: Delayed rectifier K+ channel
NEURON {
SUFFIX kdr
USEION k READ ki, ko WRITE ik
RANGE gkdrbar, ik, gk
}
UNITS {
(mA) = (milliamp)
(mV) = (millivolt)
}
INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}
PARAMETER {
v (mV)
dt (ms)
gkdrbar= 0.0338 (mho/cm2) <0,1e9>
}
STATE {
n
}
ASSIGNED {
ik (mA/cm2)
inf
tau (ms)
gk (mho/cm2)
ek (mV)
ki (mM)
ko (mM)
}
INITIAL {
rate(v)
n = inf
}
BREAKPOINT {
SOLVE states METHOD cnexp
gk= gkdrbar*n*n*n*n
ek = 25 * log(ko/ki)
ik = gk*(v-ek)
}
DERIVATIVE states {
rate(v)
n' = (inf-n)/tau
}
UNITSOFF
FUNCTION alf(v){ LOCAL va
va=v-13
if (fabs(va)<1e-04){
va=va+0.0001
alf= (-0.018*va)/(-1+exp(-(va/25)))
} else {
alf = (-0.018*(v-13))/(-1+exp(-((v-13)/25)))
}
}
FUNCTION bet(v) { LOCAL vb
vb=v-23
if (fabs(vb)<1e-04){
vb=vb+0.0001
bet= (0.0054*vb)/(-1+exp(vb/12))
} else {
bet = (0.0054*(v-23))/(-1+exp((v-23)/12))
}
}
PROCEDURE rate(v (mV)) {LOCAL q10, sum, aa, ab
aa=alf(v) ab=bet(v)
sum = aa+ab
inf = aa/sum
tau = 1/(sum)
}
UNITSON