EFFECT OF VARIOUS DEGREES AND DURATION OF MAGNESIUM-DEFICIENCY ON LIPID-PEROXIDATION AND MINERAL METABOLISM IN RATS

Severe magnesium (Mg) deficiency changed mineral homeostasis, increase d lipid peroxidation, and reduced Mg2+/Ca2+ antagonism. To investigate whether the pathobiochemical effects directly correlate with the degr ee of Mg deficiency or whether there might be a threshold for signific ant alterations, diets with 70, 110, 208, 330, and 850 ppm of Mg were fed to growing Wistar rats. After feeding the diets for 0, 10, 20, and 30 days, parameters of free radical action (malondialdehyde and vitam in E content), mineral content (Mg, Ca, Fe, Zn) in various tissues (li ver, spleen, heart, kidney, muscle) and plasma parameters (Mg, Ca, Fe, Zn, alanine- and aspartate-aminotransferase, tumor necrosis factor-al pha [TNF-alpha]) were analyzed. The tissue Mg content was either uncha nged or only slightly reduced in severe Mg deficiency. The iron (Fe) c ontent rose when the extracellular Mg2+ concentration was below 0.25 m mol/L. There was a close positive correlation between the tissue Fe an d the malondialdehyde content and a negative correlation between the m alondialdehyde and the vitamin E content. Below the threshold of about 0.25 mmol/L of plasma Mg2+ concentration, elevated zinc (Zn) concentr ations were found in liver and kidney as well as in plasma increased t ransaminases and TNF-alpha. The same threshold could be observedfor th e increase oftissue calcium (Ca) content, except in the kidney where c alcifications were found already in less severe Mg deficiency. Concern ing changed mineral homeostasis with subsequent lipid peroxidation and membrane damage, plasma Mg2+ concentrations must be below 0.25 mmol/L ; above this threshold effects of Mg deficiency alone call be compensa ted.