COMMENT
"NaV1.1" channel.
BBP 'fast' Na channel, but activation/inactivation vHalf and slope adjusted to fit experimental data.
Use this mechanism to 'mutate' given proportion of Nav1.1 channels.
ENDCOMMENT
:Reference :Colbert and Pan 2002
: Adapted by Werner Van Geit @ BBP, 2015 (with help from M.Hines):
: channel detects TTX concentration set by TTXDynamicsSwitch.mod
NEURON {
SUFFIX Nav11m
USEION na READ ena WRITE ina
USEION ttx READ ttxo, ttxi VALENCE 1
RANGE gNav11bar, gNav11, ina,mh,ms,hh,hs,tmh,thh
}
UNITS {
(S) = (siemens)
(mV) = (millivolt)
(mA) = (milliamp)
}
PARAMETER {
gNav11bar = 0.00001 (S/cm2)
mh=18.46 : activation vh
ms=7.91 : activation slope
hh=48.8 : inactivation vh
hs=6.25 : inactivation slope
tmh=25.04 : activation tau vhalf
thh=55.53 : inactivation tau vhalf
}
ASSIGNED {
ttxo (mM)
ttxi (mM)
v (mV)
ena (mV)
ina (mA/cm2)
gNav11 (S/cm2)
mInf
mTau
hInf
hTau
}
STATE {
m
h
}
BREAKPOINT {
SOLVE states METHOD cnexp
gNav11 = gNav11bar*m*m*m*h
ina = gNav11*(vena)
}
DERIVATIVE states {
if (ttxi == 0.015625 && ttxo > 1e12) {
mInf = 0.0
mTau = 1e12
hInf = 1.0
hTau = 1e12
} else {
rates()
}
m' = (mInfm)/mTau
h' = (hInfh)/hTau
}
INITIAL{
if (ttxi == 0.015625 && ttxo > 1e12) {
mInf = 0.0
mTau = 1e12
hInf = 1.0
hTau = 1e12
} else {
rates()
}
m = mInf
h = hInf
}
PROCEDURE rates(){
LOCAL qt
qt = 2.3^((3424)/10) : recordings at 24C
UNITSOFF
if(v == mh){
v = v+0.0001
}
mTau = (0.0876 + 0.35 * exp(((tmh  v)^2)/ 340.13))/qt
mInf = 1.0/(1.0+exp((mhv)/ms))
if(v == hh){
v = v + 0.0001
}
hTau = (0.438 + 12.22 * exp(((thh  v)^2)/ 547.24))/qt
hInf = 1.0/(1.0+exp((vhh)/hs))
UNITSON
}
