Biochemistry and pathobiochemistry of magnesium.

The kinetic and thermodynamic effects of Mg2+ on enzyme reactions and the effects of Mg2+ on nucleic acids and phospholipids are reviewed. Since the action of Mg2+ is depending on the Mg2+ concentration, the distribution, and the metabolism of Mg2+ in the extracellular, and the various intracellular compartments are discussed. The main result is that the intracellular Mg2+ is buffered at a level of pMg 3. In experimental Mg deficiency, cell permeability increases, as a consequence of which intracellular Na+, Ca2+ and secondarily, cAMP become elevated, whereas intracellular K+ decreases. Catecholamines are released to a higher extent, an effect that is potentiated by stress. The metabolic consequences of Mg deficiency are caused by the altered intracellular electrolyte, especially the Ca2+ concentration.