Table 1.

Experimental conditions for isolated rat kidney and rat liver mitochondrial experiments

State variables	Rat kidney		Rat liver
	External	Matrix	External	Matrix
[ATP]	1 mM	3.4 mM	1 mM	8.4 mM
[ADP]	0 mM	—	0 mM	1.66 mM
[AMP]	0 mM	—	0 mM	2.5 mM
[Pi]	2 mM	Calculated using Eq. 15	2 mM	Calculated using Eq. 15
[Mg2+]	5 mM (total)	0.5 mM (free)	5 mM (total)	0.5 mM (free)
[Ca2+]	5 μM (free)	250 nM (free)	5 μM (free)	250 nM (free)
[K+]	10 mM (total)	130 mM (free)	10 mM (total)	130 mM (free)
Water volume	—	—	4 mL	0.77 μL/mg protein∗

ΔpH as a function of external [Pi]
[Pi]e→	0 mM	0.5 mM	1 mM	2 mM	4 mM	10 mM
Model†	0.51	0.45	0.39	0.31	0.21	0.12
Data‡	0.81 ± 0.1	0.66 ± 0.03	0.52 ± 0.09	0.43 ± 0.07	0.22 ± 0.11	0.12 ± 0.06

See Hagen et al. (3) and Austin and Aprille (6,20). Note also that external pH was fixed at 7.4 in these experiments.

^∗Final concentration of mitochondria was 1 mg/mL of reaction water volume (20).

^†ΔpH values calculated using Eq. 14 with pH₀ = 0.51, pH_∞ = 0.11, and k_Pi = 0.34 mM⁻¹.

^‡ΔpH values reported in Klingenberg and Rottenberg (24).