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Investigating Cardiac Metabolism in the Isolated Perfused Mouse Heart with Hyperpolarized [1-13C]Pyruvate and 13C/31P NMR Spectroscopy
Published on: April 21, 2023
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Friction in Myocardial Anoxia Leads to Negative Excess Entropy Production, Self-Organization, and Dissipative
Yves Lecarpentier1, Victor Claes2, Jean-Louis Hébert3
1Centre de Recherche Clinique, Grand Hôpital de l'Est Francilien, 77100 Meaux, France.
International Journal of Molecular Sciences
|July 9, 2022
Summary
Severe anoxia damages heart muscle by disrupting actin-myosin interactions, leading to instability. While some function returns with re-oxygenation, myosin head damage persists, impacting heart transplantation.
Area of Science:
- Cardiovascular Physiology
- Biophysics
- Tribology
Background:
- Heart contraction relies on actin-myosin filament interaction, generating frictional forces and potential wear.
- Severe anoxia (lack of oxygen) may worsen this wear by altering molecular properties of the contractile apparatus.
Purpose of the Study:
- To investigate the effects of prolonged anoxia on the thermodynamic properties of heart muscle.
- To analyze the stability of the cardiac contractile system under anoxic conditions using far-from-equilibrium thermodynamics.
Main Methods:
- Applied far-from-equilibrium thermodynamics to isolated rat left ventricular papillary muscles (LVPMs) subjected to 3 hours of anoxia.
- Measured thermodynamic force (F/T) and thermodynamic flow (v0: myofilament sliding velocity) to calculate entropy production rates.
- Assessed system stability based on excess entropy production (EEP).
Main Results:
- Anoxia induced non-linear relationships between force and velocity, indicating the heart operated far-from-equilibrium.
- System instability was observed when excess entropy production (EEP) became negative, suggesting self-organization.
- Re-oxygenation showed partial reversibility, but approximately 20% of myosin heads remained damaged.
Conclusions:
- Prolonged anoxia destabilizes the cardiac contractile system, characterized by thermodynamic instability and potential self-organization.
- Persistent myosin head damage post-anoxia highlights the need to minimize ischemic time in heart transplantation.
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