Modelling the Roles of Individual Current Systems in Ventricular Cells and in the SA Node
Catherine
Lloyd
Bioengineering Institute, University of Auckland
Model Status
This model has been curated and unit checked by Alan Garny in collaboration with the model authors and it is known to run in COR to reproduce the published results. It also works in JSim as long as the stimulus protocol is altered.
Model Structure
Different types of ion channel, with their distinct gating and conductance properties, play a unique role in generating membrane excitation. Although the behaviours of single ion channels have been extensively studied experimentally, ionic current interactions make it difficult to deduce their individual roles in membrane excitability. In order to better understand the roles of the individual ion currents, Satoshi Matsuoka et al. have developed a mathematical model of membrane excitation for the ventricular cell.
The Matsuoka et al. mathematical model is a development of previously published cardiac cellular models. The group's general approach to modelling was based on the methods used in the Difrancesco-Noble, 1985 Model and the Luo-Rudy Ventricular Model II (dynamic), 1994. In addition, the compound Kyoto Model of Matsuoka et al. incorporates the Negroni and Lascano (1996) model of cardiac muscle contraction, allowing simulation of sarcomere shortening, and also, the gating model of Shirokov et al. is used for both the fast Na+ and L-type Ca2+ channels.
New experimental data are included, such as new kinetics of the inward rectifier K+ channel, the delayed rectifier K+ channel, and the sustained inward current (for more details on the reaction kinetics, see figure 3 below). Model simulations showed that ion conductance by the L-type Ca2+ channel (ICaL) dominates the membrane conductance during the action potential. Repolarisation occurs as the following currents are sequentially activated: IKs; IKr; and IK1. Agreement between model simulation results and experimental data was taken as supporting evidence for the validity of the model.
The complete original paper reference is cited below:
Role of Individual Ionic Current Systems in Ventricular Cells Hypothesized by a Model Study, Matsuoka S, Sarai N, Kuratomi S, Ono K, and Noma A, 2003, The Japanese Journal of Physiology, 53, 105-123. PubMed ID: 12877767
ventricular cell diagram
A schematic diagram describing the ionic components of the Matsuoka et al. 2003 ventricular cell mathematical model. Ions are exchanged between the intracellular and extracellular environments, and between the cytosol and the sarcoplasmic reticulum (SR) via channels and pumps. Unique to the ventricular cells are the transient outward current, Ito, and the slow component of the delayed rectifier K+ current, IKs.
reaction kinetics diagram
A schematic diagram describing the reaction kinetics of the ion channel gates in the Matsuoka et al. 2003 mathematical models. A) The kinetics of the sodium channel voltage-dependent gate. B) The kinetics of the Na-Ca exchange pump. C) The kinetics of the Na-K pump. D) The kinetics of the inward rectifier K+ current. E) The kinetics of the Ca2+-dependent gate of the L-type Ca2+ channel. F) The kinetics of the ultra-slow gates of several ion channels. G) The kinetics of the SR Ca2+ pump. H) The kinetics of the hyperpolarisation-activated cation current. I) The kinetics of the RyR channel in the SR.
Department of Physiology, Anatomy & Genetics, University of Oxford
Japanese Journal of Physiology
This model has been curated by Penny Noble and is known to run in PCEnv and COR and reproduce the published results.
penny.noble@dpag.ox.ac.uk
Satoshi
Matsuoka
2003-01-01 00:00
units checked, curated
This file is a CellML description of Matsuoka et al's 2003 mathematical model of the roles of individual ion currents in ventricular cells.
Role of individual ionic current systems in ventricular cells hypothesized by a model study
53(2)
105
123
Nobuaki
Sarai
Penny
Noble
J
James
Lawson
Richard
Akinori
Noma
James Lawson
2008-02-25T11:29:40+13:00
James Lawson
Removed initial value for variable Vm_old, removing model overconstraint problem in PCEnv.
Penny
Noble
J
2007-10-30T11:57:22+13:00
Oxford University
Department of Physiology, Anatomy & Genetics
Shinobu
Kuratomi
2007-10-23T00:00:00+00:00
2000
10000
0.1
keyword
cardiac
ventricular myocyte
electrophysiology
Kyoichi
Ono