The effect of media osmolarity on the Na/Mg exchanger activity. Mg²⁺-loaded cells from normal (Hb AA; ○) and sickle (Hb SS; •) erythrocytes were incubated in various media with osmolarities ranging between 210 and 590 mOsm as described in “Patients, materials, and methods.” The values represent the mean ± SE of 3 experiments in triplicate determinations. ^*P < .045, n = 3 when compared with the exchanger activity at 300 mOsm.