Contributions of a transient outward current to repolarization in human atrium.
Am J Physiol
; 257(6 Pt 2): H1773-81, 1989 Dec.
Article
em En
| MEDLINE
| ID: mdl-2557769
ABSTRACT
Conventional microelectrode recordings combined with enzymatic cell dispersion methods and a single microelectrode voltage-clamp technique were used to record transmembrane action potentials and ionic currents in isolated single myocytes and in excised segments of human right atrium. Recordings of the outward current(s), which is responsible for the resting potential and early repolarization of the action potential in human right atrium, consistently showed that this tissue has 1) a relatively small inwardly rectifying background potassium current (IK1) which generates the resting potential in mammalian ventricular tissue and Purkinje fibers, and 2) a large time- and voltage-dependent, but Ca2(+)-independent, transient outward current. A somewhat similar K+ current was originally described in neurons and recently has also been identified in a variety of mammalian cardiac tissues. As expected from previous work, this transient outward current in human atrium is blocked by 4-aminopyridine (4-AP; 0.5 mM) and exhibits time- and voltage-dependent inactivation and reactivation. Measurements of action potential shape changes and phasic tension as a function of stimulus frequency, or after 4-AP application, show that in human atrium this current can produce pronounced changes in both the early repolarization of the action potential and force generation.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Coração
Tipo de estudo:
Prognostic_studies
Limite:
Aged
/
Humans
/
Middle aged
Idioma:
En
Revista:
Am J Physiol
Ano de publicação:
1989
Tipo de documento:
Article
País de afiliação:
Canadá
País de publicação:
EEUU
/
ESTADOS UNIDOS
/
ESTADOS UNIDOS DA AMERICA
/
EUA
/
UNITED STATES
/
UNITED STATES OF AMERICA
/
US
/
USA