omega-Agatoxin-IVA-sensitive calcium channels in bovine chromaffin cells.
FEBS Lett
; 336(2): 259-62, 1993 Dec 27.
Article
em En
| MEDLINE
| ID: mdl-8262241
ABSTRACT
A large component of the whole-cell currents through Ca2+ channels in bovine adrenomedullary chromaffin cells has been shown to be insensitive to both L-type and N-type Ca2+ channel blockers, suggesting the existence of a third type of Ca2+ channel. In the present paper, omega-agatoxin-IVA (AgTx), a selective blocker of P-type Ca2+ channels in mammalian neurons, has been used to investigate the presence of this subtype of Ca2+ channel in bovine chromaffin cells. Barium currents (IBa) through Ca2+ channels were recorded in whole-cell patch-clamped bovine chromaffin cells. IBa was blocked by AgTx in a dose-dependent and irreversible manner. At the maximal concentration used (1 microM), AgTx inhibited IBa by 49.5 +/- 3%. Such a blockade was also present when bovine chromaffin cells were pretreated with 10 microM furnidipine, a novel 1,4-dihydropyridine L-type channel blocker, and after treatment with 1 microM of the N-type channel blocker, omega-conotoxin GVIA (CgTx). A combination of these three types of Ca2+ channel blockers suppressed the macroscopic Ba2+ currents by 88%. We conclude that bovine chromaffin cells, in addition to N- and L-type Ca2+ channels, possess a P-like component in their whole-cell currents through the Ca2+ channels.
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Base de dados:
MEDLINE
Assunto principal:
Venenos de Aranha
/
Bloqueadores dos Canais de Cálcio
/
Medula Suprarrenal
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
Idioma:
En
Revista:
FEBS Lett
Ano de publicação:
1993
Tipo de documento:
Article
País de afiliação:
Espanha