An Interactive Computer Model Of Rabbit Ventricular Myocyte Ion Channels and Ca Transport, 2001
Catherine
Lloyd
Bioengineering Institute, University of Auckland
Model Status
This is the original unchecked version of the model imported from the previous
CellML model repository, 24-Jan-2006.
Model Structure
In 2001 Jose Puglisi and Donald Bers published an interactive computer model of rabbit ventricular myocyte ion channels and Ca transport (see the figure below). An interactive computer program, LabHEART, was developed to simulate the action potential, ionic currents and Ca handling mechanisms in a rabbit ventricular myocyte. Please click here to download the latest version of LabHeart.
Since Hodgkin and Huxley published their mathematical model of the squid axon in 1952 several groups have extended this modelling to cardiac ionic currents and action potentials. Ca also plays an essential role in cardiac excitation-contraction coupling, and the dynamic interplay between the action potential and Ca regulation mechanisms has come to be included in cardiac cell models.
Of the many electrophysiological models, Luo and Rudy's dynamic model (1994) has perhaps become the standard, updated with modifications based on experimental data generated by other research groups (for example Zeng, Laurita, Rosenbaum and Rudy (1995), Shaw and Rudy (1997), Viswanathan, Shaw and Rudy (1999) and Faber and Rudy (2000)). Jose Puglisi and Donald Bers adapted the equations from Luo and Rudy to rabbit ventricular myocytes using values obtained from the literature and from their own laboratory. The main differences between this model and Luo-Rudy II is the inclusion of a transient outward K current (i_to) and Ca-activated Cl current (i_Cl_Ca), as well as altering the kinetics of the T-type Ca channel (i_Ca_T), the rapid component of the delayed rectifier K current (i_Kr) and the rescaling of several conductances to match results in the rabbit ventricle.
The complete original paper reference is cited below:
LabHEART: an interactive computer model of rabbit ventricular myocyte ion channels and Ca transport, Jose L. Puglisi and Donald M. Bers, 2001,
American Journal of Physiology
, 281, C2049-C2060. PubMed ID: 11698264
cell diagram of the Puglisi-Bers ventricular myocyte model showing ionic currents, pumps and exchangers within the sarcolemma and the sarcoplasmic reticulum
A schematic diagram describing the current flows across the cell membrane that are captured in the Puglisi-Bers rabbit ventricular myocyte model.
the cellml rendering of the Puglisi-Bers model
The network defined in the CellML description of the Puglisi-Bers model. A key describing the significance of the shapes of the components and the colours of the connections between them is in the notation guide. For simplicity, not all the variables are shown.
ventricular myocyte
calcium dynamics
Ventricular Myocyte
electrophysiology
rabbit
cardiac
2001-12-01
Although i_Ca_T is not generally detectable in rabbit ventricular
myocytes, Puglisi and Bers include it in the mathematical model to
make it more complete. The equation kinetics here are slightly
different from those in the modified Luo-Rudy II model (based on
Zeng et al's model, 1995), but they reproduce more accurately the
current-voltage relationship for i_Ca_T.
Jose
Puglisi
L
Catherine
Lloyd
May
American Journal of Cellular Physiology
Catherine
Lloyd
May
A transient outward potassium current has been reported in rabbit
ventricular myocytes. It can contribute to ventricular
repolarisation. This is not part of the Luo-Rudy II model. The
equations below are taken from Winslow et al (1999).
The University of Auckland
The Bioengineering Institute
c.lloyd@auckland.ac.nz
Donald
Bers
M
This is the CellML description of Puglisi and Bers' mathematical model of rabbit ventricular myocyte ion channels and Ca transport. It is a development of the Luo-Rudy II ventricular model (1994).
Catherine
Lloyd
May
Corrected alpha_j_calculation equation in fast_sodium_current_j_gate
component and removed I_S_calculation from L_type_Ca_channel
component.
Corrected units and initial values.
The University of Auckland, Bioengineering Institute
2002-02-25
Corrected several equations.
Changed equation 'i_leak_calcualtion' to 'i_leak_calculation'.
<apply xmlns="http://www.w3.org/1998/Math/MathML" xmlns:cmeta="http://www.cellml.org/metadata/1.0#" xmlns:cellml="http://www.cellml.org/cellml/1.0#" cmeta:id="calcium_overload"><eq/>
<ci> G_rel </ci>
<apply><times/>
<ci> G_rel_max </ci>
<apply><minus/>
<cn cellml:units="dimensionless"> 1.0 </cn>
<apply><exp/>
<apply><minus/>
<apply><divide/>
<ci> t </ci>
<ci> tau_on </ci>
</apply>
</apply>
</apply>
</apply>
<apply><exp/>
<apply><minus/>
<apply><divide/>
<ci> t </ci>
<ci> tau_off </ci>
</apply>
</apply>
</apply>
</apply>
</apply>
<apply xmlns="http://www.w3.org/1998/Math/MathML" xmlns:cellml="http://www.cellml.org/cellml/1.0#"><eq/>
<ci> G_rel_max </ci>
<piecewise>
<piece>
<cn cellml:units="per_millisecond"> 0.0 </cn>
<apply><lt/>
<ci> CSQN_buff </ci>
<ci> CSQN_th </ci>
</apply>
</piece>
<otherwise>
<cn cellml:units="per_millisecond"> 4.0 </cn>
</otherwise>
</piecewise>
</apply>
When the cell is under calcium-overload conditions, the equations
for G-rel and G-rel max are altered. Rather than include these
equations as part of the CellML model itself, they are presented
below within the metadata. This is because the calcium-overload
conditions are poorly defined and most modelers will be interested
in a cell under normal calcium conditions.
2002-01-31
Autumn
Cuellar
A
2003-06-05
Catherine
Lloyd
May
keyword
A calcium-activated chloride current has been reported in rabbit
Purkinje cells and atrial and ventricular myocytes. The current is
modelled by the equations below, with parameters that were chosen to fit experimental results obtained by Puglisi et al (1999).
2002-02-27
2002-06-17
LabHEART: an interactive computer model of rabbit ventricular myocyte ion channels and Ca transport
281
C2049
C2060
Catherine Lloyd
The Puglisi-Bers Model of Rabbit Ventricular Myocyte Ion Channels and Ca
transport, 2001
Ventricular Myocyte
rabbit
11698264