Model Documentation

Model Status

This version of the CellML model has been written in CellML 1.0. The model is known to run in PCEnv and COR and the CellML is valid and error free. However, as yet the CellML model does not recreate the published results - and some units still require fixing. This CellML model was based on the Matlab code provided by the original model author. We will continue to curate the model in an attempt to get it to reproduce the published results.

Model Structure

ABSTRACT: The morphology of the cardiac transverse-axial tubular system (TATS) has been known for decades, but its function has received little attention. To explore the possible role of this system in the physiological modulation of electrical and contractile activity, we have developed a mathematical model of rat ventricular cardiomyocytes in which the TATS is described as a single compartment. The geometrical characteristics of the TATS, the biophysical characteristics of ion transporters and their distribution between surface and tubular membranes were based on available experimental data. Biophysically realistic values of mean access resistance to the tubular lumen and time constants for ion exchange with the bulk extracellular solution were included. The fraction of membrane in the TATS was set to 56%. The action potentials initiated in current-clamp mode are accompanied by transient K+ accumulation and transient Ca2+ depletion in the TATS lumen. The amplitude of these changes relative to external ion concentrations was studied at steady-state stimulation frequencies of 1-5Hz. Ca2+ depletion increased from 7 to 13.1% with stimulation frequency, while K+ accumulation decreased from 4.1 to 2.7%. These ionic changes (particularly Ca2+ depletion) implicated significant decrease of intracellular Ca2+ load at frequencies natural for rat heart.

The complete original paper reference is cited below:

The functional role of cardiac T-tubules explored in a model of rat ventricular myocytes, Michal Pasek, Jiri Simurda, and Georges Christe, 2006, Philosophical Transactions of The Royal Society A , 81, 3029-3051. (Full text and PDF versions of the article are available for Journal Members on the Philosophical Transactions of The Royal Society A website.) PubMed ID: 16608703

Note that this model is based on a quantitative description of electrical activity of the rat ventricular myocyte proposed by Pandit et al. (2001), which has also been described in CellML and can be found in the CellML Model Respository.

Related Models

• The functional role of cardiac T-tubules explored in a model of rat ventricular myocytes version 1