Rb influx stimulated by acid pH in SS and AA RBCs. Cells were suspended in media of various pH for Rb influx measurements. The pH at 37°C was measured at the end of each incubation. N = 2 for SS (♦) and 4 for AA (○) RBCs. (A) Total Rb influx. Fluxes in sulfamate media were less than 2 mmol/kg Hb/h in both AA and SS RBCs and were not subtracted from the total Rb influx because in some AA samples they exceeded fluxes in the presence of Cl. Total Rb influx, therefore, slightly overestimates KCC activity in AA RBCs but much less so in SS RBCs, in which the fluxes are much higher. Curves represent third-order best-fit polynomials. (B) Rb influx as a percentage of VSmax Rb influx measured for each sample in cells adjusted to MCHC lower than 270 g/L (27 g/dL). Curves were drawn by eye.
