# A Mathematical Model of Action Potential Heterogeneity in Adult Rat Left Ventricular Myocytes

#### Model Status

This is the original unchecked version of the model imported from the previous CellML model repository, 24-Jan-2006. Update: This version was updated from version 3 so that it runs in PCEnv by James R. Lawson, on 22/03/07 Update: This version was updated from version 4 on 27/03/07 so that it produces a train of action potentials rather than just one.

There is currently an issue with Version 05 of this model. Each action potential in the train that is produced gets progressively wider. The differences in size are slight but noticeable. This issue is not present in previous versions as they do not output multiple action potentials.

#### Model Structure

Over the past decade electrophysiological studies have revealed transmural heterogeneity, or differences in the action potential waveforms recorded in cells isolated from the epicardial and the endocardial tissues in the left ventricles of mammalian hearts.

The adult rat has been widely used as an experimental model to investigate the electrical heterogeneity in the left ventricle under normal conditions and pathophysiological states. From this biophysical, experimental data, derived from patch clamp experiments, Sandeep V. Pandit, Robert B. Clark, Wayne R. Giles and Semahat S. Demir have developed a mathematical model of action potential heterogeneity in adult rat left ventricular myocytes (see
the figure
below). The mathematical models for the epicardial and endocardial cells of the rat left ventricle are based on the classical formulation of Hodgkin and Huxley (see The Hodgkin-Huxley Squid Axon Model, 1952), and are therefore similar to previous computational work carried out by this research group (see Demir *et al.* Sinoatrial Node Model 1994 and Demir *et al.* Sinoatrial Node Model 1999). The endocardial cell model is based on the epicardial formulation with only slight modifications in certain parameters and equations.

The complete original paper reference is cited below:

A Mathematical Model of Action Potential Heterogeneity in Adult Rat Left Ventricular Myocytes, , Sandeep V. Pandit, Robert B. Clark, Wayne R. Giles and Semahat S. Demir, 2001,
*Biophysical Journal*
, 81, 3029-3051. (Full text and PDF versions of the article are available for Journal Members on the Biophysical Journal website.) PubMed ID: 11720973

The raw CellML description of the Pandit *et al* 2001 model of action potential heterogeneity in adult rat left ventricular myocytes can be downloaded in various formats as described in .

A fluid compartment model of the rat epicardial/endocardial ventricular cell. |