TITLE Potasium Type A current for RD Traub, J Neurophysiol 89:909-921, 2003
COMMENT
Implemented by Maciej Lazarewicz 2003 (mlazarew@seas.upenn.edu)
ENDCOMMENT
INDEPENDENT { t FROM 0 TO 1 WITH 1 (ms) }
UNITS {
(mV) = (millivolt)
(mA) = (milliamp)
}
NEURON {
SUFFIX ka
USEION k READ ek WRITE ik
RANGE gbar, ik, m, h, alphah, betah, alpham, betam, mtau, htau
}
PARAMETER {
gbar = 0.0 (mho/cm2)
v (mV) ek (mV)
}
ASSIGNED {
ik (mA/cm2)
minf hinf (1)
mtau (ms) htau (ms)
alphah (/ms) betah (/ms)
alpham (/ms) betam (/ms)
}
STATE {
m h
}
BREAKPOINT {
SOLVE states METHOD cnexp
ik = gbar * m * m * m * m * h * ( v - ek )
: debugging:
alphah = hinf/htau
betah = 1/htau - alphah
alpham = minf/mtau
betam = 1/mtau - alpham
}
INITIAL {
settables(v)
: m = minf
m = 0
h = hinf
: h = 0.208608 : from F tcr cc run
}
DERIVATIVE states {
settables(v)
m' = ( minf - m ) / mtau
h' = ( hinf - h ) / htau
}
UNITSOFF
PROCEDURE settables(v (mV)) {
TABLE minf, hinf, mtau, htau FROM -120 TO 40 WITH 641
minf = 1 / ( 1 + exp( ( - v - 60 ) / 8.5 ) )
mtau = 0.185 + 0.5 / ( exp( ( v + 35.8 ) / 19.7 ) + exp( ( - v - 79.7 ) / 12.7 ) )
hinf = 1 / ( 1 + exp( ( v + 78 ) / 6 ) )
if( v <= -63 ) {
htau = 0.5 / ( exp( ( v + 46 ) / 5 ) + exp( ( - v - 238 ) / 37.5 ) )
}else{
htau = 9.5
}
}
UNITSON