Ovine uteroplacental glucose and oxygen metabolism in relation to chronic changes in maternal and fetal glucose concentrations

Abstract

We tested whether uterine glucose uptake rate (UtGU), placental glucose transport rate to the fetus (PGT) and uteroplacental glucose consumption rate (UPGC) were altered in chronically catheterized pregnant sheep after 2-5 week intravenous infusions of glucose or insulin that produced sustained maternal and fetal hyper- or hypoglycemia. In the hyperglycemic animals, UtGU was greater than that of controls; the excess UtGU was partitioned into non-oxidative UPGC rather than PGT. The 'normal' rate of PGT observed in the hyperglycemic animals is probably related to suppression of fetal insulin concentration which would decrease fetal glucose clearance and thus the transplacental glucose concentration gradient. The increase in UPGC may help prevent an excessive supply of glucose to the fetus. In the hypoglycemic animals, weight-specific UPGC and uteroplacental oxygen uptake were not different from controls; placental weight also was reduced, an adaptation that maintained normal placental metabolism per unit tissue and did not disproportionately deprive the fetus of glucose supply.