Video Experimental Relacionado
Updated: Jul 14, 2026
11:33
Isolation and Kv Channel Recordings in Murine Atrial and Ventricular Cardiomyocytes
Published on: March 12, 2013
Subunidad beta4 del canal de sodio codificada por SCN4B en el síndrome congénito de QT largo
Argelia Medeiros-Domingo1, Toshihiko Kaku, David J Tester
1Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México.
Circulation
|June 27, 2007
Resumen
Se identificó una nueva mutación en el gen SCN4B, que codifica la subunidad Na(v) beta4, en un paciente con síndrome congénito de QT largo (LQTS). Este hallazgo implica que SCN4B es un nuevo gen de susceptibilidad para LQT3, una forma de síndrome de QT largo.
Área de la Ciencia:
- Genética cardiovascular Genética cardiovascular Genética cardiovascular Genética cardiovascular Genética cardiovascular
- Cardiología Molecular Cardiología Molecular
- Las canalopatías son patologías de los canales.
Sus antecedentes:
- El síndrome congénito de QT largo (LQTS) es un trastorno genético que causa ritmos cardíacos peligrosos, a menudo debido a mutaciones en los genes de los canales iónicos.
- Una parte significativa de los casos de LQTS carecen de un diagnóstico genético, lo que sugiere la participación de otros genes cardíacos.
- Los canales de sodio regulados por voltaje comprenden subunidades alfa y auxiliares beta; las subunidades beta son candidatos potenciales para arritmias hereditarias.
Objetivo del estudio:
- Para identificar la causa genética de LQTS en un paciente con síntomas inexplicables y pruebas genéticas negativas en genes conocidos de LQTS.
- Para investigar el papel de las subunidades beta de los canales de sodio en el síndrome congénito de QT largo.
- Para caracterizar el impacto funcional de una nueva mutación SCN4B en la corriente cardíaca de sodio.
Principales métodos:
- Análisis genético exhaustivo de genes LQTS establecidos y de los cuatro genes de subunidad beta del canal de sodio (SCN1B-4B).
- Análisis de segregación de la mutación identificada dentro de una familia de 3 generaciones y cribado en una cohorte de pacientes con LQTS genotipo negativo.
- Mutagénesis dirigida al sitio y expresión heteróloga en células HEK293 para evaluar los efectos funcionales de la mutación en la corriente tardía de sodio.
Principales resultados:
- Se identificó una nueva mutación de mal sentido, L179F (C535T), en el gen SCN4B en un paciente con prolongación QT severa y bloqueo atrioventricular.
- La mutación SCN4B (L179F) se co-segregó con LQTS en la familia y estuvo ausente en los controles.
- La expresión heteróloga reveló que la subunidad L179F-beta4 aumentó significativamente la corriente de sodio tardía, consistente con la fisiopatología LQTS.
Conclusiones:
- El gen SCN4B, que codifica la subunidad Na(v) beta4, es un nuevo gen de susceptibilidad para el síndrome congénito de QT largo.
- Este descubrimiento amplía el panorama genético de LQTS y proporciona un diagnóstico potencial para casos previamente inexplicables.
- Los hallazgos destacan la importancia de investigar las subunidades auxiliares en las canalopatías cardíacas.
Videos de Conceptos Relacionados
01:26Voltage-gated Ion Channels
Voltage-gated ion channels are transmembrane proteins that open and close in response to changes in the membrane potential. They are present on the membranes of all electrically excitable cells such as neurons, heart, and muscle cells.
Generally, all voltage-gated ion channels have a 'voltage-sensing domain' that spans the lipid bilayer. The charged residues in the sensor move in response to the membrane potential changes that open the channel allowing ions movement. There are several types of...
Generally, all voltage-gated ion channels have a 'voltage-sensing domain' that spans the lipid bilayer. The charged residues in the sensor move in response to the membrane potential changes that open the channel allowing ions movement. There are several types of...
01:26Voltage-gated Ion Channels
Voltage-gated ion channels are transmembrane proteins that open and close in response to changes in the membrane potential. They are present on the membranes of all electrically excitable cells such as neurons, heart, and muscle cells.
Generally, all voltage-gated ion channels have a 'voltage-sensing domain' that spans the lipid bilayer. The charged residues in the sensor move in response to the membrane potential changes that open the channel allowing ions movement. There are several types of...
Generally, all voltage-gated ion channels have a 'voltage-sensing domain' that spans the lipid bilayer. The charged residues in the sensor move in response to the membrane potential changes that open the channel allowing ions movement. There are several types of...
01:22Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers
Class I antiarrhythmic drugs are used to treat various types of arrhythmias or irregular heart rhythms. These drugs block the sodium (Na+) channels in the cardiac cells, thereby affecting the movement of electrical impulses across the heart. Class I antiarrhythmic drugs are divided into three subgroups: Class IA, Class IB, and Class IC, each with distinct mechanisms of action and effects on the heart.
Class 1A Antiarrhythmic Drugs: These drugs work by moderately blocking sodium channels,...
Class 1A Antiarrhythmic Drugs: These drugs work by moderately blocking sodium channels,...
01:28Mechanism of Cardiac Arrhythmias
Arrhythmias are irregular heart rhythms occurring when the heart's electrical impulses become abnormal. These disturbances can lead to various symptoms, depending on their severity and the underlying cause. Some common factors contributing to arrhythmias include hypoxia, ischemia, electrolyte imbalances, excessive catecholamine exposure, drug toxicity, and muscle overstretching. Arrhythmias can be classified into two main types based on the rate and site of origin of abnormal heart rhythms.
01:19Ion Channels
The movement of ions like sodium, potassium, and calcium into and out of the cell is essential to maintain the electrochemical gradient in living cells. The ion channels—a class of membrane transport proteins—help maintain this ionic gradient for the smooth functioning of physiological activities such as maintaining cell size and volume, conducting nerve impulses, and gas and nutrient exchange.
Ion channels are specialized integral membrane proteins on the plasma membrane that allow specific...
Ion channels are specialized integral membrane proteins on the plasma membrane that allow specific...
01:24Non-gated Ion Channels
Ion channels are specialized proteins on the plasma membrane that allow charged ions to pass down their electrochemical gradient. Their main function is to maintain the membrane potential which is critical for cell viability. These channels are either gated or non-gated and can transport more than a thousand ions within milliseconds for the cellular event to occur.
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.