TITLE Calcium dependent potassium channel
NEURON {
SUFFIX Ikca
USEION k READ ek WRITE ik
USEION ca READ cai
RANGE gkbar, ik, Yconcdep, Yvdep
GLOBAL Yalpha, Ybeta
}
UNITS {
(mA) = (milliamp)
(mV) = (millivolt)
(molar) = (1/liter)
(mM) = (millimolar)
}
INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}
PARAMETER {
v (mV)
dt (ms)
gkbar= 0.120 (mho/cm2) <0,1e9>
ek = -80 (mV)
Ybeta = 0.05 (/ms)
cai (mM) }
STATE {
Y
}
ASSIGNED {
ik (mA/cm2)
Yalpha (/ms)
Yvdep
Yconcdep (/ms)
}
INITIAL {
rate(v,cai)
Y = Yalpha/(Yalpha + Ybeta)
}
BREAKPOINT {
SOLVE state METHOD cnexp
ik = gkbar*Y*(v - ek)
}
DERIVATIVE state {
rate(v,cai)
Y' = Yalpha*(1-Y) - Ybeta*Y
}
PROCEDURE rate(v(mV),cai(mM)) {
vdep(v)
concdep(cai)
Yalpha = Yvdep*Yconcdep
}
PROCEDURE vdep(v(mV)) {
TABLE Yvdep FROM -100 TO 100 WITH 100
Yvdep = exp((v*1(/mV)-65)/27) }
PROCEDURE concdep(cai(mM)) {
TABLE Yconcdep FROM 0 TO 50 WITH 2000
if ( fabs(cai-0.015) < 1e-5) {
Yconcdep = 500(/ms)/(1/0.0013 + 0.5*(0.015-cai)/0.0013^2 )
} else {
Yconcdep = 500(/ms)*( 0.015-cai*1(/mM) )/( exp((0.015-cai*1(/mM))/0.0013) -1 )
}
}