Further Studies on the Interaction Between Prostaglandins and Syntocinon on the Isolated Pregnant Human Myometrium

Abstract

Summary Interaction between prostaglandins and Syntocinon is shown to be of two kinds. There may be potentiation, where an increased response to Syntocinon follows combination with a low dose of prostaglandin, and enhancement, which is of much longer duration. Potentiation can be produced by both E and F prostaglandins, whereas enhancement is confined to E prostaglandins. Varying the doses of prostaglandin E is shown to have little effect on the degree of enhancement produced. The physiological implications and clinical applications of these interactions are discussed.

Misoprostol Vaginal Insert for Successful Labor Induction

“…Although no assessment was made of contraction duration, intensity, or quality, 8 these findings provide reassurance that the misoprostol vaginal insert did not appear to potentiate the effects of oxytocin, in contrast to use of some other labor induction agents. [11][12][13] The results of this phase II investigation are comparable with results of Miso-Obs-004, a phase III investigation 5 insofar as the 118 women treated with the MVI 100 in the phase II investigation had similar efficacy outcomes to the 428 MVI 100 -treated women and the 436 Cervidil-treated women in the phase III study.…”

The contribution of prostaglandin production to contractions of the isolated uterus of the rat

“…Firstly, there may be a continuous prostaglandin synthesis which sensitizes the uterus to the action of oxytocin. Prostaglandins potentiate responses to oxytocin in the rat isolated uterus and in strips of human pregnant myometrium (Pickles, Hall, Clegg and Sullivan, 1966;Brummer, 1972). However, such potentiation is non-specific and would not explain why in our experiments only oxytocin-induced responses were inhibited by indomethacin.…”

“…However, our failure to modify the action of oxytocin on the pregnant rat uterus with indomethacin would suggest that such an effect is not attributable to a gradual and progressive change in uterine prostaglandin production. Although in our experiments, indomethacin reduced prostaglandin output to amounts undetectable by bioassay, potentiation of agonist action can occur with very small amounts of prostaglandin Brummer, 1972) and thus complete inhibition of prostaglandin synthesis may be necessary in order to affect the oxytocin response.…”

The Action of Bradykinin and Oxytocin on the Isolated Whole Uterus and Myometrium of the Rat in Oestrus

“…First, there may be a continuous prostaglandin synthesis which sensitizes the uterus to oxytocin. It is well established that prostaglandins potentiate responses to oxytocin on the rat isolated uterus and on strips of human myometrium (Pickles, Hall, Clegg & Sullivan, 1966;Brummer, 1972). Second, oxytocin (but not acetylcholine or prostaglandin F2J) as well as inducing muscle contraction, may stimulate the synthesis of prostaglandins which would then potentiate the contractions induced by oxytocin, perhaps by increasing the rate and spread of depolarization, as suggested by Clegg et al (1966).…”

“…First, there may be a continuous prostaglandin synthesis which sensitizes the uterus to oxytocin. It is well established that prostaglandins potentiate responses to oxytocin on the rat isolated uterus and on strips of human myometrium (Pickles, Hall, Clegg & Sullivan, 1966;Brummer, 1972 Introduction). The endometrium appears to be the major source of prostaglandins, at least in the pregnant rat uterus Downing & Williams, 1977).…”