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Impact of High-intensity Interval Exercise and Moderate-Intensity Continuous Exercise on the Cardiac Troponin T Level at an Early Stage of Training
07:40

Impact of High-intensity Interval Exercise and Moderate-Intensity Continuous Exercise on the Cardiac Troponin T Level at an Early Stage of Training

Published on: October 10, 2019

Coexistence of cardiac troponin T variants reduces heart efficiency

Han-Zhong Feng1, J-P Jin

  • 1Department of Physiology, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI 48201, USA.

American Journal of Physiology. Heart and Circulatory Physiology
|April 27, 2010
PubMed

Insights

The presence of multiple cardiac troponin T (cTnT) variants in heart muscle impairs cardiac function. This desynchronized activation of thin filaments reduces ventricular efficiency and can lead to cardiomyopathy.

Area of Science:

  • Cardiovascular Physiology
  • Molecular Cardiology
  • Biochemistry

Background:

  • Adult cardiac muscle normally expresses a single form of cardiac troponin T (cTnT).
  • Alternative splicing variants of cTnT are found in failing hearts and are known to alter myofilament calcium sensitivity.
  • Previous hypotheses suggested that multiple functionally distinct cTnT variants could impair heart function.

Purpose of the Study:

  • To investigate if desynchronized myofilament activation, caused by the coexistence of multiple cTnT variants, decreases ventricular efficiency.
  • To examine the impact of expressing one or two cTnT variants alongside normal adult cTnT on transgenic mouse heart function.

Main Methods:

  • Studied transgenic mouse hearts expressing varying combinations of cTnT variants.
  • Assessed ex vivo working heart function, excluding systemic neurohumoral influences.
  • Measured parameters including left ventricular pressure, contractile/relaxation velocities, stroke volume, and ventricular efficiency.

Main Results:

  • Transgenic mouse hearts exhibited lower maximum left ventricular pressure, slower contractile and relaxation velocities, and reduced stroke volume compared to wild-type controls.
  • Ventricular pumping efficiency was significantly lower in transgenic hearts, correlating with the number of cTnT variants present.
  • Desynchronized thin filament activation due to multiple cTnT variants was identified as the cause of reduced myocardial efficiency.

Conclusions:

  • The coexistence of functionally distinct cTnT variants in cardiac muscle leads to desynchronized thin filament activation.
  • This desynchronization significantly reduces myocardial efficiency and ventricular performance.
  • These findings elucidate a pathogenic mechanism contributing to cardiomyopathy.

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