Vascular effects of PTHrP (1–34) and PTH (1–34) in the human fetal-placental circulation

Abstract The aim of this study was to examine the vasodilatory effects of parathyroid hormone-related protein (PTHrP) (1–34) and parathyroid hormone (PTH) (1–34) on the human fetal-placental circulation utilising an in vitro placental perfusion model. In all experiments, the vasculature of an isolated human placental cotyledon was pre-constricted with the throm☐ane A 2 mimetic U46619. A single dose of PTHrP (1–34) or PTH (1–34) (1.7–300 n m ) was then infused into the fetal-placental circulation of the cotyledon. In other experiments, cotyledons were repeatedly infused with PTHrP (1–34) or PTH (1–34) (51.3 n m ). Vasodilatory responses were significantly reduced in response to repeated exposure to PTHrP (1–34) and PTH (1–34) ( P P 10 , Leu 11 ]PTHrP (7–34) (102 nM) was infused in U46619-constricted placentae in the presence and absence of PTHrP (1–34) (10.2 nM). The PTHrP antagonist alone had no significant effect in the fetal-placental circulation. The antagonist significantly attenuated the response to PTHrP (1–34) ( P