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Sensibilidad al calcio de la liberación de glutamato en un terminal de tipo cáliz
J H Bollmann1, B Sakmann, J G Borst
1Max-Planck-Institute for Medical Research, Department of Cell Physiology, Jahnstrasse 29, D-69120 Heidelberg, Germany. jbollman@mpimf-heidelberg.mpg.de
Science (New York, N.Y.)
|August 11, 2000
Resumen
Este estudio revela una alta sensibilidad al calcio en las sinapsis auditivas del tronco cerebral de la rata, donde un pequeño aumento en el calcio intracelular desencadena rápidamente la liberación de glutamato, lo que afecta la función sináptica.
Área de la Ciencia:
- La neurociencia es la neurociencia.
- Fisiología Sináptica Fisiología Sináptica
- Neurobiología Auditiva Neurobiología auditiva.
Sus antecedentes:
- La eficacia sináptica está regulada por la concentración de calcio intracelular presináptico ([Ca2+]i).
- Comprender el papel del calcio en la liberación de neurotransmisores es crucial para el procesamiento auditivo.
Objetivo del estudio:
- Para cuantificar la sensibilidad al calcio de la liberación de glutamato en una sinapsis auditiva del tronco cerebral de una rata.
- Para comparar la liberación evocada por el calcio con la liberación evocada por el potencial de acción fisiológica.
Principales métodos:
- La fotólisis láser de calcio enjaulado se utilizó para controlar con precisión el [Ca2+] presináptico i.
- La liberación de glutamato se midió en respuesta a los transitorios de calcio controlados.
- Se generaron curvas de concentración de calcio-respuesta para la liberación.
Principales resultados:
- Un aumento de [Ca2+]i a 1 micromolar fue suficiente para provocar la liberación de glutamato.
- Se produjo un rápido agotamiento de la piscina de vesículas liberables a [Ca2+]i >30 micromolares en 0,5 milisegundos.
- Los patrones de liberación fisiológica podrían ser replicados por un aumento de [Ca2+]i a aproximadamente 10 micromolares.
Conclusiones:
- La sinapsis auditiva del tronco cerebral exhibe una alta sensibilidad al calcio para la liberación de glutamato.
- La distinción entre los mecanismos de liberación de fase y retrasada puede ser menos pronunciada de lo que se suponía anteriormente.
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