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188 lines
3.8 KiB
188 lines
3.8 KiB
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: ichanWT2005.mod |
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: Alan Goldin Lab, University of California, Irvine |
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: Jay Lickfett - Last Modified: 6 July 2005 |
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: This file is the Nav1.1 wild-type channel model described in: |
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: Barela et al. An Epilepsy Mutation in the Sodium Channel SCN1A That Decreases |
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: Channel Excitability. J. Neurosci. 26(10): p. 2714-2723 |
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: The model is derived from the one described in: |
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: Spampanato et al. (2004a) Increased Neuronal Firing in Computer Simulations |
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: of Sodium Channel Mutations that Cause Generalized Epilepsy with Febrile Seizures Plus. |
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: Journal of Neurophysiology 91:2040-2050 |
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: and |
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: Spampanato et al. (2004b) A Novel Epilepsy Mutation |
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: in the Sodium Channel SCN1A Identifies a Cytoplasmic Domain for |
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: Beta Subunit Interaction. J. Neurosci. 24(44):10022-10034 |
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: delayed rectifier removed (p.b.manis 2/22/2009) |
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UNITS { |
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(mA) = (milliamp) |
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(mV) = (millivolt) |
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(uF) = (microfarad) |
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(molar) = (1/liter) |
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(nA) = (nanoamp) |
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(mM) = (millimolar) |
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(um) = (micron) |
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(S) = (siemens) |
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FARADAY = 96520 (coul) |
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R = 8.3134 (joule/degC) |
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} |
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NEURON { |
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THREADSAFE |
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SUFFIX nav11 |
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USEION na READ ena WRITE ina VALENCE 1 |
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RANGE gna |
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RANGE gbar |
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RANGE minf, mtau, hinf, htau, sinf, stau, inat, m, h, s |
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RANGE vsna : voltage shift parameter |
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} |
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INDEPENDENT {t FROM 0 TO 100 WITH 100 (ms)} |
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PARAMETER { |
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vsna = 4.3 (mV) |
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celsius (degC) |
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dt (ms) |
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ena (mV) |
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:enat = 50 (mV) |
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gbar = 0.1 (mho/cm2) |
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q10 = 3.0 (1) |
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} |
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ASSIGNED { |
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v (mV) |
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gna (mho/cm2) |
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ina (mA/cm2) |
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minf hinf sinf |
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mtau (ms) htau (ms) stau (ms) |
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mexp hexp sexp |
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: vsna (mV) |
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} |
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STATE { |
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m h s |
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} |
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BREAKPOINT { |
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SOLVE states METHOD cnexp |
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gna = gbar*m*m*m*h*s |
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ina = gna*(v - ena) |
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} |
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UNITSOFF |
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INITIAL { |
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trates(v) |
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m = minf |
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h = hinf |
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s = sinf |
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} |
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DERIVATIVE states { : Computes state variables m, h, s and n |
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: at the current v and dt. |
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rates(v) |
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m' = (minf - m)/mtau |
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h' = (hinf - h)/htau |
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s' = (sinf - s)/stau |
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} |
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LOCAL qt |
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PROCEDURE rates(v (mV)) { :Computes rate and other constants at current v. |
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:Call once from HOC to initialize inf at resting v. |
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LOCAL alpha, beta, sum |
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qt = q10^((celsius - 22)/10) : original recordings in Barela et al made at "room temperature" |
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: "m" sodium activation system |
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minf = f_minf(v) |
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mtau = f_mtau(v)/qt |
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: "h" sodium fast inactivation system |
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hinf = f_hinf(v) |
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htau = f_htau(v)/qt |
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: "s" sodium slow inactivation system |
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sinf = f_sinf(v) |
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stau = f_stau(v)/qt |
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} |
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PROCEDURE trates(v (mV)) { :Build table with rate and other constants at current v. |
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:Call once from HOC to initialize inf at resting v. |
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LOCAL tinc |
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TABLE minf, mexp, hinf, hexp, sinf, sexp, mtau, htau, stau |
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DEPEND dt, celsius FROM -100 TO 100 WITH 200 |
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rates(v) : not consistently executed from here if usetable_hh == 1 |
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: so don't expect the tau values to be tracking along with |
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: the inf values in hoc |
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tinc = -dt : * q10 q10 is handled in rates, above |
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mexp = 1 - exp(tinc/mtau) |
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hexp = 1 - exp(tinc/htau) |
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sexp = 1 - exp(tinc/stau) |
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} |
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FUNCTION f_minf(v (mV)) { |
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f_minf = 1/(1+exp(-(v+27.4+vsna)*4.7*0.03937)) |
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} |
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FUNCTION f_mtau(v (mV)) { |
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f_mtau = 0.15 |
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} |
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FUNCTION f_hinf(v (mV)) { |
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f_hinf = 1/(1+exp((v+41.9+vsna)/6.7)) |
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} |
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FUNCTION f_htau(v (mV)) { |
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f_htau = 23.12*exp(-0.5*((v+77.58+vsna)/43.92)^2) |
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} |
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FUNCTION f_sinf(v (mV)) { |
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f_sinf = 1/(1+exp((v+46.0+vsna)/6.6)) |
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} |
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FUNCTION f_stau(v (mV)) { |
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f_stau = 1000*140.4*exp(-0.5*((v+71.3+vsna)/30.9)^2) |
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} |
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UNITSON |
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