CellML 1.1 version of the model

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

Model Status

This is a CellML 1.1 model. The units have been checked and are valid, and the model is valid CellML. Unfortunately the model is not able to be integrated in OpenCell at this point.

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 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. 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.