Magnesium effect on SO4= uptake and oxidative stress in human erythrocytes

The efficiency of Band 3 protein (B3p), mediating anion exchange across erythrocytes membrane, is reduced by H2O2 -induced oxidative stress. The aim of the present study was to prove whether magnesium (Mg), commonly used in clinics to prevent hypoxia in preterm labour and pre-eclampsia, ameliorates B3p efficiency when oxidative stress is applied. Whole blood samples were loaded with 10 mM MgCl2 and then treated for 30 min with either 300 µM or 600 µM H2O2. The rate constant for SO4= uptake through B3p and glutathione (GSH) levels were then measured. In a separate experimental set, the rate constant for SO4= uptake and GSH levels were evaluated in Mg-treated erythrocytes exposed for 30 min to NEM (0.5 to 2 mM), a thiol-alkilant agent known as kinase inhibitor. Our results show that Mg ameliorates the rate constant for SO4= uptake in both H2O2-treated and 0.5 mM NEM-treated erythrocytes, with a significant GSH levels restoration in this latter case. No GSH levels alteration was observed under H2O2±Mg treatment. In conclusion: i) both H2O2 and NEM affect B3p function and H2O2 reduces B3p efficiency without altering GSH levels; ii) Mg prevents NEM-induced damages at both B3p and GSH level putatively protecting –SH groups oxidation; iii) Mg protects Bp3 from H2O2-damage through a different pathway, i.e. phosphorylation, which is critical in ensuring B3p efficiency. Hence, further studies are needed to focus on Mg role in oxidative stress signaling in human erythrocytes.