Membrane currents and morphological properties of neurons and glial cells in the spinal cord and filum terminale of the frog

Chvátal, Alexandr; Andĕrová, Miroslava; Žiak, Drahomı́r; Orkand, Richard K.; Syková, Eva

doi:10.1016/s0168-0102(01)00211-5

Cited by 17 publications

(9 citation statements)

References 49 publications

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“…The proposed model of K + accumulation in the vicinity of astrocytes and oligodendrocytes used in the current study supports the hypothesis that oligodendrocytes are surrounded by a smaller extracellular space available for K + accumulation than are astrocytes (Berger et al, 1991; Steinhäuser et al, 1992; Chvátal et al, 1997, 1999, 2001; Anděrová et al, 2001; Vargová et al, 2001). Depolarization of the oligodendrocyte membrane produces a significant shift in membrane reversal potential to positive values, and, because the glial membrane is highly permeable to K + , this shift is caused by the large accumulation of potassium in the vicinity of the oligodendrocyte membrane.…”

Section: Discussionsupporting

confidence: 85%

Analysis of K⁺ accumulation reveals privileged extracellular region in the vicinity of glial cells in situ

Chvatal

Andĕrová

Syková

2004

J of Neuroscience Research

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Astrocytes and oligodendrocytes in rat and mouse spinal cord slices, characterized by passive membrane currents during de- and hyperpolarizing stimulation pulses, express a high resting K+ conductance. In contrast to the case for astrocytes, a depolarizing prepulse in oligodendrocytes produces a significant shift of reversal potential (Vrev) to positive values, arising from the larger accumulation of K+ in the vicinity of the oligodendrocyte membrane. As a result, oligodendrocytes express large tail currents (Itail) after a depolarizing prepulse due to the shift of K+ into the cell. In the present study, we used a mathematical model to calculate the volume of the extracellular space (ECS) in the vicinity of astrocytes and oligodendrocytes (ESVv), defined as the volume available for K+ accumulation during membrane depolarization. A mathematical analysis of membrane currents revealed no differences between glial cells from mouse (n = 59) or rat (n = 60) spinal cord slices. We found that the Vrev of a cell after a depolarizing pulse increases with increasing Itail, expressed as the ratio of the integral inward current (Qin) after the depolarizing pulse to the total integral outward current (Qout) during the pulse. In astrocytes with small Itail and Vrev ranging from -50 to -70 mV, the Qin was only 3-19% of Qout, whereas, in oligodendrocytes with large Itail and Vrev between -20 and 0 mV, Qin/Qout was 30-75%. On the other hand, ESVv decreased with increasing values of Vrev. In astrocytes, ESVv ranged from 2 to 50 microm3, and, in oligodendrocytes, it ranged from 0.1 to 2.0 microm3. Cell swelling evoked by the application of hypotonic solution shifted Vrev to more positive values by 17.2 +/- 1.8 mV and was accompanied by a decrease in ESVv of 3.6 +/- 1.3 microm3. Our mathematical analysis reveals a 10-100 times smaller region of the extracellular space available for K+ accumulation during cell depolarization in the vicinity of oligodendrocytes than in the vicinity of astrocytes. The presence of such privileged regions around cells in the CNS may affect the accumulation and diffusion of other neuroactive substances and alter communication between cells in the CNS.

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Section: Discussionsupporting

confidence: 85%

Analysis of K⁺ accumulation reveals privileged extracellular region in the vicinity of glial cells in situ

Chvatal

Andĕrová

Syková

2004

J of Neuroscience Research

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“…The spinal cords of smaller mammals and nonmammals have GNRs of 0.7–2.7 (Bjugn, ; Bjugn and Gundersen, ; Chvátal et al, ; Fig. E), so the reported nNNR of over 30 for M. fascicularis and other nonhuman primates (Burish et al, ; Fig.…”

Section: Discussionmentioning

confidence: 99%

The Cellular Composition and Glia–Neuron Ratio in the Spinal Cord of a Human and a Nonhuman Primate: Comparison With Other Species and Brain Regions

Bahney

Bartheld

2017

The Anatomical Record

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The cellular composition of brains shows largely conserved, gradual evolutionary trends between species. In the primate spinal cord, however, the glia-neuron ratio was reported to be greatly increased over that in the rodent spinal cord. Here, we re-examined the cellular composition of the spinal cord of one human and one nonhuman primate species by employing two different counting methods, the isotropic fractionator and stereology. We also determined whether segmental differences in cellular composition, possibly reflecting increased fine motor control of the upper extremities, may explain a sharply increased glia-neuron ratio in primates. In the cynomolgus monkey spinal cord, the isotropic fractionator and stereology yielded 206-275 million cells, of which 13.3-25.1% were neurons (28-69 million). Stereological estimates yielded 21.1% endothelial cells and 65.5% glial cells (glia-neuron ratio of 4.9-5.6). In human spinal cords, the isotropic fractionator and stereology generated estimates of 1.5-1.7 billion cells and 197-222 million neurons (13.4% neurons, 12.2% endothelial cells, 74.8% glial cells), and a glia-neuron ratio of 5.6-7.1, with estimates of neuron numbers in the human spinal cord based on morphological criteria. The non-neuronal to neuron ratios in human and cynomolgus monkey spinal cords were 6.5 and 3.2, respectively, suggesting that previous reports overestimated this ratio. We did not find significant segmental differences in the cellular composition between cervical, thoracic and lumbar levels. When compared with brain regions, the spinal cord showed gradual increases of the glia-neuron ratio with increasing brain mass, similar to the cerebral cortex and the brainstem. Anat Rec, 301:697-710, 2018. © 2017 Wiley Periodicals, Inc.

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“…According to Chetverukhin and Polenov (1993), glia are 4-5 times more common than neurons in the hypothalamic pre-optic area of adult Rana temporaria. Chvatal et al (2001) reported neuron/glia ratios of 1.28 and 0.5 in the spinal cord and filum terminale, respectively, of adult Rana pipiens. In the adult bullfrogs used for our study, we found neuron/glia ratios of 1.36 (16-cm female) and 1.19 (20-cm male).…”

Section: Changes In Superior Olive Over Metamorphosismentioning

confidence: 99%

Cellular and spatial changes in the anuran superior olive across metamorphosis

Templin

Simmons

2005

Hearing Research

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Membrane currents and morphological properties of neurons and glial cells in the spinal cord and filum terminale of the frog

Cited by 17 publications

References 49 publications

Analysis of K⁺ accumulation reveals privileged extracellular region in the vicinity of glial cells in situ

Analysis of K⁺ accumulation reveals privileged extracellular region in the vicinity of glial cells in situ

The Cellular Composition and Glia–Neuron Ratio in the Spinal Cord of a Human and a Nonhuman Primate: Comparison With Other Species and Brain Regions

Cellular and spatial changes in the anuran superior olive across metamorphosis

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Membrane currents and morphological properties of neurons and glial cells in the spinal cord and filum terminale of the frog

Cited by 17 publications

References 49 publications

Analysis of K+ accumulation reveals privileged extracellular region in the vicinity of glial cells in situ

Analysis of K+ accumulation reveals privileged extracellular region in the vicinity of glial cells in situ

The Cellular Composition and Glia–Neuron Ratio in the Spinal Cord of a Human and a Nonhuman Primate: Comparison With Other Species and Brain Regions

Cellular and spatial changes in the anuran superior olive across metamorphosis

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Analysis of K⁺ accumulation reveals privileged extracellular region in the vicinity of glial cells in situ

Analysis of K⁺ accumulation reveals privileged extracellular region in the vicinity of glial cells in situ