The effect of membrane depolarization on sorbitol transport via the NPP in P falciparum–infected RBCs. (A) Uptake of sorbitol into infected RBCs suspended in iso-osmotic NaCl (circles), sucrose (squares), and sorbitol (triangles) solutions in the absence (open symbols) and presence (closed symbols) of 0.2 mM NPPB. (B) Sorbitol influx (using a 60-second time point) via the NPP in infected RBCs (defined as the NPPB-sensitive influx) in iso-osmotic NaCl, sucrose, and sorbitol solutions. Data are corrected for 100% parasitemia. All values are calculated for an external sorbitol concentration of 1 mM for comparison with previous studies (assuming linear concentration dependence). Data represent averaged values derived from at least 3 separate experiments and are shown as the mean ± SEM.