title: The effect of 1 alpha-hydroxycholecalciferol on the placental transfer of calcium and phosphate in sheep.
abstract: The calcium and phosphorus concentrations in foetal tissue or the placental transfer of 45Ca and 32P, or both, were studied in fifty-five control or 1 alpha-hydroxycholecalciferol (1 alpha-(OH)D3)-treated (0.1 micrograms/kg body-weight per d for 12 d) ewes between 77 and 140 d of gestation. Treatment resulted in a significant increase in the concentration of Ca and P in foetal tissues at all stages of gestation except at 140 d when, it is suggested, foetal mineralization may approach a maximum value. This increase in Ca and P concentration in foetal tissues was associated with an increased placental transfer of Ca, though at 111 and 120 d gestation this increase was not significant. P transfer, which was only measured at 140 d gestation, was also significantly higher in treated animals. The concentrations of Ca and P in both maternal and foetal plasma were increased significantly by the 1 alpha-(OH)D3 treatment. Whereas the concentration of Ca in the plasma of foetuses was always greater than in their dams, the concentration of plasma P in treated animals, unlike controls, was lower in foetuses than dams. This suggests that the increased placental transfer of P, unlike that of Ca, may be a passive rather than an active process.
mesh_terms: D000818:Animals; D002118:Calcium / Q000097:blood / Q000378:metabolism*; D005260:Female; D005312:Fetal Blood / Q000032:analysis; D005333:Fetus / Q000378:metabolism; D006887:Hydroxycholecalciferols / Q000494:pharmacology*; D008431:Maternal-Fetal Exchange / Q000187:drug effects*; D010758:Phosphorus / Q000097:blood / Q000378:metabolism*; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy; D012756:Sheep
chemical_list: D006887:Hydroxycholecalciferols; D010758:Phosphorus; D002118:Calcium; C008088:alfacalcidol