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TITLE Mouse sodium current
: Kinetics of Carter et al. (2012)
: Based on 37 degC recordings from mouse hippocampal CA1 pyramids
NEURON {
SUFFIX NaV
USEION na READ ena WRITE ina
RANGE g, gbar
}
UNITS {
(mV) = (millivolt)
(S) = (siemens)
}
PARAMETER {
gbar = .015 (S/cm2)
: kinetic parameters
Con = 0.01 (/ms) : closed -> inactivated transitions
Coff = 40 (/ms) : inactivated -> closed transitions
Oon = 8 (/ms) : open -> Ineg transition
Ooff = 0.05 (/ms) : Ineg -> open transition
alpha = 400 (/ms)
beta = 12 (/ms)
gamma = 250 (/ms) : opening
delta = 60 (/ms) : closing
alfac = 2.51
btfac = 5.32
: Vdep
x1 = 24 (mV) : Vdep of activation (alpha)
x2 = -24 (mV) : Vdep of deactivation (beta)
}
ASSIGNED {
: rates
f01 (/ms)
f02 (/ms)
f03 (/ms)
f04 (/ms)
f0O (/ms)
f11 (/ms)
f12 (/ms)
f13 (/ms)
f14 (/ms)
f1n (/ms)
fi1 (/ms)
fi2 (/ms)
fi3 (/ms)
fi4 (/ms)
fi5 (/ms)
fin (/ms)
b01 (/ms)
b02 (/ms)
b03 (/ms)
b04 (/ms)
b0O (/ms)
b11 (/ms)
b12 (/ms)
b13 (/ms)
b14 (/ms)
b1n (/ms)
bi1 (/ms)
bi2 (/ms)
bi3 (/ms)
bi4 (/ms)
bi5 (/ms)
bin (/ms)
v (mV)
ena (mV)
ina (milliamp/cm2)
g (S/cm2)
celsius (degC)
}
STATE {
C1 FROM 0 TO 1
C2 FROM 0 TO 1
C3 FROM 0 TO 1
C4 FROM 0 TO 1
C5 FROM 0 TO 1
I1 FROM 0 TO 1
I2 FROM 0 TO 1
I3 FROM 0 TO 1
I4 FROM 0 TO 1
I5 FROM 0 TO 1
O FROM 0 TO 1
I6 FROM 0 TO 1
}
BREAKPOINT {
SOLVE activation METHOD sparse
g = gbar * O
ina = g * (v - ena)
}
INITIAL {
rates(v)
SOLVE seqinitial
}
KINETIC activation
{
rates(v)
~ C1 <-> C2 (f01,b01)
~ C2 <-> C3 (f02,b02)
~ C3 <-> C4 (f03,b03)
~ C4 <-> C5 (f04,b04)
~ C5 <-> O (f0O,b0O)
~ O <-> I6 (fin,bin)
~ I1 <-> I2 (f11,b11)
~ I2 <-> I3 (f12,b12)
~ I3 <-> I4 (f13,b13)
~ I4 <-> I5 (f14,b14)
~ I5 <-> I6 (f1n,b1n)
~ C1 <-> I1 (fi1,bi1)
~ C2 <-> I2 (fi2,bi2)
~ C3 <-> I3 (fi3,bi3)
~ C4 <-> I4 (fi4,bi4)
~ C5 <-> I5 (fi5,bi5)
CONSERVE C1 + C2 + C3 + C4 + C5 + O + I1 + I2 + I3 + I4 + I5 + I6 = 1
}
LINEAR seqinitial { : sets initial equilibrium
~ I1*bi1 + C2*b01 - C1*( fi1+f01) = 0
~ C1*f01 + I2*bi2 + C3*b02 - C2*(b01+fi2+f02) = 0
~ C2*f02 + I3*bi3 + C4*b03 - C3*(b02+fi3+f03) = 0
~ C3*f03 + I4*bi4 + C5*b04 - C4*(b03+fi4+f04) = 0
~ C4*f04 + I5*bi5 + O*b0O - C5*(b04+fi5+f0O) = 0
~ C5*f0O + I6*bin - O*(b0O+fin) = 0
~ C1*fi1 + I2*b11 - I1*( bi1+f11) = 0
~ I1*f11 + C2*fi2 + I3*b12 - I2*(b11+bi2+f12) = 0
~ I2*f12 + C3*fi3 + I4*bi3 - I3*(b12+bi3+f13) = 0
~ I3*f13 + C4*fi4 + I5*b14 - I4*(b13+bi4+f14) = 0
~ I4*f14 + C5*fi5 + I6*b1n - I5*(b14+bi5+f1n) = 0
~ C1 + C2 + C3 + C4 + C5 + O + I1 + I2 + I3 + I4 + I5 + I6 = 1
}
PROCEDURE rates(v(mV) )
{
LOCAL qt
qt = 2.3^((celsius-37)/10)
f01 = qt * 4 * alpha * exp(v/x1)
f02 = qt * 3 * alpha * exp(v/x1)
f03 = qt * 2 * alpha * exp(v/x1)
f04 = qt * 1 * alpha * exp(v/x1)
f0O = qt * gamma
f11 = qt * 4 * alpha * alfac * exp(v/x1)
f12 = qt * 3 * alpha * alfac * exp(v/x1)
f13 = qt * 2 * alpha * alfac * exp(v/x1)
f14 = qt * 1 * alpha * alfac * exp(v/x1)
f1n = qt * gamma
fi1 = qt * Con
fi2 = qt * Con * alfac
fi3 = qt * Con * alfac^2
fi4 = qt * Con * alfac^3
fi5 = qt * Con * alfac^4
fin = qt * Oon
b01 = qt * 1 * beta * exp(v/x2)
b02 = qt * 2 * beta * exp(v/x2)
b03 = qt * 3 * beta * exp(v/x2)
b04 = qt * 4 * beta * exp(v/x2)
b0O = qt * delta
b11 = qt * 1 * beta * exp(v/x2) / btfac
b12 = qt * 2 * beta * exp(v/x2) / btfac
b13 = qt * 3 * beta * exp(v/x2) / btfac
b14 = qt * 4 * beta * exp(v/x2) / btfac
b1n = qt * delta
bi1 = qt * Coff
bi2 = qt * Coff / (btfac)
bi3 = qt * Coff / (btfac^2)
bi4 = qt * Coff / (btfac^3)
bi5 = qt * Coff / (btfac^4)
bin = qt * Ooff
}
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