Placental Transfer and Fetal Tissue Uptake of Mg 28 in the Rabbit ∗

Abstract

Summary

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 hours. 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. Specific activity of magnesium in all fetal tissues studied reached a fairly constant value by 26 hours. Magnesium 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.

Mg²⁸ was supplied by Brookhaven Laboratory on allccation from U. S. Atomic Energy Comm.