Magnesium and Zinc

Mechanism

💧 Magnesium (Intracellular Cation)

• Cell Role: Coordinator of ATP-dependent reactions (the active biological complex is Mg-ATP^2-).
• Neurology: Acts as a physiological blocker of the NMDA glutamate receptor calcium channel.
• Its deficiency is associated with refractory hypokalemia, ventricular arrhythmias and tetany.

🧬 Zinc (Metalloenzymes and Zinc Fingers)

• Cell Role: Structural cofactor for RNA and DNA nuclear polymerases.
• Gene Transmission: Allows three-dimensional folding of DNA binding motifs (zinc fingers).
• Essential for epithelial cell growth, healing and immune cellular response.

Mechanisms of cellular action

1. Magnesium (Mg²⁺) and Muscle Excitability

At the level of the central nervous system and the myocardium, magnesium acts naturally as a physiological calcium antagonist. In the membranes of smooth muscle cells, it blocks voltage-activated calcium channels, inducing muscle relaxation and preventing coronary or systemic vasospasm. In neurons, blockade of the NMDA receptor stabilizes the excitatory membrane, preventing glutamate-mediated excitotoxicity.

2. Zinc (Zn²⁺) and Mucous Barrier Integrity

Zinc coordinates the activity of the enzyme carbonic anhydrase and stimulates the synthesis of tight junction proteins (such as occludin and claudin) in the enterocytes of the intestinal epithelium. During episodes of acute childhood diarrhea, zinc supplementation accelerates brush border regeneration and decreases water hypersecretion mediated by bacterial toxins.

Cross Interference of Zinc with Copper (Excess Sideroblastic Anemia)

Excessive and prolonged zinc supplementation (> 100 mg/day) competitively induces the synthesis of the intracellular storage protein metallothionein in duodenal enterocytes. Metallothionein has a substantially higher binding affinity for the copper cation (Cu²⁺) than for zinc. As a consequence, free dietary copper binds strongly to metallothionein and is trapped in enterocytes, being eliminated with physiological fecal shedding. This causes a severe copper deficiency that causes sideroblastic anemia and severe neutropenia.

Indicators and dose

Clinical Indications and Dosage

• Parenteral Magnesium Sulfate: Drug of choice for the prevention and treatment of seizures in gestational preeclampsia and eclampsia, and for the reversal of severe arrhythmias of the Torsades de Pointes type.
• Zinc Supplementation in Childhood Diarrhea (WHO Recommendation): In children under 5 years of age with acute diarrhea, 20 mg of elemental zinc per day is prescribed for 10 to 14 days (10 mg in children under 6 months) to drastically reduce the duration and severity of the clinical picture and prevent recurrences in subsequent months.