:Comment : LVA ca channel. Note: mtau is an approximation from the plots
:Reference : : Avery and Johnston 1996, tau from Randall 1997
:Comment: shifted by -10 mv to correct for junction potential
:Comment: corrected rates using q10 = 2.3, target temperature 34, orginal 21
NEURON {
SUFFIX Ca_LVAst
USEION ca READ eca WRITE ica
RANGE gCa_LVAstbar, gCa_LVAst, ica, offma, offmt, offha, offht, sloma, slomt, sloha, sloht, taummin, taumdiff, tauhmin, tauhdiff
}
UNITS {
(S) = (siemens)
(mV) = (millivolt)
(mA) = (milliamp)
}
PARAMETER {
gCa_LVAstbar = 0.00001 (S/cm2)
offma = -40.0 (mV)
offmt = -35.0 (mV)
offha = -90.0 (mV)
offht = -50.0 (mV)
sloma = 6.0 (mV)
slomt = 5.0 (mV)
sloha = 6.4 (mV)
sloht = 7.0 (mV)
taummin = 5.0 (ms)
taumdiff = 20.0 (ms)
tauhmin = 20.0 (ms)
tauhdiff = 50.0 (ms)
}
ASSIGNED {
v (mV)
eca (mV)
ica (mA/cm2)
gCa_LVAst (S/cm2)
mInf
mTau
hInf
hTau
}
STATE {
m
h
}
BREAKPOINT {
SOLVE states METHOD cnexp
gCa_LVAst = gCa_LVAstbar*m*m*h
ica = gCa_LVAst*(v-eca)
}
DERIVATIVE states {
rates()
m' = (mInf-m)/mTau
h' = (hInf-h)/hTau
}
INITIAL{
rates()
m = mInf
h = hInf
}
PROCEDURE rates(){
LOCAL qt
qt = 2.3^((34-21)/10)
UNITSOFF
mInf = 1.0000/(1+ exp((offma-v)/sloma))
mTau = (taummin + taumdiff/(1+exp(-(offmt-v)/slomt)))/qt
hInf = 1.0000/(1+ exp(-(offha-v)/sloha))
hTau = (tauhmin + tauhdiff/(1+exp(-(offht-v)/sloht)))/qt
UNITSON
}