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  • 1
    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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    Paper (German National Licenses)
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  • 2
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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