A new method of in vitro prescreening evaluation of several Mg salts.

The human amniotic membrane may be considered a model for the prescreening evaluation of the membrane effects of several Mg salts because it is an asymmetrical membrane (polarity of the 2 sides: the ratio between the total ionic conductance Gt both ways and the ratio between the ionic flux from the mother to the fetus (F1) and the ionic flux from the fetus to the mother (F2) are different from 1), samples of which can be obtained without ethical problems, and which is easily usable. Whatever the tested salt, the ratio F1/F2 must be constant or increased without alterations of the ionic fluxes (+/-20%), because a toxic metal (As) has no effect on F1/F2, but strongly decreases the ionic fluxes. To apply this model to the study of the effects of Mg salts, two conditions should be considered: 1) Mg oral therapy: Mg deficit increases the membrane fluidity and the increase of Mg concentration rigidifies the membrane, i.e. decreases Gt; the plasma level of Mg being equal to 1 mM, Mg salts would be tested at 1 mM and Gt should be decreased; and 2) Mg parenteral therapy: the Mg effects should be opposite to those of pollutants and alcohol, which reduce Gt; a dose of 3 mM is chosen and Gt should be increased. The general scheme to study Mg salts is the following: observation of the variation of F1/F2 at 1 mM and of the evolution of Gt, and identical observations at 3 mM. This in vitro prescreening method, indirectly applicable to in vivo effects, gives a classification of Mg salts which may be completed by a study of the 10 components of Gt in the case of identical results for Mg salts.