Simultaneous determinations of uterine blood flow and plasma concentrations of placental lactogen in late-pregnant goats.

Abstract

Blood flow in the middle uterine artery was measured with electromagnetic blood flow probes, and placental lactogen in jugular and uterine venous plasma was estimated as total lactogenic activity using a radioreceptor assay. There was no circadian variation in uterine arterial blood flow in late pregnancy (Days 105-124) and the pattern of blood flow varied between goats. Blood flow was quite stable for periods of up to 40 min although at other times a rapid fall (by up to 90%) was followed by a gradual recovery. These spontaneous changes lasting up to 30 min could not be consistently related to postural or behavioural changes. Acute decreases of about the same duration could also be induced by administration of adrenaline. In the short-term there was no association between uterine blood flow and total lactogenic activity in the peripheral circulation during spontaneous or adrenaline-induced depression of blood flow. More limited short-term observations on total lactogenic activity in the uterine vein also failed to show a relationship with blood flow in the uterine artery.