Magnesium content of mononuclear blood cells.

The magnesium content of mononuclear blood cells may provide a better assessment of intracellular magnesium or total body magnesium status than does measurement of magnesium in plasma or erythrocytes. We describe a method for determining this, and report results for 20 normal volunteers. The mononuclear cells are separated with a discontinuous Ficoll-Hypaque gradient, washed, centrifuged at 400 X g, and lysed by sonication in 10 mmol/L NaCl. The magnesium in the cell lysate, with 2.93 g of added lanthanum oxide per liter, is determined by atomic absorption spectrometry. The mean mononuclear cell magnesium content in our volunteers was 70.7 (SD 14.1) fg per cell and 9.29 (SD 1.85) mg/g of DNA. The CVs for the determinations of magnesium, DNA, and cell count were 3.0%, 5.0%, and 8.7%, respectively. There was a significant correlation (r = 0.67, p less than 0.001) between results by the two methods of expressing magnesium content of mononuclear cells. However, by either method there were no significant correlations among results for magnesium concentration of mononuclear cells, plasma, or erythrocytes.