/
chan_CaQ.mod
71 lines (58 loc) · 1.12 KB
/
chan_CaQ.mod
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TITLE (Q-type calcium current for MSP Neuron)
INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}
NEURON {
SUFFIX CaQ
USEION ca READ cai,cao WRITE ica
RANGE minf, mtau, ica
GLOBAL pmax
}
UNITS {
(mA) = (milliamp)
(mV) = (millivolt)
(mM) = (milli/liter)
FARADAY = 96489 (coul)
R = 8.314 (volt-coul/degC)
}
PARAMETER {
v (mV)
celsius (degC)
cai (mM)
cao (mM)
pmax = 6e-6 (cm/s)
}
STATE {
m
}
ASSIGNED {
ica (mA/cm2)
mtau (ms)
minf
}
BREAKPOINT {
SOLVE state METHOD cnexp
ica = pmax*m*m*ghk(v,cai,cao,2)
: ica = pmax*m*m*ghk(v,0.001,cao,2)
}
DERIVATIVE state {
rates(v)
m'= (minf-m) / mtau
}
INITIAL {
rates(v)
m = minf
}
FUNCTION ghk( v(mV), ci(mM), co(mM), z) (millicoul/cm3) { LOCAL e, w
w = v * (.001) * z*FARADAY / (R*(celsius+273.16))
if (fabs(w)>1e-4)
{ e = w / (exp(w)-1) }
else : denominator is small -> Taylor series
{ e = 1-w/2 }
ghk = - (.001) * z*FARADAY * (co-ci*exp(w)) * e
}
UNITSOFF
PROCEDURE rates(v(mV)) {
: TABLE minf FROM -120 TO 30 WITH 70
mtau = 0.377
minf = 1 / (1+exp((v+9)/-6.6))
}
UNITSON