Sensitivity of the Renal Adenylate Cyclase Receptor System to Parathormone during the Last Third of Pregnancy in the Rat

Abstract

During the last third of pregnancy, the rat phospho-calcic metabolism is clearly modified. Sensitivity of the renal receptor to parathormone (PTH) was investigated over this period in the fetuses and their mothers. As early as day 16.5 of pregnancy, the fetal kidney is sensitive to bovine PTH (1–34) on the basis of cAMP production. Sensitivity declines on the last day of pregnancy. The newborn kidney showed a higher response to PTH 3 h after birth than after 24 h. The basal adenylate cyclase activity in renal membranes of maternal kidney does not change. The sensitivity to PTH and to fluoride both decreased on day 18.5. A desensitization process of the PTH receptor A-C system has to be studied in order to explain these results.

GTP-Dependant Protein (Gs) Activity in Preterm Infants

“…They are also comparable with those obtained in the rat [29], This latter work showed that the adenylate cyclase system in the renal membrane, which incorporates the Gs protein without isolating it, must be func tional in the fetus in útero during the last tri mester. It would also suggest that renal resis tance may be linked with a receptor desensiti zation phenomenon with resulting parathy roid hormone excess due to the drop in serum calcium levels observed in preterm infants.…”