:Comment : LVA ca channel. Note: mtau is an approximation from the plots :Reference : : Avery and Johnston 1996, tau from Randall 1997 :Comment: shifted by -10 mv to correct for junction potential :Comment: corrected rates using q10 = 2.3, target temperature 34, orginal 21 NEURON { SUFFIX Ca_LVAst USEION ca READ eca, cai, cao WRITE ica RANGE gCa_LVAstbar, gCa_LVAst, ica GLOBAL use_ghk } UNITS { (S) = (siemens) (mV) = (millivolt) (mA) = (milliamp) } PARAMETER { gCa_LVAstbar = 0.00001 (S/cm2) use_ghk = 0 } ASSIGNED { v (mV) eca (mV) cai (mM) cao (mM) ica (mA/cm2) gCa_LVAst (S/cm2) mInf mTau hInf hTau } STATE { m h } UNITSOFF 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) } } UNITSON BREAKPOINT { SOLVE states METHOD cnexp gCa_LVAst = gCa_LVAstbar*m*m*h if (use_ghk == 0) { ica = gCa_LVAst*(v-eca) } if (use_ghk == 1) { ica = gCa_LVAst*(ghk(v,cai,cao)-106) } } DERIVATIVE states { rates() m' = (mInf-m)/mTau h' = (hInf-h)/hTau } INITIAL{ rates() m = mInf h = hInf } PROCEDURE rates(){ LOCAL qt qt = 2.3^((34-21)/10) UNITSOFF v = v + 10 mInf = 1.0000/(1+ exp((v - -30.000)/-6)) mTau = (5.0000 + 20.0000/(1+exp((v - -25.000)/5)))/qt hInf = 1.0000/(1+ exp((v - -80.000)/6.4)) hTau = (20.0000 + 50.0000/(1+exp((v - -40.000)/7)))/qt v = v - 10 UNITSON }