Figure 4.

Block of monovalent and divalent currents by Cd²⁺. Data points from Ellinor et al. (1995) are normalized inward whole cell currents carried by Li⁺ or Ba²⁺ at the indicated extracellular [Cd²⁺]. [Ba²⁺]_out = 40 mM; [Li⁺]_out = [Li⁺]_in = 100 mM. V_m = −20 mV for data and calculations. Calculated Ba²⁺ and Li⁺ currents normalized to their values at 10⁻¹⁰ and 10⁻¹² M Cd²⁺, respectively. (inset) Energy profile for Cd²⁺ (5 kT per tick). Cd²⁺ energies are the same as for Ca²⁺ in Fig. 2, except the central well, which was set at −24 kT (absolute K _d = 40 pM) to give a good fit to the data. Ba²⁺ energies same as in Fig. 2. Li⁺ energies: outer barriers, 9; inner barriers, 7; wells, −5.