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FETAL‐MATERNAL PLASMA CALCIUM RELATIONSHIPS IN THE RABBIT
Author(s) -
Graham R. W.,
Porter G. P.
Publication year - 1971
Publication title -
quarterly journal of experimental physiology and cognate medical sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0033-5541
DOI - 10.1113/expphysiol.1971.sp002115
Subject(s) - fetus , calcium , gestation , endocrinology , calcification , calcium metabolism , medicine , pregnancy , gestational age , chemistry , biology , genetics
Plasma total calcium levels have been studied in pregnant rabbits and their fetuses from 16 days gestation to term. Between 16 and 21 days gestation the observed fetal plasma calcium level falls from the maternal level or above to 1·6 mg/100 ml. below the maternal level. Thereafter, the fetal plasma calcium rises and at 30 days gestation exceeds the maternal level by 1·9 mg/100 ml. There is a high correlation between fetal and maternal levels at 21 days which is lost by 30 days. Fetal skeletal calcification was studied using an alizarin stain technique. The earliest centres of calcification were present in the clavicle and mandible at 16 days. It is concluded that the observed fall in fetal plasma calcium near mid‐gestation may be due to the onset of skeletal calcification and the increase after 21 days to one or more of a variety of factors. Five 21 days pregnant animals were infused with 1 per cent calcium chloride solution (1 g anhydrous calcium chloride in 100 g aqueous solution) for up to 2½ hr. The maternal plasma calcium concentration was elevated by 7·7 mg/100 ml. during the infusion but the fetal level was only raised by 2·0 mg/100 ml. The correlation between fetal and maternal levels was lost during the infusion. These findings are compatible with either slow calcium transfer across the placenta or fetal calcium homeostasis.