Net Transfer of Essential Metals from Mother to Fetus in the Second Half of Pregnancy in the Rat

Abstract

The blood and plasma as well as fetal, placental and whole conceptus levels of copper, iron, sodium, zinc, potassium, magnesium and calcium were measured in pregnant rats and their fetuses days 11–21 after conception. Maternal blood and plasma concentrations of these metals did not really change in the period studied. In the fetus, the concentrations of iron, zinc and calcium increased, whereas for the other metals, they remained practically unchanged during fetal development. The net cumulative levels of metals in the whole conceptus increased in parallel with fetal growth for most metals, except for the zinc and calcium concentrations which increased at a higher pace, especially after day 16. It is concluded that these data could only be explained by a balanced increase in fetal drainage from the mother, which does not deeply change the homeostatic maintenance of the maternal circulating metal pools.

Combined Effects of Pregnancy and Lewis Lung Carcinoma Bearing upon Essential Metal Tissue Content in Inbred Mice

“…Thus, the severe metal losses that characterize the final stages of Lewis lung carcinoma growth on mice [17] have not yet been achieved. In a similar way, the final exponential trans fer of metals especially calcium [5] towards the fetus in the very last days of intrauterine development [4] has not yet again been attained. In the phase of rodent reproductive cycle selected, the dependence of fetal metabolism on maternal energetic supply is con siderable, as its own autonomy is yet poorly developed [12].…”

Combined Pregnancy and Starvation Effects on Rat Tissue Iron, Zinc and Copper Contents

“…Starvation results in a decrease of tissue zinc, most remarkable on the 21st day; when the data are computed for the whole animal, this decrease is en hanced. Actually, the pattern of incorpora tion of zinc to the fetuses is rather different from those of iron and copper [12], as zinc distribution is more similar to that of cal cium [30], probably as a consequence of its participation in the processes of bone syn thesis [28]. Thus, zinc incorporation into the fetuses markedly increases towards the end of intrauterine life, when massive ossifica tion takes place [30].…”

“…We have characterized the size and avail ability of essential metal stores in the preg nant rat [ 10,11 ], as well as the pace of trans fer of those materials to the fetus during the second half of rat pregnancy [12], It has been intended here, as a continuation of these studies, to establish the ability of the mater nal organism to cope with the burden of fetal essential metal supply under the added met abolic stress of starvation.…”

Essential Metal Balance and Retention during the Second Half of Pregnancy in the Rat

“…Thus from the data of an earlier study [10], the ratio of metal retained by the mother and that accrued in the conceptus were calculated. These ratios were 4.4 for copper, 4.7 for zinc, 3.2 for iron, 9.1 for mag nesium, 5.9 for calcium, 2.9 for potassium and 2.1 for sodium.…”

“…The availability of some mineral elements in the diet is critical for the adequate supply of the dam and her fetuses [ 1 ], and the lack of some elements in the diet in sufficient amounts results in severe deficiencies [2] such as ane mia [3,4], The actual balance of essential metals in pregnant animals has been studied for some metals [5][6][7], but only at term or in special situations [5], It has been intended here to follow daily the balance of 7 essential metals: calcium, copper, iron, magnesium, zinc, sodium and potassium during the sec ond half of pregnancy in the rat, in order to gain more knowledge about the possible changes in retention from the diet, as postu lated elsewhere [8]. We also tried to deter mine the effects of increased ingestion due to pregnancy [9] in the actual balance of these metals in a situtation where it is necessary to supply the growing needs of the fetuses [ 10].…”