Glycolysis

About: Glycolysis is a research topic. Over the lifetime, 10593 publications have been published within this topic receiving 507460 citations. The topic is also known as: GO:0006096 & glycolysis.

Effects of increased heart work on glycolysis and adenine nucleotides in the perfused heart of normal and diabetic rats

Abstract: 1. In the isolated perfused rat heart, the contractile activity and the oxygen uptake were varied by altering the aortic perfusion pressure, or by the atrial perfusion technique (;working heart'). 2. The maximum increase in the contractile activity brought about an eightfold increase in the oxygen uptake. The rate of glycolytic flux rose, while tissue contents of hexose monophosphates, citrate, ATP and creatine phosphate decreased, and contents of ADP and AMP rose. 3. The changes in tissue contents of adenine nucleotides during increased heart work were time-dependent. The ATP content fell temporarily (30s and 2min) after the start of left-atrial perfusion; at 5 and 10min values were normal; and at 30 and 60min values were decreased. ADP and AMP values were increased in the first 15min, but were at control values 30 or 60min after the onset of increased heart work. 4. During increased heart work changes in the tissue contents of adenine nucleotide and of citrate appeared to play a role in altered regulation of glycolysis at the level of phosphofructokinase activity. 5. In recirculation experiments increased heart work for 30min was associated with increased entry of [(14)C]glucose (11.1mm) and glycogen into glycolysis and a comparable increase in formation of products of glycolysis (lactate, pyruvate and (14)CO(2)). There was no major accumulation of intermediates. Glycogen was not a major fuel for respiration. 6. Increased glycolytic flux in Langendorff perfused and working hearts was obtained by the addition of insulin to the perfusion medium. The concomitant increases in the tissue values of hexose phosphates and of citrate contrasted with the decreased values of hexose monophosphates and of citrate during increased glycolytic flux obtained by increased heart work. 7. Decreased glycolytic flux in Langendorff perfused hearts was obtained by using acute alloxan-diabetic and chronic streptozotocin-diabetic rats; in the latter condition there were decreased tissue contents of hexose phosphates and of citrate. There were similar findings when working hearts from streptozotocin-diabetic rats with insulin added to the medium were compared with normal hearts. 8. The effects of insulin addition or of the chronic diabetic state could be explained in terms of an action of insulin on glucose transport. Increased heart work also acted at this site, but in addition there was evidence for altered regulation of glycolysis mediated by changes in tissue contents of adenine nucleotides or of citrate.

New insights into pancreatic β-cell metabolic signaling in insulin secretion

Abstract: In recent years, it has become apparent that second messengers and factors other than ATP, metabolically sensitive K + ATP channels and Ca 2+ play essential roles in nutrient-induced insulin release. This paper reviews the evidence in support of several new concepts and hypotheses in the field of β-cell signaling. These include in particular that : a rise in cytosolic Ca 2+ is not sufficient to explain the kinetics and extent of secretion induced by glucose : variations in ADP, rather than ATP, regulate β-cell metabolism and the K + ATP channel : anaplerosis (the replenishment of the citric acid cycle with intermediates) is essential for β-cell activation : a shift from fatty acid oxidation to esterification is an important event in β-cell signaling ; malonyl-CoA and long chain acyl-CoA esters may act as metabolic coupling factors ; glycolytic oscillations underlie, in part, oscillations in electrical activity, cytosolic Ca 2+ and insulin release. A metabolic model of fuel sensing that integrates the mode of action of all classes of nutrient secretagogues is proposed.

Diabetes causes marked inhibition of mitochondrial metabolism in pancreatic β-cells.

Abstract: Diabetes is a global health problem caused primarily by the inability of pancreatic β-cells to secrete adequate levels of insulin. The molecular mechanisms underlying the progressive failure of β-cells to respond to glucose in type-2 diabetes remain unresolved. Using a combination of transcriptomics and proteomics, we find significant dysregulation of major metabolic pathways in islets of diabetic βV59M mice, a non-obese, eulipidaemic diabetes model. Multiple genes/proteins involved in glycolysis/gluconeogenesis are upregulated, whereas those involved in oxidative phosphorylation are downregulated. In isolated islets, glucose-induced increases in NADH and ATP are impaired and both oxidative and glycolytic glucose metabolism are reduced. INS-1 β-cells cultured chronically at high glucose show similar changes in protein expression and reduced glucose-stimulated oxygen consumption: targeted metabolomics reveals impaired metabolism. These data indicate hyperglycaemia induces metabolic changes in β-cells that markedly reduce mitochondrial metabolism and ATP synthesis. We propose this underlies the progressive failure of β-cells in diabetes.

Glycolytic promoters for regulated protein expression: protease inhibitor

Abstract: Promoters associated with expression of specific enzymes in the glycolytic pathway are used for expression of alien DNA, particularly yeast promoters known to provide high enzyme levels of enzymes in the glycolytic pathway are employed for expressing a mammalian protein, such as alpha-1-antitrypsin. The promoters include promoters involved in expression of pyruvate kinase, triose phosphate isomerase, phosphoglucose isomerase, phosphoglycerate mutase, hexokinase 1, hexokinase 2, glucokinase, phosphofructose kinase, and aldolase, as well as the glycolytic regulation gene. Particularly, the glycolytic regulation gene can be used in conjunction with promoters in the glycolytic pathway for regulated production of desired proteins.