Strontium-calcium discrimination during placental transfer and fetal uptake in rats: effect of gestation duration.

Abstract

SummaryThe purposes of this study were: (a) to quantitate longitudinally the uptake of 89Sr and 45Ca and the strontium–calcium discrimination of placental structures and fetuses during the final third of the rat gestation period. And, (b) to determine whether dietary protein percentage affects these responses. Twenty-eight female rats, receiving 10 or 22% casein diets, were given iv doses of 89Sr and 45Ca proportional to body weight on either day 13, 15, 16, 17, 18, 19, 20 or 21 of gestation. One day after dosing 89Sr and 45Ca content of fetuses, placentas, maternal carcass and GI tract contents were determined along with 24-hr urine and feces content. Dietary protein percentages had no significant effect on any experimental criterion. Pooled data for both diets showed uptake by placental structures of 0.36 and 0.27% of the 89Sr dose and 0.41 and 0.23% of the 45Ca dose at 13 and 21 days gestation, respectively. Parallel values for fetal uptake were 0.11 and 12.91% of the 89Sr dose and 0.14 and 20.20% of t...