Studies on the Significance of Magnesium Metabolism in Physiological and Pathological Changes During Pregnancy

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I. Comparisons of magnesium metabolism in pregnant women with that in non-pregnant subjects revealed the following findings: l) serum total Mg levels in 2^<nd> and 3^<rd> trimester were significantly lower than those of non-pregnant women and in 1^<st> trimester of pregnancy, 2) ionized Mg levels in blood in 1^<st> trimester were significantly lower than those in non-pregnant women, followed by further declining in 2^<nd> and 3^<rd> trimester, 3) platelet intracellular Mg concentration in non-pregnant women in luteal phase was significantly higher than that in follicular phase. The value in 1^<st> trimester of pregnancy was still higher than that in luteal phase, although it significantly decreased in 2^<nd> and 3^<rd> trimester compared with that in 1^<st> trimester, 4) there was an inverse correlation between intracellular ionized Mg levels and ionized Mg in blood in non-pregnant women, while no such a relationship was observed in pregnant women. In vitro experiments revealed that es … More tradiol has an effect of reducing intracellular Mg ion and that progesterone has an effect of elevating that.II. Comparisons of magnesium metabolism in preeclampsia with that in normal pregnancy revealed that 1) there were no differences in serum total Mg levels, 2) ionized Mg levels were significantly lower, 3) intracellular Mg levels were significantly lower, 4) either intracellular Mg levels of ionized Mg or its blood levels showed significant inverse correlation with mean blood pressure, 5) urinary output of Mg was significantly higher. In vitro experiments showed that PTH, Endothelin and serum obtained from patient with preeclampsia lowered the intracellular Mg concentration.III. Experiments using rats revealed that there was a mechanism that augmented active absorption of calcium, a divalent cation just like Mg. In the duodenum during pregnancy, although there was no such a system for Mg. These results suggest that gestational hormonal changes bring altered Mg metabolism in pregnant subjects and that preeclampsia is affected with relative deficient state for Mg compared with normal pregnancy. This pathological state may be an important factor in maintaining the pathophysiology Less