Table 1.

Maximum pH_L attainable as a function of intracellular pH using an apical electrogenic NBC coupled to a NHA

pHi	Maximum pHL attainable
7.0	9.02
7.5	9.52
8.0	10.02
8.5	10.52
9.0	11.02

The maximum pH_L attainable refers to the pH in the lumen that could still theoretically allow an electrogenic Na⁺/H⁺ antiporter (NHA) to function in bringing H⁺ into the cell from the lumen. These calculated values assume [Na⁺]_i=10 mmol l^–1, luminal [Na⁺]=100 mmol l^–1, and V_api=–90 mV. NBC, Na⁺/HCO₃^– co-transporter