Figure 7.

Simulations of expected dependence of Na⁺,K⁺-pump current, I_p, per pump molecule on the extracellular Na⁺ concentration based on the Albers-Post model (dotted line, K_Ko = 1.8 mM, K_No = 180 mM, and K_N1o = 40 mM) and an expanded Albers-Post model incorporating extracellular allosteric Na⁺ binding (dashed line, K_Ko = 1.8, K_No = 180 mM, and K_N1o = 40 mM). (Solid line) Simulation based on the same model incorporating allosteric Na⁺ binding, but with reduced dissociation constants for extracellular Na⁺ interaction with the transport sites (K_Ko = 1.8 mM, K_No = 68 mM, and K_N1o = 15 mM). The experimental conditions used for the simulations were identical to those of the actual experiments (see legend for Fig. 3).