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  • 1
    Electronic Resource
    Electronic Resource
    Compensation of low-pass filter properties of the current measuring internode in voltage clamped myelinated nerve fibres (1981)
    Springer
    European biophysics journal 7 (1981), S. 317-317 
    Details
    ISSN: 1432-1017
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02425448
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  • 2
    Electronic Resource
    Electronic Resource
    Incomplete sodium inactivation in nodes of ranvier treated with scorpion venom (1968)
    Springer
    Cellular and molecular life sciences 24 (1968), S. 41-42 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Voltage-clamp Versuche an markhaltigen Nervenfasern vonXenopus laevis ergaben, dass die Inaktivierung der Na-Permeabilität unter dem Einfluss von Skorpiongift extrem verlangsamt und unvollständig ist. Durch Aufspaltung der Variablenh der Ionentheorie in 2 voneinander unabhängige Komponenten kann der zeitliche Verlauf der Na-Permeabilität berechnet werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02136780
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  • 3
    Electronic Resource
    Electronic Resource
    A method for increasing the frequency response of voltage clamped myelinated nerve fibres (1981)
    Springer
    Pflügers Archiv 390 (1981), S. 288-289 
    Details
    ISSN: 1432-2013
    Keywords: Voltage clamp ; Myelinated nerve
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In voltage clamp experiments on myelinated nerve fibres the time resolution of the current measurement is limited by the low-pass characteristics of the internodes. We increased the corner frequency of the current passing internode by grounding one half of this internode externally. Using a simplified equivalent circuit we calculated an increase in the bandwidth of the internode by a factor of about 6. Consequently, the peak value of the recorded capacity current increased while its duration was considerably shortened.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00658278
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  • 4
    Electronic Resource
    Electronic Resource
    Die Wirkung von Skorpiongift auf die Ionenströme des Ranvierschen Schnürrings (1968)
    Springer
    Pflügers Archiv 303 (1968), S. 150-161 
    Details
    ISSN: 1432-2013
    Keywords: Node of Ranvier ; Sodium Inactivation ; Scorpion Venom ; Ranvierscher Schnürring ; Natrium-Inaktivierung ; Skorpiongift
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 1. Die Wirkung von Skorpiongift auf die Inaktivierung der Natrium-PermeabilitätP Na wurde in voltage-clamp-Experimenten an einzelnen markhaltigen Nervenfasern von Xenopus laevis untersucht. 2. Beim normalen Ruhepotential warP Na der vergifteten Membran stärker inaktiviert als an der unvergifteten Membran; bei starken Depolarisationen war die Inaktivierung jedoch unvollständig. 3. Der zeitliche Verlauf vonP Na konnte unter verschiedenen experimentellen Bedingungen mit den Hodgkin-Huxley-Gleichungen beschrieben werden, die wie folgt modifiziert wurden: a) die Variableh wurde durch eine schnelle Komponentex und eine langsame Komponentey ersetzt; b) die Komponentex nahm selbst bei Depolarisationen von mehr als 40 mV nicht auf Null ab.
