TITLE CaT channel alpha-1H from McRory et al, 2001 : Reversal potential described by Nernst equation : M.Migliore Jan 2003 UNITS { (mA) = (milliamp) (mV) = (millivolt) (molar) = (1/liter) (mM) = (millimolar) FARADAY = (faraday) (coulomb) R = (k-mole) (joule/degC) } PARAMETER { v (mV) celsius (degC) gbar=.008 (mho/cm2) vhalfn=-43.15 (mV) vhalfl=-73.9 (mV) kn=5.34 (1) kl=-2.76 (1) q10=2.3 cai = .00005 (mM) : initial [Ca]i = 50 nM cao = 2 (mM) : [Ca]o = 2 mM eca } NEURON { SUFFIX cat1h USEION ca READ eca WRITE ica RANGE gbar, carev GLOBAL ninf,linf,taul,taun, q10 } STATE { n l } ASSIGNED { ica (mA/cm2) : current carev (mV) : rev potential ninf linf taul taun } INITIAL { rates(v) n=ninf l=linf } BREAKPOINT { SOLVE states METHOD cnexp carev = (1e3) * (R*(celsius+273.15))/(2*FARADAY) * log (cao/cai) ica = gbar*n*l*(v-carev) } DERIVATIVE states { : exact when v held constant; integrates over dt step rates(v) n' = (ninf - n)/taun l' = (linf - l)/taul } PROCEDURE rates(v (mV)) { :callable from hoc LOCAL a,qt qt=q10^((celsius-22)/10) ninf = 1/(1 + exp(-(v-vhalfn)/kn)) linf = 1/(1 + exp(-(v-vhalfl)/kl)) taun = (0.774+0.14*exp(-v/13.27))/qt taul = (22.25+0.0455*exp(-v/7.46))/qt }