Abstract
Doses of the drugs which produce uterine contraction were given intravenously to various species of animals. Placental and ovarian circulations were measured by the thermocouple method and/or microangiography. Uterine arterial blood flow (UABF) was measured by the electromagnetic flowmeter. Both placental blood flow (PBF) and UABF decreased with the administration of ONO-802, PGE1 or PGF2α to rabbits and dogs. Oxytocin and noradrenaline also decreased PBF in rabbits. ONO-802 or PGE1 lowered arterial blood pressure (BP) in rats, rabbits and dogs. PGF2α elevated BP in rats and dogs and lowered it in rabbits. Oxytocin produced no changes in BP while noradrenaline elevated BP in rabbits. Ovarian blood flow in pregnant rabbits was reduced by ONO-802, PGE1 or PGF2α. Little influence was seen with oxytocin. Regarding the luteal microvasculature in pregnant rats, ONO-802, PGF2α, and noradrenaline exhibited vasoconstricting effects. PGF2α induced abortion and decreased plasma progesterone levels. These results suggest that the inhibitory effects of ONO-802 on the uterine and placental circulation are strongly influenced by the uterine contractile effect and that the inhibitory effect on the ovarian circulation in rats is one of pharmacological effects not concerned with the abortifacient or luteolytic effect.
