TITLE BK-type Purkinje calcium-activated potassium current
COMMENT
NEURON implementation of a BK-channel in Purkinje cells
Kinetical Scheme: Hodgkin-Huxley (m^3*z^2*h)
Modified from Khaliq et al., J.Neurosci. 23(2003)4899
Laboratory for Neuronal Circuit Dynamics
RIKEN Brain Science Institute, Wako City, Japan
http://www.neurodynamics.brain.riken.jp
Reference: Akemann and Knoepfel, J.Neurosci. 26 (2006) 4602
Date of Implementation: May 2005
Contact: akemann@brain.riken.jp
ENDCOMMENT
NEURON {
SUFFIX pcCaBK
USEION k READ ek WRITE ik
USEION ca READ cai
RANGE gkbar, gk, ik
GLOBAL minf, taum, hinf, tauh, zinf, tauz
GLOBAL zhalf
}
UNITS {
(mV) = (millivolt)
(mA) = (milliamp)
(nA) = (nanoamp)
(pA) = (picoamp)
(S) = (siemens)
(nS) = (nanosiemens)
(pS) = (picosiemens)
(um) = (micron)
(molar) = (1/liter)
(mM) = (millimolar)
}
CONSTANT {
q10 = 2.2
cvm = 28.9 (mV)
ckm = 6.2 (mV)
ctm = 0.000505 (s)
cvtm1 = 86.4 (mV)
cktm1 = -10.1 (mV)
cvtm2 = -33.3 (mV)
cktm2 = 10 (mV)
ctauz = 1 (ms)
ch = 0.085
cvh = 32 (mV)
ckh = -5.8 (mV)
cth = 0.0019 (s)
cvth1 = 48.5 (mV)
ckth1 = -5.2 (mV)
cvth2 = -54.2 (mV)
ckth2 = 12.9 (mV)
}
PARAMETER {
v (mV)
celsius (degC)
gkbar = 0.014 (S/cm2)
ek (mV)
cai (mM)
zhalf = 0.001 (mM)
}
ASSIGNED {
ik (mA/cm2)
qt
gk (S/cm2)
minf
taum (ms)
hinf
tauh (ms)
zinf
tauz (ms)
}
STATE {
m FROM 0 TO 1
z FROM 0 TO 1
h FROM 0 TO 1
}
INITIAL {
qt = q10^((celsius-22 (degC))/10 (degC))
rates(v)
m = minf
z = zinf
h = hinf
}
BREAKPOINT {
SOLVE states METHOD cnexp
gk = gkbar * m^3 * z^2 * h
ik = gk * (v - ek)
}
DERIVATIVE states {
rates(v)
m' = (minf-m)/taum
z' = (zinf-z)/tauz
h' = (hinf-h)/tauh
}
PROCEDURE rates( v (mV) ) {
v = v + 5 (mV)
minf = 1 / ( 1+exp(-(v+cvm)/ckm) )
taum = (1e3) * ( ctm + 1 (s) / ( exp(-(v+cvtm1)/cktm1) + exp(-(v+cvtm2)/cktm2) ) ) / qt
zinf = 1 /(1 + zhalf/cai)
tauz = ctauz/qt
hinf = ch + (1-ch) / ( 1+exp(-(v+cvh)/ckh) )
tauh = (1e3) * ( cth + 1 (s) / ( exp(-(v+cvth1)/ckth1) + exp(-(v+cvth2)/ckth2) ) ) / qt
}