Dataset for: The thermodynamic basis of glucose stimulated insulin release: a model of the core mechanism.
2017-07-17T17:07:06Z (GMT) by
A model for glucose sensing by pancreatic β-cells is developed and compared to the available experimental data. The model brings together mathematical representations for the activities of the glucose sensor, glucokinase, and oxidative phosphorylation. Glucokinase produces glucose 6-phosphate (G-6-P) in an irreversible reaction that determines glycolytic flux. The primary products of glycolysis are NADH and pyruvate. The NADH is reoxidized and the reducing equivalents transferred to oxidative phosphorylation by the glycerol phosphate shuttle and some of the pyruvate is oxidized by pyruvate dehydrogenase and enters the citric acid cycle. These reactions are irreversible, and result in a glucose concentration dependent reduction of the intramitochondrial NAD pool. This increases the electrochemical energy coupled to ATP synthesis, and thereby the cellular energy state ([ATP]/[ADP][Pi]). [ATP] and [Pi] are 10 to 100 times greater than [ADP], so the increase in energy state is primarily through decrease in [ADP]. The decrease in [ADP] is considered responsible for altering ion channel conductance and releasing insulin. Applied to the reported glucose concentration dependent release of insulin by perifused islet preparations (4), the model predicts that the dependence of insulin release on [ADP] is strongly cooperative with a threshold of about 30 µM and a negative Hill coefficient near -5.5. The predicted cellular energy state, [ADP], creatine phosphate/creatine ratio, and cytochrome c reduction, including their dependence on glucose concentration, are consistent with experimental data. The ability of the model to predict behavior consistent with experiment is an invaluable resource for understanding glucose sensing and planning experiments.