Magnesium reduces free radicals in an in vivo coronary occlusion-reperfusion model.
OBJECTIVE
This study demonstrated that magnesium (Mg) reduces free radicals after a brief coronary occlusion-reperfusion sequence.


BACKGROUND
Magnesium has been shown to reduce infarct size in patients with acute myocardial infarction. We hypothesized that this action of Mg occurs through its action on free radicals.


METHODS
Eighteen mongrel dogs were studied (nine control, nine receiving Mg). Catheters were placed into the coronary sinus for continuous blood withdrawal. A Varian E-4 electron paramagnetic resonance spectrometer was used to monitor the ascorbate free radical (AFR) signal in the coronary sinus blood; AFR is a measure of total oxidative stress. Occlusion of the left anterior descending coronary artery for 20 min was followed by reperfusion. The study animals received 4 g Mg intravenously starting at 15 min of occlusion (5 min before reperfusion) and continuing during reperfusion.


RESULTS
Results are presented as percent change from baseline +/- SEM. Magnesium blunted the peak AFR increase: at 4 min of reperfusion there was a 4.7 +/- 3.3% increase in AFR signal in the dogs receiving Mg versus an 18.2 +/- 3.3% increase in the control animals (p < 0.05). Total radical flux was reduced during reperfusion by 53% in the Mg dogs compared with controls (p < 0.05).


CONCLUSIONS
Magnesium attenuates AFR increase after an occlusion-reperfusion sequence. To our knowledge this is the first in vivo real-time demonstration of Mg's impact on free radicals.
Cardiovascular Center and the Electron Spin Resonance Facility, The University of Iowa, Iowa City, USA.
L A
LA
Garcia
S C
SC
Dejong
S M
SM
Martin
R S
RS
Smith
G R
GR
Buettner
R E
RE
Kerber
D000818:Animals; D001205:Ascorbic Acid / Q000037:antagonists & inhibitors / Q000097:blood; D006328:Cardiac Catheterization; D003327:Coronary Disease / Q000097:blood / Q000378:metabolism*; D003331:Coronary Vessels; D004285:Dogs; D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers / Q000008:administration & dosage / Q000627:therapeutic use*; D005609:Free Radicals / Q000037:antagonists & inhibitors / Q000097:blood; D007262:Infusions, Intravenous; D008274:Magnesium / Q000008:administration & dosage / Q000627:therapeutic use*; D009203:Myocardial Infarction / Q000473:pathology / Q000517:prevention & control; D015425:Myocardial Reperfusion; D018384:Oxidative Stress
D016166:Free Radical Scavengers; D005609:Free Radicals; D008274:Magnesium; D001205:Ascorbic Acid