//genesis
/* FILE INFORMATION
** The 1991 Traub set of voltage and concentration dependent channels
** Implemented as tabchannels by : Dave Beeman
** R.D.Traub, R. K. S. Wong, R. Miles, and H. Michelson
** Journal of Neurophysiology, Vol. 66, p. 635 (1991)
**
** This file depends on functions and constants defined in defaults.g
** As it is also intended as an example of the use of the tabchannel
** object to implement concentration dependent channels, it has extensive
** comments. Note that the original units used in the paper have been
** converted to SI (MKS) units. Also, we define the ionic equilibrium
** potentials relative to the resting potential, EREST_ACT. In the
** paper, this was defined to be zero. Here, we use -0.060 volts, the
** measured value relative to the outside of the cell.
*/
/* November 1999 update for GENESIS 2.2: Previous versions of this file used
a combination of a table, tabgate, and vdep_channel to implement the
Ca-dependent K Channel - K(C). This new version uses the new tabchannel
"instant" field, introduced in GENESIS 2.2, to implement an
"instantaneous" gate for the multiplicative Ca-dependent factor in the
conductance. This allows these channels to be used with the fast
hsolve chanmodes > 1.
*/
// Now updated for Traub et al. J Neurophysiol 2003;89:909-921.
// And for LTS and FS interneurons - Cunningham et al. PNAS 2004;101:7152-7157.
// CONSTANTS
float EREST_ACT = -0.070 /* cell resting potential */
float ENAB5FS = 0.120 + EREST_ACT // 0.050
float EKB5FS = -0.03 + EREST_ACT // -0.100
float ECAB5FS = 0.195 + EREST_ACT // 0.125
float EARB5FS = 0.030 + EREST_ACT // -0.040
float SOMA_A = 3.320e-9 // soma area in square meters
/*
For these channels, the maximum channel conductance (Gbar) has been
calculated using the CA3 soma channel conductance densities and soma
area. Typically, the functions which create these channels will be used
to create a library of prototype channels. When the cell reader creates
copies of these channels in various compartments, it will set the actual
value of Gbar by calculating it from the cell parameter file.
*/
//========================================================================
// Tabchannel gNa-transient, gNa(F) 2005/03
//========================================================================
function make_NaF10
if ({exists NaF10})
return
end
create tabchannel NaF10
setfield NaF10 \
Ek 0.05 \
Ik 0 \
Xpower 3 \
Ypower 1
setfield NaF10 \
Gbar 1 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call NaF10 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // v to units of equation
if ({ v -2.5 } < -30 )
tau = 0.0125 + 0.1525 * { exp { {{v - 2.5} + 30} / 10} }
else
tau = 0.02 + 0.145 * { exp { -1 * {{v - 2.5} + 30} / 10} }
end
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
v = v * 1000 // v to units of equation
inf = 1 / { 1 + {exp { { -1 * {v - 2.5} - 38} / 10}} }
v = v * 0.001 // reset v
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield NaF10 X_A->table[{i}] {alpha}
setfield NaF10 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield NaF10 X_A->calc_mode 1 X_B->calc_mode 1
// Y table for gate h
float dv = ({v_max} - {v_min})/{tab_divs}
call NaF10 TABCREATE Y {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // v to units of equation...
