Parathyroid hormone(1-34) and parathyroid hormone-related protein(1-34) stimulate calcium release from human syncytiotrophoblast basal membranes via a common receptor

in Journal of Endocrinology
Authors:
W Farrugia
Search for other papers by W Farrugia in
Current site
Google Scholar
PubMed
Close
,
T de Gooyer
Search for other papers by T de Gooyer in
Current site
Google Scholar
PubMed
Close
,
GE Rice
Search for other papers by GE Rice in
Current site
Google Scholar
PubMed
Close
,
JM Moseley
Search for other papers by JM Moseley in
Current site
Google Scholar
PubMed
Close
, and
ME Wlodek
Search for other papers by ME Wlodek in
Current site
Google Scholar
PubMed
Close
Free access

Sign up for journal news

The placental syncytiotrophoblast is the site for mineral and nutrient exchange across the maternal-fetal interface. It has been proposed that parathyroid hormone-related protein (PTHrP) is a key factor in the maintenance of a maternal-fetal calcium gradient. Using simultaneously prepared microvillous (maternal facing) and basal (fetal facing) syncytiotrophoblast membranes from term human placentae (n=8), we determined the relative contribution of PTH(1-34), PTHrP(1-34) and PTHrP(67-94) to the regulation of syncytiotrophoblast calcium efflux. The vesicles had correct right-side-out membrane orientation and specific markers validated the fractionation of microvillous and basal membrane vesicles. Calcium efflux was studied by preloading vesicles with calcium-45 in the presence of calcium and magnesium and then incubating the vesicles at 37 degrees C for 15 min with the peptides. In basal membranes, PTHrP(1-! 34) significantly stimulated calcium efflux at a dose of 12.5 nmol/l, whereas PTH(1-34)-stimulated efflux was significant at 50 nmol/l (P<0.05, ANOVA). This efflux was significantly reduced in the presence of the PTH/PTHrP receptor antagonist (PTHrP(7-34)). Midmolecule PTHrP(67-94) had no significant effect on basal membrane calcium efflux. PTH(1-34), PTHrP(1-34) or PTHrP(67-94) had no significant effects on MVM calcium efflux. This study, using the human syncytiotrophoblast in vitro membrane system, demonstrated that PTHrP(1-34) and PTH(1-34) stimulate calcium transport across the basal, but not microvillous, syncytiotrophoblast membrane vesicles, mediated via the PTH/PTHrP receptor.

 

  • Collapse
  • Expand