Representative recordings of whole-cell current measurements in HbS cells before and at least 3 minutes after Gd³⁺ addition (50 μM). (A,C,E) Oxygenated HbS cells. (B,D,F) Deoxygenated HbS cells. Data in panels A and B are from before Gd³⁺ addition; data in panels C and D are from at least 3 minutes after Gd³⁺ addition. All measurements were made using Na⁺-containing bath and pipette solutions. Corresponding averaged data are presented in panels E and F as means ± SEM, n = 5 (HbS oxygenated) and n = 5 (HbS deoxygenated). (G) The effect of Gd³⁺ on whole-cell conductance of deoxygenated HbS cells; dose-response curve. Relative conductance was determined at −10mV in the absence of Gd³⁺. Serial additions of Gd³⁺ were then made to the bath solution and, after each addition, a new stable value for whole-cell conductance was obtained. Data are presented as means ± SEM, n ≥ 2-5 for each concentration.