Vormann J, Förster R, Günther T
J Clin Chem Clin Biochem. 1983 Dec;21(12):765-73. doi: 10.1515/cclm.1983.21.12.765.
Pregnant rats were fed diets with an Mg2+ content of 40, 12, 6 and 3 mmol/kg from day 10-19 of pregnancy. There was a linear correlation of non-protein bound Mg2+ between foetal and maternal serum, between amniotic fluid and maternal serum, and between foetal serum and amniotic fluid, the ratios being 2.7, 2.0 and 1.3 respectively, indicating active transport of Mg2+ up to a constant concentration gradient by the placenta. In hearts, increases of Na+ and Ca2+, and decreases of Mg2+ and K+ were observed only in the group receiving the lowest Mg2+ supply. After i.v. injection of MgCl2 to pregnant rats, Mg2+ was slowly transported from maternal to foetal serum and more slowly into the amniotic fluid. The effect of isoproterenol on cardiac electrolyte content in pregnant rats was less than in non-pregnant rats, and the effect of isoproterenol in foetal rats was smaller than in maternal rats. These results are explained by inactivation of isoproterenol in the placenta, by the small diaplacental transport of isoproterenol and by a smaller isoproterenol-stimulation of foetal cardiac adenylate cyclase.
从妊娠第10天至第19天，给怀孕大鼠喂食镁离子含量分别为40、12、6和3 mmol/kg的日粮。胎儿血清与母体血清之间、羊水与母体血清之间以及胎儿血清与羊水之间的非蛋白结合镁离子呈线性相关，比例分别为2.7、2.0和1.3，这表明胎盘以恒定浓度梯度主动转运镁离子。在心脏中，仅在镁供应最低的组中观察到钠离子和钙离子增加，镁离子和钾离子减少。给怀孕大鼠静脉注射氯化镁后，镁离子从母体血清缓慢转运至胎儿血清，再更缓慢地进入羊水。异丙肾上腺素对怀孕大鼠心脏电解质含量的影响小于未怀孕大鼠，对胎儿大鼠的影响小于对母体大鼠的影响。这些结果可以通过异丙肾上腺素在胎盘中失活、异丙肾上腺素的胎盘转运量小以及胎儿心脏腺苷酸环化酶对异丙肾上腺素的刺激较小来解释。
