Brain Extracellular Space: Developmental Studies in Rat Optic Nervea

Ransom, Bruce R.; Carlini, Walter G.; Connors, Barry W.

doi:10.1111/j.1749-6632.1986.tb27141.x

Cited by 60 publications

(32 citation statements)

References 52 publications

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“…We thus conclude that, in the spinal cord as in the optic nerve (Ransom et al, 1985b), the occurrence of stimulation-evoked acid shifts is related to gliogenesis. In our experiments, the acid shift was effectively blocked by the CA inhibitor acetazolamide.…”

Section: Ph Homeostasismentioning

confidence: 91%

Role of glia in K⁺ and pH homeostasis in the neonatal rat spinal cord

Jendelová¹,

Syková²

1991

Glia

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Stimulation-evoked transient changes in extracellular potassium ([K+]e) and pH (pHe) were studied in the neonatal rat spinal cords isolated from 3-13-day-old pups. In unstimulated pups the [K+]e baseline was elevated and pHe was more acid than that in Ringer's solution (3.5 mM K+, pH 7.3-7.35). The [K+]e and pHe in 3-6-day-old pups was 3.91 +/- 0.12 mM and pHe 7.19 +/- 0.01, respectively, while in 10-13-day-old pups it was 4.35 +/- 0.15 mM and 7.11 +/- 0.01, respectively. The [K+]e changes evoked in the dorsal horn by a single electrical stimulus were as large as 1.5-2.5 mM. Such changes in [K+]e are evoked in the adult rat spinal cord with stimulation at a frequency of 10-30 Hz. The maximal changes of 2.1-6.5 mM were found at a stimulation frequency of 10 Hz in 3-6-day-old animals. In older animals the [K+]e changes progressively decreased. The poststimulation K(+)-undershoot was found after a single stimulus as well as after repetitive stimulation. In 3-8-day-old pups, the stimulation evoked an alkaline shift, which was followed by a smaller poststimulation acid shift when the stimulation was discontinued. In pups 3-4-days-old the stimulation evoked the greatest alkaline shifts, i.e., by as much as 0.05 pH units after a single pulse and by about 0.1 pH units during stimulation at a frequency of 10 Hz. In 5-8-day-old pups, the alkaline shift became smaller and the poststimulation acid shift increased.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Ph Homeostasismentioning

confidence: 91%

Role of glia in K⁺ and pH homeostasis in the neonatal rat spinal cord

Jendelová¹,

Syková²

1991

Glia

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“…Increased neuronal activity is accompanied by alterations in the composition of the brain interstitium, including elevation of K ϩ and glutamate concentration, as well as changes in extracellular pH (pH o ) (Ransom et al, 1986;Chesler and Kaila, 1992). Glial cells play a fundamental role in the restitution of the extracellular microenvironment during neuronal activity.…”

Section: Introductionmentioning

confidence: 99%

“…Glial cells play a fundamental role in the restitution of the extracellular microenvironment during neuronal activity. Buffering of K ϩ concentration and the uptake of glutamate are considered as the most important restoring functions of astrocytes (Ransom et al, 1986;Newman and Reichenbach, 1996), but these cells probably participate in the regulation of extracellular H ϩ concentration as well. The resting pH o in various brain tissues was found to be 7.2-7.4 using pH-selective microelectrodes (Ransom et al, 1986;Chesler 1990).…”

Section: Introductionmentioning

confidence: 99%

“…Buffering of K ϩ concentration and the uptake of glutamate are considered as the most important restoring functions of astrocytes (Ransom et al, 1986;Newman and Reichenbach, 1996), but these cells probably participate in the regulation of extracellular H ϩ concentration as well. The resting pH o in various brain tissues was found to be 7.2-7.4 using pH-selective microelectrodes (Ransom et al, 1986;Chesler 1990). Surprisingly, the pH o changes following neuronal stimulation were found to vary considerably among different brain areas (Chesler and Kaila, 1992;Deitmer and Rose, 1996).…”

Section: Introductionmentioning

confidence: 99%

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pH‐sensitive inwardly rectifying chloride current in cultured rat cortical astrocytes

