Inhibition of spontaneous uterine contractions during the last trimester in pregnant baboons by an oxytocin antagonist.
The effect of a potent oxytocin antagonist, produced in our laboratories, on spontaneous uterine contractions in the pregnant baboon was examined. Three types of uterine contractions were studied: immediately after operation, during the nocturnal period, and near or at labor. Bolus intravenous injections of oxytocin antagonist were given and uterine activity was examined +/- 1 hour after the injection. The oxytocin antagonist caused a precipitate decrease (approximately 70%) in contractile force (mean amplitude x frequency) in the first 15 minutes after injection (p less than 0.05); this force diminished to approximately 90% at the end of 1 hour for both nocturnal and labor contractions. In contrast, uterine contractions immediately after operation were diminished by only 60% within 60 minutes after the oxytocin antagonist. These results indicate that the oxytocin antagonist is a potent inhibitor and suggest that oxytocin is a primary regulator of spontaneous nocturnal and labor uterine contractions in the pregnant baboon.
Wilson
L
L
Department of Obstetrics and Gynecology, University of Illinois, Chicago 60612.
Parsons
M T
MT
Flouret
G
G
D000704:Analysis of Variance; D000818:Animals; D003864:Depression, Chemical; D005260:Female; D007752:Obstetric Labor, Premature / Q000517:prevention & control; D010121:Oxytocin / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D010215:Papio; D011247:Pregnancy; D015149:Tocolytic Agents; D014590:Uterine Contraction / Q000187:drug effects*; D014667:Vasopressins
D015149:Tocolytic Agents; D014667:Vasopressins; C066604:oxytocin, beta-mercapto-beta,beta-cyclopentamethylenepropionic acid-Trp(2)-Phe(3)-Ile(4)-Arg(8)-; D010121:Oxytocin