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Mechanisms of subcellular remodelling in post-infarct heart failure
1Division of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Winnipeg, Canada.
Insights
Myocardial infarction triggers heart remodeling, affecting extracellular matrix and subcellular organelles. This study details these changes, crucial for understanding cardiac dysfunction after heart attack.
Area of Science:
- Cardiology
- Pathophysiology
- Molecular Biology
Background:
- Coronary artery occlusion causes myocardial ischemia and infarction, leading to heart failure.
- Significant infarcts (>30% ventricular wall) prompt compensatory cardiac remodeling.
- This remodeling involves hypertrophy, dilatation, and changes in extracellular matrix.
Purpose of the Study:
- To elucidate the comprehensive remodeling processes in the infarcted heart.
- To investigate alterations in the extracellular matrix and subcellular organelles.
- To link these structural changes to cardiac contractile dysfunction.
Main Methods:
- Review of existing literature on myocardial infarction and cardiac remodeling.
- Analysis of changes in cardiocytes, extracellular matrix, sarcoplasmic reticulum, sarcolemma, and mitochondria.
- Correlation of structural alterations with functional deficits.
Main Results:
- Heart remodeling includes changes in cardiocyte size/shape, hypertrophy, dilatation, and extracellular matrix alterations (collagen).
- Activation of sympathetic nervous system and renin-angiotensin system, plus growth factors, contribute to remodeling.
- Subcellular organelle remodeling affects sarcoplasmic reticulum (Ca2+ handling), sarcolemma (ion channels, receptors), and potentially mitochondria.
Conclusions:
- Cardiac contractile dysfunction post-myocardial infarction is intrinsically linked to extensive remodeling.
- Both extracellular matrix and subcellular organelles undergo significant structural and functional adaptations.
- Understanding these remodeling processes is key to developing therapeutic strategies for heart failure.
Abstract:
Occlusion of a coronary artery results in myocardial ischemia and subsequent myocardial infarction. Whenever the infarct size is more than 30% of the ventricular wall, the remaining myocardium attempts to compensate for the loss of muscle mass by changing the size and shape of cardiocytes in addition to developing cardiac hypertrophy, cardiac dilatation and congestive heart failure. This remodeling of the heart is associated with changes in the extracellular matrix including collagen proteins and is most probably due to the activation of both sympathetic nervous system and renin-angiotensin system as well as increased formation of various growth factors. Alterations in contractile function of the infarcted heart are associated with remodelling of the sarcoplasmic reticulum with respect to Ca(2+)-pump and Ca(2+)-release channels as well as contractile and regulatory proteins of the myofibrils. Myocardial infarction has also been shown to result in remodelling of the sarcolemmal membrane with respect to Ca(2+)-channels, Ca(2+)-transport systems, cardiac receptors and signal transduction mechanisms. Although information regarding remodelling of mitochondria in the infarcted heart is limited, alterations in energy yielding and Ca(2+)-accumulating systems are suspected. Accordingly, it is suggested that changes in cardiac contractile dysfunction due to myocardial infarction are associated with remodeling of both extracellular matrix and subcellular organelles in the heart.