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ROLE OF 1,25‐(OH) 2 D 3 DURING PREGNANCY; STUDIES WITH PIGS SUFFERING FROM PSEUDO‐ VITAMIN D‐DEFICIENCY RICKETS, TYPE I
Author(s) -
LachenmaierCurrle Ute,
Breves G.,
Harmeyer J.
Publication year - 1989
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0144-8757
DOI - 10.1113/expphysiol.1989.sp003358
Subject(s) - calcitriol , medicine , endocrinology , pregnancy , vitamin d and neurology , rickets , transplacental , hypocalcaemia , fetus , vitamin d deficiency , vitamin , cholecalciferol , biology , calcium , placenta , genetics
Biochemical parameters of Ca homeostasis in fetal and maternal plasma and placental transfer of Ca, P i and vitamin D metabolites were measured during pregnancy and at parturition. Control pigs and pigs with inherited pseudo‐vitamin D‐deficiency rickets, type I (PVDR), which are devoid of renal calcitriol production, were used. Although sows with PVDR normally require treatment with massive doses of vitamin D at intervals of 4 weeks to stabilize Ca and P i concentrations in plasma, these plasma parameters tended to normalize during the first 3 months of pregnancy when the vitamin D treatment was discontinued about 4 weeks before conception. In homozygote sows plasma calcitriol concentrations remained unphysio‐logically low and the 25OHD 3 concentrations increased steadily during pregnancy reaching higher levels than those found in control sows. Despite hypocalcaemia and hypophosphataemia of the homozygote sows at term, fetal Ca and P i concentrations were normal. This demonstrated a higher feto‐maternal concentration gradient in PVDR pigs than in control pigs. It is concluded that maintenance of Ca and P i homeostasis of the feto‐maternal system, including active transplacental transport in pigs, is at least partly independant from calcitriol.