TITLE NaKPump adapted from Kyoto's model COMMENT Author: Fabio M Simoes de Souza The equations that simulated the Na+/K+ ATPase are described in Table S10 of Takeuchi et al. (2006) Reference: Takeuchi A, Tatsumi S, Sarai N, Terashima K, Matsuoka S, Noma A (2006) Ionic mechanisms of cardiac cell swelling induced by blocking Na+/K+ pump as revealed by experiments and simulation. J. G. Physiol. 128: 495-507. ENDCOMMENT :********************************************/ UNITS { (mV) = (millivolt) (mA) = (milliamp) (molar) = (1/liter) (mM) = (millimolar) } NEURON { SUFFIX nakpump USEION na READ nai, nao WRITE ina USEION k READ ki,ko WRITE ik RANGE imax, nai, ki RANGE y,inak } PARAMETER { celsius (degC) inakmax=1 (mA/cm2) R=8.314472 (j/(K.molar) F=96.4853 (C/mol) nao=145 (mM) ko=5 (mM) Nai_inf=5 (mM) Ki_inf=14 (mM) ouabain=0 (mM) KdNao=69.8 KdKo=0.258 KdNai=4.05 KdKi=32.88 ATPi=6.97 (mM) k2=0.04 k3=0.01 k4=0.165 y0=0 } ASSIGNED { v (mV) inak (mA/cm2) ina (mA/cm2) ik (mA/cm2) nai (mM) ki (mM) pE1Na pE1K pE2Na pE2K alfay betay Naeff (mM) k1 drugblock kelvin (degK) } STATE { y } BREAKPOINT { SOLVE states METHOD cnexp settables(nai, ki, v, celsius, ATPi,ouabain) inak=inakmax*0.001*11.5*(k1*pE1Na*y-k2*pE2Na*(1-y))*drugblock ina=3*inak ik=-2*inak } INITIAL { settables(Nai_inf, Ki_inf, v, celsius, ATPi,ouabain) y=.6224 } DERIVATIVE states { settables(nai,ki,v, celsius, ATPi,ouabain) y'=alfay*(1-y)-betay*y } UNITSOFF PROCEDURE settables(nai, ki, v, celsius, ATPi, ouabain) { drugblock=1/(1+ouabain/0.0006) k1=0.37*(1/(1+0.094/ATPi)) kelvin=celsius+273.16 Naeff=nao*exp(-0.82*F*v/R/kelvin) alfay=k2*pE2Na+k4*pE2K betay=k1*pE1Na+k3*pE1K pE1Na=1/(1+(KdNai/nai)^1.06*(1+(ki/KdKi)^1.12)) pE1K=1/(1+(KdKi/ki)^1.12*(1+(nai/KdNai)^1.06)) pE2Na=1/(1+(KdNao/Naeff)^1.06*(1+(ko/KdKo)^1.12)) pE2K=1/(1+(KdKo/ko)^1.12*(1+(Naeff/KdNao)^1.06)) } UNITSON