tau = 0.225 + 1.125 / { 1 + { exp {{v + 37} / 15} } }
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
v = v * 1000 // v to units of equation
inf = 1 / { 1 + {exp {{v + 58.3} / 6.7}} }
v = v * 0.001 // reset v
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield NaF10 Y_A->table[{i}] {alpha}
setfield NaF10 Y_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield NaF10 Y_A->calc_mode 1 Y_B->calc_mode 1
end
//========================================================================
// Tabchannel gNa-persistent (non-inactivating), gNa(P) 2005/03
//========================================================================
function make_NaP10
if ({exists NaP10})
return
end
create tabchannel NaP10
setfield NaP10 \
Ek 0.05 \
Ik 0 \
Xpower 1
setfield NaP10 \
Gbar 1 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call NaP10 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // v to units of equation
if (v < -40 )
tau = 0.025 + 0.14 * {exp {{ v + 40 }/10}}
else
tau = 0.02 + 0.145 * {exp {-1 * {v + 40}/ 10}}
end
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = -10, Vhalf = -48 in physiol units
// A = 1, B = -0.01, Vhalf = -0.048
inf = 1 / ( {exp {(v + 0.048) / -0.01}} + 1)
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield NaP10 X_A->table[{i}] {alpha}
setfield NaP10 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield NaP10 X_A->calc_mode 1 X_B->calc_mode 1
end
//========================================================================
// Tabchannel Anomalous Rectifier, gAR 2005/03
//========================================================================
function make_AR10
if ({exists AR10})
return
end
create tabchannel AR10
setfield AR10 \
Ek -0.04 \
Ik 0 \
Xpower 1
setfield AR10 \
Gbar 2.5 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call AR10 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
float tau
v = v * 1000 // v to units of equation
tau = 1 /{{exp {-14.6 - {0.086 * v} }} + {exp {-1.87 + {0.07 * v}}}}
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = 5.5, Vhalf = -75, in units: Physiological Units
// A = 1, B = 0.0055, Vhalf = -0.075
inf = 1 / ( {exp {(v + 0.075) / 0.0055}} + 1)
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield AR10 X_A->table[{i}] {alpha}
setfield AR10 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield AR10 X_A->calc_mode 1 X_B->calc_mode 1
end
//========================================================================
// Tabchannel gK-delayed rectifier, gK(DR) 2005/03
//========================================================================
function make_KDR10
if ({exists KDR10})
return
end
create tabchannel KDR10
setfield KDR10 \
Ek {EKB5FS} \
Ik 0 \
Xpower 4
setfield KDR10 \
Gbar 1250 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call KDR10 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // v to units of equation
if (v <= -10 )
tau = 0.25 + 4.35 * {exp {{ v + 10 }/10}}
else
tau = 0.25 + 4.35 * {exp {{- v - 10}/ 10}}
end
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = -11.5, Vhalf = -27, in physiological units
// A = 1, B = -0.0115, Vhalf = -0.027
inf = 1 / ( {exp {(v + 0.027) / -0.0115}} + 1)
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield KDR10 X_A->table[{i}] {alpha}
setfield KDR10 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield KDR10 X_A->calc_mode 1 X_B->calc_mode 1
end
//========================================================================
// Tabchannel gK-transient, gK(A) 2005/03
//========================================================================
function make_KA10
if ({exists KA10})
return
end
create tabchannel KA10
setfield KA10 \
Ek {EKB5FS} \
Ik 0 \
Xpower 4 \
Ypower 1
setfield KA10 \
Gbar 300 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call KA10 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // v to units of equation
tau = 0.185 + 0.5 / {{exp {{ v + 35.8 }/19.7}} + {exp {{-v - 79.7}/12.7}}}
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = -8.5, Vhalf = -60, in units: Physiological Units
// A = 1, B = -0.0085, Vhalf = -0.06
inf = 1 / ( {exp {(v + 0.06) / -0.0085}} + 1)
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield KA10 X_A->table[{i}] {alpha}
setfield KA10 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield KA10 X_A->calc_mode 1 X_B->calc_mode 1
// Y table for gate h
float dv = ({v_max} - {v_min})/{tab_divs}
call KA10 TABCREATE Y {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // temporarily set v to units of equation...
if (v < -63.0 )
tau = 0.5 / {{exp {{ v + 46 }/5}} + {exp {{ -v - 238 }/37.5}}}
else
tau = 9.5
end
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = 6, Vhalf = -78, in units: Physiological Units
// A = 1, B = 0.006, Vhalf = -0.078
inf = 1 / ( {exp {(v + 0.078) / 0.006}} + 1)
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield KA10 Y_A->table[{i}] {alpha}
setfield KA10 Y_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield KA10 Y_A->calc_mode 1 Y_B->calc_mode 1
end
//========================================================================
// Tabchannel gK2-slow, gK2 2005/03
//========================================================================
function make_K210
if ({exists K210})
return
end
create tabchannel K210
