Magnesium-deficient diet aggravates anaphylactic shock and promotes cardiac myolysis in guinea pigs.

Actively sensitized guinea pigs were rendered Mg(2+)-deficient for 2-3 weeks and then subjected to immune stress. No differences could be seen between treated and control groups prior to immune challenge. 1-2 h after antigen challenge, 95% of the Mg(2+)-deficient animals were observed to be anaphylactic, i.e. apathetic, dyspneic, and they had a rapid pulse rate. Only 4% of the control animals showed signs of anaphylaxis. Serum magnesium concentration, [Mg2+], fell from 1.32 +/- 0.07 mM in control guinea pigs to 0.56 +/- 0.04 mM in those fed an Mg(2+)-deficient diet. Cardiomyolysis (CM) developed in 19% of the anaphylactic animals and in 3% of the controls. We conclude that Mg(2+)-deficient animals continue to function, provided conditions are normal, but they are unable to withstand stress. The heart, however, appears to be better equipped to defend itself against Mg2+ deficiency and low serum [Mg2+], a supposition supported by the fact that heart [Mg2+] is not significantly reduced in hypomagnesemic guinea pigs (0.864 +/- 0.021 microgram/mg dry weight in control, and 0.834 +/- 0.062 microgram/mg dry weight in magnesium-deficient animals). The data indicate that hypomagnesemia heightens the intensity of the immune response, thereby exacerbating both anaphylactic shock (AS) and CM. A normal serum [Mg2+] would thus seem essential for protection against immune stress.