TITLE Cardiac IKs current : Hodgkin - Huxley type K channel, from Courtemanche et al Am J Physiol 1998 275:H301 NEURON { SUFFIX IKs USEION k READ ek WRITE ik RANGE gKs, ik GLOBAL minf, mtau } UNITS { (mA) = (milliamp) (mV) = (millivolt) (mM) = (milli/liter) } PARAMETER { gKs=0.258e-3 (S/cm2) <0,1e9> } STATE { m } ASSIGNED { v (mV) celsius (degC) : 37 ik (mA/cm2) minf mtau (ms) ek (mV) } INITIAL { rate(v*1(/mV)) m = minf } BREAKPOINT { SOLVE states METHOD derivimplicit ik = gKs*m*m*(v - ek) } DERIVATIVE states { : rate(v*1(/mV)) m' = (minf - m)/mtau } UNITSOFF FUNCTION alp(v(mV)) { LOCAL q10 v = v q10 = 3^((celsius - 37)/10) alp = q10*4e-5*(v - 19.9)/(1 - exp(-(v - 19.9)/17)) } FUNCTION bet(v(mV)) { LOCAL q10 v = v q10 = 3^((celsius - 37)/10) bet = q10*3.5e-5*(v - 19.9)/( exp((v - 19.9)/9) - 1) } FUNCTION ce(v(mV)) { v = v ce = 1/(1 + exp(-(v - 19.9)/12.7))^0.5 } PROCEDURE rate(v) {LOCAL a,b,c : TABLE minf, mtau DEPEND celsius FROM -100 TO 100 WITH 200 a = alp(v) b = bet(v) c = ce(v) mtau = 0.5/(a + b) minf = c } UNITSON