/
chan_BKKCa.mod
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chan_BKKCa.mod
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TITLE Kct current
COMMENT Equations from
Shao L.R., Halvorsrud R., Borg-Graham L., Storm J.F. The role of BK-type Ca2_-dependent K+ channels in spike broadening during repetitive firing in rat hippocampal pyramidal cells J.Physiology (1999),521:135-146
The Krasnow Institute
George Mason University
Copyright Maciej Lazarewicz, 2001
(mlazarew@gmu.edu)
All rights reserved.
ENDCOMMENT
NEURON {
SUFFIX BKKCa
USEION k READ ek WRITE ik
USEION ca READ cai
RANGE g, ik
GLOBAL gmax
}
UNITS {
(molar) = (1/liter)
(mM) = (millimolar)
(S) = (siemens)
(mA) = (milliamp)
(mV) = (millivolt)
}
PARAMETER {
gmax = 1.0e-3 (S/cm2)
celsius (degC)
ek (mV)
}
ASSIGNED {
v (mV)
cai (mM)
ik (mA/cm2)
k1 (/ms)
k2 (/ms)
k3 (/ms)
k4 (/ms)
q10 (1)
g (mho/cm2)
}
STATE { cst ost ist }
BREAKPOINT {
SOLVE kin METHOD sparse
g = gmax * ost
ik = gmax * ost * ( v - ek)
}
INITIAL {
SOLVE kin STEADYSTATE sparse
}
KINETIC kin {
rates(v)
~cst<->ost (k3,k4)
~ost<->ist (k1,0.0)
~ist<->cst (k2,0.0)
CONSERVE cst+ost+ist=1
}
PROCEDURE rates( v(mV)) {
k1=alp( 0.1, v, -10.0, 1.0 )
k2=alp( 0.1, v, -120.0, -10.0 )
k3=alpha( 0.001, 1.0, v, -20.0, 7.0 ) *1.0e8* ( cai*1.0(/mM) )^3
k4=alp( 0.01, v, -44.0, -5.0 )
}
FUNCTION alpha( tmin(ms), tmax(ms), v(mV), vhalf(mV), k(mV) )(/ms){
alpha = 1.0 / ( tmin + 1.0 / ( 1.0 / (tmax-tmin) + exp((v-vhalf)/k)*1.0(/ms) ) )
}
FUNCTION alp( tmin(ms), v(mV), vhalf(mV), k(mV) )(/ms){
alp = 1.0 / ( tmin + exp( -(v-vhalf) / k )*1.0(ms) )
}