reaction0000001
c3 = c2
reaction0000002
c2 = c1
reaction0000003
c1 = o
reaction0000004
o = i
reaction0000005
c1 = i
Assignment rules
aa = 0.0655*exp(0.05547153*(-36.0 + v))
ik = Gk*(v - vk)*o
a = 0.0555*exp(0.05547153*(-12.0 + v))
b = 0.002357*exp(-0.036588*v)
Gk = 0.013500000000000002*ko^0.59
bi = 1.030072027074169*exp(0.000942*v)*(ko^(-1.0))^0.3
u = (ai*bb)/bi
bb = 0.0029357000000000003*exp(-0.02158*v)
vk = (R*Temp*log(ko/ki))/F
ai = 1.9755*exp(-0.02352*(25.0 + v))/ko
v = piecewise(vtest,50.0<time<=300.0,vhold)
Function definitions
Note that constraints are not enforced in simulations. It remains the responsibility of the user to verify that simulation results satisfy these constraints.
Cellular consequences of HERG mutations in the long QT syndrome: precursors to sudden cardiac death.
Cardiovasc. Res. 2001;
50
(2):
301-313
- PubMed: 11334834
- ISSN: 0008-6363
- URL: https://ncbi.nlm.nih.gov/pubmed/11334834
Abstract
BACKGROUND: A variety of mutations in HERG, the major subunit of the rapidly activating component of the cardiac delayed rectifier I(Kr), have been found to underlie the congenital Long-QT syndrome, LQT2. LQT2 may give rise to severe arrhythmogenic phenotypes leading to sudden cardiac death.
OBJECTIVE: We attempt to elucidate the mechanisms by which heterogeneous LQT2 genotypes can lead to prolongation of the action potential duration (APD) and consequently the QT interval on the ECG.
METHODS: We develop Markovian models of wild-type (WT) and mutant I(Kr) channels and incorporate these models into a comprehensive model of the cardiac ventricular cell.
RESULTS: Using this virtual transgenic cell model, we describe the effects of HERG mutations on the cardiac ventricular action potential (AP) and provide insight into the mechanism by which each defect results in a net loss of repolarizing current and prolongation of APD.
CONCLUSIONS: This study demonstrates which mutations can prolong APD sufficiently to generate early afterdepolarizations (EADs), which may trigger life-threatening arrhythmias. The severity of the phenotype is shown to depend on the specific kinetic changes and how they affect I(Kr) during the time course of the action potential. Clarifying how defects in HERG can lead to impaired cellular electrophysiology can improve our understanding of the link between channel structure and cellular function.
OBJECTIVE: We attempt to elucidate the mechanisms by which heterogeneous LQT2 genotypes can lead to prolongation of the action potential duration (APD) and consequently the QT interval on the ECG.
METHODS: We develop Markovian models of wild-type (WT) and mutant I(Kr) channels and incorporate these models into a comprehensive model of the cardiac ventricular cell.
RESULTS: Using this virtual transgenic cell model, we describe the effects of HERG mutations on the cardiac ventricular action potential (AP) and provide insight into the mechanism by which each defect results in a net loss of repolarizing current and prolongation of APD.
CONCLUSIONS: This study demonstrates which mutations can prolong APD sufficiently to generate early afterdepolarizations (EADs), which may trigger life-threatening arrhythmias. The severity of the phenotype is shown to depend on the specific kinetic changes and how they affect I(Kr) during the time course of the action potential. Clarifying how defects in HERG can lead to impaired cellular electrophysiology can improve our understanding of the link between channel structure and cellular function.
The SBML for this model was obtained from the BioModels database (BioModels ID: BIOMD0000000121)
Biomodels notes: This model is according to the paper Cellular consequences of HEGR mutations in the long QT syndrome: precursors to sudden cardiac death. The author used Markovian model of cardiac Ikr in the paper. Figure4B in the paper has been reproduced using CellDesigner3.5.1. The cell is depolarized to the indicated test potential for 250ms (from 50ms to 300ms) from a holding potential of -40mV and then repolarized to -40mV. Change the value for vtest from -30,-20,-10,0,10,20,30,40 for each simulation in order to produce the different cureve in the paper.
JWS Online curation: This model was curated by reproducing the figures as described in the BioModels Notes. No additional changes were made.