial cells and Retzius neurones possess glutamate receptors of the AMPA-kainate type (Ballanyi et al, 1989;James and Walker, 1979;James et al, 19801, but there is no evidence so far for the existence of NMDA receptors in the leech nervous system (Ballanyi et al, 1989;Deitmer and Munsch, 1992;Dorner et al, 1990). Activation of leech glutamate receptors evokes an influx of Na' and an efflux of K+ (Dorner et al, 1990;Dorner, 19911, as well as an intra-and extracellular acidosis (Dorner, 1991;Schlue et al, 1991). The experiments presented in this article show that glutamatergic agonists also induce an increase in [Ca2+li in neuropile glial cells (see also Deitmer and Munsch, 19921, and in Retzius neurones.…”

Section: Discussionmentioning

confidence: 99%

“…Glutamatergic stimulation of both cell types evokes massive transmembrane fluxes of Na+ and K+ which led to the conclusion that the receptors are associated with unselective cation channels. Furthermore, a significant intra-and extracellular acidosis occurs the cause of which is still unknown (Dorner, 1991;Schlue et al, 1991). Finally, it has also been demonstrated in exposed neuropile glial cells that glutamatergic agonists induce an increase in the intracellular Ca2+ concentration .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Ca²⁺ influx into leech glial cells and neurones caused by pharmacologically distinct glutamate receptors

Hoschstrate

Schlue

1994

Glia

View full text Add to dashboard Cite

The effect of glutamatergic agonists on the intracellular free Ca2+ concentration ([Ca2+]i) of neuropile glial cells and Retzius neurones in intact segmental ganglia of the medicinal leech Hirudo medicinalis was investigated by using iontophoretically injected fura-2. In physiological Ringer solution the [Ca2+]i levels of both cell types were almost the same (glial cells: 58 +/- 30 nM, n = 51; Retzius neurones: 61 +/- 27 nM, n = 64). In both cell types glutamate, kainate, and quisqualate induced an increase in [Ca2+]i which was inhibited by 6,7-dinitroquinoxaline-2,3-dione (DNQX). This increase was caused by a Ca2+ influx from the extracellular space because the response was greatly diminished upon removal of extracellular Ca2+. The glutamate receptors of neuropile glial cells and Retzius neurones differed with respect to the relative effectiveness of the agonists used, as well as with regard to the inhibitory strength of DNQX. In Retzius neurones the agonist-induced [Ca2+]i increase was abolished after replacing extracellular Na+ by organic cations or by mM amounts of Ni2+, whereas in glial cells the [Ca2+]i increase was largely preserved under both conditions. It is concluded that in Retzius neurones the Ca2+ influx is predominantly mediated by voltage-dependent Ca2+ channels, whereas in neuropile glial cells the major influx occurs via the ion channels that are associated with the glutamate receptors.

show abstract

Section: Discussionmentioning

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ca²⁺ influx into leech glial cells and neurones caused by pharmacologically distinct glutamate receptors

Hoschstrate

Schlue

1994

Glia

View full text Add to dashboard Cite

show abstract

“…During the 1970-1980 decade, however, some authors began to emphasize the importance of harmonious glial-neuronal relationships (Schoffeniels et al ., 1978;Hertz and Schousboe, 1986) . Glial cells may buffer the extracellular fluid (Schlue et al, 1991) and regulate the extracellular concentrations of K + (Hertz, 1978) and NH 4 + (Cooper et al ., 1985) . They also regulate external concentrations of neurotransmitters such as glutamate (Benveniste et al ., 1984;MacCarthy et al ., 1988) and serotonin (Kimelberg and Katz, 1985) .…”

mentioning

confidence: 99%

Astroglial Cells Express Large Amounts of GABA_A Receptor Proteins in Mature Brain

