TITLE Delayed rectifier K current, for axonal compartments COMMENT from Table 4 of "A branching dendritic model of a rodent CA3 pyramidal neurone." Traub RD et al. J Physiol. (1994) implemented by Nikita Vladimirov ENDCOMMENT NEURON { SUFFIX Kdrax USEION k READ ek WRITE ik RANGE gbar, g, i GLOBAL Vm } UNITS { (S) = (siemens) (mA) = (milliamp) (mV) = (millivolt) } PARAMETER { gbar = 0 (S/cm2) Vm = -65 (mV) : resting potential } ASSIGNED { v (mV) ek (mV) ik (mA/cm2) i (mA/cm2) g (S/cm2) ninf ntau (ms) } STATE { n } BREAKPOINT { SOLVE states METHOD cnexp g = gbar * n^4 i = g * (v - ek) ik = i } INITIAL { rates(v) n = ninf } DERIVATIVE states { rates(v) n' = (ninf-n)/ntau } PROCEDURE rates(v(mV)) { LOCAL alphan, betan, small TABLE ninf, ntau FROM -100 TO 50 WITH 200 UNITSOFF small = (17.2 - (v - Vm) )/5 if ( fabs(small) > 1e-6 ) { alphan = 0.03 * ( 17.2 - (v - Vm) ) / ( exp( (17.2 - (v - Vm) )/5 ) - 1) } else { alphan = 0.03 * 5 / ( 1 + small/2 ) } betan = 0.45 * exp( (12 - (v - Vm) ) / 40 ) ninf = alphan / (alphan + betan) ntau = 1 / (alphan + betan) UNITSON }