With pregnant Wistar-rats, suffering from alimentary
magnesium deficiency, absorption and distributing of Mg28 has been studied, the latter having been applied as
aspartate and as
chloride, with and without simultaneous substitution of
vitamin B6. Absorption and tissue pooling were found to be augmented when using the
aspartate and even more when adding
vitamin B6. These differences were significant in the blood as well as in fetal and myocardial tissue. Correlation between blood-Mg28 und Mg28-activities in various tissues shows, that blood
magnesium levels indicate a
magnesium deficiency at least in the tissues of interest: fetus, myocardium, uterus and placenta. Nevertheless blood
magnesium levels fail to reflect an additional tissue pooling, that exerts a beneficial action in the respect of cardio protection and of saving beta-mimetic
tocolytics. When measuring
magnesium and
calcium excretion during chronic experiments with and without oral
magnesium aspartate substitution, it could be demonstrated, that the amount of substituted
magnesium has been pooled almost totally. Oral
magnesium substitution furthermore reduces intestinal
calcium absorption. Investigation on
calcium uptake into the maternal myocardium revealed, that oral
magnesium aspartate substitution significantly diminishes myocardial
calcium uptake, the latter among others being responsible for cardiac hazards during
tocolysis with beta-mimetic substances, while the pharmacologic
calcium-antagonist
Verapamil failed to do so.