Effect of DTT on KCC activation by acid pH in SS RBCs. (A) Rb influx activated by pH in SS RBCs with (•) and without (♦) preincubation with DTT. Fluxes are normalized to the Rb influx measured in cells from the same sample adjusted to MCHC lower than 270 g/L (27g/dL). Data from 2 independent experiments with separate donors. Curve is the best-fit third-order polynomial. (B) Regulatory volume decrease upon incubation at pH 7.0 in SS reticulocytes with initial MCHC of 300 g/L (30 g/dL); data from 3 separate donors independent of experiments in panel A. Error bars indicate standard deviation.