$1E310^{-\mathrm{pH\_ext}}$ $2$ $\frac{\mathrm{XTxP0\_NHE3\_Na}\times 2\mathrm{C\_int\_H}}{\mathrm{C\_int\_H}+1E-6}$ $\frac{\mathrm{XTxP0\_NHE3\_H}\times 2\mathrm{C\_int\_H}}{\mathrm{C\_int\_H}+1E-6}$ $\frac{\mathrm{XTxP0\_NHE3\_NH4}\times 2\mathrm{C\_int\_H}}{\mathrm{C\_int\_H}+1E-6}$ $\frac{\mathrm{C\_ext\_Na}}{\mathrm{K\_NHE3\_Na}}$ $\frac{\mathrm{C\_ext\_H}}{\mathrm{K\_NHE3\_H}}$ $\frac{\mathrm{C\_ext\_NH4}}{\mathrm{K\_NHE3\_NH4}}$ $\frac{\mathrm{C\_int\_Na}}{\mathrm{K\_NHE3\_Na}}$ $\frac{\mathrm{C\_int\_H}}{\mathrm{K\_NHE3\_H}}$ $\frac{\mathrm{C\_int\_NH4}}{\mathrm{K\_NHE3\_NH4}}$ $(1+\mathrm{alpha\_ext\_Na}+\mathrm{beta\_ext\_H}+\mathrm{gamma\_ext\_NH4})(\mathrm{XTxP\_NHE\_Na}\mathrm{alpha\_int\_Na}+\mathrm{XTxP\_NHE\_H}\mathrm{beta\_int\_H}+\mathrm{XTxP\_NHE\_NH4}\mathrm{gamma\_int\_NH4})+(1+\mathrm{alpha\_int\_Na}+\mathrm{beta\_int\_H}+\mathrm{gamma\_int\_NH4})(\mathrm{XTxP\_NHE\_Na}\mathrm{alpha\_ext\_Na}+\mathrm{XTxP\_NHE\_H}\mathrm{beta\_ext\_H}+\mathrm{XTxP\_NHE\_NH4}\mathrm{gamma\_ext\_NH4})$ $\frac{\mathrm{XTxP\_NHE\_Na}\mathrm{XTxP\_NHE\_H}}{\mathrm{sum\_NHE3}}(\mathrm{alpha\_ext\_Na}\mathrm{beta\_int\_H}-\mathrm{alpha\_int\_Na}\mathrm{beta\_ext\_H})+\frac{\mathrm{XTxP\_NHE\_Na}\mathrm{XTxP\_NHE\_NH4}}{\mathrm{sum\_NHE3}}(\mathrm{alpha\_ext\_Na}\mathrm{gamma\_int\_NH4}-\mathrm{alpha\_int\_Na}\mathrm{gamma\_ext\_NH4})$ $\frac{\mathrm{XTxP\_NHE\_Na}\mathrm{XTxP\_NHE\_H}}{\mathrm{sum\_NHE3}}(\mathrm{alpha\_int\_Na}\mathrm{beta\_ext\_H}-\mathrm{alpha\_ext\_Na}\mathrm{beta\_int\_H})+\frac{\mathrm{XTxP\_NHE\_H}\mathrm{XTxP\_NHE\_NH4}}{\mathrm{sum\_NHE3}}(\mathrm{beta\_ext\_H}\mathrm{gamma\_int\_NH4}-\mathrm{beta\_int\_H}\mathrm{gamma\_ext\_NH4})$ $\frac{\mathrm{XTxP\_NHE\_Na}\mathrm{XTxP\_NHE\_NH4}}{\mathrm{sum\_NHE3}}(\mathrm{alpha\_int\_Na}\mathrm{gamma\_ext\_NH4}-\mathrm{alpha\_ext\_Na}\mathrm{gamma\_int\_NH4})+\frac{\mathrm{XTxP\_NHE\_H}\mathrm{XTxP\_NHE\_NH4}}{\mathrm{sum\_NHE3}}(\mathrm{gamma\_ext\_NH4}\mathrm{beta\_int\_H}-\mathrm{beta\_ext\_H}\mathrm{gamma\_int\_NH4})$ $\frac{\mathrm{XTxP\_NHE\_Na}\mathrm{XTxP\_NHE\_H}}{\mathrm{XTxP\_NHE\_Na}+\mathrm{XTxP\_NHE\_H}}$ $\frac{1}{\mathrm{plot\_a}}$ $\frac{\mathrm{J\_NHE3\_Na}}{\mathrm{J\_NHE3\_Na\_Max}}$ $\frac{(1+\mathrm{alpha\_ext\_Na})\mathrm{beta\_int\_H}+\frac{(1+\mathrm{beta\_int\_H})\mathrm{alpha\_ext\_Na}\mathrm{XTxP\_NHE\_Na}}{\mathrm{XTxP\_NHE\_H}}}{1+2\mathrm{beta\_int\_H}}$