A method for measuring intracellular free magnesium concentration in platelets using flow cytometry

Magnesium is the fourth most abundant cation in the body and is involved in over 302 enzymatic reactions. Basic science research has implicated magnesium deficiency as a cause of insulin resistance which is related to hypertension, diabetes, hyperlipidemia and increased cardiovascular risk. Research in magnesium deficiency states has been hindered because magnesium is an intracellular ion and difficult to measure. Our goal was to develop a reproducible assay to measure intracellular magnesium in platelets. Healthy volunteers agreed to have blood drawn for magnesium measurement. Platelet rich plasma was harvested from a venipuncture specimen and run through the flow cytometer. A standard titer curve using known increasing concentrations of magnesium chloride was created for each specimen, and then with the other half the specimen was run to measure the true intracellular free magnesium concentration. 15 adults agreed to volunteer for this experiment. All standard titer curves for all specimens had a correlation of > 0.99. The mean concentration of intracellular free magnesium was 450.05 μM with a range of 203.68 μM to 673.50 μM. Intracellular free magnesium can reliably and reproducibly be measured in platelets using Mag Green fluorescent dye and flow cytometry. This should advance our ability to study magnesium deficient states.