    Notes: Summary 1. The action of scorpion venom on the inactivation of the sodium permeabilityP Na was studied in voltage-clamp experiments on single myelinated nerve fibres of Xenopus laevis. 2. At the normal resting potentialP Na of the poisoned membrane was more inactivated than the control; at large depolarizations inactivation was, however, incomplete. 3. The time course ofP Na under various experimental conditions could be described by theHodgkin-Huxley equations modified as follows: a) the variableh was split into a fast and a slow component (x andy, respectively); b) componentx did not vanish even for depolarizations by more than 40 mV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00592632
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  • 5
    Electronic Resource
    Electronic Resource
    Electrical responses of isolated nitella protoplasm — Excitations or artifacts? (1976)
    Springer
    Pflügers Archiv 361 (1976), S. 263-267 
    Details
    ISSN: 1432-2013
    Keywords: Isolated protoplasm ; Nitella ; Electrical responses ; RC network
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Isolated protoplasmic droplets of the alga Nifella were investigated with microelectrodes under current clamp conditions. The following observations were made: 1. Long pulses of either polarity yielded almost symmetric current-voltage relations. Near the rather small resting potential (inside negative) the measuring points lay on a straight line corresponding to an apparent surface membrane resistance of 1.7±0.45 kΩ (mean ± S.E.M.,n=5). 2. Experiments with various pulse programs revealed no mechanism comparable to Na inactivation but stressed the electrical symmetry of the droplet with respect to the resting potential. 3. Changes of the [Ca2+] in the bathing medium between 0 and 10 mM as well as of the pH between 5 and 9 did not influence the responses. Replacing K+ by Na+ (or vice versa) or exchanging NO 3 − for acetylglycine or Cl− was also ineffective. These observations are not consistent with a normal excitable surface membrane. Similar responses are obtained with a RC network which is described and which may have its substrate in histological peculiarities of the protoplasmic droplet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00587291
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  • 6
    Electronic Resource
    Electronic Resource
    Electrical responses of isolated protoplasm from Nitella (1975)
    Springer
    Pflügers Archiv 358 (1975), S. 179-187 
    Details
    ISSN: 1432-2013
    Keywords: Isolated Protoplasm ; Nitella ; Electrical Excitability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Isolated protoplasmic droplets of the algaNitella were investigated with microelectrodes in artificial vacuolar sap. The following observations were made: 1. Two types of preparations could be distinguished differing in size and in time of adaptation to artificial pond water but only slightly in their electrical behaviour. 2. The droplets proved to be electrically excitable in the sense that short current pulses elicited electrical responses which outlasted the stimuli. 3. The responses resembled nerve action potentials in shape and duration but they were graded and could be elicited as well in positive as in negative direction. Moreover, spontaneous changes of the normal resting potential (a few millivolts inside negative) did not influence their amplitudes. 4. In most cases the amplitudes of the responses grew with time and saturated after about 90 min. Before saturation the relation between stimulus strength and amplitude of responses was almost linear but became slightly S-shaped after saturation. The saturation value of the responses caused by 100 μs pulses of 1 μA/mm2 was taken as a standard response. In 32 experiments the standard response varied considerably between 2 and 90 mV and was 13 mV on the average. The observations suggest that quite different mechanisms are responsible for the transients of theNitella droplets and the all-or-none responses of nerve fibres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00583926
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  • 7
    Electronic Resource
    Electronic Resource
    Die Wirkung verschiedener Anionen auf den isolierten Ranvierschen Schnürring (1965)
    Springer
    Pflügers Archiv 282 (1965), S. 338-350 
    Details
    ISSN: 1432-2013
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The experiments were carried out on single circulated Ranvier nodes of Xenopus laevis and were concerned with the effect of replacing the NaCl in the Ringer's solution by NaNO3, NaSCN, sodium acetylglycinate, sodium pyroglutamate or Na2SO4. 2. Replacement of NaCl with NaNO3 etc. produced a slight hyperpolarization of 2–4 mV. NaNO3 and NaSCN decreased the resting membrane resistance by 15–25%. 3. The height of the action potential and the maximum rate of rise were reduced by 10–50%. The reduction was most pronounced with NaSCN. The effect on the falling phase was less prominent; it consisted mainly in a reduction of the maximum rate of repolarization. The threshold potential decreased by 2–4 mV. 4. Replacement of NaCl with NaNO3 etc. shifted the curve relating action potential amplitude or maximum rate of rise to membrane potential 5–15 mV along the voltage axis in a direction such that the fibre was more inactivated at resting membrane potential. Anodal polarization hence restored the spike amplitude and the maximum rate of rise to its normal values. 5. The depressing effect of NaNO3 etc. on spike amplitude and maximum rate of rise was reduced to about half its normal size by a fourfold increase of [Ca]0. 6. The experimental findings could be explained by assuming adsorption of external anions at the outer edge of the excitable membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00412508
