Magnesium homeostasis in mammalian cells.

Mammalian cells tightly regulate cellular Mg2+ content despite undergoing a variety of hormonal and metabolic stimulatory conditions. Evidence from several laboratories indicates that stimulatory conditions that increase cellular cAMP level result in a major mobilization of Mg2+ from cells and tissues into the bloodstream. Conversely, hormones or agents that decrease cAMP level or activate protein kinase C signaling induce a major accumulation of Mg2+ into the tissues. These Mg2+ fluxes are quite large and fast suggesting the operation of powerful transport mechanisms. At front of the recent identification of several Mg2+ entry mechanisms, the Mg2+ extrusion pathway(s) still remain(s) poorly characterized. Similarly, it remains not completely elucidated the physiological significance of these Mg2+ fluxes in the various tissues in which they occur. In the present review, we will attempt to provide a comprehensive framework of the modalities by which cellular Mg2+ homeostasis and transport are regulated, as well as examples of cellular functions regulated by changes in cellular Mg2+ level.