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This Article Full Text Full Text (PDF) All Versions of this Article: 293/5/E1352    most recent 00394.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Martins-Santos, M. E. S. Articles by Migliorini, R. H. Search for Related Content PubMed PubMed Citation Articles by Martins-Santos, M. E. S. Articles by Migliorini, R. H.

Glyceroneogenesis and the supply of glycerol-3-phosphate for glyceride-glycerol synthesis in liver slices of fasted and diabetic rats

Departments of Biochemistry-Immunology and Physiology, School of Medicine, University of São Paulo, Ribeirão Preto, São Paulo, Brazil

Submitted 21 June 2007 ; accepted in final form 24 August 2007

The pathways of glycerol-3-phosphate (G3P) generation for glyceride synthesis were examined in precision-cut liver slices of fasted and diabetic rats. The incorporation of 5 mM [U-¹⁴C]glucose into glyceride-glycerol, used to evaluate G3P generation via glycolysis, was reduced by 26–36% in liver slices of fasted and diabetic rats. The glycolytic flux was reduced by 60% in both groups. The incorporation of 1.0 mM [2-¹⁴C]pyruvate into glyceride-glycerol (glyceroneogenesis) increased 50% and 36% in slices of fasted and diabetic rats, respectively, which also showed a two-fold increase in the activity phosphoenolpyruvate carboxykinase. The increased incorporation of 1.0 mM [2-¹⁴C]pyruvate into glyceride-glycerol by slices of fasted rats was not affected by the addition of 5 mM glucose to the incubation medium. The activity of glycerokinase and the incorporation of 1 mM [U-¹⁴C]glycerol into glyceride-glycerol, evaluators of G3P formation by direct glycerol phosphorylation, did not differ significantly from controls in slices of the two experimental groups. Rates of incorporation of 1 mM [2-¹⁴C]pyruvate and [U-¹⁴C]glycerol into glucose of incubation medium (gluconeogenesis) were 140 and 20% higher in fasted and diabetic slices than in control slices. It could be estimated that glyceroneogenesis by liver slices of fasted rats contributed with 20% of G3P generated for glyceride-glycerol synthesis, the glycolytic pathway with 5%, and direct phosphorylation of glycerol by glycerokinase with 75%. Pyruvate contributed with 54% and glycerol with 46% of gluconeogenesis. The present data indicate that glyceroneogenesis has a significant participation in the generation of G3P needed for the increased glyceride-glycerol synthesis in liver during fasting and diabetes.

phosphoenolpyruvate carboxykinase; glycerokinase; [U-¹⁴C]glucose; [2-¹⁴C]pyruvate; [U-¹⁴C]glycerol; gluconeogenesis