Inhibitory actions of synthesised polyamine spider toxins and their analogues on Ca2+-activated Cl- currents recorded from cultured DRG neurones from neonatal rats.
Neurosci Lett
; 251(2): 117-20, 1998 Jul 24.
Article
em En
| MEDLINE
| ID: mdl-9718988
ABSTRACT
The whole cell variant of the patch clamp technique was used to investigate the actions of polyamine spider toxins and their analogues on high voltage-activated Ca2+ currents and Ca2+-activated Cl- currents (I(Cl(Ca))). The actions of synthesised FTX (putative natural toxin from the American funnel web spider), sFTX-3.3, Orn-FTX-3.3, Lys-FTX-3.3, and argiotoxin-636 on cultured dorsal root ganglion neurones from neonatal rats were investigated. Synthesised FTX (1 microM) inhibited I(Cl(Ca)) but did not inhibit high voltage-activated Ca2+ currents. In contrast, sFTX-3.3 (10 microM) inhibited both high voltage-activated Ca2+ currents and the associated I(Cl(Ca)) in near equal proportions. Argiotoxin-636 (1-10 microM) inhibited I(Cl(Ca)) evoked by Ca2+ entry through voltage-activated channels and by intracellular photorelease of Ca2+ from a caged precursor DM-nitrophen. This data indicates that synthesised FTX and argiotoxin-636 directly inhibit Ca2+-activated Cl- channels. In conclusion, the potency of polyamines as non-selective inhibitors of Ca2+ channels and Ca2+-activated Cl- channels is in part determined by the presence of a terminal arginine and this may involve an interaction between terminal guanidino groups and Ca2+ binding sites.
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Base de dados:
MEDLINE
Assunto principal:
Poliaminas
/
Venenos de Aranha
/
Bloqueadores dos Canais de Cálcio
/
Cálcio
/
Canais de Cloreto
/
Gânglios Espinais
/
Neurônios
Limite:
Animals
Idioma:
En
Ano de publicação:
1998
Tipo de documento:
Article