Figure 1: Cl⁻/HCO₃⁻ exchange activity across control or stomatin-deficient RBC membranes estimated from pHi changes.

(a) Individual time-courses of fluorescence and pHi changes in ghosts prepared from RBCs of a control and an OHSt patient. Ghosts resealed in the presence of a pH-sensitive dye (pyranine) were submitted to 100 mEq outwardly-directed chloride and 50 mEq inwardly-directed bicarbonate gradients at 30 °C in the stopped-flow spectrofluorometer. As a specificity control, ghosts were incubated with 20 μM DIDS for 30 minutes prior to analysis. Data from three to four time-courses were averaged. Smooth lines are monoexponential fits to the data using the simplex procedure of the Biokine (Bio-Logic), providing alkalinization rate constants (k, s⁻¹). (b) At least three experiments for each patient (Stom-positive: four controls and one Rhnull (black bars), Stom-deficient: four OHSt and one 7.2(−)CHC patient (grey bars)) were averaged and can be compared. (c) Means of the alkalinization rate constants (k, s⁻¹) ± SEM for Stom-positive and Stom-deficient were reported. p value was determined using an unpaired Student t test.