setfield K210 \
Ek {EKB5FS} \
Ik 0 \
Xpower 1 \
Ypower 1
setfield K210 \
Gbar 1 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call K210 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // v to units of equation
tau = 4.95 + 0.5 / { {exp { {v - 81} / 25.6}} + {exp { {- v - 132} / 18 }}}
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = -17, Vhalf = -10, in physiological units
// A = 1, B = -0.017, Vhalf = -0.01
inf = 1 / ( {exp {(v + 0.01) / -0.017}} + 1)
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield K210 X_A->table[{i}] {alpha}
setfield K210 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield K210 X_A->calc_mode 1 X_B->calc_mode 1
// Y table for gate h
float dv = ({v_max} - {v_min})/{tab_divs}
call K210 TABCREATE Y {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // v to units of equation
tau = 60 + 0.5 / {{exp {{ v - 1.33 }/200}} + {exp {{- v - 130}/ 7.1}}}
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = 10.6, Vhalf = -58, in units: Physiological Units
// A = 1, B = 0.0106, Vhalf = -0.058
inf = 1 / ( {exp {(v + 0.058) / 0.0106}} + 1)
// alpha & beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield K210 Y_A->table[{i}] {alpha}
setfield K210 Y_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield K210 Y_A->calc_mode 1 Y_B->calc_mode 1
end
//========================================================================
// Tabchannel gK-muscarinic receptor supressed, gK(M) 2005/03
//========================================================================
function make_KM10
if ({exists KM10})
return
end
create tabchannel KM10
setfield KM10 \
Ek {EKB5FS} \
Ik 0 \
Xpower 1
setfield KM10 \
Gbar 75 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call KM10 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// alpha
float alpha
// A = 0.02, B = -5, Vhalf = -20, in units: Physiological Units
// A = 20, B = -0.005, Vhalf = -0.02
alpha = 20 / ( {exp {(v + 0.02) / -0.005}} + 1)
// beta
float beta
// A = 0.01, B = -18, Vhalf = -43, in physiological units
// A = 10, B = -0.018, Vhalf = -0.043
beta = 10 * {exp {(v + 0.043) / -0.018}}
// alpha and beta
float tau = 1/(alpha + beta)
setfield KM10 X_A->table[{i}] {alpha}
setfield KM10 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield KM10 X_A->calc_mode 1 X_B->calc_mode 1
end
//========================================================================
// Tabchannel gCa(L)-low threshold, transient, gCa(L) 2005/03
//========================================================================
function make_CaL10
if ({exists CaL10})
return
end
create tabchannel CaL10
setfield CaL10 \
Ek 0.125 \
Ik 0 \
Xpower 2 \
Ypower 1
setfield CaL10 \
Gbar 1 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call CaL10 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // v to units of equation
tau = 0.204 + 0.333 / { {exp {{15.8 + v} / 18.2 }} + {exp {{- v - 131} / 16.7}} }
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = -6.2, Vhalf = -56.0, in physiol units
// A = 1, B = -0.0062, Vhalf = -0.056
inf = 1 / ( {exp {(v + 0.056) / -0.0062}} + 1)
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield CaL10 X_A->table[{i}] {alpha}
setfield CaL10 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield CaL10 X_A->calc_mode 1 X_B->calc_mode 1
// Y table for gate h
float dv = ({v_max} - {v_min})/{tab_divs}
call CaL10 TABCREATE Y {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // v to units of equation
if (v < -81.0 )
tau = 0.333 * {exp {{ v + 466 } / 66.6}}
else
tau = 9.32 + 0.333 * {exp {{ - v - 21 } / 10.5}}
end
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = 4, Vhalf = -80, in physiol units
// A = 1, B = 0.004, Vhalf = -0.08
inf = 1 / ( {exp {(v + 0.08) / 0.004}} + 1)
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield CaL10 Y_A->table[{i}] {alpha}
setfield CaL10 Y_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield CaL10 Y_A->calc_mode 1 Y_B->calc_mode 1
end
//==========================================================================
// Tabchannel gCaH-high threshold calcium, gCa(L) "long" 2003/05
//==========================================================================
function make_CaH10
if ({exists CaH10})
return
end
create tabchannel CaH10
setfield CaH10 \
Ek 0.125 \
Ik 0 \
Xpower 2
setfield CaH10 \
Gbar 5 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call CaH10 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
float alpha
// A = 1.6, B = -13.888889, Vhalf = 5 in physiological units
// A = 1600, B = -0.013888889000000001, Vhalf = 0.005
alpha = 1600 / ( {exp {(v - 0.005) / -0.013888889000000001}} + 1)
// beta
float beta
// A = 0.1, B = -5, Vhalf = -8.9 in physiol. units
// A = 100, B = -0.005, Vhalf = -0.0089
if ( {abs {(v + 0.0089)/ -0.005}} < 1e-6)
beta = 100 * (1 + (v + 0.0089)/-0.005/2)
else
beta = 100 * ((v + 0.0089) / -0.005) /(1 - {exp {-1 * (v + 0.0089)/-0.005}})
end
// alpha & beta
float tau = 1/(alpha + beta)
setfield CaH10 X_A->table[{i}] {alpha}
setfield CaH10 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield CaH10 X_A->calc_mode 1 X_B->calc_mode 1
end
//========================================================================
// Ca conc, Traub et al. J Neurophysiol 2003;89:909-921.