Bureau

Khallou-Laschet

Bureau-Heeren

et al. 1995

Journal of Neurochemistry

View full text Add to dashboard Cite

GABAA receptors were characterized in cellular fractions isolated from adult bovine brain. The fraction enriched in cortical astrocytes is very rich in high‐affinity binding sites for [3H]flunitrazepam and other “central‐type” benzodiazepine ligands. The amount of specific [3H]flunitrazepam binding was more than five times higher in the glial fraction than in synaptosomal and perikaryal fractions. [3H]Flunitrazepam was displaced by low concentrations of clonazepam and other specific ligands for central GABAA receptors. Specific binding sites for GABA, flunitrazepam, barbiturates, and picrotoxin‐like convulsants were characterized. Allosteric interactions between the different sites were typical of central‐type GABAA receptors. The presence of α‐subunit(s), as revealed by [3H]flunitrazepam photoaffinity labeling, was demonstrated in all brain fractions at molecular mass 51–53 kDa. Photoaffinity labeling was highest in the glial fraction. However, in primary cultured astrocytes from neonate rat cortex, no photoaffinity labeling was detected. Information obtained from astrocytes in culture should thus be taken with caution when extrapolated to differentiated astroglial cells. Our results actually show that, in mature brain, most of the fully pharmacologically active GABAA receptors are extrasynaptic and expressed in astroglia.

show abstract

Modulation of Ca 2+ Influx in Leech Retzius Neurons. I. Effect of Extracellular pH

Hochstrate

Dierkes

Kilb

et al. 2001

Journal of Membrane Biology

View full text Add to dashboard Cite

We investigated the cytosolic free Ca2+ concentration ([Ca2+]i) of leech Retzius neurons in situ while varying the extracellular and intracellular pH as well as the extracellular ionic strength. Changing these parameters had no significant effect on [Ca2+]i when the membrane potential of the cells was close to its resting value. However, when the cells were depolarized by raising the extracellular K+ concentration or by applying the glutamatergic agonist kainate, extracellular pH and ionic strength markedly affected [Ca2+]i, whereas intracellular pH changes appeared to have virtually no effect. An extracellular acidification decreased [Ca2+]i, while alkalinization or reduction of the ionic strength increased it. Correspondingly, [Ca2+]i also increased when the kainate-induced extracellular acidification was reduced by raising the pH-buffering capacity. At low extracellular pH, the membrane potential to which the cells must be depolarized to evoke a detectable [Ca2+]i increase was shifted to more positive values, and it moved to more negative values at high pH. We conclude that in leech Retzius neurons extracellular pH, but not intracellular pH, affects [Ca2+]i by modulating Ca2+ influx through voltage-dependent Ca2+ channels. The results suggest that this modulation is mediated primarily by shifts in the surface potential at the extracellular side of the plasma membrane.

show abstract

Glial H⁺ Transport and Control of pH

Cited by 15 publications

References 80 publications

Ca²⁺ influx into leech glial cells and neurones caused by pharmacologically distinct glutamate receptors

Ca²⁺ influx into leech glial cells and neurones caused by pharmacologically distinct glutamate receptors

Astroglial Cells Express Large Amounts of GABA_A Receptor Proteins in Mature Brain

Modulation of Ca 2+ Influx in Leech Retzius Neurons. I. Effect of Extracellular pH

Contact Info

Product

Resources

About

Glial H+ Transport and Control of pH

Cited by 15 publications

References 80 publications

Ca2+ influx into leech glial cells and neurones caused by pharmacologically distinct glutamate receptors

Ca2+ influx into leech glial cells and neurones caused by pharmacologically distinct glutamate receptors

Astroglial Cells Express Large Amounts of GABAA Receptor Proteins in Mature Brain

Modulation of Ca 2+ Influx in Leech Retzius Neurons. I. Effect of Extracellular pH

Contact Info

Product

Resources

About

Glial H⁺ Transport and Control of pH

Ca²⁺ influx into leech glial cells and neurones caused by pharmacologically distinct glutamate receptors

Ca²⁺ influx into leech glial cells and neurones caused by pharmacologically distinct glutamate receptors

Astroglial Cells Express Large Amounts of GABA_A Receptor Proteins in Mature Brain