Passive ER Model

This is supplementary material for: R. Bertram and A. Sherman. 2004. Filtering of calcium transients by the endoplasmic reticulum in pancreatic beta-cells, Biophys. J., 87:3775-3785. [PubMed]

Cartoons of Two-Compartment (Left) and Three-Compartment (Right) Models

This simple model with a passive ER reproduces all the experiments in Arredouani et al, AJP 282:E982-E991, 2002

XPP files by figure:

• Two-Compartment Model (no CICR) (Figures 2 - 6; see ode file for details of how to produce each figure)
  Key Finding: Tg increases peak Ca, lowers nadir in agreement with experiment.
  Effects of increasing glucose and external Ca are also reproduced, and the effect of increasing ER leak is predicted.
• Compound Ca Oscillations (Figures 7, 8; see ode file for details of how to produce each figure)
  Key Finding: Ca builds with each pulse in the compound burst provided the kineteics of cytosolic Ca are neither too slow nor too fast.
• Two-Compartment Model (with CICR) (Figures 9, 10; see ode file for details of how to produce each figure)
  Key Finding: If CICR is strong enough to produce net emptying of the ER during the active phase of a burst, then dumping the stores with Tg reduces Ca amplitude, in contradiction to the experiments.
  Note: kserca3=0.05, kserca2b=0.002 ms^{-1}; incorrect in Table 1 of paper.
• Three-Compartment (Subspace) Model (Figure 11)
  Modified from subspace model (model 2) in M. Zhang, P. Goforth, A. Sherman, R. Bertram, and L. S. Satin. 2003. The Ca2+ dynamics of isolated mouse beta-cells and islets: Implications for mathematical models, . Biophys. J. 84:2852-2870. [PubMed] [XPP Files]

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Last updated 07/07/07