title: Effect of fetal intravascular 4-aminoantipyrine infusions on myometrial activity (contractures) at 125 to 143 days' gestation in the pregnant sheep.
abstract: Myometrial activity of low amplitude and long duration--contractures--is present throughout gestation in the pregnant ewe and other species. This activity differs from the contractions of labor and delivery. Between 125 and 143 days' gestation, 4-aminoantipyrine infused into the fetus at rates that produced maternal uterine vein plasma concentrations of 4-aminoantipyrine of 5.95 +/- 1.23 (mean +/- SEM, n = 5) mg X 100 ml-1 markedly depressed both total myometrial electromyographic activity to 28.6% and frequency of contractures to 30.5% of preinfusion values. By 60 minutes of infusion, maternal uterine vein plasma 13,14-dihydro-15-keto prostaglandin F2 alpha concentration was reduced to 14% of the resting level. Two conclusions were drawn from this study. First, prostaglandins are involved in the regulation of contractures. Second, when infusions of 4-aminoantipyrine are used to quantify uterine or umbilical blood flow, the possibility exists that changes will occur in physiologic systems that are modified by prostaglandins.
mesh_terms: D000675:Ampyrone / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D000818:Animals; D000983:Antipyrine / Q000031:analogs & derivatives*; D015237:Dinoprost / Q000031:analogs & derivatives*; D004576:Electromyography; D005260:Female; D005312:Fetal Blood / Q000032:analysis; D005333:Fetus; D007263:Infusions, Parenteral; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000187:drug effects*; D011460:Prostaglandins F / Q000097:blood; D012756:Sheep; D014590:Uterine Contraction / Q000187:drug effects*; D014599:Uterus / Q000098:blood supply
chemical_list: D011460:Prostaglandins F; D000675:Ampyrone; C008228:15-keto-13,14-dihydroprostaglandin F2alpha; D015237:Dinoprost; D000983:Antipyrine