Figure 4.

Effect of TEA on the apparent K⁺ _o affinity for activation of Na,K pump current. Na,K pump current was measured in the presence of 0 (•), 5 (○), and 25 mM TEA (▾) and K _0.5 values were calculated at each V _M as described in the text. Curves are functions determined by simultaneously fitting all the data to Eq. 2 with γ_K fixed at a value of 0.55. The resulting parameter values for K ⁰ _0.5, K ⁰ _Q, γ_Q, λ_K, and λ_Q are listed in the text.