Albrecht, Colegrove, Hongpaisan, Pivovarova, Andrews, Friel, 2001

Model Status

This model is consistently represented within the CellML but contains sets of algebraic equations that prevent the model from being solved in currently available software - 03/08.

Model Structure

Calcium is an important signalling ion, and changes in Ca²⁺ concentration ([Ca²⁺]) regulate diverse processes in many cellular compartments. In excitable cells, depolarisation-induced Ca²⁺ entry increases [Ca²⁺]_i, leading to secondary changes in [Ca²⁺] within organelles such as mitochondria and ER that regulate specific Ca²⁺-sensitive targets within these organelles. Although mitochondria accumulate Ca²⁺ in response to depolarisation-evoked [Ca²⁺]_i elevations (see The Colegrove et al Model Of Mitochondrial Ca²⁺ Uptake And Release, 2000), the ER has been described as either a Ca²⁺ source or sink. Different modes of net ER Ca²⁺ transport are expected to have very different effects on cytoplasmic and intraluminal Ca²⁺ signals and on the processes they regulate.

In their 2001 model, Meredith A. Albrecht, Stephen L. Colegrove, Jarin Hongpaisan, Natalia B. Pivovarova, S. Brian Andrews and David D. Friel have examined the relationship between changes in [Ca²⁺]_i and [Ca²⁺]_ER during weak depolarisation in sympathetic neurons. The total Ca²⁺ flux during the recovery phase following membrane depolarisation was divided into four components (see the figure below). One representing net Ca²⁺ extrusion across the plasma membrane (J_extru), one representing Ca²⁺ entry through voltage-gated Ca²⁺ channels (J_ICa), one representing ER Ca²⁺ uptake via a Ca²⁺ ATPase (J_SERCA) and one representing passive ER Ca²⁺ release. This mathematical model has been translated into a CellML description which can be downloaded in various formats as described in .

The complete original paper reference is cited below:

Multiple Modes of Calcium-induced Calcium Release in Sympathetic Neurons I: Attenuation of Endoplasmic Reticulum Ca²⁺ Accumulation at Low [Ca²⁺]_i during Weak Depolarisation, Meredith A. Albrecht, Stephen L. Colegrove, Jarin Hongpaisan, Natalia B. Pivovarova, S. Brian Andrews and David D. Friel, 2001, The Journal Of General Physiology , 118, 83-100. (Full text and PDF versions of the article are available for Journal Members on the JGP website.) PubMed ID: 11429446

Schematic of the model indicating Ca2+ compartmentation in the extracellular matrix, cytosol and the ER and pathways for Ca2+ ion movement between the compartments.