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.
Department of Obstetrics and Gynaecology, National University of Ireland Galway, and the Clinical Science Institute, University College Hospital Galway, Ireland.
M M
MM
Slattery
M J
MJ
O'leary
J J
JJ
Morrison
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