Increased gluconeogenesis in the rat at term gestation.

In this study the contribution of maternal gluconeogenesis to the glucose homeostasis of the maternal-fetal unit has been studied in fed term pregnant rats. We have measured the activity of two gluconeogenic enzymes, the rates of lactate turnover and the rates of gluconeogenesis from lactate in fed term pregnant rats. A decrease in plasma glucose and liver glycogen concentrations, and an increase of plasma lactate and alanine concentrations were observed in fed 22-day pregnant rats compared to virgin controls. Also, liver and kidney phosphoenolpyruvate carboxykinase activities and liver lactate dehydrogenase and hexose bisphosphatase activities significantly increased in fed term pregnant rats compared to virgin rats. The lactate turnover rate and the rate of gluconeogenesis in vivo from L-[U14C] Lactate increased four- and two-fold respectively in fed pregnant rats compared to fed virgins.