TITLE cal :High-threshold Ca current
NEURON {
SUFFIX cal
USEION ca READ eca WRITE ica
RANGE gcal, ica, qca
}
UNITS {
(molar) = (1/liter)
(mV) = (millivolt)
(mA) = (milliamp)
(mM) = (millimolar)
FARADAY = 96485.309 (coul/mole)
PI = (pi) (1)
}
INDEPENDENT {t FROM 0 TO 1 WITH 100 (ms)}
PARAMETER {
gcal = 0.0 (mho/cm2)
}
ASSIGNED {
ica (mA/cm2)
v (mV)
eca (mV)
diam (um)
}
STATE { m c qca }
BREAKPOINT {
SOLVE castate METHOD sparse
ica = gcal*m*m*(v-eca)
}
INITIAL {
m=m_inf(v)
c=1-m
ica = gcal*m*m*(v-eca)
qca=0
}
LOCAL a1, a2
KINETIC castate {
a1 = a_m(v)
a2 = a_c(v)
~ c <-> m (a1, a2)
CONSERVE m + c = 1
COMPARTMENT diam*diam*PI/4 { qca }
~ qca << (-ica*diam*PI*(1e4)/FARADAY )
}
FUNCTION a_m(v(mV)) {
TABLE FROM -150 TO 150 WITH 200
a_m = 1.6/(1+exp(-0.072*(v-65)))
}
FUNCTION a_c(v(mV)) {
TABLE FROM -150 TO 150 WITH 200
a_c = 0.02*(v-51.1)/(exp((v-51.1)/5)-1)
}
FUNCTION m_inf(v(mV)) {
m_inf = a_m(v)/(a_m(v)+a_c(v))
}