RESUMEN

El ion Ca²⁺ cumple múltiples funciones celulares. En el músculo liso de las vías aéreas participa de forma importante en la contracción. Los estímulos hormonales y neurogénicos generan incrementos en la concentración de Ca²⁺ intracelular ([Ca²⁺]i); la fuente para el incremento de Ca²⁺ es intracitoplasmática y extracitoplasmática. Para lograr este aumento de la [Ca²⁺]i es necesaria la participación de proteínas membranales y del retículo sarcoplásmico. Dentro de estas proteínas se encuentra el intercambiador Na⁺/Ca²⁺ (NCX) que se localiza en la membrana plasmática y actúa como un cotransportador de intercambio iónico. Su función principal es sacar un Ca²⁺ del citoplasma al espacio extracelular e introducir tres Na⁺ del espacio extracelular al citoplasma, sin gasto de ATP, y contribuir así a mantener los niveles basales de [Ca²⁺]i. Sin embargo, cuando diferentes agonistas broncoconstrictores activan canales catiónicos inespecíficos y éstos incrementan las concentraciones intracelulares de Ca²⁺ y Na⁺, este último ion activa la llamada fase reversa del NCX (NCX_REV), invirtiéndose entonces su función, es decir, ahora introduce Ca²⁺ y saca Na⁺ al espacio extracelular. Este artículo refiere algunos indicios que apuntan a que la inhibición del NCX_REV tendría relevancia como terapia adyuvante en pacientes asmáticos y muestra, por primera vez, evidencias experimentales de la funcionalidad del NCX_REV en el músculo liso de las vías aéreas del humano.

PALABRAS CLAVE

Músculo liso de la vía aérea, intercambiador Na⁺/Ca²⁺, KB-R7943, SEA 0400, SN-6.

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