Abstract
Objective To investigate the effects of different pharmacological induction agents on myometrial
contractility.
Study Design Myometrial biopsies were obtained from 13 term nonlaboring women undergoing scheduled
cesarean delivery. Tissue strips were suspended in organ chambers for isometric tension
recording. The effects of cumulative doses (10−10 mol/L to 10−5 mol/L) of prostaglandin E1 (PGE1), E2 (PGE2), and oxytocin on spontaneous uterine
contractility were determined. Areas under the contraction curve were compared using
one-way analysis of variance on ranks with Dunn post hoc test.
Results Oxytocin-induced myometrial contractility was superior to PGE1, PGE2, and time controls
(CTR) at all the concentrations tested. When only prostaglandins were compared with
CTR, PGE1 10−5 mol/L increased myometrial contractility, and PGE2 had no effects.
Conclusion Oxytocin and prostaglandins have different effects on myometrial contractility accounting
for different mechanisms of action and side effects. The increased uterine contractility
observed with PGE1 as compared with PGE2 can contribute to explain the higher success
of vaginal delivery.
Keywords
prostaglandin E1 - prostaglandin E2 - oxytocin - uterine contractility - organ chamber
