Differences in outward currents between neonatal and adult rabbit ventricular cells.
Am J Physiol
; 266(3 Pt 2): H1184-94, 1994 Mar.
Article
em En
| MEDLINE
| ID: mdl-8160822
In adult rabbit ventricular preparations, action potential duration is significantly increased when stimulation frequency is increased from 0.1 to 1.0 Hz. In neonatal preparations, a similar change in stimulation frequency produced no significant increase in action potential duration. To identify the ionic basis for this difference, we studied different outward currents in single myocytes from papillary muscle and from epicardial tissue of adult and neonatal rabbits. The densities of the outward currents in neonatal cells were about one-half of the current density in adult cells. The density of the voltage-activated transient outward current (I(to1)) was smaller in cells from papillary muscle than in cells from epicardium in adult and newborn rabbits. We found major differences in the kinetic behavior of I(to1) between adult and neonatal cells: 1) the rate of apparent inactivation was faster in neonatal cells, and 2) the recovery from inactivation was significantly faster in neonatal cells, with a time constant of 113 vs. 1,356 ms. We propose that this marked difference in the recovery from inactivation of I(to1) is the basis for the difference in frequency dependence of action potential duration.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Envelhecimento
/
Coração
/
Animais Recém-Nascidos
Limite:
Animals
Idioma:
En
Revista:
Am J Physiol
Ano de publicação:
1994
Tipo de documento:
Article
País de afiliação:
México
País de publicação:
Estados Unidos