HEPATIC GLUCOSE-PRODUCTION FROM L-ALANINE IS ABSENT IN PERFUSED LIVEROF DIABETIC RATS

The effects of L-alanine on hepatic glucose production in diabetic rat s and the corresponding controls was investigated. Diabetes was obtain ed with an injection iv of streptozotocin (STZ) or alloxan. Livers fro m diabetic and control rats after 24 hours of fasting were perfused in situ and glucose production from L-alanine and several gluconeogenic substrates were measured. Hepatic gluconeogenesis from L-alanine was a bsent in rats with diabetes induced by STZ or alloxan. STZ-diabetic ra ts also shown this metabolic change when the period of diabetes was pr olonged. It was concluded that this efffect may be partly at least, th e consequence of an increased NADH/NAD+ ratio in the diabetic rat live r, which indicates that the Cytosolic redox potential is favorable to pyruvate conversion to L-lactate but not to glucose. However, consider ing that glucose production from pyruvate, L-lactate, glycerol and sor bitol was not affected by the diabetic condition, the rate of conversi on of L-alanine to pyruvate can contribute to the lack of gluconeogene sis when this amino acid was employed as a substrate.