Effects of extracellular calcium on electrical bursting and intracellular and luminal calcium oscillations in insulin secreting pancreatic beta-cells

Effects of extracellular calcium on electrical bursting and intracellular and luminal calcium oscillations in insulin secreting pancreatic beta-cells

Model Status

This CellML model runs in both OpenCell and COR to reproduce the published results. The value for the variable 'Ca_o' in the component 'calcium_current' can be altered to 0, 2.5, 5 or 7.5 mM to reproduce figures 5 a,b,c,d, respectively.

Model Structure

ABSTRACT: The extracellular calcium concentration has interesting effects on bursting of pancreatic beta-cells. The mechanism underlying the extracellular Ca2+ effect is not well understood. By incorporating a low-threshold transient inward current to the store-operated bursting model of Chay, this paper elucidates the role of the extracellular Ca2+ concentration in influencing electrical activity, intracellular Ca2+ concentration, and the luminal Ca2+ concentration in the intracellular Ca2+ store. The possibility that this inward current is a carbachol-sensitive and TTX-insensitive Na+ current discovered by others is discussed. In addition, this paper explains how these three variables respond when various pharmacological agents are applied to the store-operated model.

The original paper reference is cited below:

Effects of extracellular Calcium on Electrical Bursting and Intracellular and Luminal Calcium Oscillations in Insulin Secreting Pancreatic Beta-Cells, Teresa Ree Chay, 1997, Biophysical Journal , 73, 1673-1688. PubMed ID: 9284334

A schematic representation of the current and fluxes captured by the Chay 1997 pancreatic beta-cell model. This diagram shows the plasma membrane currents associated with burst and spike oscillations: the fast current, Ifast; the calcium current, I Ca2+ ; the cationic nonselective inward current, INS; the delayed-rectifying K+ current, IK(dr), the calcium-sensitive K+ current, IK(Ca); the ATP-sensitive K+ current, IK(ATP); and the Na+ leak current, INa(L). The ER intracellular Ca2+ store is also shown with its associated transmembrane calcium fluxes: calcium release, Jrel; and calcium uptake by the Ca2+-ATPase, Jpump.