Figure 3. Properties of the H⁺ short-circuit current (I_SC).

A, magnitude of I_SC is similar when the H⁺ gradient is imposed in different directions. B, net H⁺ flux (J), calculated from I_SC, is proportional to the H⁺ concentration difference (Δ[H⁺]). Lines were fitted by linear regression to the equation, J =P×Δ[H⁺]. The indicated estimates for the permeability P_H (× 10⁻⁶ cm s⁻¹) were derived from the slopes.