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[Effect of magnesium on postischemic reperfused myocardial mitochondria]
Abstract:
Isovolumic rat heart preparations were exposed to low flow ischemia (0.2 ml/min) for 60 min, followed by 30 min of reperfusion. The concentration of Mg2+ was maintained 1.2 mmol/L throughout the study in group 2, while increased to 15 mmol/L or depleted to zero during ischemia only in group 3 and group 1 respectively. High concentration Mg2+ showed a significantly protective effect on Ca-ATPase activity and synthesis ability of ATP in myocardial mitochondria, and decreased its calcium overload. Thus it appears that high concentration Mg2+ infusion may partially reverse postischemic reperfusion injury to heart.
Insights
High magnesium (Mg2+) concentrations during ischemia protected heart mitochondria by preserving calcium-ATPase activity and adenosine triphosphate (ATP) synthesis. This suggests high Mg2+ may mitigate reperfusion injury.
Area of Science:
- Biochemistry
- Cardiovascular Physiology
- Mitochondrial Function
Background:
- Myocardial ischemia-reperfusion injury is a significant clinical problem.
- Calcium overload and impaired mitochondrial function contribute to this injury.
- Magnesium ions (Mg2+) play a crucial role in cellular energy metabolism and enzyme function.
Purpose of the Study:
- To investigate the protective effects of varying magnesium (Mg2+) concentrations during ischemia on myocardial mitochondria.
- To assess the impact of Mg2+ on calcium overload and adenosine triphosphate (ATP) synthesis during reperfusion.
Main Methods:
- Isolated isovolumic rat heart preparations were subjected to 60 minutes of low-flow ischemia followed by 30 minutes of reperfusion.
- Three groups were studied: normal Mg2+ (1.2 mmol/L), zero Mg2+, and high Mg2+ (15 mmol/L) during ischemia.
- Mitochondrial Ca-ATPase activity, ATP synthesis, and calcium content were measured.
Main Results:
- High Mg2+ concentration significantly preserved Ca-ATPase activity compared to normal and zero Mg2+ groups.
- Elevated Mg2+ levels maintained ATP synthesis ability in myocardial mitochondria.
- High Mg2+ treatment reduced calcium overload in mitochondria during reperfusion.
Conclusions:
- High concentration Mg2+ infusion demonstrates a protective effect against ischemia-reperfusion injury in the heart.
- Mg2+ appears to protect mitochondrial function by maintaining Ca-ATPase activity and ATP synthesis.
- This suggests a potential therapeutic strategy for mitigating postischemic cardiac damage.