: Six state HMM kinetic scheme for the WT Voltage-Gated Sodium Channel Nav1.7
: From the paper Kinetic Modeling of Nav1.7 Provides Insight Into Erythromelalgia-associated F1449V Mutation
: Gurkiewicz et al., J.Neurophysiol. (2011).
NEURON {
SUFFIX nav1p7
USEION na READ ena WRITE ina
RANGE i, gbar, g
RANGE Q10f, Q10b
}
UNITS {
(S) = (siemens)
(molar) = (1/liter)
(mM) = (millimolar)
(mV) = (millivolts)
(mA) = (milliamp)
}
PARAMETER {
gbar = 0.012 (S/cm2)
: =18e-9/(100e-12*1e8) (S/cm2) : 18(nS)/100(um)^2
a12 = 18 (/ms)
a21 = 1.1 (/ms)
a23 = 27 (/ms)
a32 = 14 (/ms)
a34 = 65 (/ms)
a43 = 1 (/ms)
a45 = 1.6 (/ms)
a54 = 3e-5 (/ms)
a56 = 51 (/ms)
a65 = 3.8e8 (/ms)
a35 = 0.22 (/ms)
a53 = 6.3e-8 (/ms)
a36 = 0.01 (/ms)
a63 = 0.02 (/ms)
a26 = 0.26 (/ms)
a62 = 0.29 (/ms)
z12 = 0.023 (/mV)
z21 = 0.034 (/mV)
z23 = 0.041 (/mV)
z32 = 0.054 (/mV)
z34 = 0.064 (/mV)
z43 = 0.02 (/mV)
z45 = 0.012 (/mV)
z54 = 2e-5 (/mV)
z56 = 0.035 (/mV)
z65 = 0.22 (/mV)
z35 = 0.057 (/mV)
z53 = 0.039 (/mV)
z36 = 0.095 (/mV)
z63 = 0.184 (/mV)
z26 = 1.4e-3 (/mV)
z62 = 4.4e-3 (/mV)
Q10f=2.3 (1)
Q10b=1.5 (1)
Q10TEMP = 24 (degC)
}
ASSIGNED {
v (mV)
ena (mV)
ina (mA/cm2)
i (mA/cm2)
k12 (/ms)
k21 (/ms)
k23 (/ms)
k32 (/ms)
k34 (/ms)
k43 (/ms)
k45 (/ms)
k54 (/ms)
k56 (/ms)
k65 (/ms)
k35 (/ms)
k53 (/ms)
k36 (/ms)
k63 (/ms)
k26 (/ms)
k62 (/ms)
celsius (degC)
qtf (1)
qtb (1)
g (S/cm2)
}
STATE { c1 c2 c3 o I1 I2 }
BREAKPOINT {
SOLVE states METHOD sparse
g = gbar*o
i =g*(v - ena)
ina=i
}
INITIAL {
qtf = Q10f^((celsius-Q10TEMP)/10)
qtb = Q10b^((celsius-Q10TEMP)/10)
SOLVE states STEADYSTATE sparse}
KINETIC states {
rates(v)
~c1 <-> c2 (k12,k21)
~c2 <-> c3 (k23,k32)
~c3 <-> o (k34,k43)
~o <-> I1 (k45,k54)
~I1 <-> I2 (k56,k65)
~c3 <-> I1 (k35,k53)
~c3 <-> I2 (k36,k63)
~c2 <-> I2 (k26,k62)
CONSERVE c1+c2+c3+o+I1+I2=1
}
PROCEDURE rates(v(mV)) (/ms) {
k12 = a12*exp(z12*v)*qtf
k21 = a21*exp(-z21*v)*qtb
k23 = a23*exp(z23*v)*qtf
k32 = a32*exp(-z32*v)*qtb
k34 = a34*exp(z34*v)*qtf
k43 = a43*exp(-z43*v)*qtb
k45 = a45*exp(z45*v)*qtb
k54 = a54*exp(-z54*v)*qtf
k56 = a56*exp(z56*v)*qtb
k65 = a65*exp(z65*v)*qtf
k35 = a35*exp(z35*v)
k53 = a53*exp(-z53*v)
k36 = a36*exp(z36*v)
k63 = a63*exp(z63*v)
k26 = a26*exp(z26*v)
k62 = a62*exp(-z62*v)
}