TITLE Borg-Graham type generic K-A channel UNITS { (mA) = (milliamp) (mV) = (millivolt) } PARAMETER { v (mV) ek (mV) celsius (degC) gkabar=.01 (mho/cm2) vhalfn=-33.6 (mV) vhalfl=-83 (mV) a0l=0.08 (/ms) a0n=0.02 (/ms) zetan=-3 (1) zetal=4 (1) gmn=0.6 (1) gml=1 (1) } NEURON { SUFFIX borgka USEION k READ ek WRITE ik RANGE gkabar,gka, ik GLOBAL ninf,linf,taul,taun } STATE { n l } INITIAL { rates(v) n=ninf l=linf } ASSIGNED { ik (mA/cm2) ninf linf taul taun gka } BREAKPOINT { SOLVE states METHOD cnexp gka = gkabar*n*l ik = gka*(v-ek) } FUNCTION alpn(v(mV)) { alpn = exp(1.e-3*zetan*(v-vhalfn)*9.648e4/(8.315*(273.16+celsius))) } FUNCTION betn(v(mV)) { betn = exp(1.e-3*zetan*gmn*(v-vhalfn)*9.648e4/(8.315*(273.16+celsius))) } FUNCTION alpl(v(mV)) { alpl = exp(1.e-3*zetal*(v-vhalfl)*9.648e4/(8.315*(273.16+celsius))) } FUNCTION betl(v(mV)) { betl = exp(1.e-3*zetal*gml*(v-vhalfl)*9.648e4/(8.315*(273.16+celsius))) } DERIVATIVE states { rates(v) n' = (ninf - n)/taun l' = (linf - l)/taul } PROCEDURE rates(v (mV)) { :callable from hoc LOCAL a,q10 q10=3^((celsius-30)/10) a = alpn(v) ninf = 1/(1 + a) taun = betn(v)/(q10*a0n*(1+a)) a = alpl(v) linf = 1/(1+ a) taul = betl(v)/(q10*a0l*(1 + a)) }