TABLE I.

Measured Intracellular pH, H⁺ Concentration, and Computed H⁺ Equilibrium Potential in HEPES and in CO₂/HCO₃ ⁻-buffered Saline at pH 7.4 and 7.9

I	SNAT3 + H2O	SNAT3 + CA	SNAT3 + H2O	SNAT3 + CA
In HEPES	pHo 7.4	pHo 7.4	pHo 7.9	pHo 7.9
pHi	7.34 ± 0.03	7.25 ± 0.03	7.16 ± 0.05	7.24 ± 0.03
	(n = 14)	(n = 13)	(n = 7)	(n = 9)
[H+]i (nM)	46	56	69	58
EH+ (mV)	−4	−9	−43	−39
II	SNAT3 + H2O	SNAT3 + CA	SNAT3 + H2O	SNAT3 + CA
In CO2/HCO3 −	pHo 7.4	pHo 7.4	pHo 7.9	pHo 7.9
pHi	6.81 ± 0.04	6.73 ± 0.04	6.90 ± 0.09	6.93 ± 0.07
	(n = 15)	(n = 10)	(n = 6)	(n = 9)
[H+]i (nM)	155	186	126	118
EH+ (mV)	−35	−39	−59	−57
III	SNAT3 + H2O	SNAT3 + CA	SNAT3 + CA	SNAT3 + CA
In CO2/HCO3 −	pHo 7.9	WT pHo 7.9	V143Y pHo 7.9	HEX pHo 7.9
pHi	6.83 ± 0.05	6.82 ± 0.05	6.79 ± 0.03	6.78 ± 0.08
	(n = 9)	(n = 13)	(n = 8)	(n = 6)
[H+]i (nM)	148	151	162	166
EH+ (mV)	−63	−63	−65	−66