//========================================================================
/****************************************************************************
Next, we need an element to take the Calcium current calculated by the Ca
channel and convert it to the Ca concentration. The "Ca_concen" object
solves the equation dC/dt = B*I_Ca - C/tau, and sets Ca = Ca_base + C. As
it is easy to make mistakes in units when using this Calcium diffusion
equation, the units used here merit some discussion.
With Ca_base = 0, this corresponds to Traub's diffusion equation for
concentration, except that the sign of the current term here is positive, as
GENESIS uses the convention that I_Ca is the current flowing INTO the
compartment through the channel. In SI units, the concentration is usually
expressed in moles/m^3 (which equals millimoles/liter), and the units of B
are chosen so that B = 1/(ion_charge * Faraday * volume). Current is
expressed in amperes and one Faraday = 96487 coulombs. However, in this
case, Traub expresses the concentration in arbitrary units, current in
microamps and uses tau = 13.33 msec (50 msec soma, 20 msec dendrites in the
2003 J Neurophys paper). If we use the same concentration units,
but express current in amperes and tau in seconds, our B constant is then
10^12 times the constant (called "phi") used in the paper. The actual value
used will typically be determined by the cell reader from the cell
parameter file (will vary inversely with surface area of compartment).
However, for the prototype channel we wlll use Traub's
corrected value for the soma. (An error in the paper gives it as 17,402
rather than 17.402.) In our units, this will be 17.402e12.
****************************************************************************/
function make_Ca_s10
if ({exists Ca_s10})
return
end
create Ca_concen Ca_s10
// params for Ca pool model
setfield Ca_s10 \
tau { 1.0 / 20 } \
Ca_base 0
addfield Ca_s10 addmsg1
setfield Ca_s10 \
addmsg1 "../CaH10 . I_Ca Ik"
end
/*
This Ca_concen element should receive an "I_Ca" message from the calcium
channel, accompanied by the value of the calcium channel current. As we
will ordinarily use the cell reader to create copies of these prototype
elements in one or more compartments, we need some way to be sure that the
needed messages are established. Although the cell reader has enough
information to create the messages which link compartments to their channels
and to other adjacent compartments, it must be provided with the information
needed to establish additional messages. This is done by placing the
message string in a user-defined field of one of the elements which is
involved in the message. The cell reader recognizes the added field names
"addmsg1", "addmsg2", etc. as indicating that they are to be
evaluated and used to set up messages. The paths are relative to the
element which contains the message string in its added field. Thus,
"../Ca_hip_traub91" refers to the sibling element Ca_hip_traub91 and "."
refers to the Ca_hip_conc element itself.
*/
/****************************************************************************/
function make_Ca_d10
if ({exists Ca_d10})
return
end
create Ca_concen Ca_d10
// params for Ca pool in dendrite
setfield Ca_d10 \
tau { 1.0 / 50 } \
Ca_base 0
addfield Ca_d10 addmsg1
setfield Ca_d10 \
addmsg1 "../CaH10 . I_Ca Ik"
end
/*
This Ca_concen element should receive an "I_Ca" message from the calcium
channel, accompanied by the value of the calcium channel current. As we
will ordinarily use the cell reader to create copies of these prototype
elements in one or more compartments, we need some way to be sure that the
needed messages are established. Although the cell reader has enough
information to create the messages which link compartments to their channels
and to other adjacent compartments, it must be provided with the information
needed to establish additional messages. This is done by placing the
message string in a user-defined field of one of the elements which is
involved in the message. The cell reader recognizes the added field names
"addmsg1", "addmsg2", etc. as indicating that they are to be
evaluated and used to set up messages. The paths are relative to the
element which contains the message string in its added field. Thus,
"../Ca_hip_traub91" refers to the sibling element Ca_hip_traub91 and "."
refers to the Ca_hip_conc element itself.
*/
//===============================================================================
// Ca-dependent K Channel - K(C) - (vdep_channel with table and tabgate)2005/03
//===============================================================================
/*
The expression for the conductance of the potassium C-current channel has a
typical voltage and time dependent activation gate, where the time dependence
arises from the solution of a differential equation containing the rate
parameters alpha and beta. It is multiplied by a function of calcium
concentration that is given explicitly rather than being obtained from a
differential equation. Therefore, we need a way to multiply the activation
by a concentration dependent value which is determined from a lookup table.
