Polyamine effects on human myometrial contractility.
OBJECTIVE
This study was undertaken to investigate the effects of the polyamine spermine on human uterine contractility.


METHODS
Under physiologic conditions, an isometric tension recording was performed in isolated myometrial strips from biopsy specimens obtained at elective cesarean delivery (n = 24 specimens) and from premenopausal hysterectomy specimens (n = 6 specimens). The effects of spermine (1 micromol/L-10 mmol/L in cumulative doses) on spontaneous, agonist-induced myometrial contractions were measured, and dose response curves were constructed. The pD(2) (-log EC(50)) values and the maximal inhibition values achieved were compared for spontaneous and agonist-induced contractions.


RESULTS
Spermine exerted a potent relaxant effect on all spontaneous and agonist-induced myometrial contractions, with mean maximal inhibition values between 62.8% +/- 4.3% and 91.4% +/- 1.8% and pD(2) values between 2.66 +/- 0.23 and 4.01 +/- 0.20. Its inhibitory effect varied significantly with different contraction types (pD(2), P <.05; mean maximal inhibition, P <.001), and it was least potent on BAY K 8644-elicited contractions (pD(2), P <.05; mean maximal inhibition, P <.01).


CONCLUSIONS
The polyamine spermine exerts a potent relaxant effect on human uterine tissue. This effect appears to be mediated, at least partially, by calcium antagonism. Polyamines may play a role in the maintenance of uterine quiescence during pregnancy.
Houlihan
Diarmaid D
DD
Department of Obstetrics and Gynecology, Clinical Science Institute, National University of Ireland Galway, University College Hospital, Galway, Ireland.
Dennedy
Michael C
MC
Morrison
John J
JJ
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D002120:Calcium Channel Agonists / Q000494:pharmacology; D002585:Cesarean Section; D005260:Female; D005865:Gestational Age; D005905:Glyburide / Q000494:pharmacology; D006801:Humans; D007044:Hysterectomy; D008751:Methylene Blue / Q000494:pharmacology; D009215:Myometrium / Q000187:drug effects; D010121:Oxytocin / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011073:Polyamines / Q000494:pharmacology*; D011247:Pregnancy; D013096:Spermine / Q000008:administration & dosage / Q000494:pharmacology; D014590:Uterine Contraction / Q000187:drug effects*
D000316:Adrenergic alpha-Agonists; D002120:Calcium Channel Agonists; D011073:Polyamines; D010656:Phenylephrine; D013096:Spermine; D010121:Oxytocin; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D005905:Glyburide; D008751:Methylene Blue