: sodium-potassium ATPase adapted from Randall Rasmusson 2004
NEURON {
SUFFIX nakpump
USEION na READ nai, nao WRITE ina
USEION k READ ko WRITE ik
RANGE Imax, Km_nai, Km_ko
RANGE inak, fnak
}
UNITS {
(molar) = (1/liter)
(mM) = (millimolar)
(mA) = (milliamp)
(mV) = (millivolts)
}
PARAMETER {
Imax = .0667 (mA/cm2) <0, 1e6>: BR model trsducer zone 0.2 mA/cm2
Km_nai = 21 (mM) <0, 1e6>
Km_ko = 1.5 (mM) <0, 1e6>
Q10=1.16 (1)
Q10TEMP = 24 (degC)
RdivF = 0.0861728 (mV/degC)
}
ASSIGNED {
ko (mM)
nai (mM)
nao (mM)
v (mV)
celsius (degC)
qt (1)
fnak (1)
inak (mA/cm2)
ik (mA/cm2)
ina (mA/cm2)
}
BREAKPOINT {
inak = finak(v)
ina = 3.0*inak
ik = -2.0*inak
}
INITIAL {
qt = Q10^((celsius-Q10TEMP)/10)
}
FUNCTION finak(Vm (mV)) (mA/cm2) {
LOCAL delta1, x1
UNITSOFF
x1 = Vm/(RdivF*(273.15+celsius))
delta1 = (exp(nao/67.3)-1.0)/7.0
fnak = 1.0/(1.0+0.1245*exp(-0.1*x1)+0.0365*delta1*exp(-1.0*x1))
finak = Imax * fnak *(1.0/(1+(Km_nai/nai)^4))*ko/(ko+Km_ko)*qt
UNITSON
}