Glyceroneogenesis and the supply of glycerol-3-phosphate for glyceride-glycerol synthesis in liver slices of fasted and diabetic rats
| Autor: | Danúbia Frasson, Maria Antonieta Rissato Garófalo, Valéria Ernestânia Chaves, Maria E.S. Martins-SantosM.E. Martins-Santos, Renata Polessi Boschini, Isis do Carmo Kettelhut, Renato Helios Migliorini |
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| Rok vydání: | 2007 |
| Předmět: |
Glycerol
Male medicine.medical_specialty Physiology Endocrinology Diabetes and Metabolism Glyceride Biology In Vitro Techniques Diabetes Mellitus Experimental Glycerides chemistry.chemical_compound Adenosine Triphosphate Biosynthesis Physiology (medical) Internal medicine Glycerol Kinase Pyruvic Acid medicine Glyceroneogenesis Animals Carbon Radioisotopes Rats Wistar Triglycerides Phosphate Rats Endocrinology Glucose chemistry Biochemistry Gluconeogenesis Liver Glycerophosphates Glycerol 3-phosphate Phosphoenolpyruvate carboxykinase Food Deprivation Phosphoenolpyruvate Carboxykinase (ATP) |
| Zdroj: | American journal of physiology. Endocrinology and metabolism. 293(5) |
| ISSN: | 0193-1849 |
| Popis: | 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 phospho enolpyruvate 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. |
| Databáze: | OpenAIRE |
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