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[Molecular mechanisms of cardiac insufficiency in myocardial ischemia]
Insights
Heart muscle insufficiency during ischemia is not due to ATP levels but a rapid decrease in creatine phosphate. This energy depletion impairs contractility and leads to cell damage.
Area of Science:
- Cardiology
- Biochemistry
- Pathophysiology
Background:
- Myocardial contractility reduction under ischemia is a key concern.
- Existing hypotheses fail to explain rapid contractility loss despite stable ATP levels.
Purpose of the Study:
- To analyze the pathogenesis of heart muscle insufficiency under ischemia.
- To investigate the role of energy supply mechanisms in ischemic cardiomyopathy.
Main Methods:
- Analysis of existing hypotheses on myocardial energy metabolism.
- Correlation of creatine phosphate levels with cardiac contractility.
- Review of recent data on energy transfer from mitochondria.
Main Results:
- Stable ATP levels do not explain reduced contractility in ischemic myocardium.
- Early reduction in creatine phosphate concentration correlates with decreased contractility.
- Mitochondrial energy transfer via creatine phosphate is crucial for ATP synthesis in myofibrils.
Conclusions:
- Reduced creatine phosphate synthesis is the leading factor in ischemic heart muscle pathogenesis.
- This energy deficit causes early contractility reduction and later cell damage.
- The creatine phosphokinase reaction is vital for maintaining cardiac function under stress.
Abstract:
An analysis of the main concepts of the pathogenesis of heart muscle insufficiency under ischaemia was conducted. None of the hypotheses postulating the invariability of the energy supply to the myofibrills was shown to explain the fast reduction of the contractility of the ischaemic myocardium. These hypotheses are based on the experimental fact of the ATP level in the myocardium practically undergoing no reduction under ischaemia. At the same time, one of the earliest changes in the heart muscle under ichaemia consists in creatine phosphate concentration reduction that correlates with the decrease in the contractility. The recently obtained data indicate that the energy synthesized in the mitochondria of the cardiac muscle is carried away from them in the form of energy of creatine phosphate molecules that is later used for ATP synthesis in the myofibrill creatine phosphokinase reaction. A scheme is suggested that implies that under ischaemia severe changes in the energy supply consisting in creatine phosphate synthesis reduction are the leading factor in the pathogenesis resulting on the early stages of the process in a reduction of the contractility, and on the later ones--in irreversible damages of the membrane systems and cell destruction.