Table 4. Influence on the current, surface pH (pH_s) and internal pH (pH_i) in cells as a function of the type of transport mechanism^*.

Mechanism	Current	pHs	pHi
NH4+ uniport	yes	Increase	Decrease
NH3 uniport	No current	Decrease	Increase
Transport both	yes	Increase first then recovers if NH4+ flux is higher than NH3	Decrease first then recovers if NH4+ flux is higher than NH3
		Decrease first then recovers if NH3 flux in higher than NH4+	Increase first then recovers if NH3 flux in higher than NH4+

^*pH_s: pH at the external surface of the membrane. pH_i: pH inside the compartment