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La activación del quimiorreflejo tónico no contribuye al aumento de la actividad del nervio simpático muscular en la
P van de Borne1, R Oren, E A Anderson
1Cardiovascular Center, University of Iowa, Iowa City 52242, USA.
Circulation
|September 15, 1996
Resumen
En pacientes con insuficiencia cardíaca, el aumento de la actividad nerviosa simpática no es causado por quimiorreceptores hiperactivos. Respirar oxígeno puro no alteró la actividad del nervio simpático, refutando la hipótesis del quimiorreflejo.
Área de la Ciencia:
- Fisiología cardiovascular fisiología cardiovascular.
- La neurociencia es la neurociencia.
- Investigación de la insuficiencia cardíaca Investigación de la insuficiencia cardíaca.
Sus antecedentes:
- La insuficiencia cardíaca se asocia con un aumento de la actividad del sistema nervioso simpático.
- Esta activación simpática puede deberse a una alteración de la señalización del tronco cerebral o a una mayor sensibilidad de los quimiorreceptores.
- El papel de los aferentes quimiorreceptores excitatorios en el impulso simpático de la insuficiencia cardíaca no está claro.
Objetivo del estudio:
- Investigar la hipótesis de que la activación tónica de los aferentes quimiorreceptores excitatorios contribuye a una elevada actividad simpática en la insuficiencia cardíaca.
- Para determinar si la desactivación de los quimiorreceptores al respirar oxígeno al 100% afecta la actividad nerviosa simpática en pacientes con insuficiencia cardíaca.
Principales métodos:
- La actividad del nervio simpático se midió desde el nervio peroneal en 12 pacientes con insuficiencia cardíaca crónica (clase III de la NYHA, LVEF 24±2%).
- Se realizaron mediciones mientras los pacientes respiraban aire ambiente y oxígeno al 100% para desactivar los quimiorreceptores.
- La actividad del nervio simpático en reposo también se registró en 9 controles sanos.
Principales resultados:
- Los pacientes con insuficiencia cardíaca mostraron una actividad nerviosa simpática en reposo significativamente mayor (59±5 ráfagas/min) en comparación con los controles (36±4 ráfagas/min).
- Respirar oxígeno al 100% aumentó la saturación de oxígeno (94% a 99%) pero no alteró significativamente la actividad del nervio simpático muscular (798±122 U/min en aire ambiente frente a 824±35 U/min en 100% O2).
- La presión arterial no se vio afectada por la administración de oxígeno.
Conclusiones:
- El estudio concluye que el aumento de la actividad simpática eferente a la circulación muscular en pacientes con insuficiencia cardíaca no se explica por la activación tónica de los aferentes quimiorreflejos excitatorios.
- Estos hallazgos sugieren que otros mecanismos son responsables del aumento del impulso simpático observado en la insuficiencia cardíaca.
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