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  • 8
    Electronic Resource
    Electronic Resource
    Die Wirkung von Skorpiongift auf die Ionenströme des Ranvierschen Schnürrings (1968)
    Springer
    Pflügers Archiv 303 (1968), S. 133-149 
    Details
    ISSN: 1432-2013
    Keywords: Node of Ranvier ; Ionic Currents ; Scorpion Venom ; Ranvierscher Schnürring ; Ionenströme ; Skorpiongift
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 1. Die Wirkung von Skorpiongift (10−6 g/ml) auf die Ionenströme einzelner markhaltiger Nervenfasern von Xenopus laevis wurde in voltage-clamp-Experimenten untersucht. 2. Skorpiongift beeinflußt sowohl die Natrium- als auch die Kalium-Permeabilität der Schnürringmembran. 3. Die hauptsächlichen Wirkungen des Skorpiongiftes auf die Natrium-PermeabilitätP Na sind: a) Die maximale Natrium-Permeabilität $$\bar P_{_{{\rm N}a} } $$ wird auf 60% ihres an der unvergifteten Membran gemessenen Wertes reduziert. b) Die Natriuminaktivierung wird stark verlangsamt und verläuft in zwei Phasen. c) Der zeitliche Verlauf vonP Na kann unter der Annahme beschrieben werden, daß die Variableh aus zwei Komponentenx undy besteht, deren Zeitkonstanten τ x und τ y 4 bzw. 200 mal so groß sind wie τ h der unvergifteten Membran. 4. Die Wirkungen des Skorpiongiftes auf die Kalium-PermeabilitätP K sind: a) Die maximale Kalium-PermeabilitätP K' wird auf etwa 35% ihres Normalwertes vermindert. b) Der Anstieg vonP K bei Depolarisation wird verlangsamt; zwei Phasen können unterschieden werden. 5. Die Wirkungen auf die Natrium-Inaktivierung und auf die Kalium-Permeabilität können die unter dem Einfluß von Skorpiongift beobachtete extreme Verlängerung des Aktionspotentials erklären.
    Notes: Summary 1. The action of scorpion venom (10−6 g/ml) on the ionic currents of single myelinated nerve fibres of Xenopus laevis was studied in voltage clamp experiments. 2. Scorpion venom was found to affect the sodium permeability as well as the potassium permeability of the nodal membrane. 3. The main effects of scorpion venom on the sodium permeabilityP Na are: a) The maximum sodium permeability $$\bar P_{_{{\rm N}a} } $$ is reduced to 60% of its value in the unpoisoned membrane. b) The sodium inactivation is markedly slowed and proceeds in two phases. c) The time course ofP Na can be described assuming that the variableh is the sum of two componentsx andy, whose time constants τ x and τ y are 4 and 200 times τh of the unpoisoned membrane. 4. The effects of scorpion venom on the potassium permeabilityP K are: a) The maximum potassium permeabilityP K' is reduced to about 35% of its normal value. b) The increase ofP K' upon depolarisation is slowed down; two phases can be distinguished. 5. The effects on sodium inactivation and potassium permeability may explain the extreme prolongation of the action potential under the influence of scorpion venom.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00592631
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  • 9
    Electronic Resource
    Electronic Resource
    Intracellular application of strong currents under current clamp conditions (1974)
    Springer
    Pflügers Archiv 350 (1974), S. 335-340 
    Details
    ISSN: 1432-2013
    Keywords: Current Clamp ; Current Source ; Metal Microelectrode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An electronic circuit is described consisting mainly of a current source with an output impedance near 1 GΩ and with a rise time of 16 μs. Combination of this circuit with a fine electropolished platinum microelectrode enables the application of rapid current steps of up to several microamperes to cells of low input resistance under current clamp conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00592641
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  • 10
    Electronic Resource
    Electronic Resource
    A method for electrical measurements on isolated protoplasmic droplets from Nitella (1974)
    Springer
    Pflügers Archiv 350 (1974), S. 341-346 
    Details
    ISSN: 1432-2013
    Keywords: Isolated Protoplasm ; Nitella Cells ; Excitability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A special recording chamber has been constructed which allows for the perfusion of the fragile protoplasmic droplets from Nitella cells while making electrical measurements on the preparation. Measurements were made of the potential of the interior of the droplet relative to the bathing medium, under resting conditions and during electrical stimulation. In a bathing medium whose cationic concentration resembled the natural vacuolar sap, a small resting potential of between 0 and −30 mV was observed. Stimulation with depolarizing current shocks of 100 μs in duration and of up to 0.28 mA/cm2 elicited active responses of up to 130 mV which outlasted the stimulus artifacts. The responses were graded but they resembled nerve action potentials in shape and duration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00592642
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