TITLE potassium delayed rectifier Kv2.1 membrane channel for GPi neuron model COMMENT Potassium Kv2.1 membrane channel for GPi exhibiting *slow* deactivating components. Based on derived kinetics from Baranauskas 1999. Their primary experiments were performed at 35degC. Baranauskas 1999 -- Say in paper: Vh=-18mV, Vc=7mV Based on my own fitting of their data: Vh=-21.98mV, Vc=8.245mV Hernandez 1999 -- tau at -40mV is 28.80ms Scaled the Gillies2006 curve to match this point Disregard Q10 given the proximity of the experiments to 36degC ENDCOMMENT UNITS { (mV) = (millivolt) (mA) = (milliamp) } INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)} NEURON { SUFFIX KDRs USEION k READ ki,ek WRITE ik RANGE gk } PARAMETER { v (mV) dt (ms) gk = 0.0030 (mho/cm2) : Baranauskas 1999 ek ki celsius } STATE { pslowd pslowi } ASSIGNED { ik (mA/cm2) pinf_sd ptau_sd (ms) pinf_si ptau_si (ms) } BREAKPOINT { SOLVE states METHOD cnexp ik = (gk)*pslowd*pslowi*(v-ek) } UNITSOFF INITIAL { settables(v) pslowd = pinf_sd pslowi = pinf_si } DERIVATIVE states { settables(v) pslowd' = (pinf_sd-pslowd)/ptau_sd pslowi' = (pinf_si-pslowi)/ptau_si } PROCEDURE settables(v) { LOCAL rate_k TABLE pinf_sd, ptau_sd, pinf_si, ptau_si DEPEND celsius FROM -100 TO 100 WITH 400 rate_k = 4^((36-23)/10) pinf_sd = 1/(1+exp(-(v+21.98)/8.245)) : slow deactivating component (parameters from Baranauskus1999) :pinf_sd = 1/(1+exp((17.5-v)/10)) : slow deactivating component (from Mohapatra/Held modelDB) ptau_sd = rate_k*5/(exp((v+30)/14) + exp(-(v+30)/20)) + 5 : slow deactivating component (from Mohapatra/Held modelDB) pinf_si = 0.74/(1 + exp((v+25)/12)) + 0.26 : slow inactivating component (from Mohapatra/Held modelDB) ptau_si = rate_k*500/(exp((v-50)/20) + exp((50-v)/20))+800 : slow inactivating component (from Mohapatra/Held modelDB) } UNITSON