<prompt> The Second most important intracellular cation isMagnesiumCalciumSodiumIron  <response>: A Magnesium MAGNESIUM is the second most important intracellular divalent cation and is involved in a variety of metabolic processes including glucose metabolism, ion channel translocation, stimulus-contraction coupling, stimulus secretion coupling, peptide hormone receptor signal transduction. Normal concentrations of extracellular magnesium and calcium are crucial for normal muscular activity. 