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Research and Development of High-performance Explosives
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Los potenciales de acción deben admitir calcio para evocar la liberación del transmisor
1Department of Molecular and Cell Biology, University of California, Berkekey 94720.
Nature
|March 14, 1991
Resumen
La liberación de neurotransmisores depende del calcio interno, no sólo de la tensión. Elevar el calcio interno sin influjo, incluso sin potenciales de acción, desencadenó la liberación, apoyando la hipótesis del calcio para la señalización neuronal.
Área de la Ciencia:
- La neurociencia es la neurociencia.
- Biología celular Biología celular.
- Neurotransmisión de las neuronas.
Sus antecedentes:
- Dos hipótesis explican la liberación de neurotransmisores: la hipótesis del calcio y la hipótesis del voltaje del calcio.
- La hipótesis del calcio postula que los iones de calcio desencadenan la liberación después de que la despolarización abre canales.
- La hipótesis de voltaje de calcio sugiere que la despolarización desencadena directamente la liberación a través de cambios de conformación de proteínas inducidos por voltaje en presencia de calcio.
Objetivo del estudio:
- Investigar los mecanismos subyacentes a la liberación de neurotransmisores en la unión neuromuscular del cangrejo.
- Para diferenciar entre la hipótesis del calcio y la hipótesis del calcio-voltaje.
Principales métodos:
- La afluencia de calcio fue bloqueada usando iones de cobalto o manganeso en una solución de Ringer libre de calcio.
- La concentración interna de calcio ([Ca2+]i) se elevó utilizando un compuesto de calcio enjaulado.
- La liberación del transmisor se midió en la unión neuromuscular del cangrejo.
- Fura-2 fue utilizado para medir los niveles intracelulares de calcio.
Principales resultados:
- Cuando se bloqueaba la afluencia de calcio, el calcio interno elevado por sí solo era suficiente para causar la liberación de neurotransmisores.
- Los potenciales de acción presinápticos no afectaron la liberación del transmisor bajo estas condiciones.
- Los resultados indican que la despolarización no se requiere directamente para desencadenar la liberación cuando el calcio interno es alto.
Conclusiones:
- Los hallazgos apoyan fuertemente la hipótesis del calcio para la liberación de neurotransmisores.
- Los mecanismos de señalización neuronal están impulsados principalmente por la dinámica del calcio intracelular.
- Los canales de calcio controlados por voltaje juegan un papel crucial en el inicio del proceso de liberación dependiente del calcio.
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