Inactivation of human sodium channels and the effect of tocainide.
Pflugers Arch
; 415(6): 693-700, 1990 Mar.
Article
em En
| MEDLINE
| ID: mdl-2159618
ABSTRACT
The inactivation of the sodium channels in human medulloblastoma cells was investigated with the whole-cell recording technique. The potential dependence of inactivation ("inactivation curve") was determined by imposing a series of prepulses of varying amplitude on the membrane potential and measuring the maximum sodium current flowing after each prepulse at the test potential of -20 mV. The time dependence of inactivation was investigated by determining inactivation curves with prepulses of variable duration. A prolongation of the prepulse increased the degree of inactivation, even when the prepulse duration was much greater than the time constant for fast inactivation. This is explained by the existence of two additional states of "intermediate" inactivation of the sodium channel, the transition to which is slower than that to the state of fast inactivation and faster than that to the state of slow inactivation. The antiarrhythmic drug tocainide had no effect on fast inactivation, but a strong effect on intermediate inactivation. This explains the use dependence of this drug. The reaction model given by Chiu (1977) for the transitions from the open into the closed state of inactivation and vice versa is extended.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Canais de Sódio
/
Neoplasias Cerebelares
/
Lidocaína
/
Meduloblastoma
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Revista:
Pflugers Arch
Ano de publicação:
1990
Tipo de documento:
Article