STIMULATION OF OVINE PLACENTAL CALCIUM-TRANSPORT BY PURIFIED NATURAL AND RECOMBINANT PARATHYROID HORMONE-RELATED PROTEIN (PTHRP) PREPARATIONS
SK ABBAS, DW PICKARD, CP RODDA, JA HEATH, RG HAMMONDS, WI WOOD, IW CAPLE, TJ MARTIN, AD CARE
QUARTERLY JOURNAL OF EXPERIMENTAL PHYSIOLOGY AND COGNATE MEDICAL SCIENCES | CAMBRIDGE UNIV PRESS | Published : 1989
Perfusion in situ of the placenta of previously thyroparathyroidectomized fetal lambs has been used to compare the ability of various forms of parathyroid hormone-related protein (PTHrP) to stimulate placental calcium transport. Whereas PTHrP (1-34) was without effect, PTHrP (1-141) was active but usually after a delay of up to 1 h, in common with the effect noted when using extracts of fetal parathyroid glands. In contrast, PTHrP (1-84) and PTHrP (1-108), tended to show a more rapid stimulatory action. It is suggested that post-translational processing of PTHrP (1-141) may occur as an activating step in the placenta in vivo.