Fetal and material ovine placental lactogen during hyperglycaemia, hypoglycaemia and fasting.

Hyperglycaemia was produced in chronically catheterized fetal lambs and pregnant-ewes by the infusion of glucose into the fetus. Plasma concentration of placenta lactogen did not change significantly in either fetal or maternal circulation. Fetal and maternal hypoglycaemia was induced by administration of insulin to the fetus and ewe separately. Plasma concentrations of placental lactogen in the fetus did not change significantly but maternal plasma concentrations fell slightly after hypoglycaemia in either fetus or ewe. Plasma concentrations of placental lactogen rose in both the ewe and fetus during prolonged fasting of the ewe. These results neither confirm nor refute a role for placental lactogen in intermediary metabolism of the pregnant ewe and fetus but glucose concentration alone is unlikely to be a significant factor in the control of secretion of this hormone.