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  • 1
    Electronic Resource
    Electronic Resource
    Ionic selectivity, saturation and block in gramicidin A channels: (1977)
    Springer
    The journal of membrane biology 31 (1977), S. 383-417 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A model for the gramicidin A channel is proposed which extends existing models by adding a specific cationic binding site at each entrance to the channel. The binding of ions to these outer channel sites is assumed to shift the energy levels of the inner sites and barriers and thereby alter the channel conductance. The resulting properties are analyzed theoretically for the simplest case of two inner sites and a single energy barrier. This four-site model (two outer and two inner) predicts that the membrane potential at zero current (U 0) should be described by a Goldman-Hodgkin-Katz equation with concentration-dependent permeability ratios. The coefficients of the concentration-dependent terms are shown to be related to the peak energy shifts of the barrier and to the binding constants of the outer sites. The theory also predicts the channel conductance in symmetrical solutions to exhibit three limiting behaviors, from which the properties of the outer and inner sites can be characterized. In two-cation symmetrical mixtures the conductance as a function of mole fraction is shown to have a minimum, and the related phenomenon of inhibition and block exerted by one ion on the other is explained explicitly by the theory. These various phenomena, having ion interactions in a multiply occupied channel as a common physical basis, are all related (by the theory) through a set of measurable parameters describing the properties of the system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01869414
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  • 2
    Electronic Resource
    Electronic Resource
    Ionic selectivity, saturation, and block in gramicidin a channels (1978)
    Springer
    The journal of membrane biology 40 (1978), S. 97-116 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A theory, recently developed by Sandblom, Eisenman and Neher (1977) for the conductance of single gramicidin A channels predicts three limiting behaviors of the relation between conductance and salt concentration. These are: (i) a saturating behavior resembling a simple adsorption isotherm at medium and high concentrations, (ii) a decrease in conductance at the highest obtainable concentrations and (iii) deviations from the isotherm at very low concentrations. Features i and ii have been described before. Experimental evidence for point iii is given here. The new feature points towards interactions among ions in the channel at ionic concentrations as low as 1–10mm. Particular emphasis is given to the behavior at very low salt concentrations and the experimental problems encountered in this situation. In addition, mutual blocking effects among monovalent ions in symmetrical salt mixtures are characterized and found to be in satisfactory agreement with theoretical expectations, based upon the single salt conductance data presented here and zero-current potentials in salt mixtures to be described in a subsequent paper.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01871143
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  • 3
    Electronic Resource
    Electronic Resource
    Direct modulation of synaptic vesicle priming by GABA B receptor activation at a glutamatergic synapse (2003)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 424 (2003), S. 775-778 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Second messenger cascades involving G proteins and calcium are known to modulate neurotransmitter release. A prominent effect of such a cascade is the downmodulation of presynaptic calcium influx, which markedly reduces evoked neurotransmitter release. Here we show that G-protein-mediated ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature01859
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  • 4
    Electronic Resource
    Electronic Resource
    Intracellular calcium dependence of transmitter release rates at a fast central synapse (2000)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 406 (2000), S. 889-893 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Calcium-triggered fusion of synaptic vesicles and neurotransmitter release are fundamental signalling steps in the central nervous system. It is generally assumed that fast transmitter release is triggered by elevations in intracellular calcium concentration ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35022702
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  • 5
    Electronic Resource
    Electronic Resource
    Molecular biology meets microelectronics (2001)
    [s.l.] : Nature Publishing Group
    Nature biotechnology 19 (2001), S. 114-114 
    Details
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] The marriage of living cells and silicon devices is not without practical difficulties. Technical problems and the characteristics of cell–substrate interactions have, so far, prevented the routine integration of biology and microelectronics for the design of biosensors and medical ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/84359
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  • 6
    Electronic Resource
    Electronic Resource
    Regulation of calcium influx by second messengers in rat mast cells (1988)
    [s.l.] : Nature Publishing Group
    Nature 334 (1988), S. 499-504 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Biphasic increases in the free intracellular calcium concentration, consisting of a large initial transient followed by a sustained elevation, are frequently observed in non-excitable cells following stimulation. In rat peritoneal mast cells a cAMP- and Ca-activated chloride current can ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/334499a0
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  • 7
    Electronic Resource
    Electronic Resource
    Intracellularly injected tetanus toxin inhibits exocytosis in bovine adrenal chromaffin cells (1986)
    [s.l.] : Nature Publishing Group
    Nature 324 (1986), S. 76-78 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] We examined cultured bovine adrenal chromaffin cells, isolated as described6, using the whole-cell configuration of the patch-clamp technique7. This allows one to monitor exocytosis using membrane capacitance as a measure of the cell surface area. Capacitance and surface area change considerably as ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/324076a0
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  • 8
    Electronic Resource
    Electronic Resource
    Receptor-operated Ca channels (1987)
    [s.l.] : Nature Publishing Group
    Nature 326 (1987), S. 242-242 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] THERE is hardly any tissue where receptor-operated calcium channels have not been postulated. Evidence from biochemical and tracer flux studies indicates that they are involved in many diverse cellular functions (see ref. 1 for a review). In contrast, electrophysiologists have had until recently ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/326242a0
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  • 9
    Electronic Resource
    Electronic Resource
    Calcium dependence of the rate of exocytosis in a synaptic terminal (1994)
    [s.l.] : Nature Publishing Group
    Nature 371 (1994), S. 513-515 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Synaptic terminals of goldfish retinal bipolar neurons1'2 have been previously shown to be well-suited for the study of secretion using combined measurements of [Ca2+]j and capacitance3. These techniques were used in single bipolar cell synaptic terminals filled with the photolysable Ca2+-chelator ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/371513a0
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  • 10
    Electronic Resource
    Electronic Resource
    Delay in vesicle fusion revealed by electrochemical monitoring of single secretory events in adrenal chromaffin cells (1992)
    [s.l.] : Nature Publishing Group
    Nature 356 (1992), S. 60-63 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Isolated bovine chromaffin cells were used to study catecholamine release under patch-clamp whole-cell recording conditions. We applied short step depolarizations to open voltage-gated calcium channels7, thereby injecting calcium to activate secretion8. When the tip of a carbon-fibre ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/356060a0
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