TITLE Large conductance Ca2+ activated K+ channel mslo
COMMENT
Parameters from Cox et al. (1987) J Gen Physiol 110:257-81 (patch 1).
Current Model Reference: Anwar H, Hong S, De Schutter E (2010) Controlling Ca2+-activated K+ channels with models of Ca2+ buffering in Purkinje cell. Cerebellum*
*Article available as Open Access
PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/20981513
Written by Sungho Hong, Okinawa Institute of Science and Technology, March 2009.
Contact: Sungho Hong (shhong@oist.jp)
Adapted by: Haroon Anwar (anwar@oist.jp)
ENDCOMMENT
NEURON {
SUFFIX mslo_DP
USEION k READ ek WRITE ik
USEION ca READ cai
USEION ca2 READ ca2i VALENCE 2
RANGE g, gbar, ik
GLOBAL frac1, frac2
}
UNITS {
(mV) = (millivolt)
(S) = (siemens)
(molar) = (1/liter)
(mM) = (millimolar)
FARADAY = (faraday) (kilocoulombs)
R = (k-mole) (joule/degC)
}
CONSTANT {
q10 = 3
}
PARAMETER {
gbar = 0.01 (S/cm2)
Qo = 0.73
Qc = -0.67
k1 = 1.0e3 (/mM)
onoffrate = 1 (/ms)
L0 = 1806
Kc = 11.0e-3 (mM)
Ko = 1.1e-3 (mM)
pf0 = 2.39e-3 (/ms)
pf1 = 7.0e-3 (/ms)
pf2 = 40e-3 (/ms)
pf3 = 295e-3 (/ms)
pf4 = 557e-3 (/ms)
pb0 = 3936e-3 (/ms)
pb1 = 1152e-3 (/ms)
pb2 = 659e-3 (/ms)
pb3 = 486e-3 (/ms)
pb4 = 92e-3 (/ms)
}
ASSIGNED {
: rates
c01 (/ms)
c12 (/ms)
c23 (/ms)
c34 (/ms)
o01 (/ms)
o12 (/ms)
o23 (/ms)
o34 (/ms)
f0 (/ms)
f1 (/ms)
f2 (/ms)
f3 (/ms)
f4 (/ms)
c10 (/ms)
c21 (/ms)
c32 (/ms)
c43 (/ms)
o10 (/ms)
o21 (/ms)
o32 (/ms)
o43 (/ms)
b0 (/ms)
b1 (/ms)
b2 (/ms)
b3 (/ms)
b4 (/ms)
v (mV)
cai (mM)
ca2i (mM)
ek (mV)
ik (milliamp/cm2)
g (S/cm2)
celsius (degC)
frac1
frac2
}
STATE {
C0 FROM 0 TO 1
C1 FROM 0 TO 1
C2 FROM 0 TO 1
C3 FROM 0 TO 1
C4 FROM 0 TO 1
O0 FROM 0 TO 1
O1 FROM 0 TO 1
O2 FROM 0 TO 1
O3 FROM 0 TO 1
O4 FROM 0 TO 1
}
BREAKPOINT {
SOLVE activation METHOD sparse
g = gbar * (O0 + O1 + O2 + O3 + O4)
ik = g * (v - ek)
}
INITIAL {
: rates(v, cai)
: SOLVE seqinitial
SOLVE activation STEADYSTATE sparse
}
KINETIC activation {
rates(v, cai*frac1 + ca2i*frac2)
~ C0 <-> C1 (c01,c10)
~ C1 <-> C2 (c12,c21)
~ C2 <-> C3 (c23,c32)
~ C3 <-> C4 (c34,c43)
~ O0 <-> O1 (o01,o10)
~ O1 <-> O2 (o12,o21)
~ O2 <-> O3 (o23,o32)
~ O3 <-> O4 (o34,o43)
~ C0 <-> O0 (f0 , b0)
~ C1 <-> O1 (f1 , b1)
~ C2 <-> O2 (f2 , b2)
~ C3 <-> O3 (f3 , b3)
~ C4 <-> O4 (f4 , b4)
CONSERVE C0 + C1 + C2 + C3 + C4 + O0 + O1 + O2 + O3 + O4 = 1
}
PROCEDURE rates(v(mV), ca (mM)) {
LOCAL qt, alpha, beta
qt = q10^((celsius-23 (degC))/10 (degC))
c01 = 4*ca*k1*onoffrate*qt
c12 = 3*ca*k1*onoffrate*qt
c23 = 2*ca*k1*onoffrate*qt
c34 = 1*ca*k1*onoffrate*qt
o01 = 4*ca*k1*onoffrate*qt
o12 = 3*ca*k1*onoffrate*qt
o23 = 2*ca*k1*onoffrate*qt
o34 = 1*ca*k1*onoffrate*qt
c10 = 1*Kc*k1*onoffrate*qt
c21 = 2*Kc*k1*onoffrate*qt
c32 = 3*Kc*k1*onoffrate*qt
c43 = 4*Kc*k1*onoffrate*qt
o10 = 1*Ko*k1*onoffrate*qt
o21 = 2*Ko*k1*onoffrate*qt
o32 = 3*Ko*k1*onoffrate*qt
o43 = 4*Ko*k1*onoffrate*qt
alpha = exp(Qo*FARADAY*v/R/(273.15 + celsius))
beta = exp(Qc*FARADAY*v/R/(273.15 + celsius))
f0 = pf0*alpha*qt
f1 = pf1*alpha*qt
f2 = pf2*alpha*qt
f3 = pf3*alpha*qt
f4 = pf4*alpha*qt
b0 = pb0*beta*qt
b1 = pb1*beta*qt
b2 = pb2*beta*qt
b3 = pb3*beta*qt
b4 = pb4*beta*qt
}