: HH TEA-sensitive Purkinje potassium current
: Created 8/5/02 - nwg
: Suffix from kpkj to Kv3_4
NEURON {
SUFFIX Kv3_4
USEION k READ ek WRITE ik
RANGE gkbar, ik
RANGE minf, hinf, mtau, htau
}
UNITS {
(mV) = (millivolt)
(mA) = (milliamp)
}
CONSTANT {
q10 = 3
}
PARAMETER {
v (mV)
gkbar = .004 (mho/cm2)
mivh = -24 (mV)
mik = 15.4 (1)
mty0 = .00012851
mtvh1 = 100.7 (mV)
mtk1 = 12.9 (1)
mtvh2 = -56.0 (mV)
mtk2 = -23.1 (1)
hiy0 = .31
hiA = .69
hivh = -5.802 (mV)
hik = 11.2 (1)
ek
}
ASSIGNED {
ik (mA/cm2)
minf
mtau (ms)
hinf
htau (ms)
qt
}
STATE {
m
h
}
INITIAL {
rates(v)
m = minf
h = hinf
qt = q10^((celsius-37 (degC))/10 (degC))
}
BREAKPOINT {
SOLVE states METHOD cnexp
ik = gkbar * m^3 * h * (v - ek)
}
DERIVATIVE states {
rates(v)
m' = (minf - m) / mtau
h' = (hinf - h) / htau
}
PROCEDURE rates( Vm (mV)) {
LOCAL v
v = Vm + 11 : Account for Junction Potential
minf = 1/(1+exp(-(v-mivh)/mik))
mtau = (1000) * mtau_func(v) /qt
hinf = hiy0 + hiA/(1+exp((v-hivh)/hik))
htau = 1000 * htau_func(v) / qt
}
FUNCTION mtau_func (v (mV)) (ms) {
if (v < -35) {
mtau_func = (3.4225e-5+.00498*exp(-v/-28.29))*3
} else {
mtau_func = (mty0 + 1/(exp((v+mtvh1)/mtk1)+exp((v+mtvh2)/mtk2)))
}
}
FUNCTION htau_func(Vm (mV)) (ms) {
if ( Vm > 0) {
htau_func = .0012+.0023*exp(-.141*Vm)
} else {
htau_func = 1.2202e-05 + .012 * exp(-((Vm-(-56.3))/49.6)^2)
}
}