Effect of magnesium supplement in a biological medium (milk) on multiple ionic exchangers in a human membrane.

The effects of magnesium supplement in a biological medium (milk) diluted in a survival medium (1/20 dilution in Hanks' solution) have been studied on the multiple ionic exchangers in a human membrane, the amniotic membrane, which is a leaky and asymmetrical membrane. In normal milk, the Ca/Mg molar ratio (MR) is equal to 6.0. In this study, this ratio has been modified to between 0.36 and 6.0, with particular attention to MR values of 0.36, 0.6, 1.0, and 2.0. The transamniotic conductance, Gt, is a function of the Ca/Mg MR: Gt decreases when the MR increases from 0.36 to 6.0, with an inflexion point to 0.7. In the human amnion, Gt is the sum of three paracellular components (Gp) and nine cellular components (Gc). The addition of normal milk (MR = 6) or magnesium-supplemented milk (MR = 0.36, 0.6, 1.0 or 2.0) induces variation in 2 Gp (GpNa and GpK) and three cellular conductances (Na+ and K+ channels and Na/Mg exchanger). Among the MR values studied, MR = 0.36 increased all five components. These data show the relationship between magnesium and milk components and the cellular targets of magnesium supplements and define the best Ca/Mg molar ratio in the biological medium.