The effect of magnesium sulfate on action potential duration and cardiac arrhythmias.
To evaluate the electrophysiologic and antiarrhythmic effects, Mg was infused at 15 mg/h (n = 5) or an equal volume of saline (1.2 mL/h) (n = 5) and electrocardiogram and action potential duration (APD) recorded every 15 minutes. Rats were anesthetized with 70 mg/kg pentobarbital intraperitoneally. Mg increased QT 15 +/- 6% on average compared with 1 +/- 4 for saline P < 0.01. Mg increased QT, 0, 0, 6 +/- 4, 13 +/- 5, 16 +/- 4, 23 +/- 5, 29 +/- 8, and 32 +/- 5% over baseline after a 2 hours infusion (P < 0.01). APD increased by 0, 6 +/- 3, 8 +/- 8, 14 +/- 4, 16 +/- 12, 21 +/- 4, 25 +/- 5% change from baseline (P < 0.05). The mean percentage of increase was 12 +/- 8 for the Mg group and 1 +/- 3 for the saline group (P < 0.05). The JT interval also increased after Mg (P < 0.01). After Mg loading, coronary occlusion of the left anterior descending coronary artery was performed. Ventricular premature contractions (VPCs), ventricular tachycardia (VT), and ventricular fibrillation (VF) were frequent in the saline control group, with 2 dying in VF; with only scattered VPCs and short runs of nonsustained VT in the Mg group. The results of these findings indicate that infusion of MgSO4 can prolong the QRS, QT, and JT intervals in the rat and these changes correlate well with arrhythmia suppression.
Somberg
John C
JC
Division of Clinical Pharmacology, Rush University, Chicago, Illinois, USA. jsomberg@rush.edu
Cao
Wei
W
Cvetanovic
Ivana
I
Ranade
Vasant V
VV
Molnar
Janos
J
D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D001145:Arrhythmias, Cardiac / Q000188:drug therapy* / Q000503:physiopathology; D004562:Electrocardiography; D008278:Magnesium Sulfate / Q000627:therapeutic use*; D051381:Rats
D000889:Anti-Arrhythmia Agents; D008278:Magnesium Sulfate