Role of magnesium in glutathione metabolism of rat erythrocytes.

The effects of dietary magnesium (Mg) on glutathione (GSH) metabolism were studied in rat erythrocytes. Young male and young adult female rats were fed a powdered diet containing either 12 ppm Mg (deficient rats) or 662 ppm Mg (control rats) for 14 to 28 days. Results showed that Mg deficiency in male rats had a decreased body weight gain, lower values in plasma hematocrit and Mg ion, but increased organ weights. The concentrations of erythrocyte GSH as measured by alloxan were reduced in male and female rats receiving a Mg-deficient diet. This decrease was confirmed by determining GSH with DTNB reagent [5,5'-dithiobis(2-nitrobenzoic acid)]. Mg-deficient rats, however, had higher levels of liver and kidney GSH, but no effect in other soft tissues examined. The decrease of erythrocyte GSH was not due to feed intake, the availability of its precursors, or the activities of GSH-related enzymes and can be reversed by Mg supplementation. Mg-deficient rats had a reduced blood ATP and a 6-fold increase in the activity of plasma gamma-glutamyl transpeptidase. These findings suggest that Mg is essential in the maintenance of GSH concentration to protect against oxidative damage in the erythrocyte membrane.