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  1. Article: Space charge-limited conductance in lipid bilayer membranes.

    Neumcke, B / Läuger, P

    The Journal of membrane biology

    2013  Volume 3, Issue 1, Page(s) 54–66

    Abstract: A mathematical treatment is given for the flux of ions of one charge sign across lipid bilayer membranes. This treatment is a generalization of a previous analysis of the membrane conductance by D. Walz, E. Bamberg and P. Läuger which was restricted to ... ...

    Abstract A mathematical treatment is given for the flux of ions of one charge sign across lipid bilayer membranes. This treatment is a generalization of a previous analysis of the membrane conductance by D. Walz, E. Bamberg and P. Läuger which was restricted to systems with negligible space charge in the membrane. The present theory includes space charge effects, and it is no longer assumed that the electric field strength in the membrane is constant. It is found that the ohmic membrane conductivity λ0 is reduced by space charges; if only ions of one charge sign are soluble in the membrane, λ0 approaches a limiting value for increasing concentration of the permeable ion in the aqueous solution. The theory also predicts the range in which the constant field approximation is valid. It is found that space charge effects become predominant when the mean concentration of the permeable ion in the membrane exceeds 5×10(-5) M. The currentvoltage characteristic of the membrane remains practically linear even in the presence of a high space charge. It is therefore concluded that the experimentally observed nonlinearity is caused mainly by the distortion of the potential energy profile of an ion due to image forces.
    Language English
    Publishing date 2013-10-31
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3082-x
    ISSN 1432-1424 ; 0022-2631
    ISSN (online) 1432-1424
    ISSN 0022-2631
    DOI 10.1007/BF01868006
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  2. Article: Transport mechanism of hydrophobic ions through lipid bilayer membranes.

    Ketterer, B / Neumcke, B / Läuger, P

    The Journal of membrane biology

    2013  Volume 5, Issue 3, Page(s) 225–245

    Abstract: Evidence is presented that the transport of lipid-soluble ions through bilayer membranes occurs in three distinct steps: (1) adsorption to the membranesolution interface; (2) passage over an activation barrier to the opposite interface; and (3) ... ...

    Abstract Evidence is presented that the transport of lipid-soluble ions through bilayer membranes occurs in three distinct steps: (1) adsorption to the membranesolution interface; (2) passage over an activation barrier to the opposite interface; and (3) desorption into the aqueous solution. Support for this mechanism comes from a consideration of the potential energy of the ion, which has a minimum in the interface. The formal analysis of the model shows that the rate constants of the individual transport steps can be determined from the relaxation of the electric current after a sudden change in the voltage. Such relaxation experiments have been carried out with dipicrylamine and tetraphenylborate as permeable ions. In both cases the rate-determining step is the jump from the adsorption site into the aqueous phase. Furthermore, it has been found that with increasing ion concentration the membrane conductance goes through a maximum. In accordance with the model recently developed by L. J. Bruner, this behavior is explained by a saturation of the interface, which leads to a blocking of the conductance at high concentrations.
    Language English
    Publishing date 2013-10-31
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3082-x
    ISSN 1432-1424 ; 0022-2631
    ISSN (online) 1432-1424
    ISSN 0022-2631
    DOI 10.1007/BF01870551
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  3. Article: Diversity of sodium channels in adult and cultured cells, in oocytes and in lipid bilayers.

    Neumcke, B

    Reviews of physiology, biochemistry and pharmacology

    1990  Volume 115, Page(s) 1–49

    MeSH term(s) Animals ; Cells, Cultured ; Electric Conductivity ; Electrophysiology ; Ion Channel Gating/physiology ; Lipid Bilayers/metabolism ; Oocytes/metabolism ; Sodium Channels/metabolism
    Chemical Substances Lipid Bilayers ; Sodium Channels
    Language English
    Publishing date 1990
    Publishing country Germany
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 125106-5
    ISSN 1617-5786 ; 0303-4240
    ISSN (online) 1617-5786
    ISSN 0303-4240
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  4. Article: Natriumkanäle in elektrisch erregbaren Membranen.

    Neumcke, B

    Die Naturwissenschaften

    1985  Volume 72, Issue 1, Page(s) 17–24

    Abstract: Properties of sodium channels in electrically excitable membranes can be obtained from sodium currents, gating currents, sodium-current fluctuations and currents through single channels. Gating processes in sodium channels are related to intramembranous ... ...

