TITLE kc :Fast Ca-dependent K current NEURON { SUFFIX kc USEION k READ ek WRITE ik USEION ca READ cai RANGE gkc, ik, alpha, beta } UNITS { (molar) = (1/liter) (mV) = (millivolt) (mA) = (milliamp) (mM) = (millimolar) FARADAY = 96485.309 (coul/mole) PI = (pi) (1) } INDEPENDENT {t FROM 0 TO 1 WITH 100 (ms)} PARAMETER { gkc = 0.0 (mho/cm2) } ASSIGNED { ik (mA/cm2) alpha (/ms) beta (/ms) ek (mV) diam (um) v (mV) cai (mM) } STATE { m qk } BREAKPOINT { SOLVE states METHOD cnexp ik = gkc*min(cai/250(mM),1)*m*(v-ek) } INITIAL { settables(v) m = alpha/(alpha+beta) ik = gkc*min(cai/250(mM),1)*m*(v-ek) qk = 0 } DERIVATIVE states { settables(v) m' = alpha*(1-m)-beta*m qk' = (-ik*diam*PI*(1e4)/FARADAY)/(diam*diam*PI/4) } UNITSOFF PROCEDURE settables(v (mV)) { TABLE alpha, beta FROM -120 TO 40 WITH 641 if( v <= -10.0 ) { alpha = 1/18.975*(exp((v-10+60)/11-(v-6.5+60)/27)) beta = 2*exp((-v+6.5-60)/27) }else{ alpha = 2*exp((-v+6.5-60)/27) beta = 0 } } UNITSON FUNCTION min(x,y) { if (x<=y){ min = x }else{ min = y } }