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Efectos de los nuevos agentes inotrópicos en la sensibilidad Ca++ de las proteínas contráctiles
Circulation
|March 1, 1986
Resumen
Los nuevos fármacos cardiotónicos, el sulmazol y el pimobendano, mejoran la contracción del músculo cardíaco al aumentar la sensibilidad del miofillamento al calcio. Este efecto de sensibilización al calcio contribuye a su acción inotrópica positiva en el músculo cardíaco.
Área de la Ciencia:
- Cardiología Cardiología.
- Farmacología Farmacología.
- Fisiología Muscular Fisiología Muscular
Sus antecedentes:
- La contracción del músculo cardíaco está regulada por el calcio intracelular, pero esta relación no es fija.
- Los nuevos fármacos inotrópicos positivos pueden modular esta relación, afectando la contractilidad del corazón.
- El estudio de la sensibilidad al calcio en las fibras cardíacas despellejadas permite un control preciso de las condiciones iónicas.
Objetivo del estudio:
- Investigar el mecanismo de acción de los nuevos fármacos cardiotónicos, el sulmazol y el pimobendano.
- Para determinar si estos fármacos modulan la sensibilidad de los miofilmentos cardíacos al calcio.
- Para explorar el papel de la troponina en los efectos de las drogas.
Principales métodos:
- Los experimentos se llevaron a cabo en fibras cardíacas de mamíferos con piel química, que carecían de un retículo sarcoplasmático funcional.
- Las fibras fueron expuestas a diferentes concentraciones de calcio (Ca++) en un ambiente iónico controlado.
- Se midieron los efectos del sulmazol y el pimobendano en la contracción inducida por el calcio.
Principales resultados:
- El sulmazol y el pimobendano aumentaron la contracción inducida por el calcio en las fibras cardíacas descascaradas en un 30-50% a bajos niveles de calcio (1 microM).
- Este efecto se atribuyó al aumento de la sensibilidad de los miofilantes al calcio, potencialmente a través de una mayor afinidad de la troponina con el calcio para el sulmazol.
- No se observó ningún efecto en las fibras musculares lisas despellejadas que carecen de troponina.
Conclusiones:
- Los efectos inotrópicos positivos del sulmazol y el pimobendano pueden deberse en parte a su acción sensibilizante para el calcio sobre los miofilantes cardíacos.
- Estos fármacos mejoran la respuesta contráctil del músculo cardíaco al calcio.
- Otros mecanismos que aumentan el calcio libre intracelular también pueden contribuir a su efecto general.
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