Rates of gluconeogenesis in perfused liver of alloxan-diabetic fed rats

The maximal capacity of the liver to produce glucose was examined using a technique, which permited to investigate gluconeogenesis in diabetic fed rats. Diabetes was obtained with an iv injection of alloxan (40 mg/kg). Livers from diabetic fed rats were perfused in situ and gluconeogenesis from different glucose precursors were measured one week after alloxan injection. Hepatic gluconeogenesis from L-alanine (5 mM) was absent. However, increased urea, pyruvate and L-lactate production was observed during L-alanine infusion. Differently of L-alanine, alloxan-diabetic fed rats showed increased hepatic glucose production from pyruvate (5 mM), L-lactate (2 mM) and D-frutose (5 mM). Additionally, increased L-lactate production from pyruvate and pyruvate production from L-lactate were observed. However, pyruvate production from L-lactate was lower in the diabetic group when compared with control group. Moreover similar tendency were observed for L-alanine and D-frutose. Taken together our results demonstrate influence of the cytosolic redox potential (NADH/NAD(+) ratio) in the metabolic fate L-alanine. Additionally, in contrast to L-alanine, diabetic rats not only showed increased rate of glucose production from L-glutamine (5 mM) but also higher values than control rats.