: iC fast Ca2+/V-dependent K+ channel NEURON { SUFFIX sAHP USEION k READ ek WRITE ik USEION cas READ casi VALENCE 2 RANGE gk, i , ctau, cinf, gsAHPbar : ,ik } UNITS { (mM) = (milli/liter) (mA) = (milliamp) (mV) = (millivolt) } PARAMETER { gsAHPbar= 2.318144e-05 : 0.0001 (mho/cm2) : } ASSIGNED { v (mV) ek (mV) casi (mM) ik (mA/cm2) i (mA/cm2) cinf ctau (ms) gk (mho/cm2) } STATE { c } BREAKPOINT { SOLVE states METHOD cnexp gk = gsAHPbar*c ik = gk*(v-ek) i = ik } INITIAL { rate(v,casi) c = cinf } DERIVATIVE states { rate(v,casi) c' = (cinf-c)/ctau } UNITSOFF FUNCTION calf(v (mV), casi (mM)) (/ms) { LOCAL vs, va UNITSOFF vs=10*log10(1000*casi) calf = 0.0048/exp(-0.5*(vs-35)) UNITSON } FUNCTION cbet(v (mV), casi (mM))(/ms) { LOCAL vs, vb UNITSOFF vs=10*log10(1000*casi) cbet = 0.012/exp(0.2*(vs+100)) UNITSON } UNITSON PROCEDURE rate(v (mV), casi (mM)) {LOCAL csum, ca, cb UNITSOFF ca=calf(v, casi) cb=cbet(v, casi) csum = ca+cb if (v < -65 ) { ::::::::::::::::::::::::::: 67.5 cinf = 0 } else{ cinf = ca/csum } ctau = 48 UNITSON }