I(Kr) contributes to the altered ventricular repolarization that determines long-term cardiac memory.
Cardiovasc Res
; 71(1): 88-96, 2006 Jul 01.
Article
em En
| MEDLINE
| ID: mdl-16626671
ABSTRACT
OBJECTIVE:
Cardiac memory (CM) is characterized by an altered T-wave morphology, which reflects altered repolarization gradients. We hypothesized that the delayed rectifier currents, I(Kr) and I(Ks), might contribute to these repolarization changes.METHODS:
We studied conscious, chronically instrumented dogs paced from the postero-lateral left ventricular (LV) wall at rates 5-10% faster than sinus rate for 3 weeks. ECGs during sinus rhythm were recorded on days 0, 7, 14 and 21 of pacing. Within 3 weeks, CM achieved steady state, hearts were excised, and epicardial and endocardial tissues and myocytes were studied.RESULTS:
In unpaced controls, action potential duration to 50% and 90% repolarization (APD) in epicardium was shorter than in endocardium (P < 0.05); in CM epicardial APD increased at CL > or = 500 ms, while endocardial APD was either unchanged or decreased such that the transmural gradient seen in controls diminished (P < 0.05). A transmural I(Kr) gradient occurred in controls (epicardium>endocardium, P < 0.05) and was reversed in CM. No I(Ks) transmural gradient was found in controls, while in CM endocardial I(Ks) was greater than epicardial at greater than +50 mV. Canine ERG (cERG) mRNA and protein in epicardium > endocardium in controls (P < 0.05), and this difference was lost in CM. Expression levels of KCNQ1 and KCNE1 protein were similar in all groups.CONCLUSIONS:
A transcriptionally induced change in epicardial I(Kr) contributes to the altered ventricular repolarization that characterizes CM.
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Coleções:
01-internacional
Temas:
Geral
Base de dados:
MEDLINE
Assunto principal:
Pericárdio
/
Potenciais de Ação
/
Canais de Potássio Corretores do Fluxo de Internalização
/
Miócitos Cardíacos
Limite:
Animals
Idioma:
En
Revista:
Cardiovasc Res
Ano de publicação:
2006
Tipo de documento:
Article
País de afiliação:
Estados Unidos