TITLE LCa calcium channel with fixed reversal potential
: Implemented in Rubin and Cleland, J. Neurophysiol 2006
: LCa channel with parameters from US Bhalla and JM Bower,
: J. Neurophysiol. 69:19481983 (1993)
: Adapted from /usr/local/neuron/demo/release/nachan.mod  squid
: by Andrew Davison, The Babraham Institute.
: 250898
NEURON {
SUFFIX ICa
USEION ca WRITE ica
RANGE gcabar, ica
GLOBAL sinf, rinf, stau, rtau
}
UNITS {
(mA) = (milliamp)
(mV) = (millivolt)
(molar) = (1/liter)
(mM) = (millimolar)
}
INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}
CONSTANT { eca = 70 (mV) }
PARAMETER {
v (mV)
dt (ms)
gcabar = 0.120 (mho/cm2) <0,1e9>
: eca = 70 (mV)
}
STATE {
r s
}
ASSIGNED {
ica (mA/cm2)
sinf
rinf
stau (ms)
rtau (ms)
}
INITIAL {
rates(v)
s = sinf
r = rinf
}
BREAKPOINT {
SOLVE states METHOD cnexp
ica = gcabar*s*r*(v  eca)
}
DERIVATIVE states {
rates(v)
s' = (sinf  s)/stau
r' = (rinf  r)/rtau
}
FUNCTION alp(v(mV),i) (/ms) {
if (i==0) {
alp = 7.5(/ms)/(1 + exp((v *1(/mV) + 13)/7))
}else if (i==1){
alp = 0.0068(/ms)/(1 + exp((v *1(/mV) + 30)/12))
}
}
FUNCTION bet(v(mV),i)(/ms) {
if (i==0) {
bet = 1.65(/ms)/(1 + exp((v *1(/mV)  14)/4))
}else if (i==1){
bet = 0.06(/ms)/(1 + exp(v* 1(/mV)/11))
}
}
PROCEDURE rates(v(mV)) {LOCAL a, b
TABLE sinf, rinf, stau, rtau FROM 100 TO 100 WITH 200
a = alp(v,0) b=bet(v,0)
stau = 1/(a + b)
sinf = a/(a + b)
a = alp(v,1) b=bet(v,1)
rtau = 1/(a + b)
rinf = a/(a + b)
}
