Effect of parathyroid hormone-related peptide on human and rat myometrial contractility in vitro.
OBJECTIVE
The aims of this study were primarily to investigate the effects of parathyroid hormone-related peptide (human fragment 1-34) on human nonpregnant and pregnant (nonlabor and labor) myometrial contractility in vitro and secondarily to compare these effects with those of parathyroid hormone-related peptide on rat myometrial contractility.


METHODS
Isometric tension recording was performed under physiologic conditions in isolated myometrial strips obtained at hysterectomy and cesarean delivery and from Sprague-Dawley rats. The effect of cumulative additions of parathyroid hormone-related peptide (1, 10, and 100 nmol/L) on myometrial contractility was measured and the significance of results was assessed by 2-way analysis of variance.


RESULTS
Parathyroid hormone-related peptide exerted a statistically significant net relaxant effect on myometrial contractility in human nonpregnant myometrium (34.71%; P<.01), in human pregnant myometrium obtained before (18.27%; P <.05) but not after (10.32%; P>.05) the onset of labor, and in rat tissue (31.60%; P<.01).


CONCLUSIONS
Parathyroid hormone-related peptide exerts a relaxant effect on human and rat myometrial tissue. In human myometrium, sensitivity to parathyroid hormone-related peptide is reduced in pregnancy and abolished by the onset of labor.
Slattery
M M
MM
Department of Obstetrics and Gynaecology, National University of Ireland Galway, and the Clinical Science Institute, University College Hospital Galway, Ireland.
O'leary
M J
MJ
Morrison
J J
JJ
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D002585:Cesarean Section; D005260:Female; D006801:Humans; D007044:Hysterectomy; D044162:Parathyroid Hormone-Related Protein; D010656:Phenylephrine; D011247:Pregnancy; D011506:Proteins / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014590:Uterine Contraction / Q000187:drug effects*
D000316:Adrenergic alpha-Agonists; C470121:PTHLH protein, human; D044162:Parathyroid Hormone-Related Protein; D011506:Proteins; D010656:Phenylephrine