Related Experiment Videos
The role of magnesium in postischemic cardiac dysfunction
K E Sommers1, A Ohkado, E Simplaceanu
1Division of Cardiothoracic Surgery, University of Pittsburgh School of Medicine, PA 15213.
Surgery
|August 1, 1992
Summary
Postischemic myocardial stunning involves elevated intracellular magnesium (Mg2+), impairing heart function. Treatments that restore function also normalize Mg2+ levels, suggesting Mg2+ plays a key role in recovery after ischemia.
Area of Science:
- Cardiology
- Biochemistry
- Physiology
Background:
- Postischemic myocardial stunning's biochemical basis remains unclear.
- Magnesium (Mg2+) regulates cellular energy and excitation-contraction coupling.
- Altered Mg2+ regulation may cause postischemic dysfunction.
Purpose of the Study:
- To investigate the role of magnesium regulation in postischemic myocardial stunning.
- To determine if altered intracellular Mg2+ levels correlate with impaired cardiac function after ischemia.
Main Methods:
- Langendorff-perfused rabbit heart model.
- 31P nuclear magnetic resonance spectroscopy to measure intracellular Mg2+ and high-energy phosphates.
- Assessment of adenosine triphosphate (ATP), phosphocreatine, and delta GATP pre- and post-ischemia.
- Comparison of hearts treated with control Krebs-Henseleit solution, dobutamine, or pyruvate post-reperfusion.
Main Results:
- Postischemic hearts showed impaired function (77% of preischemic rate-pressure product) in the control group.
- Dobutamine and pyruvate treatments restored function to preischemic levels.
- Intracellular Mg2+ was significantly elevated in postischemic control hearts compared to preischemic and treated groups.
- ATP levels decreased similarly across all groups post-ischemia.
Conclusions:
- Postischemic "stunned" hearts exhibit elevated Mg2+ associated with reduced contractile function.
- Inotropic agents improve function by lowering Mg2+ to preischemic levels.
- Mg2+ likely plays a crucial regulatory role in the post-ischemic heart.