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La liberación de Ca2+ inducida por el inositol 1,4,5-trisfosfato es un fenómeno de estado estacionario controlado por
L Missiaen1, H De Smedt, G Droogmans
1Laboratorium voor Fysiologie, KUL Campus Gasthuisberg, Leuven, Belgium.
Nature
|June 18, 1992
Resumen
Las bajas concentraciones de inositol 1,4,5-trisfosfato (InsP3) causan una rápida liberación de calcio (Ca2+) de las reservas. La liberación adicional es más lenta, lo que sugiere que las reservas se vuelven menos sensibles a InsP3 a medida que se agotan, apoyando un mecanismo de liberación de estado estacionario.
Área de la Ciencia:
- Biología celular Biología celular.
- La bioquímica es la bioquímica.
- Fisiología Fisiología Fisiología.
Sus antecedentes:
- El inositol 1,4,5-trisfosfato (InsP3) desencadena una rápida liberación de calcio intracelular (Ca2+) en el cuerpo.
- La liberación bifásica de Ca2+ tiene dos mecanismos propuestos: liberación de todo o nada o de estado estacionario.
- Estudios previos mostraron heterogeneidad del receptor InsP3 in vitro.
Objetivo del estudio:
- Investigar el mecanismo de la liberación bifásica de Ca2+ provocada por InsP3.3.
- Para determinar si el agotamiento de las reservas de Ca2+ afecta la sensibilidad InsP3.
Principales métodos:
- Los experimentos se llevaron a cabo utilizando células de músculo liso A7r5 permeabilizadas.
- Las células fueron incubadas en un medio libre de Ca2+ y cargadas con 45Ca2+.
- Se midió la liberación de Ca2+ inducida por InsP3, seguida de recarga y reestimulación.
Principales resultados:
- La cantidad de Ca2+ restante después de la liberación inicial fue independiente de los niveles iniciales de Ca2+ almacenados.
- Los almacenes parcialmente agotados mostraron una menor sensibilidad a InsP3.
- Las reservas de recarga restauraron la sensibilidad InsP3, permitiendo una mayor liberación de Ca2+.
Conclusiones:
- La liberación de Ca2+ de las reservas se produce a través de un mecanismo de estado estacionario.
- El contenido almacenado de Ca2+ influye en la sensibilidad InsP3, y el agotamiento la reduce.
- Este hallazgo concilia la liberación bifásica de Ca2+ con las propiedades del receptor InsP3.
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