Makara¹,

Petheő²,

Tóth³

et al. 2001

Glia

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The effect of pH(o) on plasma membrane chloride current of cultured rat cortical astrocytes was investigated using the whole-cell patch-clamp technique. In the presence of intra- and extracellular solutions with symmetrical high Cl(-) content and K(+) channel inhibitors, the cells exhibited an inwardly rectifying current. The current activated slowly at potentials negative to -40 mV and did not display time-dependent inactivation. The current was inhibited by 0.1 mM Cd(2+), 0.1 mM Zn(2+), 1 mM 9-anthracene-carboxylic acid, and 0.2 mM 5-nitro-2-(3-phenylpropylamino)benzoic acid, but not by 10 mM Ba(2+) or 3 mM Cs(+). Reversal potential of the current followed the chloride equilibrium potential and was not influenced by changes in K(+) or Na(+) concentration. The inwardly rectifying chloride current was augmented by extracellular acidosis and reduced by alkalosis. The pH sensitivity was most pronounced in the physiologically relevant pH(o) range of 6.9--7.9. Lowering pH to 6.4 induced no additional increase in steady-state current amplitude compared with pH(o) 6.9, but it substantially slowed the activation kinetics. According to its kinetic and pharmacological properties this chloride current is similar to that found in cultured rat astrocytes after long-term treatment with dibutyryl-cAMP, however, in our cultures it was consistently expressed without any treatment with the drug. Considering that astrocytes possess carbonic anhydrase and Cl(-)/HCO3(-) antiporter, this current may participate in the regulation of the interstitial and astrocyte pH.

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“…Thus, pH, is more alkaline (pH 6.9-7.4) than the electrochemical equilibrium for H+ (~pH 6.1) and, as a consequence, cells continuously extrude acid into the extracellular space. The amount of acid extrusion changes during neuronal activity, and pH transients of several tenths of pH units can be recorded in the extracellular space (38)(39)(40)(41) (Fig. 3a).…”

Section: Glial Modulation Of [K+]omentioning

confidence: 99%

Review : Glial Neuronal Interactions: A Physiological Perspective

Sontheimer

1995

Neuroscientist

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Throughout the nervous system, neurons are closely surrounded by glial cells, leaving only a 20-nm wide extracellular space filled with interstitial fluid. Ions, transmitters, hormones, nutrients, and waste products all share this narrow diffusion pathway. Because the interstitial space occupies only a small volume, neuronal activity can lead to appreciable changes in the extracellular concentration of ions, protons, and neurotransmitters. These changes can affect neuronal activity and are believed to be influenced by glial cells. The proximity of glial processes to synapses and axons make glial cells ideal partners to sequester ions and transmitters released by neurons. The failure of glial cells to perform such essential homeostatic functions can have profound effects, and these homeostatic activities may constitute one way in which glial cells can influence neuronal signaling. In addition, glial cells, which, unlike most neurons, are coupled to each other through gap-junctions, communicate with each other and possibly also with adjacent neurons through propagated intracellular Ca 2+ waves. The importance of such interglial signaling is not understood. Additionally, glial cells and neurons mutually modulate their expression of ion channels, most likely through factors released into the extracellular space. The range of responses observed in glial cells and their intimate anatomical relationship with neurons suggest a broader role for glia than is currently appreciated. It also emphasizes the importance of a better understanding of glial-neuronal interactions to an understanding of brain function. The Neuroscientist 1: [328][329][330][331][332][333][334][335][336][337] 1995

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Brain Extracellular Space: Developmental Studies in Rat Optic Nervea

Cited by 60 publications

References 52 publications

Role of glia in K⁺ and pH homeostasis in the neonatal rat spinal cord

Role of glia in K⁺ and pH homeostasis in the neonatal rat spinal cord

pH‐sensitive inwardly rectifying chloride current in cultured rat cortical astrocytes

Review : Glial Neuronal Interactions: A Physiological Perspective

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Brain Extracellular Space: Developmental Studies in Rat Optic Nervea

Cited by 60 publications

References 52 publications

Role of glia in K+ and pH homeostasis in the neonatal rat spinal cord

Role of glia in K+ and pH homeostasis in the neonatal rat spinal cord

pH‐sensitive inwardly rectifying chloride current in cultured rat cortical astrocytes

Review : Glial Neuronal Interactions: A Physiological Perspective

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Role of glia in K⁺ and pH homeostasis in the neonatal rat spinal cord

Role of glia in K⁺ and pH homeostasis in the neonatal rat spinal cord