: Fast Na+ channel NEURON { SUFFIX Nafcr USEION na READ ena WRITE ina RANGE gnafbar, ina, gna } UNITS { (mA) = (milliamp) (mV) = (millivolt) } INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)} PARAMETER { v (mV) dt (ms) gnafbar= 0.086 (mho/cm2) <0,1e9> ena = 55 (mV) } STATE { m h } ASSIGNED { ina (mA/cm2) minf hinf mtau (ms) htau (ms) gna (mho/cm2) } INITIAL { rate(v) m = minf h = hinf } BREAKPOINT { SOLVE states METHOD cnexp gna = gnafbar*m*m*m*h ina = gna*(v-55) } DERIVATIVE states { rate(v) m' = (minf-m)/mtau h' = (hinf-h)/htau } UNITSOFF FUNCTION malf( v){ LOCAL va va=v+28 if (fabs(va)<1e-04){ malf= -0.2816*(-9.3 + va*0.5) }else{ malf = -0.2816*(v+28)/(-1+exp(-(v+28)/9.3)) } } FUNCTION mbet(v(mV))(/ms) { LOCAL vb vb=v+1 if (fabs(vb)<1e-04){ mbet = 0.2464*(6 + vb*0.5) }else{ mbet = 0.2464*(v+1)/(-1+exp((v+1)/6)) } } FUNCTION half(v(mV))(/ms) { LOCAL vc vc=v+43.1 if (fabs(vc)<1e-04){ half=0.098*(20 + vc*0.5) }else{ half=0.098/exp((v+23.1)/20) :was 43.1 } } FUNCTION hbet(v(mV))(/ms) { LOCAL vd vd=v+13.1 if (fabs(vd)<1e-04){ hbet=1.4*(10 + vd*0.5) }else{ hbet=1.4/(1+exp(-(v+25.1)/10)) :was 13.1 changed july 30, 2007 } } PROCEDURE rate(v (mV)) {LOCAL q10, msum, hsum, ma, mb, ha, hb ma=malf(v) mb=mbet(v) ha=half(v) hb=hbet(v) msum = ma+mb minf = ma/msum mtau = 1/(msum) hsum=ha+hb hinf=ha/hsum htau = 1 / (hsum) } UNITSON