This is the general mathematical model for the NHE3 model with modifications to enable simulations which are capable of reproducing Figure 4B in the original paper. The simulation experiment for this model can be obtained by loading the corresponding SED-ML document into OpenCOR and executing the simulation. The results of which are shown below. A rendering of the mathematical model itself is available here.

In Figure 4, the Na^{+} influx is computed as a function of external NH_{4}^{+} concentration at two different values of external pH. Internal and external Na^{+} concentrations are fixed at 0.0 and 0.1 mM; internal pH is 6.0; and external NH_{4}^{+} concentration is varied from 1.0 to 40.0 mM. In *Figure 4B* external pH is 7.5.

A screenshot illustrating the results when the associated SED-ML document is loaded into OpenCOR and the simulation executed.

This can be reproduced directly from the repository by choosing the **Launch with OpenCOR** link from the *Views Available*.