This is accomplished by using the Z gate with the new tabchannel "instant"
field, introduced in GENESIS 2.2, to implement an "instantaneous" gate for
the multiplicative Ca-dependent factor in the conductance.
*/
function make_KCs10
if ({exists KCs10})
return
end
create tabchannel KCs10
setfield KCs10 \
Ek {EKB5FS} \
Ik 0 \
Xpower 1 \
Zpower 1
setfield KCs10 \
Gbar 120 \
Gk 0
float tab_divs = 1041
float v_min = -0.12
float v_max = 0.14
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call KCs10 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// alpha
float alpha
v = v * 1000 // v to units of equation
if (v < -10 )
alpha = 2 * {2 / 37.95} * { exp { {{v + 50 } / 11} - {{ v + 53.5} / 27} } }
else
alpha = 2 * 2 * {exp { { {-1 * v} - 53.5 } / 27 }}
end
v = v * 0.001 // reset v
// units of alpha
alpha = alpha * 1000
// beta
float beta
v = v * 1000 // v to units of equation
alpha = alpha * 0.001 // alpha to units of equation
if (v < -10 )
beta = 4 * {exp { { {-1 * v} - 53.5 } / 27 }} - alpha
else
beta = 0.0
end
v = v * 0.001 // reset v
alpha = alpha * 1000 // reset alpha
// correct units of beta
beta = beta * 1000
// alpha and beta
float tau = 1/(alpha + beta)
setfield KCs10 X_A->table[{i}] {alpha}
setfield KCs10 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield KCs10 X_A->calc_mode 1 X_B->calc_mode 1
// concentration dependent term (voltage independent)
float conc_min = 0
float conc_max = 1000
float dc = ({conc_max} - {conc_min})/{tab_divs}
float ca_conc = {conc_min}
call KCs10 TABCREATE Z {tab_divs} {conc_min} {conc_max}
float const_state
for (i = 0; i <= ({tab_divs}); i = i + 1)
ca_conc = ca_conc * 0.000001 // ica_conc to units of equation
if (ca_conc < 0.00025 )
const_state = {ca_conc / 0.00025}
else
const_state = 1
end
ca_conc = ca_conc * 1000000 //reset ca_conc
setfield KCs10 Z_A->table[{i}] {0}
setfield KCs10 Z_B->table[{i}] {const_state}
ca_conc= ca_conc + dc
end
tweaktau KCs10 Z
addfield KCs10 addmsg1
setfield KCs10 addmsg1 "../Ca_s10 . CONCEN Ca"
end
function make_KCd10
if ({exists KCd10})
return
end
create tabchannel KCd10
setfield KCd10 \
Ek {EKB5FS} \
Ik 0 \
Xpower 1 \
Zpower 1
setfield KCd10 \
Gbar 120 \
Gk 0
float tab_divs = 1041
float v_min = -0.12
float v_max = 0.14
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call KCd10 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// alpha
float alpha
v = v * 1000 // V to units of equation
if (v < -10 )
alpha = {4 / 37.95} * { exp { {{v + 50 } / 11} - {{ v + 53.5} / 27} } }
else
alpha = 4 * {exp { { {-1 * v} - 53.5 } / 27 }}
end
v = v * 0.001 // reset v
// correct units of alpha
alpha = alpha * 1000
// beta
float beta
v = v * 1000 // temporarily set v to units of equation...
alpha = alpha * 0.001 // alpha to units of equation
if (v < -10 )
beta = 4 * {exp { { {-1 * v} - 53.5 } / 27 }} - alpha
else
beta = 0.0
end
v = v * 0.001 // reset v
alpha = alpha * 1000 // resetting alpha
// correct units of beta
beta = beta * 1000
// alpha and beta
float tau = 1/(alpha + beta)
setfield KCd10 X_A->table[{i}] {alpha}
setfield KCd10 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield KCd10 X_A->calc_mode 1 X_B->calc_mode 1
// concentration dependent term (voltage independent)
float conc_min = 0
float conc_max = 1000
float dc = ({conc_max} - {conc_min})/{tab_divs}
float ca_conc = {conc_min}
call KCd10 TABCREATE Z {tab_divs} {conc_min} {conc_max}
float const_state
for (i = 0; i <= ({tab_divs}); i = i + 1)
ca_conc = ca_conc * 0.000001 // ca_conc to units of equation
if (ca_conc < 0.00025 )
const_state = {ca_conc / 0.00025}
else
const_state = 1
end
ca_conc = ca_conc * 1000000 //reset ca_conc
setfield KCd10 Z_A->table[{i}] {0}
setfield KCd10 Z_B->table[{i}] {const_state}
ca_conc= ca_conc + dc
end
tweaktau KCd10 Z
addfield KCd10 addmsg1
setfield KCd10 addmsg1 "../Ca_d10 . CONCEN Ca"
end
//========================================================================
// Tabulated Ca-dependent K AHP Channel,gK(AHP) 2003/05
//========================================================================
/* This is a tabchannel which gets the calcium concentration from Ca_hip_conc
in order to calculate the activation of its Z gate. It is set up much
like the Ca channel, except that the A and B tables have values which are
functions of concentration, instead of voltage.
