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Bases moleculares de la regulación a la baja de la corriente de rectificación hacia adentro de K (((+) acoplada a la
1Department of Pharmacology, University of Technology, Dresden, Germany. dobrev@rcs.urz.tu-dresden.de
Circulation
|November 21, 2001
Resumen
La fibrilación auricular crónica (FA) en humanos desregula hacia abajo la corriente de rectificación hacia adentro de K (((+) acoplada a la proteína G (I (((K,ACh)) y regula hacia arriba la corriente de rectificación hacia adentro de K (((+) (I (((K1)). Esta remodelación eléctrica en AF adapta los miocitos a altas tasas.
Área de la Ciencia:
- Cardiología Cardiología.
- Electrofisiología y electrofisiología.
- Biología Molecular Biología Molecular
Sus antecedentes:
- El sistema nervioso parasimpático está implicado en la patogénesis de la fibrilación auricular (FA).
- El papel de la corriente de rectificación hacia adentro de K (((+) acoplada a la proteína G (I (((K,ACh)) en la FA crónica sigue sin estar claro.
Objetivo del estudio:
- Investigar cambios en I(K,ACh) y su subunidad GIRK4 en miocitos auriculares humanos de pacientes con FA crónica.
- Examinar la relevancia funcional de las corrientes iónicas alteradas en AF.
Principales métodos:
- Registros electrofisiológicos en miocitos auriculares humanos aislados.
- Análisis cuantitativo de los niveles de ARNm de GIRK4 y Kir2.1 utilizando la reacción en cadena de la polimerasa de transcripción inversa competitiva.
- Evaluación de la duración del potencial de acción y la respuesta a la estimulación del receptor muscarínico.
Principales resultados:
- La densidad de I(K,ACh) se redujo en aproximadamente un 50% en los miocitos AF, con una disminución del ARNm GIRK4.
- La densidad de corriente de rectificación hacia adentro (I(K1) se duplicó en la AF, con un aumento del ARNm Kir2.1.
- La duración del potencial de acción se redujo en la FA y el acortamiento mediado por el receptor muscarínico se atenuó.
Conclusiones:
- La FA crónica conduce a la regulación ascendente transcripcional de I(K1) y a la regulación descendente de I(K,ACh) en las aurículas humanas.
- Estos cambios en los canales iónicos atenuan los efectos del receptor muscarínico en los potenciales de acción.
- Los miocitos auriculares regulan a la baja I ((K,ACh) para adaptarse a las altas tasas crónicas, contrarrestando los efectos de remodelación eléctrica.
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