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Updated: Aug 8, 2026
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Ex Vivo Assessment of Contractility, Fatigability and Alternans in Isolated Skeletal Muscles
Published on: November 1, 2012
Los roles relativos de los mecanismos dependientes y independientes de Ca2 ((+) y Ca2 ((+) en la disfunción
1Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Circulation
|August 1, 1990
Resumen
La insuficiencia cardíaca hipoxica no es causada por niveles bajos de calcio. En cambio, la acumulación de fosfato inorgánico (Pi) y, en menor medida, la acidez, perjudica la contracción del músculo cardíaco durante la hipoxia.
Área de la Ciencia:
- Fisiología cardiovascular fisiología cardiovascular.
- Regulación del metabolismo
- Energética cardíaca Energética cardíaca
Sus antecedentes:
- La disfunción contráctil cardíaca es una consecuencia conocida de la hipoxia y la inhibición metabólica.
- Los mecanismos precisos, ya sea debido a la reducción del calcio activador o la acumulación de metabolitos inhibidores, siguen siendo objeto de debate.
Objetivo del estudio:
- Diferenciar las funciones del calcio intracelular ([Ca2+]i) y el fosfato inorgánico ([Pi]) en la disfunción contráctil hipóxica.
- Para investigar el impacto del pH intracelular (pHi) en la función cardíaca durante la hipoxia.
Principales métodos:
- Corazones de hurones perfundidos utilizados sometidos a condiciones hipóxicas controladas (10% O2).
- Se empleó la espectroscopia de resonancia magnética nuclear (RMN), incluida la RMN de flúor-19, para medir [Ca2+]i, [Pi] y pHi.
- La presión desarrollada ventricular izquierda cuantificada (LVDP) para evaluar la función contráctil.
Principales resultados:
- La hipoxia redujo el LVDP a aproximadamente el 60% de los valores de control.
- La RMN reveló un aumento de [Pi] y una leve acidosis intracelular (disminución del pHi) durante la hipoxia.
- Tanto el aumento [Pi] como la disminución de pHi se correlacionaron con la reducción de LVDP, con [Pi] mostrando una influencia dominante.
- [Ca2+]i al final de la diástole no cambió, mientras que el pico sistólico [Ca2+]i aumentó paradójicamente; la amplitud transitoria de Ca2+ no se correlacionó con la disminución de la presión.
Conclusiones:
- La insuficiencia contráctil en la hipoxia leve en estado estacionario está mediada principalmente por la acumulación de fosfato inorgánico ([Pi]).
- La acidosis intracelular (acumulación de H+) también contribuye a, pero es secundaria a, [Pi] en causar disfunción hipóxica.
- La disponibilidad reducida o la regulación del calcio activador ([Ca2+]i) no es la causa principal del deterioro contráctil en estas condiciones.
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