@article{Blanchard1999Verat-6811,
  year={1999},
  title={Veratridine-mediated Ca2+ dynamics and exocytosis in Paramecium cells},
  volume={169},
  issn={0022-2631},
  journal={Journal of Membrane Biology},
  pages={155--165},
  author={Blanchard, Marie-Pierre and Klauke, Norbert and Zitzmann, Sabine and Plattner, Helmut}
}

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    <dc:creator>Blanchard, Marie-Pierre</dc:creator>
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    <dc:language>eng</dc:language>
    <dc:date rdf:datatype="http://www.w3.org/2001/XMLSchema#dateTime">2011-03-24T17:29:21Z</dc:date>
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    <dc:creator>Plattner, Helmut</dc:creator>
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    <dcterms:abstract xml:lang="eng">We analyzed [Ca2+]i transients in Paramecium cells in response to veratridine for which we had previously established an agonist effect for trichocyst exocytosis (Erxleben &amp; Plattner, 1994. J. Cell Biol. 127:935 945; Plattner et al., 1994. J. Membrane Biol. 158:197 208). Wild-type cells (7S), nondischarge strain nd9 28°C and trichocyst-free strain  trichless  (tl), respectively, displayed similar, though somewhat diverging time course and plateau values of [Ca2+]i transients with moderate [Ca2+]o in the culture/assay fluid (50 mM&lt;br /&gt;or 1 mM). In 7S cells which are representative for a normal reaction, at [Ca2+]o = 30 nM (c.f. [Ca2+]i rest 4 = ~50 to 100 nM), veratridine produced only a small cortical [Ca2+]i transient. This increased in size and spatial distribution at [Ca2+]o = 50 mM of 1 mM. Interestingly with unusually high yet nontoxic [Ca2+]o = 10 mM, [Ca2+]i transients were much delayed and also reduced, as is trichocyst exocytosis. We interpret our results as follows. (i) With [Ca2+]o = 30 nM, the restricted residual response observed is due to Ca2+ mobilization from subplasmalemmal stores. (ii) With moderate [Ca2+]o = 50 mM to 1 mM, the established membrane labilizing effect of veratridine may activate not only subplasmalemmal stores but also Ca2+o influx from the medium via so far unidentified (anteriorly enriched) channels. Visibility of these phenomena is best in tl cells, where free docking sites allow for rapid Ca2+ spread, and least in 7S cells, whose perfectly assembled docking sites may  consume  a large part of the [Ca2+]i increase. (iii) With unusually high [Ca2+]o, mobilization of cortical stores and/or Ca2+o influx may be impeded by the known membrane stabilizing effect of Ca2+o counteracting the labilizing/channel activating effect of veratridine. (iv) We show these effects to be reversible, and, hence, not to be toxic side-effects, as confirmed by retention of injected calcein.&lt;br /&gt;(v) Finally, Mn2+ entry during veratridine stimulation, documented by Fura-2 fluorescence quenching, may indicate activation of unspecific Me2+ channels by veratridine. Our data have some bearing on analysis of other cells, notably neurons, whose response to veratridine is of particular and continous interest.</dcterms:abstract>
    <dcterms:title>Veratridine-mediated Ca2+ dynamics and exocytosis in Paramecium cells</dcterms:title>
    <dcterms:issued>1999</dcterms:issued>
    <dcterms:bibliographicCitation>First publ. in: Journal of Membrane Biology 169 (1999), pp. 155-165</dcterms:bibliographicCitation>
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    <dc:contributor>Klauke, Norbert</dc:contributor>
    <dc:contributor>Plattner, Helmut</dc:contributor>
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