Changes in glial K+ currents with decreased extracellular volume in developing rat white matter
Jazyk angličtina Země Spojené státy americké Médium print
Typ dokumentu srovnávací studie, časopisecké články, práce podpořená grantem, Research Support, U.S. Gov't, Non-P.H.S., Research Support, U.S. Gov't, P.H.S.
Grantová podpora
GM48190
NIGMS NIH HHS - United States
P0I-NS07464
NINDS NIH HHS - United States
RR-03051
NCRR NIH HHS - United States
PubMed
9211994
DOI
10.1002/(sici)1097-4547(19970701)49:1<98::aid-jnr11>3.0.co;2-0
PII: 10.1002/(SICI)1097-4547(19970701)49:1<98::AID-JNR11>3.0.CO;2-0
Knihovny.cz E-zdroje
- MeSH
- corpus callosum cytologie růst a vývoj metabolismus MeSH
- difuze MeSH
- draslík metabolismus MeSH
- draslíkové kanály fyziologie MeSH
- druhová specificita MeSH
- extracelulární prostor * MeSH
- gating iontového kanálu * MeSH
- krysa rodu Rattus MeSH
- membránové potenciály MeSH
- metoda terčíkového zámku MeSH
- myelinová pochva fyziologie MeSH
- myši MeSH
- oligodendroglie metabolismus MeSH
- potkani Wistar MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
- Research Support, U.S. Gov't, P.H.S. MeSH
- srovnávací studie MeSH
- Názvy látek
- draslík MeSH
- draslíkové kanály MeSH
Whole cell patch-clamp recordings of K+ currents from oligodendrocyte precursors in 10-day-old rats (P10) and, following myelination, in mature oligodendrocytes from 20-day-old rats (P20) were correlated with extracellular space (ECS) diffusion parameters measured by the local diffusion of iontophoretically injected tetramethylammonium ions (TMA+). The aim of this study was to find an explanation for the changes in glial currents that occur with myelination. Oligodendrocyte precursors (P10) in slices from corpus callosum were characterized by the presence of A-type K+ currents, delayed and inward rectifier currents, and lack of tail currents after the offset of a voltage jump. Mature oligodendrocytes in corpus callosum slices from P20 rats were characterized by passive, decaying currents and large tail currents after the offset of a voltage jump. Measurements of the reversal potential for the tail currents indicate that they result from increases in [K+]e by an average of 32 mM during a 20 msec 100 mV voltage step. Concomitant with the change in oligodendrocyte electrophysiological behavior after myelination there is a decrease in the ECS of the corpus callosum. ECS volume decreases from 36% (P9-10) to 25% (P20-21) of total tissue volume. ECS tortuosity lambda = (D/ADC)0.5, where D is the free diffusion coefficient and ADC is the apparent diffusion coefficient of TMA+ in the brain, increases as measured perpendicular to the axons from 1.53 +/- 0.02 (n = 6, mean +/- SEM) to 1.70 +/- 0.02 (n = 6). TMA+ non-specific uptake (k') was significantly larger at P20 (5.2 +/- 0.6 x 10(-3) s(-1), n = 6) than at P10 (3.5 +/- 0.4 x 10(-3) s(-1), n = 6). It can be concluded that membrane potential changes in mature oligodendrocytes are accompanied by rapid changes in the K+ gradient resulting from K+ fluxes across the glial membrane. As a result of the reduced extracellular volume and increased tortuosity, the membrane fluxes produce larger changes in [K+]e in the more mature myelinated corpus callosum than before myelination. These conclusions also account for differences between membrane currents in cells in slices compared to those in tissue culture where the ECS is essentially infinite. The size and geometry of the ECS influence the membrane current patterns of glial cells and may have consequences for the role of glial cells in spatial buffering.
Citace poskytuje Crossref.org
Diffusion in brain extracellular space