    Title translation Sodium channels in electrically excitable membranes.
    Abstract Properties of sodium channels in electrically excitable membranes can be obtained from sodium currents, gating currents, sodium-current fluctuations and currents through single channels. Gating processes in sodium channels are related to intramembranous charge displacements and are modified by toxins, local anaesthetics and chemical agents. From the results a schematic diagram of a sodium channel can be derived.
    MeSH term(s) Action Potentials ; Animals ; Cell Membrane/drug effects ; Cell Membrane/physiology ; Electrophysiology ; Ion Channels/drug effects ; Ion Channels/physiology ; Ion Channels/ultrastructure ; Microscopy, Electron, Scanning ; Muscles/physiology ; Neurons/physiology ; Ranidae ; Tetrodotoxin/pharmacology
    Chemical Substances Ion Channels ; Tetrodotoxin (4368-28-9)
    Language German
    Publishing date 1985-01
    Publishing country Germany
    Document type English Abstract ; Journal Article
    ZDB-ID 123257-5
    ISSN 1432-1904 ; 0028-1042
    ISSN (online) 1432-1904
    ISSN 0028-1042
    DOI 10.1007/bf00405322
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  5. Article: Electrophysiology and morphology of myelinated nerve fibers. VII. The myelinated nerve: some unsolved problems.

    Neumcke, B

    Experientia

    1983  Volume 39, Issue 9, Page(s) 976–979

    MeSH term(s) Animals ; Cell Membrane Permeability ; Electrophysiology ; Ion Channels/metabolism ; Kinetics ; Membrane Potentials ; Nerve Fibers, Myelinated/physiology ; Sodium/metabolism
    Chemical Substances Ion Channels ; Sodium (9NEZ333N27)
    Language English
    Publishing date 1983-09-15
    Publishing country Switzerland
    Document type Journal Article ; Review
    ZDB-ID 1972-0
    ISSN 0014-4754
    ISSN 0014-4754
    DOI 10.1007/bf01989762
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  6. Article: Differential activation of ATP-sensitive potassium channels during energy depletion in CA1 pyramidal cells and interneurones of rat hippocampus.

    Zawar, C / Neumcke, B

    Pflugers Archiv : European journal of physiology

    2000  Volume 439, Issue 3, Page(s) 256–262

    Abstract: In the hippocampus, pyramidal cells are more vulnerable than granule cells and interneurones to energy depletion during hypoxia and ischaemia. The aim of the present study was to explore whether this difference is related to the lower expression of ... ...

    Abstract In the hippocampus, pyramidal cells are more vulnerable than granule cells and interneurones to energy depletion during hypoxia and ischaemia. The aim of the present study was to explore whether this difference is related to the lower expression of adenosine 5'-triphosphate-sensitive potassium (K(ATP)) channels in pyramidal cells compared to other hippocampal neurones. Hippocampal slices were prepared from 10- to 13-day-old rats, and CAI pyramidal cells and interneurones of the stratum radiatum were visually and electrophysiologically identified. Energy depletion was produced by removing glucose from the bath or by inhibiting mitochondrial metabolism using rotenone. In the perforated-patch configuration, both protocols elicited outward currents in only a minority of the pyramidal cells but in most of the interneurones. The currents started to develop 9-57 min after glucose deprivation and 4-16 min after rotenone application and reversed near the K+ equilibrium potential. Bath-applied diazoxide (0.3 mM), an opener of K(ATP) channels, could activate additional currents. The sulphonylureas tolbutamide (0.5 mM) or glibenclamide (20 microM), two blockers of K(ATP) channels, totally inhibited the currents induced by energy depletion and activated by diazoxide. The results demonstrate the differential activation of K(ATP) channels during energy depletion in pyramidal cells and interneurones, and suggest that channel activation is neuroprotective against the deleterious effects of energy depletion.
    MeSH term(s) ATP-Binding Cassette Transporters ; Animals ; Diazoxide/pharmacology ; Electric Stimulation ; Electrophysiology ; Energy Metabolism/drug effects ; Glucose/metabolism ; Hippocampus/cytology ; Hippocampus/drug effects ; In Vitro Techniques ; Interneurons/drug effects ; Interneurons/metabolism ; KATP Channels ; Patch-Clamp Techniques ; Potassium Channel Blockers ; Potassium Channels/agonists ; Potassium Channels, Inwardly Rectifying ; Pyramidal Cells/drug effects ; Pyramidal Cells/metabolism ; Rats ; Rats, Wistar ; Rotenone/pharmacology ; Sulfonylurea Compounds/pharmacology ; Uncoupling Agents/pharmacology
    Chemical Substances ATP-Binding Cassette Transporters ; KATP Channels ; Potassium Channel Blockers ; Potassium Channels ; Potassium Channels, Inwardly Rectifying ; Sulfonylurea Compounds ; Uncoupling Agents ; uK-ATP-1 potassium channel ; Rotenone (03L9OT429T) ; Glucose (IY9XDZ35W2) ; Diazoxide (O5CB12L4FN)
    Language English
    Publishing date 2000-01
    Publishing country Germany
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 6380-0
    ISSN 1432-2013 ; 0031-6768
    ISSN (online) 1432-2013
    ISSN 0031-6768
    DOI 10.1007/s004249900184
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  7. Article: Fluctuation of Na and K currents in excitable membranes.

