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Predicate | Object |
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
1
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pubmed:dateCreated |
1993-1-27
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pubmed:abstractText |
Activity-related transient changes in extracellular K+ concentration ([K+]e) and pH (pHe) were studied by means of ion-selective microelectrodes in neonatal rat spinal cords isolated from pups 2-14 days of age. Pups 1 to 2 days old were X-irradiated to impair gliogenesis and spinal cords were isolated 2-13 days postirradiation (PI). In 2- to 14-day-old pups PI stimulation produced ionic changes that were the same as those in 3- to 6-day-old control (non-irradiated) pups; e.g. the [K+]e increased by 4.03 +/- 0.24 mM (mean +/- S.E.M., n = 30) at a stimulation frequency of 10 Hz and this was accompanied by an alkaline shift of 0.048 +/- 0.004 pH units (mean +/- S.E.M., n = 32) pH units. By contrast, stimulation in non-irradiated 10- to 14-day-old pups produced smaller [K+]e changes, of 1.95 +/- 0.12 mM (mean +/- S.E.M., n = 30), and an acid shift of 0.035 +/- 0.003 pH units which was usually preceded by a scarcely discernible initial alkaline shift, as is also the case in adult rats. Our results show that the decrease in [K+]e ceiling level and the development of the acid shift in pHe are blocked by X-irradiation. Concomitantly, typical continuous development of GFAP-positive reaction was disrupted and densely stained astrocytes in gray matter of 10- to 14-day-old pups PI revealed astrogliosis. In control 3- to 6-day-old pups and in pups PI the stimulation-evoked alkaline, but not the acid, shift was blocked by Mg2+ and picrotoxin (10(-6) M). The acid shift was blocked, and the alkaline shift enhanced, by acetazolamide, Ba2+, amiloride and SITS. Application of GABA evoked an alkaline shift in the pHe baseline which was blocked by picrotoxin and in HEPES-buffered solution. By contrast, the stimulus-evoked alkaline shifts were enhanced in HEPES-buffered solutions. The results suggest a dual mechanism of the stimulus-evoked alkaline shifts. Firstly, the activation of GABA-gated anion (Cl-) channels induces a passive net efflux of bicarbonate, which may lead to a fall in neuronal intracellular pH and to a rise in the pHe. Secondly, bicarbonate independent alkaline shifts may arise from synaptic activity resulting in a flux of acid equivalents.
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pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
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pubmed:month |
Oct
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pubmed:issn |
0006-8993
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
23
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pubmed:volume |
594
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
19-30
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pubmed:dateRevised |
2003-11-14
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pubmed:meshHeading |
pubmed-meshheading:1467938-Animals,
pubmed-meshheading:1467938-Animals, Newborn,
pubmed-meshheading:1467938-Astrocytes,
pubmed-meshheading:1467938-Electric Stimulation,
pubmed-meshheading:1467938-Homeostasis,
pubmed-meshheading:1467938-Hydrogen-Ion Concentration,
pubmed-meshheading:1467938-Immunoenzyme Techniques,
pubmed-meshheading:1467938-Ion Transport,
pubmed-meshheading:1467938-Neuroglia,
pubmed-meshheading:1467938-Potassium,
pubmed-meshheading:1467938-Rats,
pubmed-meshheading:1467938-Spinal Cord,
pubmed-meshheading:1467938-X-Rays
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pubmed:year |
1992
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pubmed:articleTitle |
K+ and pH homeostasis in the developing rat spinal cord is impaired by early postnatal X-irradiation.
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pubmed:affiliation |
Laboratory of Cellular Neurophysiology, Czechoslovak Academy of Sciences, Bulovka, Prague.
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pubmed:publicationType |
Journal Article
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