Magnesium sulfate is widely used in the treatment of pre eclampsia/eclampsia, and furthermore the use of the agent for treatment of premature labor is increasing.Preeclampsia is characterized by peripheral vasoconstriction with elevated systemic blood pressure and decreased uteroplacental blood flow. These changes may be partly caused by an increased responsiveness of the blood vessels to endogenous pressor agents. Magnesium deficiency has been suggested to be involved in the pathogenesis of this vasoconstriction and the increased responsiveness and hence the development of preeclampsia. Thus, magnesium supplementation during pregnancy is recommended in several countries.The present study investigated whether the magnesium intake among pregnant women in Denmark was sufficient. Furthermore, the intake of magnesium was evaluated in relation to the development of preeclampsia and intrauterine growth retardation. Since the intake of magnesium does not necessarily reflect the status of magnesium in the body, the magnesium content was determined in biopsies obtained from skeletal muscle and the uterus.In the light of the therapeutic use of magnesium sulfate and the hypothesis that magnesium deficiency may be involved in the development of enhanced sensitivity of the uteroplacental vessels in preeclampsia, the effect of magnesium on fetal and maternal uteroplacental resistance arteries was investigated in an organ bath model. Moreover, pos-Abbreviations: Mg++: magnesium; K+: potassium; Ca++: Na": sible mechanisms behind the effect of magnesium were suggested.Magnesium sulfate seems to be an effective tocolytic agent. Thus, the effect of magnesium on isolated myometrium was investigated and compared to the effect of the P,-adrenoceptor terbutaline. Since this agent has been thought to act through a stimulation of the active Na,K-transport, the effects of magnesium and terbutaline on active Na, K-transport were assessed by ion flux experiments and studies of contractile tension development.The study of magnesium intake among pregnant women comprised 965 women in the 30th week of pregnancy (1). The intake of magnesium was assessed by a questionnaire and an interview concerning the dietary intake. The intake of magnesium was sufficient and the distribution of the intake was similar in all pregnancy groups irrespective of the later pregnancy outcome. Serum samples were obtained in connection with the interview, and serum-magnesium was determined. No differences concerning serum-magnesium were found. Moreover, n o differences in magnesium status, as assessed by determination of magnesium in biopsies from skeletal muscle and uterus, were found between normal pregnant women and women with preeclampsia or intrauterine growth retardation. Routine magnesium supplementation during pregnancy is therefore not to be recommended in populations of relatively high socio-economic status.The effects of Mg++ were studied in human umbilical arteries, stem villous and maternal intramyometrial arteries (2,3). The vessels were dissected and mou...
