Thanks ted for the reply,
I have made a naacc.mod file (just changed the ion name and initial concentrations). This is the mod file and it is compiling correctly
Code: Select all
COMMENT
Na moves between intra- and extracellular volumes
and diffuses from extracellular volume into a sink of fixed volume.
Extracellular volume is a specified fraction rho of intracellular volume.
Sink Volume is a specified fraction rhosnk of intracellular volume
ENDCOMMENT
NEURON {
SUFFIX naacc
USEION na READ ina WRITE nao,nai
RANGE rho,rhosnk,nas,taus
}
UNITS {
(mV) = (millivolt)
(mA) = (milliamp)
FARADAY = (faraday) (coulombs)
(molar) = (1/liter)
(mM) = (millimolar)
}
PARAMETER {
nai0 = 15.7 (mM) : Initial na Conc within the section
nao0 = 116 (mM) : Initial na conc in Extracellular space
nas0 = 116 (mM) : Initial na conc in Sink
rhosnk = 1 (1) : Ratio of Sink Volume to section volume
rho = 0.2 (1) : Ratio of ECS volume to section volume
taus = 50 (ms) : tau for diffusion from ECS to Sink
}
ASSIGNED {
ina (mA/cm2)
diam (micron)
nax (mM)
nai (mM)
}
INITIAL {
nai = nai0
nao = nao0
nas = nas0
nax = nai + nao*rho + nas*rhosnk
}
STATE {
nao (mM)
nas (mM)
}
BREAKPOINT {
SOLVE state METHOD cnexp
}
DERIVATIVE state {
nao'=(1e4)*4*ina/(rho*diam*FARADAY)+(nas-nao)/taus
nas'= (nao-nas)/taus
nai= nax-nao*rho-nas*rhosnk
}
However, when i tried inserting the mechanism into a simple cell and simulated it for some time, there was a change in the nai and nao values even without inserting any action potential.
Is this what you meant when you said "if the membrane of your model cell has nonzero sodium conductance, and v-ena < 0, then there will be an influx of Na, and nai and nao will change. This will occur with the accumulation mechanism you were originally looking at, and with the mechanism that I suggested you construct by modifying kacc."
Here is the hoc code that i used for the above test
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load_file("nrngui.hoc")
objref stim,shape,naplot,voltplot
create soma
access soma
soma nseg = 1
soma diam = 18.8
soma L = 18.8
soma Ra = 123.0
soma insert hh
soma insert naacc
/*
objectvar stim
soma stim = new IClamp(0.5)
stim.del = 100
stim.dur = 100
stim.amp = 0.1
*/
tstop = 3000
steps_per_ms = 10
dt = 0.1
// SODIUM GRAPH
naplot=new Graph()
naplot.size(0,tstop,-0.0001,55)
naplot.xaxis() naplot.yaxis()
naplot.addvar("soma.nai(0.5)",2,0)
naplot.addvar("soma.nao(0.5)",3,0)
naplot.save_name("graphList.")
graphList.append(naplot)
// VOLTAGE GRAPH
voltplot=new Graph()
voltplot.size(0,tstop,-90,50)
voltplot.xaxis() voltplot.yaxis()
voltplot.addvar("soma.v(0.5)",1,0)
voltplot.addvar("soma.ena(0.5)",2,0)
voltplot.addvar("soma.ek(0.5)",3,0)
voltplot.save_name("graphList.")
graphList.append(voltplot)
nrncontrolmenu()
run()
Am now waiting for the pump mechanism and custom initializations that you have so kindly offered to provide.
As an aside, is it possible to insert images within the posts?
thanks a lot