TITLE HH P/N calcium channel
NEURON {
SUFFIX Icapn
USEION ca WRITE ica
RANGE gbar, ica, h, m, g
GLOBAL minf, hinf, mtau, htau
}
UNITS {
(mA) = (milliamp)
(mV) = (millivolt)
}
PARAMETER {
v (mV)
gbar = 0.1 (mho/cm2) <0,1e9>
e = 100 (mV)
}
STATE {
m
h
g (mho/cm2)
}
ASSIGNED {
ica (mA/cm2)
minf
hinf
mtau (ms)
htau (ms)
}
INITIAL {
rates(v)
m = minf
h = hinf
}
BREAKPOINT {
SOLVE states METHOD cnexp
g = gbar*m*m*h
ica = g*(v  e)
}
DERIVATIVE states {
: computes state variables m and h at present v, t
rates(v)
m' = (minf  m)/mtau
h' = (hinf  h)/htau
}
PROCEDURE rates(v(mV)) {
UNITSOFF
mtau = 0.4 + 0.7/(exp((5v)/15) + exp((5v)/(15)))
minf = 1/(1+exp(10v)/4)
htau = 300 + 100/(exp((40v)/9.5) + exp((40v)/(9.5)))
hinf = 1/(1+exp((25v)/(2)))
UNITSON
}
