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Changes of IK, ATP current density and allosteric modulation during chronic atrial fibrillation / 中华医学杂志(英文版)
Chinese Medical Journal ; (24): 1161-1166, 2005.
Artigo em Inglês | WPRIM | ID: wpr-288260
ABSTRACT
<p><b>BACKGROUND</b>Atrial fibrillation (AF) is the most common supraventricular arrhythmia in clinical practice. Chronic atrial fibrillation (CAF) is associated with ionic remodeling. However, little is known about the activity of ATP-sensitive potassium current (IK, ATP) during CAF. So we studied the changes of IK, ATP density and allosteric modulation of ATP-sensitivity by intracellular pH during CAF.</p><p><b>METHODS</b>Myocardium samples were obtained from the right auricular appendage of patients with rheumatic heart disease complicated with valvular disease in sinus rhythm (SR) or CAF. There were 14 patients in SR group and 9 patients in CAF group. Single atrial cells were isolated using an enzyme dispersion technique. IK, ATP was recorded using the whole-cell and inside-out configuration of voltage-clamp techniques. In whole-cell model, myocytes of SR and CAF groups were perfused with simulated ischemic solution to elicit IK, ATP. In inside-out configuration, the internal patch membranes were exposed to different ATP concentrations in pH 7.4 and 6.8.</p><p><b>RESULTS</b>Under simulated ischemia, IK, ATP current density of CAF group was significantly higher than in SR group [(83.5 +/- 10.8) vs. (58.7 +/- 8.4) pA/pF, P < 0.01]. IK, ATP of the two groups showed ATP concentration-dependent inhibition. The ATP concentration for 50% current inhibition (IC50) for the SR group was significantly different in pH 7.4 and pH 6.8 (24 vs. 74 micromol/L, P < 0.01). The IC50 did not change significantly in CAF group when the pH decreased from 7.4 to 6.8.</p><p><b>CONCLUSIONS</b>During CAF, IK, ATP current density was increased and its allosteric modulation of ATP-sensitivity by intracellular pH was diminished.</p>
Assuntos
Texto completo: DisponíveL Índice: WPRIM (Pacífico Ocidental) Assunto principal: Farmacologia / Fisiologia / Fibrilação Atrial / Canais de Potássio / Trifosfato de Adenosina / Doença Crônica / Relação Dose-Resposta a Droga / Regulação Alostérica / Concentração de Íons de Hidrogênio / Metabolismo Limite: Adulto / Feminino / Humanos / Masculino Idioma: Inglês Revista: Chinese Medical Journal Ano de publicação: 2005 Tipo de documento: Artigo

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Texto completo: DisponíveL Índice: WPRIM (Pacífico Ocidental) Assunto principal: Farmacologia / Fisiologia / Fibrilação Atrial / Canais de Potássio / Trifosfato de Adenosina / Doença Crônica / Relação Dose-Resposta a Droga / Regulação Alostérica / Concentração de Íons de Hidrogênio / Metabolismo Limite: Adulto / Feminino / Humanos / Masculino Idioma: Inglês Revista: Chinese Medical Journal Ano de publicação: 2005 Tipo de documento: Artigo