TITLE squid sodium, potassium delayed rectifier, and potassium A channels : Anna's version adding some shift values UNITS { (molar) = (1/liter) (S) = (siemens) (mA) = (milliamp) (mV) = (millivolt) F = (faraday) (coulomb) R = (mole k) (mV-coulomb/degC) (mM) = (millimolar) } NEURON { SUFFIX hh3 USEION na READ nai WRITE ina USEION k WRITE ik RANGE sshift, shift,gnabar,gkhhbar,gkabar,ina,ikhh,ika,ik,ena,gk,gna,gka GLOBAL minf,hinf,ninf } INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)} PARAMETER { v (mV) dt (ms) nai (mM) celsius = 35.0 (degC) gnabar = 550.0e-6 (S/cm2) gkhhbar = 665.0e-6 (S/cm2) gkabar = 266.0e-6 (S/cm2) ek = -90.0 (mV) nao = 145 (mM) qv = 60.0 (mV) qs = 5.0 (1) shift=0 (mV) sshift=0 (mV) } STATE { m <1e-4> h <1e-4> n <1e-4> p <1e-4> q <1e-4> } ASSIGNED { ina (mA/cm2) ik (mA/cm2) ika (mA/cm2) ikhh (mA/cm2) ena (mV) minf hinf ninf qinf pinf gna gk gka } BREAKPOINT { SOLVE states METHOD cnexp nai = 0.81 ena = R*(celsius+273.15)/F*log(nao/nai) : ena=77.0 ina = gnabar*m*m*m*h*(v - ena) ikhh = gkhhbar*n*n*n*(v - ek) ika = gkabar*p*p*p*q*(v - ek) ik = ika + ikhh gk = n*n*n gna = m*m*m*h gka = p*p*p*q } UNITSOFF INITIAL { m = boltz(v,-34.6-shift,6.0-sshift) h = boltz(v,-56.8-shift,-7.8) n = boltz(v,-25.0,12.0) p = boltz(v,-43.0,24.0) q = boltz(v,-qv,-qs) } DERIVATIVE states { :Computes state variables m, h, and n LOCAL minf,hinf,ninf,pinf,qinf,mtau,htau,ntau,ptau,qtau minf = boltz(v,-34.6-shift,6.0-sshift) hinf = boltz(v,-56.8-shift,-7.8) ninf = boltz(v,-25,12.0) pinf = boltz(v,-43.0,24.0) qinf = boltz(v,-qv,-qs) mtau = 1*boltz(v,-45.0,-1.5) - 1*boltz(v,-65.0,-0.5) +0.04 htau = 3*56.0*boltz(v,-29.0,-4.5) - 3*56.0*boltz(v,-49.0,-2.0) +2.0 ntau = 19.0/(1.0 + exp((v+ 39.0)/8.0)) - 0.0/(1.0 + exp((v+ 59.0)/20.0))+1.0 ptau = 2.*exp(-(v+50)*(v+50)/550)+1.1 qtau = 20.0 m' = (minf-m)/mtau h' = (hinf-h)/htau n' = (ninf-n)/ntau p' = (pinf-p)/ptau q' = (qinf-q)/qtau } FUNCTION boltz(x,y,z) { boltz = 1/(1 + exp(-(x - y)/z)) } UNITSON