simbiology diffusion across membrane

Hi all,

I would like to simulate diffusion of compound A across a membrane. My idea is to use a first order mass-balance reaction. The transfer rate is known.This works, if the concentration of compound A is set to constant. However, I would like to dose that compound and attach decay reactions.

The volume of the 'extracellular' compartment is 10e12 times greater than the 'intracellular' compartment. So I expected the extracellular concentration to stay more or less constant. However, this is not the case, they meet in the middle. (More precisely, reaction: A_extra --> A_intra, with A_intra0 = 0, yields A_intra = A_extra/2)

Generally, I would like to know how to model the diffusion process across the membrane, taking into account large volume difference.

Any suggestions are greatly appreciated.

Cheers, Michael

[Gafooruddin Moulana Rasheed]

I have almost the same question