[K(+)](e) increase accompanies many pathological states in the CNS and evokes changes in astrocyte morphology and glial fibrillary acidic protein expression, leading to astrogliosis. Changes in the electrophysiological properties and volume regulation of astrocytes during the early stages of astrocytic activation were studied using the patch-clamp technique in spinal cords from 10-day-old rats after incubation in 50 mM K(+). In complex astrocytes, incubation in high K(+) caused depolarization, an input resistance increase, a decrease in membrane capacitance, and an increase in the current densities (CDs) of voltage-dependent K(+) and Na(+) currents. In passive astrocytes, the reversal potential shifted to more positive values and CDs decreased. No changes were observed in astrocyte precursors. Under hypotonic stress, astrocytes in spinal cords pre-exposed to high K(+) revealed a decreased K(+) accumulation around the cell membrane after a depolarizing prepulse, suggesting altered volume regulation. 3D confocal morphometry and the direct visualization of astrocytes in enhanced green fluorescent protein/glial fibrillary acidic protein mice showed a smaller degree of cell swelling in spinal cords pre-exposed to high K(+) compared to controls. We conclude that exposure to high K(+), an early event leading to astrogliosis, caused not only morphological changes in astrocytes but also changes in their membrane properties and cell volume regulation.
- MeSH
- astrocyty fyziologie MeSH
- draslík farmakokinetika MeSH
- draslíkové kanály řízené napětím fyziologie MeSH
- financování organizované MeSH
- gliový fibrilární kyselý protein metabolismus MeSH
- glióza patofyziologie MeSH
- hypotonické roztoky farmakologie MeSH
- imunohistochemie MeSH
- koncentrace vodíkových iontů MeSH
- krysa rodu rattus MeSH
- membránové potenciály fyziologie účinky léků MeSH
- metoda terčíkového zámku MeSH
- mícha cytologie MeSH
- osmotický tlak MeSH
- potkani Wistar MeSH
- sodík metabolismus MeSH
- sodíkové kanály fyziologie MeSH
- velikost buňky MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
Red blood cell Na+ content as well as ouabain-resistant Na+ and Rb+ (K+) transport (susceptible or resistant to inhibition by loop diuretics) were determined in spontaneously hypertensive rats (SHR) and normotensive Brown Norway (BN) rats the erythrocytes of which were incubated in either saline or Mg(2+)-sucrose medium. Elevated ouabain-resistant Na+ net uptake contrasted with slightly decreased red blood cell Na+ content in SHR compared with BN rats. Acceleration of furosemide- and bumetanide-sensitive Na+ fluxes contributed to enhanced ouabain-resistant Na+ influx into SHR erythrocytes in saline medium, whereas higher furosemide- or bumetanide-resistant Na+ efflux caused greater ouabain-resistant Na+ efflux in Mg(2+)-sucrose medium. Furosemide- and bumetanide-resistant Rb+ leaks were augmented in SHR erythrocytes. The association of the disclosed ion transport alterations with blood pressure was examined in 20 recombinant inbred strains derived from F2 SHR x BN hybrids. Ouabain-resistant Na+ uptake as well as furosemide- and bumetanide-resistant Na+ inward leaks (but not red blood cell Na+ content or furosemide- and bumetanide-sensitive Na+ net uptake) cosegregated with systolic and pulse pressures but not diastolic pressure of the recombinant inbred strains. In contrast, neither ouabain-resistant Na+ efflux nor any component of ouabain-resistant Rb+ uptake correlated positively with blood pressure of the recombinant inbred strains. Increased ouabain-resistant Na+ influx was compensated for by accelerated ouabain-sensitive Na+ extrusion because red blood cell Na+ content was not elevated in the hypertensive strains. Thus, high cell Na+ turnover rates might be related to genetic hypertension if an altered Na+ inward leak would be less effectively compensated for in tissues involved in cardiovascular regulation.
- MeSH
- analýza rozptylu MeSH
- biologický transport MeSH
- bumetanid farmakologie MeSH
- draslík farmakokinetika MeSH
- erytrocyty * metabolismus MeSH
- furosemid farmakologie MeSH
- genetické markery MeSH
- hybridizace genetická MeSH
- hypertenze * patofyziologie MeSH
- krevní tlak genetika účinky léků MeSH
- krysa rodu rattus MeSH
- ouabain farmakologie MeSH
- potkani inbrední BN MeSH
- potkani inbrední SHR MeSH
- rubidium farmakokinetika MeSH
- sodík * farmakokinetika MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- práce podpořená grantem MeSH
The activity of transport adenosine triphosphatases (ATPases) in saponin-treated erythrocytes as well as the passive membrane permeability for 86Rb+ (K+), 45Ca2+ uptake (in the presence of orthovanadate) and the rate of Na(+)-H+ exchange in intact erythrocytes were studied in spontaneously hypertensive rats (SHR), Wistar-Kyoto (WKY) and Brown-Norway (BN.lx) rats. Higher Na+,K(+)-ATPase activity, lower Ca(2+)-ATPase activity, increased passive K+ permeability and greater 45Ca2+ uptake were observed in erythrocytes from SHR compared with BN.lx rats. Similar differences in the last two parameters were also disclosed by a comparison of SHR and WKY rats. The rate of Na(+)-H+ exchange in SHR erythrocytes was greater than in WKY rats but equal to that of BN.lx rats. A genetic analysis did not reveal a significant correlation between Na(+)-H+ exchange rate and blood pressure in F2 SHR x WKY hybrids.
- MeSH
- adenosintrifosfatasy * metabolismus MeSH
- draslík farmakokinetika MeSH
- erytrocyty * metabolismus MeSH
- hypertenze * metabolismus MeSH
- iontová výměna MeSH
- kationty * farmakokinetika MeSH
- krysa rodu rattus MeSH
- potkani inbrední BN MeSH
- potkani inbrední SHR MeSH
- potkani inbrední WKY MeSH
- protony MeSH
- sodík farmakokinetika MeSH
- vápník farmakokinetika MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- srovnávací studie MeSH
- MeSH
- draslík farmakokinetika MeSH
- glukosa metabolismus MeSH
- krysa rodu rattus MeSH
- vápník farmakokinetika MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- klinická studie MeSH
