Placental Transfer and Fetal Tissue Uptake of Mg28 in the Rabbit

Abstract

Mg28 was injected intravenously into 11 pregnant rabbits between 28 and 30 days of gestation. Fetuses and placentas were removed at intervals ranging from 7 minutes to 26 hr. Maternal tissue uptake of Mg28 resembled that previously found in nonpregnant young adult rabbits, except that uptake in bone and muscle was slower. Concentration of Mg28 in the placenta rapidly rose above the maternal plasma level. The specific activity of Mg in all fetal tissues studied reached a fairly constant value by 26 hr. Mg turnover in tissues of the fetus in utero, especially in bone and muscle, is considerably more rapid than that in the respective tissues of the mother.