Interrelationship between magnesium and potassium in preventing myocardial ischemia-reperfusion arrhythmia.
OBJECTIVE
To assess the interrelationship between Mg2+ and K+ in preventing reperfusion arrhythmia (RA).


METHODS
72 rat hearts were randomly divided into 6 equal groups, and perfused with various combinations of Mg2+ and K+ in the perfusate by Langendorff method. Each heart was subjected to coronary occlusion for 15 minutes followed by 12-minute reperfusion. The incidence of RA was recorded. The concentration of K+ and malondialdehyde (MDA) in the coronary effluent before and after reperfusion were measured with increasing concentrations of Mg2+ and fixed concentration of K+.


RESULTS
All forms of ventricular arrhythmias occurred after reperfusion but with decreased incidence by increasing Mg2+ and K+. When both Mg2+ and K+ were in high level, no VF appeared on reperfusion. However, when they were both in low level, 100% of hearts developed severe arrhythmia. The concentration of K+ and MDA in the coronary effluent was markedly increased compared with that before reperfusion, and the loss of K+ and malondialdehyde (MDA) decreased with increasing Mg2+.


CONCLUSIONS
Mg2+ may prevent or reduce the incidence of RA by maintaining the integrity of intracellular K+ and by reducing the lipid peroxide reaction.
Xiang
S
S
Department of Cardiovascular Diseases, Tongji Hospital, Tongji Medical University, Wuhan.
Zhao
H
H
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology / Q000517:prevention & control*; D002314:Cardioplegic Solutions; D004357:Drug Synergism; D008274:Magnesium / Q000494:pharmacology*; D008315:Malondialdehyde / Q000097:blood; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D011188:Potassium / Q000494:pharmacology*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar
D002314:Cardioplegic Solutions; D008315:Malondialdehyde; D008274:Magnesium; D011188:Potassium