*/
function make_KAHPs10
if ({exists KAHPs10})
return
end
create tabchannel KAHPs10
setfield KAHPs10 \
Ek {EKB5FS} \
Ik 0 \
Zpower 1
setfield KAHPs10 \
Gbar 1 \
Gk 0
float tab_divs = 1041
float c
float conc_min = 0
float conc_max = 1000
float dc = ({conc_max} - {conc_min})/{tab_divs}
float ca_conc = {conc_min}
call KAHPs10 TABCREATE Z {tab_divs} {conc_min} {conc_max}
for (c = 0; c <= ({tab_divs}); c = c + 1)
// alpha
float alpha, v
ca_conc = ca_conc * 0.000001 // ca_conc to units of equation
if (ca_conc < 0.0005 )
alpha = ca_conc/0.05
else
alpha = 0.01
end
ca_conc = ca_conc * 1000000 // resetting ca_conc
// correct units of alpha
alpha = alpha * 1000
// beta
float beta
ca_conc = ca_conc * 0.000001 // ca_conc to units of equation
beta = 0.001
ca_conc = ca_conc * 1000000 // resetting ca_conc
// correct units of beta
beta = beta * 1000
// alpha and beta
float tau = 1/(alpha + beta)
setfield KAHPs10 Z_A->table[{c}] {alpha}
setfield KAHPs10 Z_B->table[{c}] {alpha + beta}
ca_conc = ca_conc + dc
end // end of for (c = 0; c <= ({tab_divs}); c = c + 1)
setfield KAHPs10 Z_conc 1
setfield KAHPs10 Z_A->calc_mode 1 Z_B->calc_mode 1
addfield KAHPs10 addmsg1
setfield KAHPs10 \
addmsg1 "../Ca_s10 . CONCEN Ca"
end
function make_KAHPd10
if ({exists KAHPd10})
return
end
create tabchannel KAHPd10
setfield KAHPd10 \
Ek {EKB5FS} \
Ik 0 \
Zpower 1
setfield KAHPd10 \
Gbar 1 \
Gk 0
float tab_divs = 1041
float c
float conc_min = 0
float conc_max = 1000
float dc = ({conc_max} - {conc_min})/{tab_divs}
float ca_conc = {conc_min}
call KAHPd10 TABCREATE Z {tab_divs} {conc_min} {conc_max}
for (c = 0; c <= ({tab_divs}); c = c + 1)
// alpha
float alpha
ca_conc = ca_conc * 0.000001 //set ca_conc to units of equation
if (ca_conc < 0.0005 )
alpha = ca_conc/0.05
else
alpha = 0.01
end
ca_conc = ca_conc * 1000000 // resetting ca_conc
// correct units of alpha
alpha = alpha * 1000
// beta
float beta
ca_conc = ca_conc * 0.000001 //set ca_conc to units of equation
beta = 0.001
ca_conc = ca_conc * 1000000 // resetting ca_conc
// correct units of beta
beta = beta * 1000
// alpha and beta
float tau = 1/(alpha + beta)
setfield KAHPd10 Z_A->table[{c}] {alpha}
setfield KAHPd10 Z_B->table[{c}] {alpha + beta}
ca_conc = ca_conc + dc
end // end of for (c = 0; c <= ({tab_divs}); c = c + 1)
setfield KAHPd10 Z_conc 1
setfield KAHPd10 Z_A->calc_mode 1 Z_B->calc_mode 1
addfield KAHPd10 addmsg1
setfield KAHPd10 \
addmsg1 "../Ca_d10 . CONCEN Ca"
end