Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Electronic Resource  (4)
  • Inorganic Chemistry  (2)
  • ATP  (1)
  • Anticonvulsant  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 93 (1993), S. 279-287 
    ISSN: 1432-1106
    Keywords: Valproate ; Anticonvulsant ; Sodium inactivation ; Patch clamp ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cultured rat hippocampal neurons with short processes were investigated using the whole cell voltage clamp under conditions appropriate for isolating Na+ currents. After incubation of the neuron culture for a period of 15–30 min in 1 mM sodium valproate, several parameters of the Na+ current were changed. The peak Na+ conductance g p, measured using hyperpolarizing prepulses, was reduced by valproate in a voltage-dependent manner. In the membrane voltage range from -30 to +20 mV, this reduction showed a linear dependence on voltage, increasing from about zero to approximately 30% of g p, the maximum peak Na+ conductance of the neuron. At the holding voltage of -70 mV, the inactivation parameter h t8 decreased from 0.88 in the control to 0.64 in the valproate solution. This reduction originated mainly from a 10 mV shift in the sigmoid relation between h t8 and membrane voltage along the voltage axis to hyperpolarizing potentials. The decay of the maximum peak Na+ current (inactivation) could be fitted by a biexponential function. Time constants of the fast and slow component at -20 mV decreased in valproate by about 50%. Valproate also retarded the recovery from inactivation, as determined at the holding voltage. The sigmoid recovery from inactivation could reasonably be described by an exponential function with time constant τ r and delay time Δt. Both τ r and At increased more than 200% in valproate. Our results indicate that valproate affected the Na+ current in hippocampal neurons in a way that contributed to a considerable depression of Na+ reactivation. This explains the frequency-dependent inhibition of action potentials as observed in mammalian central nervous tissue and may be the principal action of the anticonvulsant.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-2013
    Keywords: Key words Mouse dorsal root ganglion (DRG) neurons ; Hyperpolarization-activated current ; Ih ; cAMP ; ATP ; Rp- and Sp-cAMPS ; Resting membrane potential ; Activation curve
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  In mouse dorsal root ganglion (DRG) neurons the activation curve of the hyperpolarization-activated current (I h) shifted towards depolarized potentials when cAMP was present in the pipette. The relation between the midpoint potential and cAMP concentration could be described by a Hill function with a half-maximal concentration of 0.55 μM cAMP, reflecting a direct action of cAMP on the channel. With 5 mM ATP and a saturating concentration of cAMP an additional shift of the midpoint potential is observed which can be explained by phosphorylation. Application of Rp-cAMPS and Sp-cAMPS support the hypothesis of both a phosphorylation pathway and a direct effect exhibited by these molecules. The bell-shaped curves, relating the time constants for the slow and fast current components to the voltage, shifted towards positive membrane potentials when cAMP and ATP were in the pipette. The fully activated I h/voltage relation and the reversal potential were not dependent on the presence of cAMP or ATP in the pipette. The mean resting membrane potential of –59 mV, using the perforated-patch configuration, hyperpolarized in the presence of extracellular CsCl. In the whole-cell configuration the resting membrane potential was significantly more negative at 0 μM cAMP (–61 mV) than at 100 μM cAMP (–57 mV). Thus, the activation of I h, regulated by both the intracellular cAMP and the ATP concentration, may influence the excitability of DRG neurons.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 189 (1930), S. 101-112 
    ISSN: 0863-1786
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1. Es wird die Eignung der selenigen Säure für analytische Zwecke gezeigt und.
    Additional Material: 12 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Über die Bildung von [Na(POCl3)4]+-Komplexionen. Leitfähigkeits-, Raman- und NMR-Untersuchungen im System Phosphorylchlorid-Natriumtetrachloroaluminat bzw. analoger VerbindungenLeitfähigkeiten, Raman- sowie 27Al-, 23Na- und 31P-NMR-Spektren des Systems POCl3-NaAlCl4 wurden in Abhängigkeit vom Molenbruch x(NaAlCl4) im lösungsmittelreichen Gebiet gemessen. Zusätzlich erfolgte die Registrierung der Raman-Spektren der Lösungen von NaFeCl4, LiAlCl4, LiFeCl4 und KAlCl4 in POCl3. In den Li+- bzw. Na+-Ionen enthaltenden Proben konnte unter bestimmten Bedingungen ein von Temperatur und Salzkonzentration abhängiger Phasenübergang von der flüssigen in die feste Phase beobachtet werden. Deutliche Veränderungen in den Ramanspektren der Elektrolytlösungen im Vergleich zum reinen Lösungsmittel POCl3 belegen die Existenz von intermolekularen Wechselwirkungen, durch die das POCl3-Molekül beeinflußt wird. Die Annahme der Bildung von [M(POCl3)4]+-Solvaten (M = Li, Na) aufgrund der Ramanergebnisse wird durch die Resultate der NMR-Spektroskopie unterstützt.
    Notes: The system POCl3-NaAlCl4 was investigated by measuring the conductivity and the Raman and NMR spectra (27Al, 23Na and 31P) as a function of the mol fraction x of NaAlCl4 in POCl3. Additionally, Raman spectra of POCl3 solutions of NaFeCl4, LiAlCl4, LiFeCl4, and KAlCl4 were recorded. In solutions containing Li+ or Na+ ions a liquid to solid (or jelly) phase transition was observed under certain conditions, dependent on salt concentration and temperature. Observed changes in the Raman spectra of the electrolyte solutions in comparison to the pure solvent POCl3 demonstrate the existence of interactions. Clearly, the POCl3 eigenfrequencies and hence the molecules are pertubed. The formation of [M(POCl3)4]+ complexes (M = Li, Na) can be deduced from the Raman measurements. NMR investigations support this conclusion. For assigning of Raman spectra, (Li+, K+) cation and ([FeCl4]-, [SbCl6]-) anion substitutions were employed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...