Modelling the interrelations between calcium oscillations and ER membrane potential oscillations

Model Status

This is the original unchecked version of the model imported from the previous CellML model repository, 24-Jan-2006.

Model Structure

Oscillations in the cytosolic calcium concentration ([Ca²⁺]_i), in the form of repetitive spikes, may be stimulated by hormones or neurotransmitters in a variety of cell types, including hepatocytes, oocytes, cardiomyocytes and fibroblasts. It is generally accepted that the mechanism underlying these calcium oscillations is related to the calcium-induced calcium release (CICR) mechanism. Often, secondary messengers such as inositol 1,4,5-trisphosphate (IP₃) are also involved. Calcium oscillations play a role in the regulation of cell excretion, muscle contraction, activation of mammalian oocytes, call signalling and other cellular activities.

Calcium oscillations and their underlying molecular mechanisms have been the subject of interest for several mathematical models, including:

• Li and Rinzel, IP3-Mediated Ca²⁺ Oscillations - A Simplified Model, 1994;

• D. Friel, [Ca²⁺]_i Oscillations in in Sympathetic Neurons, 1995;

• Chay et al., Intracellular Calcium Spikes in Non-Excitable Cells, 1995; and

• Keizer and Levine, RyR Adaptation and Ca²⁺ Oscillations, 1996.

In the Marhl et al. 1997 publication described here, the authors present an electrochemical model which accounts for intracellular calcium oscillations and their interrelations with oscillations of the potential difference across the membrane of the endoplasmic reticulum (ER) or other inracellular calium stores (see the figure below). The model shows tht when a calcium buffering system such as calmodulin is included, calcium oscillations can arise without a permanent influx of calium into the cell.

The complete original paper reference is cited below:

Modelling the interellations between calcium oscillations and ER membrane potential oscillations, Marko Marhl, Stefan Schuster, Milan Brumen, and Reinhart Heinrich, 1997, Biophysical Chemistry, 63, 221-239. PubMed ID: 12362939

Schematic diagram of the model system.