-
Notifications
You must be signed in to change notification settings - Fork 1
/
Cav2.mod
148 lines (116 loc) · 2.57 KB
/
Cav2.mod
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
TITLE Cav2.1 (P-type) calcium channel
COMMENT
NEURON implementation of a Cav2.1 calcium channel
Kinetical scheme: Hodgkin-Huxley (m), no inactivation
Model includes a calculation of the gating current
Modified from Khaliq et al., J. Neurosci. 23(2003)4899
Reference: Akemann et al. (2009) 96:3959-3976
Laboratory for Neuronal Circuit Dynamics
RIKEN Brain Science Institute, Wako City, Japan
http://www.neurodynamics.brain.riken.jp
Date of Implementation: April 2007
Contact: akemann@brain.riken.jp
ENDCOMMENT
NEURON {
SUFFIX Cav2
USEION ca READ cai, cao WRITE ica
NONSPECIFIC_CURRENT i
RANGE pbar, ica, i, igate, nc
GLOBAL minf, taum
GLOBAL gateCurrent, punit
}
UNITS {
(mV) = (millivolt)
(mA) = (milliamp)
(nA) = (nanoamp)
(pA) = (picoamp)
(S) = (siemens)
(nS) = (nanosiemens)
(pS) = (picosiemens)
(um) = (micron)
(molar) = (1/liter)
(mM) = (millimolar)
}
CONSTANT {
e0 = 1.60217646e-19 (coulombs)
q10 = 2.7
F = 9.6485e4 (coulombs)
R = 8.3145 (joule/kelvin)
cv = 19 (mV)
ck = 5.5 (mV)
zm = 4.6244 (1) : gating charge
}
PARAMETER {
gateCurrent = 0 (1) : gating currents ON = 1 OFF = 0
pbar = 3e-5 (cm/s)
punit = 3.290e-13 (cm3/s) : unitary calcium permeability
monovalConc = 140 (mM)
monovalPerm = 0 (1)
}
ASSIGNED {
celsius (degC)
v (mV)
cai (mM)
cao (mM)
ica (mA/cm2)
i (mA/cm2)
igate (mA/cm2)
nc (1/cm2) : membrane density of channel
minf (1)
taum (ms)
T (kelvin)
E (volt)
zeta (1)
qt (1)
}
STATE { m }
INITIAL {
nc = pbar / punit
qt = q10^((celsius-22 (degC))/10 (degC))
T = kelvinfkt( celsius )
rates(v)
m = minf
}
BREAKPOINT {
SOLVE states METHOD cnexp
ica = (1e3) * pbar * m * ghk(v, cai, cao, 2)
igate = nc * (1e6) * e0 * zm * mgateFlip()
if (gateCurrent != 0) {
i = igate
}
}
DERIVATIVE states {
rates(v)
m' = (minf-m)/taum
}
FUNCTION ghk( v (mV), ci (mM), co (mM), z ) (coulombs/cm3) {
E = (1e-3) * v
zeta = (z*F*E)/(R*T)
: ci = ci + (monovalPerm) * (monovalConc) :Monovalent permeability
if ( fabs(1-exp(-zeta)) < 1e-6 ) {
ghk = (1e-6) * (z*F) * (ci - co*exp(-zeta)) * (1 + zeta/2)
} else {
ghk = (1e-6) * (z*zeta*F) * (ci - co*exp(-zeta)) / (1-exp(-zeta))
}
}
PROCEDURE rates( v (mV) ) {
minf = 1 / ( 1 + exp(-(v+cv)/ck) )
taum = (1e3) * taumfkt(v)/qt
}
FUNCTION taumfkt( v (mV) ) (s) {
UNITSOFF
if ( v > -50 ) {
taumfkt = 0.000191 + 0.00376 * exp(-((v+41.9)/27.8)^2)
} else {
taumfkt = 0.00026367 + 0.1278 * exp(0.10327*v)
}
UNITSON
}
FUNCTION kelvinfkt( t (degC) ) (kelvin) {
UNITSOFF
kelvinfkt = 273.19 + t
UNITSON
}
FUNCTION mgateFlip() (1/ms) {
mgateFlip = (minf-m)/taum
}