Active sodium ion pumping in a membrane

[mms]

Hello

Assume I have a membrane of volume V, and potential Vm across it.Inside, there's some concentration of sodium Cna(in), chloride Ccl(in) and neutral macromolecule b (Cb).

Also, the sodium is being actively transported from the inside to the outside with Jna_a the active current density (constant). The outside has also some concentration of sodium Cna(out) and chloride Ccl(out). And lastly, the conductivity of the sodium is Gna and of chloride Gcl.

I am asked the following: Using the parameters above, what is the condition for electric neutrality, osmotic balance and equilibrium for each of the chloride and sodium ions?

I answered that following:

• For electric neutrality, simply that Cna(in)=Ccl(in) as well as Cna(out)=Ccl(out)

• For osmotic balance Cna(in)+Ccl(in)+Cm=Cna(out)+Ccl(out)

• For the equilibrium of chloride ions Vm=Vcl_Nernst

• For the equilibrium of sodium ions Vm=Vna_Nernst

There's more to this question but I want to understand first if I got this right.

But I'm quite unsure of the last two conditions for the ions. Feels that it's wrong.

Can anybody tell me if that's correct or not?

Thanks in advance.