Time-dependent changes in membrane excitability during glucose-induced bursting activity in pancreatic β cells
| Autor: | Enrique Santos, Chae Young Cha, Takao Shimayoshi, Akira Amano, Akinori Noma |
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| Rok vydání: | 2011 |
| Předmět: |
Time Factors
Physiology Differential equation Action Potentials Biology Article Membrane Potentials Cell membrane Bursting Adenosine Triphosphate Cytosol Insulin-Secreting Cells medicine Animals Equilibrium point Membrane potential Cell Membrane Glucose medicine.anatomical_structure Membrane Biochemistry Commentary Biophysics Calcium Intracellular |
| Zdroj: | The Journal of General Physiology |
| ISSN: | 1540-7748 0022-1295 |
| Popis: | In our companion paper, the physiological functions of pancreatic β cells were analyzed with a new β-cell model by time-based integration of a set of differential equations that describe individual reaction steps or functional components based on experimental studies. In this study, we calculate steady-state solutions of these differential equations to obtain the limit cycles (LCs) as well as the equilibrium points (EPs) to make all of the time derivatives equal to zero. The sequential transitions from quiescence to burst–interburst oscillations and then to continuous firing with an increasing glucose concentration were defined objectively by the EPs or LCs for the whole set of equations. We also demonstrated that membrane excitability changed between the extremes of a single action potential mode and a stable firing mode during one cycle of bursting rhythm. Membrane excitability was determined by the EPs or LCs of the membrane subsystem, with the slow variables fixed at each time point. Details of the mode changes were expressed as functions of slowly changing variables, such as intracellular [ATP], [Ca2+], and [Na+]. In conclusion, using our model, we could suggest quantitatively the mutual interactions among multiple membrane and cytosolic factors occurring in pancreatic β cells. |
| Databáze: | OpenAIRE |
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