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  • 1
    Electronic Resource
    Electronic Resource
    Mitochondrial release of Ca2+ during sustained nerve activity in the electric organ of Torpedo marmorata (1980)
    Springer
    Experimental brain research 38 (1980), S. 405-417 
    Details
    ISSN: 1432-1106
    Keywords: Calcium ; Mitochondria ; Cholinergic nerve ending ; Torpedo ; Transmitter release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The calcium content of mitochondria isolated from the Torpedo electric organ was determined by atomic absorption spectroscopy. The mitochondrial fraction was found to contain 830 ng-atom Ca/mg protein. For comparison a fraction of isolated nerve endings contained 250 ng-atom Ca/mg protein. When tissue was continuously stimulated at a frequency of 5 Hz via the electromotor nerves, the Ca content of the mitochondrial fraction which is likely to contain both pre- and postsynaptic mitochondria was reduced proportionally to the decrease in transmitter content of the isolated nerve terminal fraction. After 5,000 pulses, the mitochondrial fraction had lost 80% of its Ca contents. When tissue was stimulated after previous perfusion with d-tubocurarine and blockade of electrical response the same number of pulses caused only a loss of 20–40% in the Ca content of the mitochondrial fraction. Release of transmitter was not affected by d-tubocurarine. The results suggest that repetitive stimulation in the absence of postsynaptic receptor blockade causes loss of Ca from both nerve terminal mitochondria and mitochondria of the myotube-derived electrocytes. In the presence of d-tubocurarine Ca is lost from presynaptic mitochondria only.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237520
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Preferential calcium staining of mitochondria in stimulated cholinergic nerve endings (1980)
    Springer
    Experimental brain research 38 (1980), S. 419-424 
    Details
    ISSN: 1432-1106
    Keywords: Mitochondria ; Calcium staining ; Cholinergic nerve ending ; Torpedo ; Transmitter release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The fine structure of the Torpedo electric organ was investigated during different functional states using fixation media with elevated calcium concentrations. When electric tissue was stimulated (5,000 pulses, 5 Hz) and subsequently fixed in an s-collidine buffered aldehyde fixative containing 5 mM CaCl2 mitochondria in both nerve terminals and postsynaptic electroplaque cells showed electron-dense deposits. When tissue blocks were stimulated in the presence of d-tubocurarine (250 μM) which blocked electrical response deposits were restricted to presynaptic mitochondria. Electron-dense deposits were never observed in unstimulated tissue. The observations suggest that after stimulation mitochondria have an increased calcium binding capacity. In conjunction with previous biochemical findings (Schmidt and Zimmermann, 1980), we suggest that this increased binding capacity is due to a previous stimulation induced loss of calcium from activated mitochondria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237521
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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