TITLE T-calcium channel : T-type calcium channel for Mala Shah UNITS { (mA) = (milliamp) (mV) = (millivolt) (molar) = (1/liter) (mM) = (millimolar) FARADAY = 96520 (coul) R = 8.3134 (joule/degC) KTOMV = .0853 (mV/degC) } PARAMETER { v (mV) celsius = 25 (degC) gcatbar=.003 (mho/cm2) cai = 50.e-6 (mM) cao = 2 (mM) q10 = 5 mmin=0.2 hmin=10 a0h =0.015 zetah = 3.5 vhalfh = -75 gmh=0.6 a0m =0.04 zetam = 2 vhalfm = -28 gmm=0.61 vhm=-60 vhh=-85 } NEURON { SUFFIX cat USEION ca READ cai,cao WRITE ica RANGE gcatbar, ica, gcat GLOBAL hinf,minf,mtau,htau } STATE { m h } ASSIGNED { ica (mA/cm2) gcat (mho/cm2) hinf htau minf mtau } INITIAL { rates(v) m = minf h = hinf } BREAKPOINT { SOLVE states METHOD cnexp gcat = gcatbar*m*m*h ica = gcat*ghk(v,cai,cao) } DERIVATIVE states { : exact when v held constant rates(v) m' = (minf - m)/mtau h' = (hinf - h)/htau } FUNCTION ghk(v(mV), ci(mM), co(mM)) (mV) { LOCAL nu,f f = KTF(celsius)/2 nu = v/f ghk=-f*(1. - (ci/co)*exp(nu))*efun(nu) } FUNCTION KTF(celsius (DegC)) (mV) { KTF = ((25./293.15)*(celsius + 273.15)) } FUNCTION efun(z) { if (fabs(z) < 1e-4) { efun = 1 - z/2 }else{ efun = z/(exp(z) - 1) } } FUNCTION alph(v(mV)) { alph = exp(0.0378*zetah*(v-vhalfh)) } FUNCTION beth(v(mV)) { beth = exp(0.0378*zetah*gmh*(v-vhalfh)) } FUNCTION alpmt(v(mV)) { alpmt = exp(0.0378*zetam*(v-vhalfm)) } FUNCTION betmt(v(mV)) { betmt = exp(0.0378*zetam*gmm*(v-vhalfm)) } PROCEDURE rates(v (mV)) { :callable from hoc LOCAL a,b, qt qt=q10^((celsius-25)/10) minf = (1/(1 + exp(-(v-vhm)/10))) mtau = betmt(v)/(qt*a0m*(1+alpmt(v))) if (mtau