Fig. 1. Time course of SO₄⁼ uptake in human erythrocytes with or without 10 mM Mg²⁺ or treated with 10 μM DIDS. Points represent the mean ± SD from at least 5 separate experiments (see Table 1), where **p<0.01 and ***p<0.001 versus Mg²⁺-treated erythrocytes.