TITLE Medium duration Ca-dependent potassium current : : Ca++ dependent K+ current IC responsible for medium duration AHP : : Original file written by Alain Destexhe, Salk Institute, Nov 3, 1992 : Modified by Geir Halnes, Norwegian University of Life Sciences, Mar 13, 2011 INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)} NEURON { THREADSAFE SUFFIX iahp USEION k READ ek WRITE ik VALENCE 1 USEION Ca READ Cai VALENCE 2 RANGE gkbar, g, minf, taum GLOBAL beta, cac, m_inf, tau_m, x } UNITS { (mA) = (milliamp) (mV) = (millivolt) (molar) = (1/liter) (mM) = (millimolar) } PARAMETER { v (mV) ek = -90 (mV) celsius = 36 (degC) Cai = 5e-5 (mM) : Initial [Ca]i = 50 nM (Cai is simulated by separate mod-file) gkbar = 1.3e-4 (mho/cm2) : Conductance (modified from hoc-file) beta = 0.02 (1/ms) : Backward rate constant cac = 4.3478e-4(mM) : Middle point of m_inf fcn taumin = 1 (ms) : Minimal value of the time cst x = 2 : Binding cites } STATE { m } ASSIGNED { ik (mA/cm2) g (mho/cm2) m_inf tau_m (ms) minf taum tadj } BREAKPOINT { SOLVE states METHOD cnexp minf = m_inf taum = tau_m g = gkbar*m*m ik = g * (v - ek) } DERIVATIVE states { evaluate_fct(v,Cai) m' = (m_inf - m) / tau_m } UNITSOFF INITIAL { : activation kinetics are assumed to be at 22 deg. C : Q10 is assumed to be 3 VERBATIM Cai = _ion_Cai; ENDVERBATIM tadj = 3 ^ ((celsius-22.0)/10) evaluate_fct(v,Cai) m = m_inf minf = m_inf taum = tau_m } PROCEDURE evaluate_fct(v(mV),Cai(mM)) { LOCAL car, tcar car = (Cai/cac)^x m_inf = car / ( 1 + car ) tau_m = 1 / beta / (1 + car) / tadj if(tau_m < taumin) { tau_m = taumin } : min value of time cst } UNITSON