Disorders of Magnesium Balance
Magnesium is an important intracellular cation that functions as a cofactor in many enzyme pathways. Only 1–2% of total body magnesium stores is present in the ECF compartment; 67% is contained in bone, and the remaining 31% is intracellular. Magnesium has been reported to decrease anesthetic require-ments, attenuate nociception, blunt the cardiovascular response to laryngoscopy and intubation, and poten-tiate NMBs. Suggested mechanisms of action include altering central nervous system neurotransmitterrelease, moderating adrenal medullary catechol-amine release, and antagonizing the effect of calcium on vascular smooth muscle. Magnesium impairs the calcium-mediated presynaptic release of acetylcholine and may also decrease motor end-plate sensitivity to acetylcholine and alter myocyte membrane potential.
In addition to the treatment of magnesium deficiency, administration of magnesium is utilized therapeutically for preeclampsia and eclampsia, torsades de pointes and digoxin-induced cardiac tachyarrhythmias, and status asthmaticus.