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  • Aplysia neuron  (1)
  • Naspike  (1)
  • Stereochemistry  (1)
  • barium current  (1)
  • 1
    Electronic Resource
    Electronic Resource
    The stereochemical configuration of the natural 23,25,26-trihydroxyvitamin D"3
    Amsterdam : Elsevier
    FEBS Letters 156 (1983), S. 321-324 
    Details
    ISSN: 0014-5793
    Keywords: 23,25,26-Trihydroxyvitamin D"3 ; 25-Hydroxyvitamin D"3-26,23-lactone ; Co-chromatography ; Metabolic pathway ; Stereochemistry ; Vitamin D"3 metabolite
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0014-5793(83)80521-3
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Separation of ionic currents in the somatic membrane of frog sensory neurons (1984)
    Springer
    The journal of membrane biology 78 (1984), S. 19-28 
    Details
    ISSN: 1432-1424
    Keywords: frog sensory neuron ; internal perfusion ; Naspike ; Ca spike ; ionic currents ; Ca current
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Electrical properties of isolated frog primary afferent neurons were examined by suction pipette technique, which combines internal perfusion with current or voltage clamp using a switching circuit with a single electrode. When K+ in the external and internal solutions was totally replaced with Cs+, extremely prolonged Ca spikes, lasting for 5 to 10 sec, and Na spikes, having a short plateau phase of 10 to 15 msec, were observed in Na+-free and Ca2+-free solutions, respectively. Under voltage clamp, Ca2+ current (I Ca) appeared at around −30 mV and maximum peak current was elicited at about 0 mV. With increasing test pulses to the positive side,I Ca became smaller and flattened but did not reverse. Increases of [Ca] o induced a hyperbolic increase ofI Ca and also shifted itsI-V curve along the voltage axis to the more positive direction. Internal perfusion of F− blockedI Ca time-dependently. The Ca channel was permeable to foreign divalent cations in the sequence ofI Ca〉I Ba〉I Sr≫I Mn〉I Zn. Organic Ca-blockers equally depressed the divalent cation currents dose- and time-dependently without shifting theI-V relationships, while inorganic blockers suppressed these currents dose-dependently and the inhibition appeared much stronger in the order ofI Ba=I Sr〉I Ca〉I Mn=I Zn.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01872528
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Reduction of the voltage-dependent calcium current inAplysia neurons by pentobarbital (1986)
    Springer
    Cellular and molecular neurobiology 6 (1986), S. 293-305 
    Details
    ISSN: 1573-6830
    Keywords: Aplysia neuron ; calcium channel ; barium current ; pentobarbital ; voltage clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Effects of pentobarbital on the calcium current ofAplysia neurons were investigated under current- and voltage-clamp conditions using the conventional two-microelectrode technique. 2. Pentobarbital attenuated the progressive broadening of repeated action potentials of somata, suggesting a reduction in the calcium current. 3. When calcium ion was replaced with barium ion in the perfusing solution, in which neither sodium nor potassium ions carried transmembrane currents, the barium current (I Ba) which flowed through the calcium channel of the cell membrane was generated by depolarizing pulses of several hundred milliseconds applied every 1 min from a holding potential of - 50 mV. TheI Ba was not affected by tetrodotoxin (30µM). The current was decreased by pentobarbital (0.1–5 mM) in a dose-dependent manner. The inhibition was much greater at a lower pH of the perfusate, indicating that the uncharged form of the agent was responsible. 4. The voltage-dependent inactivation of theI Ba proceeded with two time constants [190 ± 21 and 2020 ± 146 msec (N = 4) at - 10 mV], both of which were shortened by adding 1 mM pentobarbital [to 120 ± 18 and 540 ± 51 msec (N = 4), respectively]. 5. TheI Ba recovered from the inactivation with two time constants [60 ± 7 and 871 ± 76 msec (N = 3) at - 50 mV]. The anesthetic (1 mM) prolonged both of them, to 124 ± 20 and 1480 ± 172 msec (N = 3), respectively, resulting in a use-dependent depression of the current at 2-Hz stimulation. 6. Pentobarbital reduced theI Ba to a greater extent when the holding potential was more positive (- 30 instead of - 50 mV), indicating a higher affinity of the drug to the inactivated state of the channel. 7. These findings suggest that the attenuation of the progressive broadening of successive spikes by pentobarbital is due to a decrease in the voltage- and time-dependent calcium current, ending in depression of transmitter release from the nerve terminal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00711115
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    Paper (German National Licenses)
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