Fig. 5.

Steady-state Ba²⁺ sensitivity of Kir2.1/Kir2.2 channels. a A representative outside-out recording for Kir2.1 monomeric channels (macroscopic currents) at a holding potential of −50 mV. Concentrations of 0, 0.25, 1, 5, 10, and 100 μM Ba²⁺ are indicated. The dashed line represents the zero current level. b Ba²⁺ dose–response relationships. The data were fit with the Hill equation and the corresponding fits are plotted using smooth lines. c Kd values for Ba²⁺ block at -50 mV for each construct. c Insert, averaged K_d values for channels with the same stoichiometries: 1, Kir2.1 Mono/1-1-1-1; 2, 2-1-1-1/1-1-1-2/1-2-1-1; 3, 1-1-2-2/1-2-1-2; 4, 1-2-2-2; and 5, Kir2.2 Mono/2-2-2-2