Arrhythmogenic threshold of the myocardium under conditions of magnesium deficiency.

We studied the arrhythmogenic threshold of the myocardium after injection of CaCl2 to magnesium-deficient rats receiving Mg2+ L-aspartate, MgCl2, their combination with vitamin B6, and reference preparations Magne B6 and MgSO4 until complete compensation of magnesium level in the plasma and erythrocytes. Magnesium-deficient diet and deionized water were used for inducing alimentary Mg2+ deficiency and modeling pathological changes in rats. After reducing Mg2+ level to 0.7 mmol/liter in the plasma and to 1.5 mmol/liter in erythrocytes, Mg L-aspartate, MgCl2, their combination with vitamin B6, as well as Mg2+ deficiency led to a decrease in the dose of CaCl2 provoking heart rhythm disturbances in 50% animals and shortening of animal life span. Administration of the test magnesium salts increased the arrhythmogenic threshold; Mg2+ salts were comparable by their efficiency with Magne B6 and were far superior to MgSO4.