    Neumcke, B

    International review of neurobiology

    1982  Volume 23, Page(s) 35–67

    MeSH term(s) Animals ; Batrachotoxins/pharmacology ; Benzocaine/pharmacology ; Diffusion ; Electric Conductivity ; Extracellular Space/physiology ; Ion Channels/drug effects ; Ion Channels/physiology ; Kinetics ; Mathematics ; Membranes/physiology ; Motor Neurons/physiology ; Neurons, Afferent/physiology ; Onium Compounds/pharmacology ; Potassium/metabolism ; Protons ; Random Allocation ; Saxitoxin/pharmacology ; Sodium/metabolism ; Tetraethylammonium ; Tetraethylammonium Compounds/pharmacology ; Tetrodotoxin/pharmacology ; Toxins, Biological/pharmacology ; Venoms/pharmacology
    Chemical Substances Batrachotoxins ; Ion Channels ; Onium Compounds ; Protons ; Tetraethylammonium Compounds ; Toxins, Biological ; Venoms ; Saxitoxin (35523-89-8) ; Tetrodotoxin (4368-28-9) ; Tetraethylammonium (66-40-0) ; Sodium (9NEZ333N27) ; trimethyloxonium (RG47L030LR) ; Potassium (RWP5GA015D) ; Benzocaine (U3RSY48JW5)
    Language English
    Publishing date 1982
    Publishing country United States
    Document type Comparative Study ; Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 209876-3
    ISSN 0074-7742
    ISSN 0074-7742
    DOI 10.1016/s0074-7742(08)60621-2
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  8. Article: Differences in electrophysiological properties of motor and sensory nerve fibres.

    Neumcke, B

    Journal de physiologie

    1981  Volume 77, Issue 9, Page(s) 1135–1138

    Abstract: Differences in the electrophysiological properties of amphibian motor and sensory nerve fibres are reviewed. It is concluded that the differences are mainly due to an altered K-conduction system which suggests the presence of different K channels in the ... ...

    Abstract Differences in the electrophysiological properties of amphibian motor and sensory nerve fibres are reviewed. It is concluded that the differences are mainly due to an altered K-conduction system which suggests the presence of different K channels in the two types of nerve fibres.
    MeSH term(s) Action Potentials ; Animals ; Electric Stimulation ; Electrophysiology ; Ion Channels/physiology ; Kinetics ; Motor Neurons/physiology ; Neurons, Afferent/physiology ; Potassium/metabolism ; Potassium/pharmacology ; Rana esculenta
    Chemical Substances Ion Channels ; Potassium (RWP5GA015D)
    Language English
    Publishing date 1981-05
    Publishing country France
    Document type Comparative Study ; Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 219137-4
    ISSN 0021-7948 ; 0368-3834
    ISSN 0021-7948 ; 0368-3834
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  9. Article: 1/f noise in membranes.

    Neumcke, B

    Biophysics of structure and mechanism

    1978  Volume 4, Issue 3, Page(s) 179–199

    Abstract: The present situation of 1/f noise in the passage of ions across membranes is examined. A survey of biological and synthetic membranes is given at which a 1/f frequency dependence has been observed in the spectrum of voltage or current fluctuations. ... ...

    Abstract The present situation of 1/f noise in the passage of ions across membranes is examined. A survey of biological and synthetic membranes is given at which a 1/f frequency dependence has been observed in the spectrum of voltage or current fluctuations. Empirical relations and theories of 1/f noise in membranes are critically discussed.
    MeSH term(s) Biological Transport, Active ; Cell Membrane/physiology ; Diffusion ; Electrophysiology ; Ion Channels ; Membrane Potentials ; Membranes, Artificial ; Models, Biological ; Nerve Fibers, Myelinated/physiology ; Potassium/metabolism ; Sodium/metabolism ; Time Factors
    Chemical Substances Ion Channels ; Membranes, Artificial ; Sodium (9NEZ333N27) ; Potassium (RWP5GA015D)
    Language English
    Publishing date 1978-07-12
    Publishing country Germany
    Document type Journal Article ; Review
    ZDB-ID 125324-4
    ISSN 0340-1057
    ISSN 0340-1057
    DOI 10.1007/bf02426084
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  10. Article: Some similarities between processes at biological membranes and lipid bilayers.

    Neumcke, B

    Biophysics of structure and mechanism

    1976  Volume 2, Issue 1, Page(s) 93–94

    Abstract: Several processes at biological membranes can be simulated by experiments with artificial lipid bilayer membranes. Three selected examples are discussed: The uncoupler induced proton permeability of lipid bilayers, the initiation of action potential like ...

    Abstract Several processes at biological membranes can be simulated by experiments with artificial lipid bilayer membranes. Three selected examples are discussed: The uncoupler induced proton permeability of lipid bilayers, the initiation of action potential like voltage responses in lipid membranes, and the reconstitution of active cation pumps across planar lipid bilayers or lipid vesicles.
    MeSH term(s) Lipids ; Membranes/metabolism ; Membranes/physiology ; Membranes, Artificial
    Chemical Substances Lipids ; Membranes, Artificial
    Language English
    Publishing date 1976-04-15
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 125324-4
    ISSN 0340-1057
    ISSN 0340-1057
    DOI 10.1007/bf00535655
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