Decreased uterine blood flow in the diabetic pregnant rat does not modify the augmented glucose transfer to the fetus.

Abstract

To determine whether changes in uterine blood flow affect placental glucose transfer in the diabetic pregnant rat, on the 7th day of gestation rats were intravenously treated with either streptozotocin (45 mg/kg) (diabetics) or buffer (controls). On the 20th day of gestation, fetal body weight and uterine blood flow appeared reduced whereas fetal/maternal plasma glucose was enhanced and lactate ratios were unchanged in diabetics versus controls. After 20 min of (U- 14C)-D-glucose infusion through the maternal left uterine artery, plasma values of fetuses from left and right uterine horns were higher for 14C-glucose and lower for 14C-lactate in diabetics versus controls, and placental glucose transfer was greatly augmented in diabetics whether or not uterine blood flow was included in its calculation. Whereas a linear correlation existed between placental glucose transfer and maternal plasma glucose concentration, transferred glucose conversion into lactate remained stable even when the maternal glucose level was high. It was concluded that enhanced placental glucose transfer in the pregnant diabetic rat is not modified by reduced uterine blood flow. The limited capacity of the fetus to handle the great incoming flux of glucose through the placenta of a severely diabetic mother produces permanent hyperglycemia which may impair fetal growth.