COMMENT
kca.mod
Calciumdependent potassium channel
Based on
Pennefather (1990)  sympathetic ganglion cells
taken from
Reuveni et al (1993)  neocortical cells
Author: Zach Mainen, Salk Institute, 1995, zach@salk.edu
ENDCOMMENT
INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}
NEURON {
SUFFIX kca
USEION k READ ek WRITE ik
USEION ca READ cai
RANGE n, gk, gbar
RANGE ninf, ntau
GLOBAL Ra, Rb, caix
GLOBAL q10, temp, tadj, vmin, vmax
}
UNITS {
(mA) = (milliamp)
(mV) = (millivolt)
(pS) = (picosiemens)
(um) = (micron)
}
PARAMETER {
gbar = 10 (pS/um2) : 0.03 mho/cm2
v (mV)
cai (mM)
caix = 1
Ra = 0.01 (/ms) : max act rate
Rb = 0.02 (/ms) : max deact rate
dt (ms)
celsius (degC)
temp = 23 (degC) : original temp
q10 = 2.3 : temperature sensitivity
vmin = 120 (mV)
vmax = 100 (mV)
}
ASSIGNED {
a (/ms)
b (/ms)
ik (mA/cm2)
gk (pS/um2)
ek (mV)
ninf
ntau (ms)
tadj
}
STATE { n }
INITIAL {
rates(cai)
n = ninf
}
BREAKPOINT {
SOLVE states
gk = tadj*gbar*n
ik = (1e4) * gk * (v  ek)
}
LOCAL nexp
PROCEDURE states() { :Computes state variable n
rates(cai) : at the current v and dt.
n = n + nexp*(ninfn)
VERBATIM
return 0;
ENDVERBATIM
}
PROCEDURE rates(cai(mM)) {
LOCAL tinc
a = Ra * cai^caix
b = Rb
ntau = 1/(a+b)
ninf = a*ntau
tadj = q10^((celsius  temp)/10)
tinc = dt * tadj
nexp = 1  exp(tinc/ntau)
}
