$\mathrm{epsilon}=e^{\frac{F\mathrm{u\_e\_m}}{\mathrm{RT}}}$ $\mathrm{Q\_HCO3\_o}=\mathrm{K\_HCO3\_o}\mathrm{q\_HCO3\_o}\mathrm{Q\_HCO3\_i}=\mathrm{K\_HCO3\_i}\mathrm{q\_HCO3\_i}$ $\frac{d \mathrm{q\_HCO3\_i}}{d t}=0.5$ $\mathrm{v\_HCO3\_m}=\mathrm{kappa\_HCO3\_m}(\mathrm{Q\_HCO3\_o}\mathrm{epsilon}-\mathrm{Q\_HCO3\_i})$