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: Hodgkin - Huxley k channel
NEURON {
SUFFIX HHk
USEION k READ ek WRITE ik
RANGE gkbar, ik, g
GLOBAL inf, tau
}
UNITS {
(mA) = (milliamp)
(mV) = (millivolt)
}
PARAMETER {
gkbar= 0.036 (mho/cm2) <0,1e9>
}
STATE {
n
}
ASSIGNED {
v (mV)
ek (mV)
celsius (degC)
ik (mA/cm2)
inf
tau (ms)
g (mho/cm2)
}
INITIAL {
rate(v)
n = inf
}
BREAKPOINT {
SOLVE states METHOD cnexp
g = gkbar*n*n*n*n
ik = g*(v - ek)
}
DERIVATIVE states {
rate(v)
n' =(inf - n)/tau
}
FUNCTION alp(v(mV))(/ms) { LOCAL q10
v = -v - 65
q10 = 3^((celsius - 6.3)/10 (degC))
alp = q10 * 0.01(/ms-mV)*expM1(v + 10, 10(mV))
}
FUNCTION bet(v(mV))(/ms) { LOCAL q10
v = -v - 65
q10 = 3^((celsius - 6.3)/10 (degC))
bet = q10 * 0.125(/ms)*exp(v/80(mV))
}
FUNCTION expM1(x (mV),y (mV)) (mV) {
if (fabs(x/y) < 1e-6) {
expM1 = y*(1 - x/y/2)
}else{
expM1 = x/(exp(x/y) - 1)
}
}
PROCEDURE rate(v (mV)) {LOCAL a, b
TABLE inf, tau DEPEND celsius FROM -100 TO 100 WITH 200
a = alp(v) b=bet(v)
tau = 1/(a + b)
inf = a/(a + b)
}
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