Ca(2+) and Na(+) contribute to the swelling of differentiated neuroblastoma cells induced by equinatoxin-II.
Toxicon
; 38(11): 1547-60, 2000 Nov.
Article
em En
| MEDLINE
| ID: mdl-10775755
ABSTRACT
Equinatoxin-II (EqTx-II), a cytotoxic protein (mol.wt 20 kDa) isolated from the sea anemone Actinia equina, was found to consistently increase the three-dimensional projected area of differentiated neuroblastoma (NG108-15) cells provided Ca(2+) was present in the medium. No swelling was detected when external NaCl was replaced by sucrose, but replacement of NaCl by Na-isethionate did not prevent the swelling, as revealed by confocal laser scanning microscopy. In addition, microspectrofluorometric measurements in cells preloaded with the Ca(2+) indicator fura-2/AM revealed that EqTx-II (100 nM) markedly increased the fluorescence (F(340)/F(380)) ratio indicating a rise of intracellular Ca(2+) concentration ([Ca(2+)](i)). The elevation of [Ca(2+)](i) exhibited two components that seem to be related to the kinetics of EqTx-II-induced Ca(2+) entry since pretreatment of cells with Ca(2+)-ATPase inhibitors (thapsigargin), Ca(2+) channel blockers (nifedipine and Gd(3+)) or prolonged exposure to a high K(+) (75 mM) medium did not alter EqTx-II-induced Ca(2+) signals. As far as we know, this is the first demonstration that EqTx-II causes swelling of neuroblastoma cells and that this effect is correlated both with an increase of [Ca(2+)](i) and needs the presence of extracellular Na(+). It is suggested that EqTx-II has the ability to insert into the plasma membrane of neuroblastoma cells and to form pores altering the membrane permeability and the intracellular osmolality, inducing a marked influx of water into the cells.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Sódio
/
Cálcio
/
Venenos de Cnidários
/
Citotoxinas
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Neuroblastoma
Limite:
Animals
Idioma:
En
Revista:
Toxicon
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
França
País de publicação:
ENGLAND
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ESCOCIA
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GB
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GREAT BRITAIN
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INGLATERRA
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REINO UNIDO
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SCOTLAND
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UK
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UNITED KINGDOM